Sports Biomechanics and Kinesiology

Sports Biomechanics and Kinesiology
by Sushil Kalta, PhD

UNIT – I: INTRODUCTION TO BIOMECHANICS
Meaning of Biomechanics and its importance in Physical Education and Sports Biomechanical Principles of Movements Analysis of fundamental Movements: Walking, Running, throwing, Lifting, Pulling, Catching and Climbing. Fluids Mechanics: Static and Dynamic Projectile Motion

Meaning of Biomechanics and its importance in Physical Education and Sports
Meaning of Biomechanics: Biomechanics is not kinesiology (which is often another name for physical education). There are numerous titles of books that are confusing, especially since the titles suggest more than the definition of biomechanics that was stated earlier. Examples include, but are limited to, Fundamentals of Sports Biomechanics, The Mechanics of Athletics, Scientific Principles of Coaching,

Biomechanics Analysis of Sport, Biomechanics of Sports Techniques, Biomechanics of Human Motion, and Mechanical Kinesiology. All movements of organisms are governed by the laws of mechanics Every movement is mechanical in nature involving locomotion(movement) of the body mass in space and time Movements of living beings are governed by mechanical laws but are also subjected to biological laws Biomechanics studies the mechanical movements of living beings from the mechanical point, keeping in view the biological constraints under which these movements takes place

The mechanical laws are applied considering the mechanical capacities of the locomotor apparatus of the organism, which functionally depends upon the biological conditions of the organism External environmental conditions are also considered Thus the biomechanics is applied form of mechanics, applicable to the motion of living bodies Athletic performances are approaching the physiological limits Thus it has become important how mechanical energy can be best applied to achieve the goal, analyze the existing techniques and, if needed, refine them to make maximum use of mechanical energy Importance/Role of Biomechanics in Physical Education and Sports Commonness in between i.e. movement Evaluation of existing techniques for learning and training processes

To find out faults in the execution of the movements by an athlete
To find out the cause of faults exhibited during the execution of skills/movements Development of new technique that are more efficient than the existing technique Quantification of various motor abilities Analysis of training exercises and equipments :and to assist in the development of training exercises and equipments Perfection and refinement of various investigational procedures : and to make these applicable under field conditions Development of biomechanical principles as general orientation

Biomechanical Principles of Movements
It is important to develop the ability to observe human movement in a sports context in a systematic way and understand that there are different phases within any given movement. Within each phase of a specific movement there are key components of the movement and specific biomechanical principles that apply. Athletes at all levels will benefit from the ability of the professionals in physical education and sports to analyse movement appropriately. Biomechanical Principles: The lower the center of gravity, the larger the base of support, the closer the line of gravity to the center of the base of support, and the greater the mass, the STABILITY increases.

The production of maximum force requires the use of all the joints that can be used.
The production of maximum velocity requires the use of joints in order –from the largest to the smallest The greater the applied impulse, the greater the increase in velocity Movement usually occurs in the direction opposite that of the applied force. Angular motion is produced by the application of a force acting at some distance from an axis, i.e., by Torque Angular momentum is constant when an athlete or object is free in the air Apply forces in the direction you want an object to travel

Analysis of fundamental Movements: Walking, Running, throwing, Lifting, Pulling, Catching and Climbing. Equilibrium Newton’s Laws of Motion Levers Center of gravity Forces (centripetal and centrifugal)

Fluids Mechanics: Static and Dynamic
Fluid: Having particles which easily move and change their relative position without a separation of the mass, and which easily yield to pressure; capable of flowing; liquid or gaseous. Mechanics: The branch of physics that is concerned with the analysis of the action of forces on matter or material systems Fluid Mechanics: is the branch of physics that studies fluids (liquids, gases, and plasmas) and the forces on them. Fluid Statics and Fluid Dynamics form the two constituents of Fluid Mechanics. Fluid mechanics can be divided into fluid statics, the study of fluids at rest; fluid kinematics, the study of fluids in motion; and fluid dynamics, the study of the effect of forces on fluid motion. It is a branch of continuum mechanics, a subject which models matter without using the information that it is made out of atoms, that is, it models matter from a macroscopic viewpoint rather than from a microscopic viewpoint. Fluid mechanics, especially fluid dynamics, is an active field of research with many unsolved or partly solved problems.

Fluid mechanics can be mathematically complex, and can best be solved by numerical methods, typically using computers. A modern discipline, called computational fluid dynamics (CFD), is devoted to this approach to solving fluid mechanics problems. Particle image velocimetry, an experimental method for visualizing and analyzing fluid flow, also takes advantage of the highly visual nature of fluid flow The two fluids that we encounter in our movement activities are air and water. Air a gaseous fluid and a water a liquid fluid behave according to the same mechanical principles The term fluid resistance is commonly used to mean the type of force, this is known technically as drag force. In air it is called aerodynamics drag force and in water it is called hydrodynamics drag force the study of the properties of moving air, and especially of the interaction between the air and solid bodies moving through it(aerodynamics).

The dynamics of fluids in water.(hydrodynamics)
The environment encountered may be the air as in javelin, discus, badminton, and volleyball etc. or combination of air and water as in swimming, rowing, yachting etc In certain events the effect of environment may be very small as in putting the shot, while in other sports activities the effect may be very large, as in discus, javelin However, the resistance air and water impedes (obstruct) the movement yet in the absence of these forces the locomotion of the body will not occur e.g. water resistance required by the swimmer in order to push his body. Similarly, a discus gets lift from the air and thus goes further Wind tunnel measure the force of air

The component of the force acting at right angle to the drag component is called lift
The resultant of the two components is the effect that air resistance ultimately has on body or on an object in the flight Thus, air resistance tends to oppose the forward motion of the body in flight and provides lift Dynamic fluid mechanics: In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids (liquids and gases). It has several subdisciplines, including aerodynamics (the study of air and other gases in motion) and hydrodynamics (the study of liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space and modelling fission weapon detonation.

Fluid Resistance: when a body or object moves in the air it exerts the force on air and in turn air exerts equal and opposite force on the body(Newton’s III law) Three major fluid forces of interest: Drag, Lift and Buoyancy The component of force exerted by the air on the body in flight which acts in the direction of the airflow, is called drag Surface Drag/Skin Friction:The reaction of the force exerted by the body on the air is called surface drag or skin friction or surface friction, it is caused by viscous drag in the boundary layer around the object. The boundary layer at the front of the object is usually laminar and relatively thin, but becomes turbulent and thicker towards the rear. The position of the transition point depends on the shape of the object. There are two ways to decrease friction drag: the first is to shape the moving body so that laminar flow is possible, like an airfoil. The second method is to decrease the length and cross-section of the moving object as much as is practicable. To do so, a designer can consider the fineness ratio, which is the length of the aircraft divided by its diameter at the widest point (L/D).

The magnitude of the surface drag depends on the following factors:
Velocity: surface drag is directly proportional to the flow of wind Surface Area: the larger the surface area of the body higher will be the surface drag Density: higher the density or viscosity of a fluid the more will be drag for example drag on the ball will be more in water than in air Smoothness of the Surface: surface drag is inversely proportional to the smoothness of the surface. The rougher the texture of the surface of the body the higher will be the surface drag Form Drag: when air drives pass or is forced to either side of a fast moving body, a part of the air that strikes the frontal surface of the body is diverted outward

This air breaks away from the body and loose contact with it but after travelling a certain distance it reunites with the main stream of the air by force exerted by the neighboring layers of the air Thus, an air pocket or low-pressure zone is formed behind the body where the air reunites The air acts on the body and results in high-pressure zone on the frontal surface and low-pressure zone acting on the rear surface The resultant of the two forces acting on the body, because of the pressure difference is called form drag This drag comes into existence because of the pressure difference on two sides of the body therefore it is also termed as pressure drag The form drag depends upon the following factors Cross Sectional Area: the area exposed or perpendicular to the approaching air flow which is also called profile is cross section area

If the body is exposed more to the air flow form drag will be higher
If the body is placed in three different positions i.e. parallel, perpendicular or incline to the flow the object will have a difference in the magnitude of the drag Shape of the Body: the shape of the body determines how smoothly a body can pass the air flow In the case of an object that is streamlined, the low-pressure zone is small since air just passes the tapering end with minimal disruption of the layers of air and the form drag is less This is the reason why the javelins and arrows are made streamlined Smoothness of the Surface: directly proportional to the smoothness of the body Wave Drag: it is applicable in aquatic sports and comes into existence at the interface of two fluids e.g. water and air in swimming.

For example, when the swimmer moves near to the surface of the water there is formation of waves
These waves are formed against the leading surface of the body or the body parts Force is applied by the body parts to form these waves and therefore there is a reaction force of the waves on the body With the increase of the speed of the swimmer and by the up and down movements of the body parts, the reaction force also increases As this drag comes into existence at the interface of two fluids it is important only in activities such as swimming, rowing, yachting etc. Total Drag: the sum of all three drags i.e. surface drag, form drag, and wave drag acting on a body, when in motion in a fluid

Lift: The lift force acts in a direction that is perpendicular to the relative flow
Represents a net force(A net force is the sum of all forces acting on an object. A net force is capable of accelerating a mass. For instance, if the wheels of a car push it forward with 5 Newtons and drag is 3 Newtons , the net force is 2 Newtons , forward. Motion to the right is positive.) that acts perpendicular to the direction of the relative motion of the fluid; The lift force is not necessarily vertical Created by different pressures on opposite sides of an object due to fluid flow past the object example: Airplane wing (hydrofoil) Bernoulli’s principle: velocity is inversely proportional to pressure. Fast relative velocity lower pressure Slow relative velocity higher pressure

The Magnus effect describes the curved path that is observed by spinning projectiles. Explained by Bernoulli’s principle and the pressure differences caused by relative differences in flow velocities. Static fluid mechanics: Fluid Statics deals with fluids at rest while Fluid Dynamics studies fluids in motion. In this chapter we discuss Fluid Statics. A fluid at rest has no shear stress (A shear stress, often denoted τ (Greek: tau), is the component of stress (The stress applied to a material is the force per unit area applied to the material. The maximum stress a material can stand before it breaks is called the breaking stress or ultimate tensile stress. Tensile means the material is under tension. The forces acting on it are trying to stretch the material, In continuum mechanics, stress is a physical quantity that expresses the internal forces that neighbouring particles of a continuous material exert on each other, while strain is the measure of the deformation of the material) coplanar with a material cross section. Shear stress arises from the force vector component parallel to the cross section). Consequently, any force developed is only due to normal stresses (Normal stress on the other hand, arises from the force vector component perpendicular to the material cross section on which it acts) .i.e, pressure. Such a condition is termed the hydrostatic condition. In fact, the analysis of hydrostatic systems is greatly simplified when compared to that for fluids in motion.

Though fluid in motion gives rise to many interesting phenomena, fluid at rest is by no means less important. Its importance becomes apparent when we note that the atmosphere around us can be considered to be at rest and so are the oceans. The simple theory developed here finds its application in determining pressures at different levels of atmosphere and in many pressure-measuring devices. Further, the theory is employed to calculate force on submerged objects such as ships, parts of ships and submarines. The other application of the theory is in the calculation of forces on dams and other hydraulic systems.

Buoyancy: Associated with how well a body floats or how high it sits in the fluid.
Archimede’s principle: any body in a fluid medium will experience a buoyant force equal to the weight of the volume of fluid which is displaced. Example: a boat on a lake. A portion of the boat is submerged and displaces a given volume of water. The weight of this displaced water equals the magnitude of the buoyant force acting on the boat. The boat will float if its weight in air is less than or equal to the weight of an equal volume of water. Buoyancy is closely related to the concept of density. Density = mass/volume

There are a few types of buoyancy.
A NEGATIVELY-buoyant item, or a body that will sink in a fluid :: Even with the buoyant force pushing the body up (which it always does), a negatively buoyant mass will have the force of gravity pull the body downward until it reaches a solid surface below it, such as the floor. Even though buoyancy lost the battle against gravity, this body still has the upward lift of the force working in its favour. If you measure the weight of the body before it is placed in the fluid, it will weigh more than it does after it has sunk to the bottom of the fluid. This is because even though the item has sunk down, buoyancy is still trying to push it upward. A NEUTRALLY-buoyant item, or a body that will stay where it is placed in the vertical direction in a tank of fluid :: In this case, the buoyant force is equal to the gravitational force, so the body neither sinks nor floats. This is the ideal model for a submarine, as a neutrally buoyant item takes the least amount of force to keep it submerged in a position or to be moved in any direction in a fluid. A POSITIVELY-buoyant item, or an item whose buoyant force is so great that it can push a body upward and fight the pull of gravity :: When this type of buoyancy exists, it can be said that the body is floating. If it were to be held at the bottom of the fluid and weighed, it would weigh a negative value and be constantly pushed up and away from the scale.

Projectile Motion Projectile Motion: in many sports activities such as football, hammer throw, cricket, basketball etc. the athlete projects an object in the air A projectile is any object that is given an initial velocity, and then follows a path determined entirely by gravity. A projectile is any object that once projected or dropped continues in motion by its own inertia and is influenced only by the downward force of gravity. In certain other activities like diving, jumping etc. the athlete projects himself in the air In such activities, the quality of performance depends upon factors that govern the outcome of the projectile Thus knowledge of projectile motion helps in adjusting one or more of the factors affecting motion to have better performance

To study the behavior of projectile, the effect of air resistance is excluded, but considered later
If we exclude air resistance, there are two forces acting on the body. Inertial force which is constant and is determined at release and second force because of acceleration due to gravity which is constant and acting in downward direction In this situation horizontal velocity of the body remains constant as there is no force acting on it in horizontal direction(air resistance ignored)

However vertical velocity initially decreases at constant rate (9
However vertical velocity initially decreases at constant rate (9.81m/s) and then increases at constant rate In this situation where the horizontal velocity remains constant and vertical velocity is changing at constant rate, the projectile in place of going straight in the direction of release follows a curvilinear path called parabola and the motion is called projectile motion Fundamental Definitions: Trajectory: path taken by a projectile is called the trajectory Range: horizontal distance covered by the projectile is called the range Angle of Release: the angle at which a projectile is released or projected in the air is called the angle of release Height of Projectile: the maximum vertical distance above the ground that projectile reaches during its flight path

Relative Height of Release: the vertical distance between the point of release and the point of landing is called the relative height of release. It can be positive and negative. Higher release is positive and lower release is considered negative Time of Flight: the total time taken by the projectile to complete its trajectory is called time of flight Time of Ascent: time taken to reach the peak height by a projectile Time of Descent: time taken by projectile to land from the peak height There are three different situations in a projectile motion and these depends on the point of release and the point of landing of the projectile

These situations are: Point of release and landing are same Point of release higher than the point of landing Point of landing higher than the point of release A) when the release and landing are at the same level: Examples: football kicked above the ground, golf ball hit for a long shot, hockey ball hit in a rising shot, certain gymnastic exercises Characteristics: I) Time of ascent is equal to the time of descent Implications: in activities like a forward roll in gymnastics, at least half of the movement should be completed before reaching the peak height

In these activities, the time of flight is one of the major limiting factor in the execution of the skill In case half of the skill is not completed before reaching the peak height, it will be difficult to complete the skill as the time during ascent and descent are equal and more than half of the skill is to be completed in the latter half i.e. during descent In receiving a football pass in which ball is kicked above the ground, if half of the distance is covered before the ball starts descending, there will be a beneficial effect as the receiver will have sufficient time to reach the intended place where the ball was directed by the passer to position himself

II) The range of an object or implement will be higher if the release velocity is higher
Implications: in situations where range is the major consideration, like a long pass in football, a long drive in golf etc., the kicking foot or golf club should make a forceful impact on the ball in order to impart maximum possible velocity III) The range will be maximum at a constant velocity when the angle of release is 45 degree Implications: in situations where range is the major consideration an object should be released at 45 degree IV) Time of flight will be more at a constant velocity when the angle of release is more than 45 degree

Implications: in activities involving skills on trampoline or somersaults, the body should be projected at higher angles In these activities, range is of minor consideration and major consideration is the time achieved during the flight phase, as the skills are to be executed in a very limited time in the flight phase Thus, to increase the duration of the flight phase, there should be a higher angle of projection V) The range at a given angle with a constant velocity remains unchanged at a higher or lesser angle, the sum of which is 90 degree(complimentary angles). In other words, equal deviation from the optimum angle of projection on either side produces the same range 10 degree positive negative from 45 degree i.e. 35 degree and 55 degree (sum of 35 and 55 =90) produce same range at a given velocity

Implications: while executing a pass to a teammate, when there is a danger from the opponent to intercept the pass, lower angle of the two complimentary angles should be used Lower angle will keep the ball in air for shorter time and there will be less chance of interception While striking a shuttle in badminton, a ball in tennis, in a defensive shot the higher angle should be used The higher angle of projection will keep shuttle or ball in air for longer time which will allow a player position himself to counteract the opponents stroke

B) when the point of release is higher than the point of landing
Examples: shot put, discus throw, diving, long jump(with reference to c. g) etc Characteristics: I) The range will be greater if the release velocity is higher In activities like shot put, discus, hammer etc. the implement should be released at the maximum velocity Implications: In these activities and in long jump, the range is a major consideration; and range is directly proportional to the release velocity. Higher release velocity results in greater range or the distance covered by the implement or jumper

II) The range is dependent on angle of release
In this situation, optimum angle of release is always less than 45 degree Implications: For throwing events such as shot put, discus, hammer etc. the implement must always be released at an angle that is less than 45 degree III) The optimum angle of release is dependent on the release velocity(beside the relative height of release) There is no fixed optimum angle of release. As the release velocity increases the optimum angle of release approaches closer to 45 degree Implications: a thrower who is not able to impart a sufficiently high velocity at the time of release, should throw the implement 5 to 10 degree less than 45 degree

A long jumper, who is not able to achieve sufficiently high velocity at take off, should not imitate the take off angle of the long jumpers but should have the take off at lower angles IV) Range is dependent on the relative height of release The greater the relative height of release the greater, will be the range Implications: depending upon individuals reach at peak extension of the throwing arm, a thrower must release the implement at the maximum possible height in order to obtain the benefit of larger distance If all things are equal, a taller thrower will throw a implement to a larger distance than a shorter thrower

V) An equal change in the height of release, angle of release and velocity of release do not produce an equal resultant change in range Example: if the velocity of take off in the case of long jump is increased by 5%, the jumping distance increases by 54cm, where as by change of 5% in the angle of release and relative height of release the jumping distance increases by 16cm and 4cm only (Hay 1978) We may conclude that release velocity is the major determining factor for the loss or gain in the range, next come the angle of release and lastly the relative height of release

C) When the point of landing is higher than the point of release
This situation in sports is very rare Example: shooting in basketball, high jump or pole vault etc In basketball maximum range is not of consideration and in jump aim is fulfilled when bar is cleared Characteristics: I) Higher the angle of release the greater will be the accuracy, and the closer is the angle of entry to 90 degree, the margin for error increases and hence accuracy increases The margin for error means that there is a margin to compensate for small deviations or error

Higher the margin, larger degree of error is compensated resulting in better accuracy
Implications: during actual playing situations the angle of release of ball should be greater than 46 degree. However, the angle of entry should be close to 90 degree as possible(Hay 1978) II) As the distance from the basket increases, margin of error decreases hence accuracy decreases Implications: in basketball, scoring a basket should be attempted as close to the basket as possible, when ever conditions permit during the actual play (e.g., lay up shot or short jump shots). This is one of the reason that three points are awarded for shot above 6.25m distance

III) As the relative height of release increases the margin for error increases and hence accuracy increases Implications: the ball should be released at the maximum possible height above the ground i.e. jump and shoot(under the condition of actual play) Tall player can be better at scoring a basket if all other things are equal The factors mentioned above are purely mechanical in nature and subject to biomechanical influences e.g., theoretically in long jump 43 degree may be optimum angle of projection, but velocity at a take off decreases at such a high angle because of limitations of human biomechanical apparatus The air resistance also influence these factors Similarly in team games, where tactical situations are involved, these situations play influencing role over the mechanical factors Thus in practice, such influences must be considered while applying these mechanical factors

Unit-II The concept of Structural Kinesiology, its academics and Professional objectives Professional application of Structural Kinesiology The Fundamental Movements of Joints and their Terminology The Structural Classification of Skeletal Muscles and types of Contractions Classification of Muscle produced Movements The Techniques of Muscular analysis

Classification of Joints- movable, partly moveable and immoveable
The attachment(origin and insertion) and actions of muscles of following joints Shoulder Girdle and Shoulder Joint, Elbow Joint, Hip Joint, Knee Joint, Ankle and foot joints, Neck and Trunk Region

Concept of Structural Kinesiology: movement is a part of everyday living of an individual. It is involved from morning to sleep. Muscular contraction is involved in our activity. Rest and sleep involve activity i.e., movement. Movement is observable and has attracted man since evolution. Even animals know that movement is a sign of living. Generally movement is active participation. The science of motion of organisms: structural kinesiology includes bones, joints and muscles, in the study/analysis of motion. Inquiring and scientific minds has always attracted to human movements and such scientists have attempted to understand, analyze and teach skills to others, understanding has led to improvement of less energy demands.

Present day emphasis increased interests in investigation, in physical education frequent movement principles, fundamentals of skills, body mechanics are designed to help students become more proficient and adapt more easily to new skills Aim of Structural Kinesiology: to help individuals, students, players, coaches become more proficient and adapt more easily to new skills Objectives of Structural Kinesiology: To study the principles of movements(progression, specificity, individuality etc.) To study the fundamentals of skills(direction, intensity, control, etc.) Academic and Professional objectives of Structural Kinesiology: To study the body mechanics

To study the involvement of bones, joints and muscles
Degree of involvement Sequence of movement To study the techniques and tools used in movement analysis Professional Application of Structural Kinesiology: Organize and application of facts and principles learned in other basic sciences i.e. anatomy, physiology , physics (integrate all fields) to motion Analysis and evaluation of activities/human movements Analysis should make for better and easier teaching To understand the problems of efficiency and economy Give better appreciation of posture- Make aware of irregular and unusual performance Prevent injuries Rehabilitation Evaluation of exercise and its effects on human structure Discover and recognize principles of movements

The Fundamental Movements of Joints and their Terminology:
Flexion: reduction of angle between two adjacent bones Hyper flexion: body parts flexed beyond normal range Dorsi flexion: foot coming toward tibia Planter flexion: foot go to posterior aspect of foot Extension: increase of angle between two adjacent bones Hyper extension: exceeds extension movements from normal range i.e. 180 Abduction: body parts goes away from midline Adduction: body part come closer to midline Rotation: movement around vertical axis through horizontal plane

Supination: outward rotation of forearm
Pronation: inward rotation of forearm Circumduction: orderly sequence of the movement of flexion, extension, abduction and adduction into one composite movement Inversion: turning the sole of the foot inward Eversion: turning of the sole outward Protraction: lowering the jaw ,sticking out the tongue Retraction: raising the jaw , pulling in the tongue

The Structural Classification of Skeletal Muscles:
Skeletal muscles contains four essential structures contractile(muscular) tissue, conductile(nervous) tissue, blood vessels, connective(supportive) tissue Contractile tissue consists of fleshy fibers (muscle cells) bound together into bundles(fasciculi) by connective tissue which contains elastic fibers Each fiber is enclosed in an elastic sheath(sarcolemme) which is believed to act as an insulator so prevent diffusion

of stimuli from one muscle fiber to the other
This permits the small groups of fibers to contract without the whole muscle being involved. In some of the bigger muscles one portion of the muscle may be obviously contracted while other parts remain relaxed Each muscle fiber derives motor nerve supply from a nerve twig (branch) which penetrates the sarcolemma and terminates immediately inside the sheath at the motor-end plate. Nerve impulse released at the motor end plate release the chemical substance (acetylcholine) which is believed to activate the muscle fiber Blood vessels are very numerous in muscles. The larger veins and arteries are lodged in the perimysium between the fasciculi

Capillaries form an extensive network throughout the whole muscle
Capillaries form an extensive network throughout the whole muscle. The general distribution of blood vessels appears to be so arranged to minimize the degree of circulatory interference resulting from muscular contraction Connective tissue of a skeletal muscles has many functions to perform it consists of two kinds of fibers Collagenous (white substance, resistant to tensile forces, form substance of tendons and ligaments,) and Elastic(consist of yellow substance called ‘elastin’, less numerous, run singly, and form a wide branching network, stretch easily and quickly recoil their normal length when tension is released) The variable influencing the muscle structure/function is the arrangement of fibers within a muscle

The orientation of fibers within a muscle and the arrangements by which fiber attach to muscle tendon vary considerably among the muscles of the human body These structural considerations affect the strength of muscular contraction and the range of motion through which a muscle group can move a body segment The two categories of muscle fiber arrangement are termed parallel and pennate/oblique The parallel and pennate arrangements have further sub classifications In parallel fiber arrangement, all fibers are oriented parallel to the longitudinal axis of the muscle. The Sartorius, rectus abdominus, and biceps brachii have parallel fiber orientation

Parallel Muscles: Muscle fasciculi are parallel to the line of pull Consist of parallel fibers of equal size Range of movement is maximum Force of contraction is less Muscle fiber contract with equal length Quadrilateral (rectangular): pronator and thyroid Rhomboid: major and minor Fusiform(ends tapered): biceps brachii Strape Like(narrow strip): sartorius, rectus abdominus Circular: orbicularis oculi eyelids) Oblique/ Pennate (feather)Muscles: the muscle fasciculi are oblique to the line of pull. A pennate fiber arrangement is one in which the fibers lie at an angle to the muscles longitudinal axis.

Each fiber in pennate muscle attaches to one or more tendons, some of which extend the entire length of the muscle The fiber of a muscle may exhibit more than one angle of pennation(angle of attachment) to a tendon. The tibialis posterior, rectus femoris, and deltoid muscle have pennate fiber arrangements Consist of oblique fibers(feather like) Muscle fibers are of variable sizes Range of movement is reduced Force of contraction is powerful Fibers contract with unequal length Unipennate: palmer Bipennate: rectus femoris

Multipennate: deltoid
Circumpennate/cylindrical: tibialis anterior Triangular: aductor longus/temporilis Spiral or twisted: latissimus dorsi Types of Muscular Contractions: the muscular contraction refers to the development of tension within the muscle. A contractile organ comprises of muscle tissue, blood vessels, connective tissue and lymphatic’s. Skeletal muscles are directly or indirectly attached to the skeletal and appear stratified when seen through microscope. 40% of the total weight of the human body comprises of the skeletal muscles and 10% of the smooth and cardiac muscles

Types of muscles Voluntary/skeletal muscles Involuntary/smooth muscles Cardiac muscle Striated/skeletal muscles are of the main concern from the biomechanical point of view. It has four functional properties. Irritability- muscle response to various stimulus Contractibility- capacity to shorten while receives strength stimulus Extensibility: muscle is able to lengthen Elasticity: it has the characteristic to return to its original place

Types of muscular contractions: there are basically two types of muscle contractions(static and dynamic) Isometric contraction: iso means same and metric means length, it develop tension but no change in the length of the muscles. Tension is insufficient to cause any joint movement against the given resistance; thus it is called static contraction. Although there is slight shortening of muscle but this shortening is accompanied with a simultaneous lengthening of the tendon of the muscle, thus the total length of the muscle remains the same. This condition occurs when resistance and muscle force are in equilibrium e.g. force against the firm support. Isotonic contraction: in this contraction, the muscle tension remains the same but the contraction is associated with the change in the length of the muscle. This is dynamic condition, it is of two types

Concentric contraction: where a muscle develops sufficient contraction to overcome a resistance and the length of the muscle shortens. This contraction is accompanied with the movement of the body part e.g. flexion at the elbow joint as lifting a weight. Eccentric contraction: external resistance is more than the developed muscle tension resulting in the lengthening of the muscle, called eccentric contraction. This is also accompanied by the movement of body part e.g. heavy load is held in the hand and the load results in the straightening of the arm (extension at the elbow). Isokinetic contraction: constant speed in and over the full range of motion e.g. running on treadmill Classification of Muscle produced Movements: muscle movements/contractions are of many types according to the task demands. It may vary in speed, force and duration. The following are different movements produced by the muscles

Maximum force movements: the muscles contract at maximum speed and force. There are two types of maximum force movements; Continuous force movements: in this type of movement, muscle tension is almost maximum throughout the range of motion. Most weight training exercise are examples of this type, some gymnastics activities such as chin-ups, pull-ups are also continuous force movements Ballistic movements: these are fast and short movements of the muscles. After the initial burst of muscle activity, the muscle force is reduced and action continues due to momentum generated. The speed of movement gradually decreases due to the resistance of antagonist muscles, resistance in joints, and external resistance such as the pull of the gravity, the opposing momentum of a ball, or other forces

Near the end of ballistic movement, antagonist muscles provide braking action through eccentric contraction. If the braking action is initiated too soon, the movement appears jerky and lacks fluidity, and if braking action is initiated too late, the performer is likely to loose balance and/ or may not be in a position for the next movement. There are many examples of ballistic movements in sports- swing of clubs, rackets, or bats; throwing a punch, a ball, a discus, or javelin; running, jumping, or dribbling a ball Slow tension movements: the movements when speed and force are of secondary consideration to steadiness and accuracy. During slow tension movements the strength of the contraction of agonist and antagonist muscles are almost equal to hold the body or its segment stabilized and steady.

Examples are provided in aiming a gun, an arrow, or a dart; threading a needle, in gymnastics balancing a foot etc. Rapid tension movements: these movements are those in which the direction of movement is quickly reversed, as in typing, or strumming a guitar. The maximal speed is determined by learning, the weight of the object being manipulated, and strength of the muscle involved The following truth relating to muscular contraction must be noted: Anatomical principle: a muscle fiber can only develop tension within itself

When a fiber or muscle develop tension both ends tend to move
When a fiber or muscle develop tension both ends tend to move. These movements occur depends on resistance and the activity of these muscles. When a muscle develop tension, it tends to perform all of its possible action at all joints it crosses The above truths suggests that, to bring about the movement of human body, muscles act together rather than individually with each playing a specific role, this is one important feature of coordinated movements When muscles are categorized according to role, individual muscles or groups of muscles are described in terms that demonstrate the specific role that the muscle plays during action When using this type of role designation, it does not matter what action is being performed (flexion, extension etc.) but only what role muscle plays

The Techniques of Muscular analysis: the principle properties of the muscles are excitability, conductivity and contractibility. The last-named is manifested either in shortening of the muscle by tension. The following are the techniques of muscular analysis Palpation: Physical Examination Electromyography(EMG): it is a technique for evaluating and recording the electrical activity produced using a instrument called electromyograph, to produce a record called an electromyogram.

An electromyogram detects the electrical potential generated by the muscle cells, when these muscle cells are electrically or neurologically activated. The signals can be analyzed to detect medical abnormalities, activation level, recruitment order or to analyze the biomechanics of human or animal movements Myography: muscular contraction is recorded by means of myography i.e. a recording of the contraction by means of lever attached to one end of the muscle. The free end of the lever draws a contraction curve, or myogram, on the chart of a Kymyograph The method is simple and does not need complex equipment

Its shortcomings, however, is that the inertia of the lever and friction against the surface of the chart produce a slight distortion in the recording. To correct that defect a special pick-up device is now used to convert the mechanical changes (linear displacement or efforts of the muscle) into variations of an electric current, which are registered by a loop or a cathode-ray oscillograph. Photokymograph: it is another accurate method used in recording of muscle contraction, in which optical recording on a photokymograph is done by using a light beam reflected by a mirror, fastened to the belly of the muscle Ergoraphy: under laboratory conditions muscular fatigue is studied by means of ergographs- instruments for recording the amplitude of movements rhythmically performed by a group of muscles

One such instrument is Mosso’s ergograph which records the force and frequency of flexion of the fingers and yields summary information on the work done by the flexor of that finger and by the common flexors of all the fingers of the hand The subject, bending and extending the finger to the rhythm of a metronome, raises and lowers a load suspended from it. Ergographs reproducing various working movements of man are of special interest; the first of these instruments was one used by Sechenov to study the movements made in working with hand-saw

Changing the load and the frequency of metronome beats, it is possible to establish the rhythm and load at which a given individual is capable under the experimental conditions of doing the greatest amount of work in the shortest possible time The form of the fatigue curve and the amount of work performed vary extraordinarily with different individuals and even in the same individual under different conditions, as was demonstrated by the ergograms recorded by Mosso on himself before and after passing his students, which indicated a sharp reduction of working capacity after intense mental work

intramuscular surface electromyography Photo kymograph

Palpation: Ergoraphy: Videokymography

Classification of joints
Structural classification (binding tissue) Structural classification names and divides joints according to the type of binding tissue that connects the bones to each other. There are three structural classifications of joints: fibrous joint– joined by dense regular connective tissue that is rich in collagen fibers cartilaginous joint– joined by cartilage synovial joint – not directly joined – the bones have a synovial cavity and are united by the dense irregular connective tissue that forms the articular capsule that is normally associated with accessory ligaments.

Functional classification (movement)
Joints can also be classified functionally according to the type and degree of movement they allow: Joint movements are described with reference to the basic anatomical planes Synarthrosis – permits little or no mobility. Most synarthrosis joints are fibrous joints (e.g., skull sutures). amphiarthrosis – permits slight mobility. Most amphiarthrosis joints are cartilaginous joints (e.g., intervertebral discs). synovial joint (also known as a diarthrosis) – freely movable. Synovial joints can in turn be classified into six groups according to the type of movement they allow: plane joint, ball and socket joint, hinge joint, pivot joint, condyloid joint and saddle joint Joints can also be classified, according to the number of axes of movement they allow, into nonaxial (gliding, as between the proximal ends of the ulna and radius), monoaxial (uniaxial), biaxial and multiaxial. Another classification is according to the degrees of freedom allowed, and distinguished between joints with one, two or three degrees of freedom. A further classification is according to the number and shapes of the articular surfaces: flat, concave and convex surfaces. Types of articular surfaces include trochlear surfaces.

Biomechanical classification
Joints can also be classified based on their anatomy or on their biomechanical properties. According to the anatomic classification, joints are subdivided into simple and compound, depending on the number of bones involved, and into complex and combination joints: Simple joint: two articulation surfaces (e.g. shoulder joint, hip joint) Compound joint: three or more articulation surfaces (e.g. radiocarpal joint) Complex joint: two or more articulation surfaces and an articular disc or meniscus (e.g. knee joint)

Classification of Joints- Movable, Partly Moveable and Immoveable: The junction where two or more bone articulate with each other, is called joint. There are three types of joints Freely Moveable/Synovial or Diarthroses Joint: these joints vary widely in structure and movement capabilities. At diarthrodial joints a separation or cavity is present between the articulating bones, a ligamentus capsule surrounds the joint, and a synovial membrane lining the interior of the joint capsule secretes a lubricant known as synovial fluid, further these joints are classified into following categories Plane; arthrodial/Gliding joints- in these joints the articulating bone surfaces are nearly flat, and the only movement permitted is nonaxial gliding. Examples include intercarpal, intertarsal joints and the facets joints of the vertebrae

Hinge joints(ginglymus)- one articulating bone surface is convex and other is concave in these joints. Strong collateral ligaments restrict movements to a planar, hinge like motion. Examples include elbow(ulnohumeral), inter-phalangeal Pivot joints(screw; trochoid)-in these joints, rotation is permitted around one axis. Examples include atlantoaxial joint and the proximal and distal radioulnar joints Condyloid(ovoid; ellipsoidal)- one articulating bone surface is an ovular convex, and the other is reciprocally shaped concave surface in these joints. Flexion, extension, abduction, adduction, and Circumduction are permitted. Examples include the second through fifth meta carpo- phalangeal joints and the radio carpal joints

Saddle (sellar)- the articulating bone surfaces are both shaped like the seat of the riding saddle in these joints. Movement capability is the same as that of the Condyloid joint but with greater range of movement is allowed. An example is carpo- metacarpal joint of thumb Ball and socket(spheroidal)- in these joints the surfaces of the articulating bones are reciprocally convex and concave. Rotation in all the three palnes of movemant is permitted. Examples include hip, and shoulder joints Slightly Moveable/Cartilaginous or Ampiarthroses: these cartilaginous joints attenuate applied forces and permit more motion of the adjacent bones than synarthrodial joints

A) synchondroses: in these joints the articulating bones are separatde by a thin layer of fibro cartilage. Examples include the sternocostal joints and epiphyseal plate (before ossicification) B) symphyses: in these joints, thin plate of hyaline cartilage separates a disc of fibro cartilage from the bones. Examples include the vertebral joints and pubic symphysis Fixed/Fibrous or Synarthroses Joint: these joints can attenuate force(absorb shock) but permit little or no movement of the articulating bones A) sutures: these joints have only a slight separation of adjacent bones, and the fibrous tissue of the joints is continuous with the periostem. The only examples in the human body is the sutures of the skull

B) syndesmoses: in these joints, dense fibrous tissue binds the bones together, permitting extremely limited movement. Examples include the coracoacromial, mid radioulnar, mid tibiofibular, and inferior tibiofibular joints The Attachment(Origin and Insertion) and Actions of Muscles of Following Joints Attachment: Shoulder Girdle and Shoulder Joint: Trapezius, Levator Scapula, Romboids, Seratus Interior, Pectoralis Minor and Major, Deltoids, Superaspinatus, Teres Minor and Major, Infraspinatus, Subscapularis and Biceps Attachment: to produce a movement muscles must be attached at both ends to the bones, cartilages, ligaments, skin or to other muscles.

Muscles fibers are not directly attached to other structures, but the connective tissue of the muscles is continued to blend with that of the other structures When the connective tissue linking the ends of the muscles to other structures assumes a definite form it is called tendon, or an aponeurosis. Tendons(‘sinews’, or ‘leaders’) consists of white fibrous tissue and are usually cord-like or band-like in appearance The flat fibrous sheet attachments of muscles like the abdominal muscles are called aponeuroses Usually one end of muscle remains more or less stationary while other is the more moveable part The more stable end of a muscle is termed as its origin and the more moveable end is called the insertion

The origin of a muscle is usually the more proximal end, i. e
The origin of a muscle is usually the more proximal end, i.e. nearer to the center of the body As a rule, muscles are inserted into bones immediately distal to the main joint upon which they act. By this arrangement the speed and range of movement in the bony levers are increased, with corresponding loss of power, for example, quadriceps of the thigh is inserted(through the patellar ligament) into the upper end of tibia, so that contraction of quadriceps moves the foot through a greater range and at a greater speed than the upper end of tibia It is estimated that muscle fibers are capable of contracting to about forty percent of their un contracted length

On this basis, muscles would require to be much longer than they are to get the necessary range of movement in the limbs were it not for the above arrangement When a muscle contracts it tends to approximate both ends, but the origin is usually anchored by the action of other muscles, so that the insertion becomes the moveable point In some movements the position may be reversed, i.e. the insertion becomes the stable point to cause movement of the origin In the performance of movements certain muscles must relax to allow others to shorten

The Attachment (Origin and Insertion) and Actions of Muscles of Shoulder Girdle and Shoulder Joint

Name Origin Insertion Action Trapezius (1) Base of occipital bone (2) spinous processes of all cervical and dorsal vertebrae (3) ligamentum nucahe (1) outer third of posterior border of clavicle (2) top of acromion (3) upper border of spine of scapula (1) upward rotation of scapula (2) adduction of scapula (3) depression of scapula Levator Scapula (1) transverse processes of upper 4 or 5 cervical vertebrae (1) vertebral border of scapula between superior angle and spine. (1) elevation of scapula (2) slight adduction of scapula Romboids (1) spinous processes of 7th cervical and upper 4 thoracic vertebrae (1) vertebral border of scapula from spine to inferior angle (1) downward rotation of scapula

Name Origin Insertion Action Seratus Anterior (1) 8 digitations from the outer surface of upper 8 ribs (along the side and front of thorax) (1) upper 2 digitations on ventral surface of whole vertebral border of scapula (2) lower 5 digitations on ventral surface of inferior angle of scapula (1) abduction of scapula (2) upward rotation of scapula Pectorial Major Sternum clavicle, seven upper costal cartilages. Outer ridge bicipital groove of humerus Draws arm forwards and upwards, raises body to arms. Pectoralis Minor (1) Outer surface of 3rd, 4th, and 5th ribs (1) caracoid process of scapula (1) downward rotation of scapula (2) elevation of ribs if scapula is fixed

Name Origin Insertion Action Deltoids Outer third of clavicle. Outer edge acromion process. Lower border of spine of scapula Deltoid impression on outer side of shaft of humerus. Raises arm, draws it back by posterior fibres, and forward by anterior fibres Superaspinatus Fossa above spine of scapula. Great tuberosity of humerus (upper facet). Assists deltoid in raising arm, rotates outwards. Teres mionr Axillary border of scapula. Great tuberosity of humerus (lower facet). Rotates humerus outwards.

Name Origin Insertion Action Teres Major (1) Dorsal surface of lower third of axillary border of scapula (1) Medial lip of bicipital groove of humerus (1) depression of the humerus (2) adduction of the humerus (3) inward rotation of the humerus Infraspinatus (1) infraspinous fossa of the scapula (1) middle portion of the greater tuberosity of the humerus (1) outward rotation of the humerus (2) extension of humerus backward in horizontal plane when arm starts in an abducted position. Subscapularis (1) ventral surface of the scapula (1) lesser tuberosity of the humerus (1) Inward rotation of the humerus Biceps (1) supraglenoid fossa on the scapula (2) coracold process of the scapula (1) bicipital tuberosity on radius (1) flexion of forearm (2) supination of hand (3) flexion of the humerus

The Attachment (Origin and Insertion) and Actions of Muscles of Elbow Joint

Name Origin Insertion Action Biceps Brachii (1) Apex of glenoid cavity. (2) Coracoid process of scapula. Tuberosity of radius. Flexes and supinates forearm. Pronator Teres (1) Inner condyle of humerus (2) medial border of coronoid process of the ulna (1) middle of the outer surface of the radius (1) pronation of the hand (2) flexion of the forearm Brachoradialis (1) upper portion of lateral epicondylar ridge on humerus (1) styloid process of the radius (1) flexion of the forearm (2) helps to start either supination or pronation depending upon the starting position of the forearm.

Name Origin Insertion Action Brachialis Anticus (1) middle of the anterior surface of the humerus (1) anterior surface of coronoid process of the ulna (1) flexion of the forearm Triceps (1) infraglenoid fossa of the scapula (2) posterior surface of the humerus above and below the musculospiral groove (1) olecranon process of the ulna (1) extension of the forearm (2) long head, slight extension of the humerus Pronator Quadratus (1) lower anterior surface of the ulna (1) lower portion of the anterior and lateral surface of the radius (1) pronation of the land Supinator (1) lateral condyle of humerus (2) upper lateral surface of the ulna (3) ligaments of the elbow (1) upper portion of posterior and lateral surfaces of the radius (1) supination of the hand

The Attachment (Origin and Insertion) and Actions of Muscles of Hip Joint

Name Origin Insertion Action Illiopsoas Minor (1) sides of the bodies of the 12th thoracic and all the lumbar vertebrae (2) upper half of the anterior surface of the ilium (1) lesser trochanter of the femur (1) flexion of trunk on high, or high on trunk. (2) outward rotation of femur Illiopsoas Major Pactinues (1) ascending ramus of the os pubis (2) iliopectineal line of the ilium (1) pectineal line of the femur (from the lesser trochanter to the lines apsera) (1) adduction of the femur (2) flexion of the femur (3) outward rotation of the femur

Name Origin Insertion Action Rectus Femoris (1) anterior inferior spine of the ilium (2) anterior margin of the acetabulum (1) tuberosity of the tibia (1) flexion of trunk on high, or of high on trunk. (2) extension of the knee Sartorius (1) anterior superior spine of the ilium (1) medial surface of the greater trochanter (1) abduction o the femur (2) inward rotation of femur by the anterior fibers (3) outward rotation of femur by posterior fibers Tensor Fascia Lata (1) aponeurosis just off the crest of the ilium behind the anterior superior spine (1) fascia latae half way down the high (1) abduction of the femur (2) flexion of the femur (3) inward rotation of the femur

Name Origin Insertion Action Biceps Femoris (1) lower surface of the tuberosity of the ischium (2) full length of linea aspera (1) lateral surface of the head of the fibula (1) extension of the hip (2) flexion of the knee (3) outward rotation of the lower leg Semimembranious (1) upper and lateral surface of the tuberosity of the ischium (1) inner surface of medial condyle of the tibia (1) extension of the hip (3) inward rotation of the lower leg Semitendinosus (1) upper medial surface of the shaft of the tibia (1) extension of the hip Glteus Maximus (1) lateral posterior surface of the ilium (2) posterior surface of the sacrum and coccyx. (3) greater sacrosciatic ligament (1) gluteal line of the femur (from the greater trochanter to the linea aspera) (1) extension of the femur (2) outward rotation of the femur

Name Origin Insertion Action Obturator Externus Obturator Internus
(1) outer surface of lower half of the obturator membrane (2) outer surface of the rami of the pubis and of the ischium (1) in the fossa between the greater trochanter and the neck of the femur (1) outward rotation of the femur Obturator Internus (1) inner surface of the ilium and pubis from foramen to iliopectineal line (2) inner surface of the obturator membrane (3) inner surface of the rami of the pubis and of the ischium (1) inner border of greater trochanter of the femur Adductor Magnus (1) lateral surface of the body of the ischium (2) lateral surface of the rami of the pubius and of the ischium (1) entire length of the linea aspera (2) adductor tubercle (1) adduction of the femur (2) slight flexion of the femur when leg starts in a fully extended position. (3) slight extension of the femur when leg starts in a fully flexed position. (4) slight outward rotation of the femur Adductor Longus (1) descending ramus of the os pubis (1) middle third of the lnea aspera on the femur (1) adduction of the femur (2) slight flexion of the femur when the leg starts in a fully extended position. (3) slight outward rotation of the femur Adductor Brevis (1) anterior surface of the body of the os pubis (1) upper third of the linea aspera on the femur (2) slight flexion of the femur when the leg starts in a fully extended position.

The Attachment (Origin and Insertion) and Actions of Muscles of Knee Joint

Name Origin Insertion Action Rectus Femoris (1) anterior inferior spine of the ilium (2) anterior margin of the acetabulum (1) tuberosity of the tibia (1) flexion of trunk on high, or of high on trunk. (2) extension of the knee Vastus Medialis (1) medial lip of the linea aspera (1) extension of the knee Vastus Lateralis Vastus Intermedius (1) anterior surface of the femur

Name Origin Insertion Action Bicepsfemoris (1) lower surface of the tuberosity of the ischium (2) full length of the linea aspera (1) lateral surface of the head of the fibula (1) extension of the hip (2) flexion of the knee (3) inward rotation of the lower leg Smeimembranosus (1) upper and lateal surface of the tuberosity of the ischium (1) inner surface of the medial condoyle of the tibia Semitendinisus (1) upper medial surface of the shaft of the tibia

Name Origin Insertion Action Sartorius (1) anterior superior spine of the ilium (1) medial surface of the greater trochanter (1) abduction o the femur (2) inward rotation of femur by the anterior fibers (3) outward rotation of femur by posterior fibers Popliteus (1) lateral surface of the lateral condyle of the femur (1) upper posterior surface of the tibia (1) flexion of the knee (2) inward rotation of the lower leg Gastrocnemius (1) posterior surface of the condyles of the femur (1) lower posterior surface of the os calcis (1) extension of the ankle (2) flexion of the knee

The Attachment (Origin and Insertion) and Actions of Muscles of Ankle and Foot Joint

Name Origin Insertion Action Gastrocnemius (1) posterior surface of the condyles of the femur (1) lower posterior surface of the os calcis (1) extension of the ankle (2) flexion of the knee Soleus (1) posterior surface of the head of the fibula (2) oblique line of the tibia (1) lower posterior surface of the os calcis Tibialis Anterior shaft of tibia and interosseous membrane medial cuneiform & base of first metatarsal extends the foot; inverts foot at subtalar and transverse tarsal joints; supports medial longitudinal arch Tibialis Posterior shafts of tibia and fibula & interosseous membrane tuberosity of navicular bone plantar flexes foot; inverts foot at subtalar and transverse tarsal joints; supports medial longitudinal arch of foot

Name Origin Insertion Action Flexor Digitorum Longus (1) inner surface of the os calcis (2) plantar fascia (1) 4 tendon,s each to 2nd phalanx of the 4 toes (1) flexion of the toes Extensor Digitorum Longus (1) outer surface of the os calcis (2) lateral talocalcaneal ligament (1) 1st phalanx of great toe (2) tendon of the extensor longus digitorum to 2nd, 3rd and 4th toes (1) extension of the first 4 toes Peroneus brevis (1) lower third of the lateral surface of the fibula (1) tuberosity of the 5th metatarsal (1) extension of the ankle

Name Origin Insertion Action Extensor Hallucis Longus (1) middle of the anterior surface of the fibula (2) interosseous membrane (1) base of the last phalanx of the 1st toe (1) extension of the 1st toe (2) flexion of the ankle

The Attachment (Origin and Insertion) and Actions of Muscles of Neck and Trunk Region

Name Origin Insertion Action Sternomastoid (1) upper border of sternum (2) sterna end of the clavicle (1) mastoid process of the temporal bone (1) together, flexion of the head and neck (2) singly, rotation of the head Trapezius (1) Base of occipital bone (2) spinous processes of all cervical and dorsal vertebrae (3) ligamentum nucahe (1) outer third of posterior border of clavicle (2) top of acromion (3) upper border of spine of scapula (1) upward rotation of scapula (2) adduction of scapula (3) depression of scapula Splenius (1) spinous process of the 7th cervical and of the upper 6 thoracic vertebrae (2) ligamentum nuchae and supraspinous ligament (1) Lateral portion of the base of the occipital bone, and the mastoid process (2) transverse processes of upper 3 or 4 cervical vertebrae (1) together, extension of the head and neck (2) singly, bends the head sideward and backward. (3) aids in rotation of the head

Name Origin Insertion Action Capitis (1) spinous process of the 7th cervical and of the upper 6 thoracic vertebrae (2) ligamentum nuchae and supraspinous ligament (1) Lateral portion of the base of the occipital bone, and the mastoid process (2) transverse processes of upper 3 or 4 cervical vertebrae (1) together, extension of the head and neck (2) singly, bends the head sideward and backward. (3) aids in rotation of the head Infraspinatus (1) infraspinous fossa of the scapula (1) middle portion of the greater tuberosity of the humerus (1) outward rotation of the humerus (2) extension of humerus backward in horizontal plane when arm starts in an abducted position. Levator Scapulae (1) transverse processes of upper 4 or 5 cervical vertebrae (1) vertebral border of scapula between superior angle and spine. (1) elevation of scapula (2) slight adduction of scapula

Name Origin Insertion Action Teres Major Teres Minor Serratus Anterior
(1) Dorsal surface of lower third of axillary border of scapula (1) Medial lip of bicipital groove of humerus (1) depression of the humerus (2) adduction of the humerus (3) inward rotation of the humerus Teres Minor (1) dorsal surface of the upper two thirds of the axillary border of the scapula (1) inferior portion of the greater tuberosity of the humerus (1) outward rotation of the humerus (2) extension of humerus backward in horizontal plane when arm starts in an abducted position Serratus Anterior (1) 8 digitations from the outer surface of upper 8 ribs (along the side and front of thorax) (1) upper 2 digitations on ventral surface of whole vertebral border of scapula (2) lower 5 digitations on ventral surface of inferior angle of scapula (1) abduction of scapula (2) upward rotation of scapula

Name Origin Insertion Action Latissimus Dorsi Erector Spial
(1) spines of the last 6 thoracic vertebrae (2) posterior portion of last 3 ribs. (3) lumbar aponeurosis (1) Bottom of the bicipital groove on the humerus (1) depression of the humerus (2) adduction of the humerus (3) inward rotation of the humerus (4) rotation of the trunk backward when the arms are fixed overhead. Erector Spial (1) posterior iliac crest (2) lower posterior surface of sacrum (3) spinous processes of al lumbar and of last 2 thoracic vertebrae (4) transverse processes of all the thoracic vertebrae (1) posterior portion of ribs (2) transverse possesses of vertebrae the full length of the spine (3) base of the occipital around as far as the mastoid process. (1) together, extension of the spine, either localized or full length of spine. (2) singly, lateral bending of spine, either localized or full length of spine. (3) singly, aids in rotation of the trunk. Rectus Abdominus (1) xiphoid process (2) cartilage of the 6th, 7th, and 8th ribs (1) crest of the os pubis (1) together, flexion of the trunk (2) singly, lateral flexion

Name Origin Insertion Action Oblique Internus Oblique Externus
(1) Outer half of Poupart’s ligament (2) anterior half of middle lip of iliac crest (3) lumbar fascia (1) crystal cartilage of 7th to 10th ribs (2) Linea alba (1) together, flexion of the trunk (2) singly, lateral flexion and rotation of the trunk Oblique Externus (1) Outer border of lower 8 ribs (1) anterior half of outer lip of iliac crest (2) Poupart’s ligament (3) linea alba (1) together, flexion of trunk (2) singly, lateral flexion and rotation of trunk

UNIT-III: LINEAR AND ANGULAR KINETICS & KINEMATICS
Newton’s law of gravitation Momentum and impulse Eccentric force, couple, moment of force, torque moment of inertia and angular momentum transfer of angular velocity equilibrium and stability, Interrelationship between displacement, velocity and acceleration vectors projectile motion Angular distance and angular displacements Angular speed, angular velocity and angular acceleration Centripetal and centrifugal force, Friction

Newton’s Law of Gravitation: every particle of matter in the universe attracts every particle with force, which is directly proportional to the product of masses of the particles and inversely proportional to the square of distance between them The forces, which attracts each other, are so small that they are not of any significance in sports except when one of the body is earth

The earth is not a spherical body but is flattened at poles
In such case, a useful relation that the acceleration due to gravity is inversely proportional to the square of distance from the center of the earth can be deduced Thus the value of g changes from the center of earth The earth is not a spherical body but is flattened at poles Hence, the distance from the center of the earth to its surface(s) is more at the equator than at poles This difference is approximately 21 km which lead to higher value of g at poles than at equator This difference in the value of g affect the weight of a body Thus whereas, the mass of the body is constant, the weight of a body is variable quantity and it changes its magnitude depending on the location of the body in relation to the earth

Example: a wrestler will weigh less in Mexico city, which is nearer to the equator and is at a high altitude than it would weigh in Alaska which is nearer to the north pole and is close to the sea level Further more, as the value of g is smaller at equator than at poles, it is more favorable for throwers and jumpers to achieve greater distance closer to the equator Example: if all other things are equal, a javelin could be expected to travel a distance of 15.75cm more in Melbourne(1956 Olympics) than at Helsinki(1952 Olympics) and in the case of long jump the distance jumped could be 3.65 inches longer(Heiskannan,1955)

Momentum: it is the quality of motion of body in linear motion
Momentum: it is the quality of motion of body in linear motion. It is equal to the product of the body’s mass and velocity It is a commonly used term in sports. A team that has the momentum is on the move and is going to take some effort to stop. A team that has a lot of momentum is really on the move and is going to be hard to stop. Momentum is a physics term; it refers to the quantity of motion that an object has. A sports team that is on the move has the momentum. If an object is in motion (on the move) then it has momentum. Momentum can be defined as "mass in motion." All objects have mass; so if an object is moving, then it has momentum - it has its mass in motion. The amount of momentum that an object has is dependent upon two variables: how much stuff is moving and how fast the stuff is moving. Momentum depends upon the variables mass and velocity. In terms of an equation, the momentum of an object is equal to the mass of the object times the velocity of the object.

Impulse: impulse of a force is the product of the force and the time for which the force acts
In classical mechanics, the impulse of force is defined as the product of the average force multiplied by the time it is exerted. Impulse is a vector quantity since force is a vector quantity. Newton's Second Law of Motion describes the transfer of energy for impulse turbines. The product obtained by multiplying the average value of a force by the time during which it acts. The impulse equals the change in momentum produced by the force in this time interval. It is measured by recording the force time curve

Eccentric Force, Couple, Moment of Force, Torque
Eccentric Force: a force applied at a distance away from an axis of rotation, therefore a force causing a rotational moment (torque). Applies to all muscle actions at joints, whether the muscle itself is acting eccentrically or concentrically. Couple: A couple is a pair of forces which are equal in magnitude but opposite in direction, are equidistant from the axis of rotation, and act to produce pure rotation

Torque: A turning or twisting force.
Moment of Force: the measure of a force's tendency to produce torsion and rotation about an axis, equal to the vector product of the radius vector from the axis of rotation to the point of application of the force and the force vector. Torque: A turning or twisting force. Torque, moment or moment of force, is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist to an object. The turning or rotational effect of an eccentric force. Equal to the product of perpendicular components of force and distance (from the force’s line of action) Any eccentric force will cause a torque “Moment arm” is a special name given to the distance from force’s line of action and the axis of rotation.

Moment of Inertia and Angular Momentum
Moment of inertia is the mass property of a rigid body that defines the torque needed for a desired change in angular velocity about an axis of rotation. Moment of inertia depends on the shape of the body and may be different around different axes of rotation. A larger moment of inertia around a given axis requires more torque to increase the rotation, or to stop the rotation, of a body about that axis. Moment of inertia depends on the amount and distribution of its mass, and can be found through the sum of moments of inertia of the masses making up the whole object, under the same conditions. In classical mechanics, moment of inertia may also be called mass moment of inertia, rotational inertia, polar moment of inertia, or the angular mass.

In physics, angular momentum, moment of momentum, or rotational momentum is the amount of rotation an object has, taking into account its mass and shape. It is a vector quantity that represents the product of a body's rotational inertia and rotational velocity about a particular axis. The angular momentum of a system of particles (e.g. a rigid body) is the sum of angular momenta of the individual particles. For a rigid body rotating around an axis of symmetry (e.g. the blades of a ceiling fan), the angular momentum can be expressed as the product of the body's moment of inertia, I, (i.e., a measure of an object's resistance to changes in its rotation velocity) and its angular velocity

Transfer of Angular Velocity
In physics, the angular velocity is defined as the rate of change of angular displacement and is a vector quantity which specifies the angular speed (rotational speed) of an object and the axis about which the object is rotating. Transfer of angular velocity means the shifting of velocity generated in one segment of the body/joint to the other. The following factors determine the transfer: Kinetic chain Kinetic link

Equilibrium and Stability
Equilibrium: when a body is neither having linear motion nor rotation and is at rest, it is said to be in a state of equilibrium Conditions of Equilibrium: the first characteristic of the body in equilibrium is that the resultant of all the components of forces acting on the body is zero The second condition of a body in equilibrium is that the resultant of all the movement of forces in any direction should be zero Types of Equilibrium: Stable Equilibrium: when the body is in equilibrium and has a tendency to return to its original position when unbalancing forces are applied on it then the body is said to be in a state of stable equilibrium e.g., gymnast hanging on a horizontal bar, in this case when a force is applied on the gymnast it results in rotation but after some time gymnast regains his original place Pendulum is other example of stable equilibrium

Unstable Equilibrium: when a body has a tendency to move away from its original position when an unbalancing force is applied on it then it is said to be in in a state of unstable equilibrium Example of unstable equilibrium is hand stand on parallel bar Neutral Equilibrium: in this case, the body has a tendency to change its position under the influence of an applied force but the new acquired position is similar to the original position e.g., ball lying on a level surface

Stability: it is the measure in equilibrium, which determines how quickly an object or a body can come out of the resting position or will remain in its original position when unbalancing forces are impressed upon the body Factors Affecting Stability: Stability is directly proportional to the area of base on which the body rests, wider the base higher will be the stability and vice versa Example Judo, hand stand and hockey Stability is inversely proportional to the height of centre of gravity above the area of base. Higher the C.G less will be the stability and vice versa Catching heavy objects knee bent, to stop quickly C.G will be lowered For equilibrium to exit, the C.G must fall within the area of base e.g., while walking on a light rope arms coordinated

Stability in given direction is directly proportional to the horizontal distance between the C.G and the limits of the base in that direction. The larger is the horizontal distance, the higher will be the stability e.g., starts, swimming Shape of the base: the area of base should be increased in the direction of the on coming unbalancing force e.g., boxing, cricket Stability is directly proportional to the weight of the body. The greater the weight of the body higher is the stability and vice-versa

Interrelationship between Displacement, Velocity and Acceleration
Kinematics is the description of motion; it concerns only the accurate description of the positions of objects, and the change in their positions. It does not deal with the sources of their motion Kinematics is the branch of biomechanics about the study of movement with reference to the amount of time taken to carry out the activity. Displacement is a vector which points from the initial position of an object to its final position. The standard units of displacement are meters. Velocity is a vector which shows the direction and rate of motion. The standard units of velocity are meters per second. Speed and velocity are not the same thing: speed is a scalar, whereas velocity is a vector. One must use different rules when combining speeds and combining velocities.

The average velocity of an object is the total displacement during some extended period of time, divided by that period of time. Instantaneous velocity, on the other hand, describes the motion of a body at one particular moment in time. Acceleration is a vector which shows the direction and magnitude of changes in velocity. Its standard units are meters per second per second, or meters per second squared. Average acceleration is the total change in velocity (magnitude and direction) over some extended period of time, divided by the duration of that period. Instantaneous acceleration is the rate and direction at which the velocity of an object is changing at one particular moment. In everyday English, we use the term decelerate to describe the slowing of a body, but physicists use the word accelerate to denote both positive and negative changes in speed.

The relationship between displacement, velocity and acceleration is often termed kinematics.
Vector: A study of motion will involve the introduction of a variety of quantities that are used to describe the physical world. Examples of such quantities include distance, displacement, speed, velocity, acceleration, force, mass, momentum, energy, work, power, etc. All these quantities can by divided into two categories - vectors and scalars. A vector quantity is a quantity that is fully described by both magnitude and direction. On the other hand, a scalar quantity is a quantity that is fully described by its magnitude. The emphasis of this unit is to understand some fundamentals about vectors and to apply the fundamentals in order to understand motion and forces that occur in two dimensions.

Vector quantities are often represented by scaled vector diagrams
Vector quantities are often represented by scaled vector diagrams. Vector diagrams depict a vector by use of an arrow drawn to scale in a specific direction. Such diagrams are commonly called as free-body diagrams. An example of a scaled vector diagram is shown in the diagram. The vector diagram depicts a displacement vector. Observe that there are several characteristics of this diagram that make it an appropriately drawn vector diagram. A vector arrow (with arrowhead) is drawn in a specified direction. The vector arrow has a head and a tail. the magnitude and direction of the vector is clearly labelled. In this case, the diagram shows the magnitude is 20 m and the direction is (30 degrees West of North).

Vector Diagram Here is a man walking up a hill. His direction of travel is defined by the angle theta relative to the vertical axis and by the length of the arrow going up the hill. He is also being accelerated downward by gravity. figure

Angular Distance and Angular Displacements
Angular Distance: the angle traversed by a rotating body is called angular distance In other words, it is the angle between the initial and final position measured following the path of rotation

Angular Displacement Two quantities distance and displacement are seemed to be similar in meaning but both are different from each other. The first quantity is scalar while the second one is a vector quantity. Distance shows covered surface in motion while displacement also shows the covered distance but it shows the complete change in the position of moving objects. This is described by both quantities that are a magnitude and direction of motion. It’s a change from initial to final state of motion. When an object is rotated around axis then it is very difficult to analyse its motion because at every point of the path, the quantities like velocity, acceleration is changed. For a rigid body, particles are in constant motion, so the rotation of a rigid body on a circular path is called the rotational motion. But when an object is moved on a curved or circular path then this change in its position from initial to final state is shown by the angular displacement. This rotational quantity is angled at which a body rotates around the axis. Let’s discuss the angular displacement, its formula, and problems based on this.

Angular Displacement Two quantities distance and displacement are seemed to be similar in meaning but both are different from each other. The first quantity is scalar while the second one is a vector quantity. Distance shows covered surface in motion while displacement also shows the covered distance but it shows the complete change in the position of moving objects. This is described by both quantities that are a magnitude and direction of motion. It’s a change from initial to final state of motion. When an object is rotated around axis then it is very difficult to analyse its motion because at every point of the path, the quantities like velocity, acceleration is changed. For a rigid body, particles are in constant motion, so the rotation of a rigid body on a circular path is called the rotational motion. But when an object is moved on a curved or circular path then this change in its position from initial to final state is shown by the angular displacement. This rotational quantity is angled at which a body rotates around the axis. Let’s discuss the angular displacement, its formula, and problems based on this. What is Angular Displacement? We know that the Displacement is the shortest distance from the initial position to final position irrespective of the path taken by it to reach the final position. It is the virtual straight line connecting initial position and the final position. Here we can see the distance travelled (Actual Path) is AB + BC, but displacement is AC. where, AC = AB + BC. Now, What is Angular displacement?, In simple words we can say displacement covered in terms of angle. Thus, the displacement of the body moving in the curved path is represented by Angular displacement. or It is defined as the angle in radians through which a point has been rotated about a specified axis. It is the distance an object moves in a curved path. It is represented by the length of the arc of curved path. The arc is measured in the angle and hence angular displacement is also measured as an angle.

Angular Speed, Angular Velocity and Angular Acceleration:
Angular Speed: the angular speed of a body is defined as the rate at which angular distance is covered It is computed by dividing the total angular distance covered by the time taken Angular Velocity: the angular velocity of a rotating body is defined as the rate at which angular displacement has occurred

It is determined by dividing angular displacement by the time taken
Angular Acceleration: the rate of change of angular velocity is called angular acceleration It is computed by dividing the change in angular velocity by the time taken Angular Motion Vectors: the graphical representation of a vector is denoted in the form of straight line (representative of its magnitude) with an arrow (representative of its direction) The magnitude of the angular motion is represented in the usual way i.e., by the length of the straight line The representation of direction is by the right hand thumb rule According to this rule, the direction of the angular motion vector is represented by an arrow drawn in the direction of the extended thumb of the right hand positioned in such a way that the curled fingers point in the direction of rotation

Clockwise rotation is negative and anticlockwise rotation is positive
Angular velocity can be clockwise or counterclockwise around the axis of rotation. Two directions along the axis of rotation Angular velocity can point either way By convention the direction follows the thumb if the rotation follows the curve of the right hand. Interrelationship between Linear Motion and Angular Motion: majority of movements encountered in sports, are neither linear nor angular, but are combination of two The angular motion of the various segments of the body is coordinated in such a way that it produces linear motion in some other body segment Furthermore, in many activities like hammer and discus, body rotation takes place before the release of the implement

Whereas in certain activities a back swing is executed, as in golf, hockey or in cricket which imparts momentum to the ball Thus the knowledge of the relationship between the two types of motion is important Linear velocity = angular velocity x radius of rotation: the higher is the angular velocity and /or longer is the radius of rotation, the higher will be linear velocity and vice versa Tangential acceleration = angular acceleration x radius of rotation: Tangent : A line, curve, or surface meeting another line, curve, or surface at a common point and sharing a common tangent line or tangent plane at that point. In physics, tangential acceleration is a measure of how the tangential velocity of a point at a certain radius changes with time. Tangential acceleration is just like linear acceleration, but it’s specific to the tangential direction, which is relevant to circular motion. You start with the magnitude of the angular acceleration

which tells you how the speed of the object in the tangential direction is changing.
For example, when you start a lawn mower, a point on the tip of one of its blades starts at a tangential velocity of zero and ends up with a tangential velocity with a pretty large magnitude. So how do you determine the point’s tangential acceleration? tangential acceleration equals angular acceleration multiplied by the radius. Implications of the relationship: In order to achieve the maximum velocity at the time of release in the hammer throw, the hammer should be rotated at the maximum velocity along with the maximum

possible radius of rotation. The same holds true for the discus throw
In situations where the linear velocity is constant, angular velocity is inversely proportional to the radius of rotation In diving, after the diver leaves the board, linear velocity is constant but decreasing the radius of rotation increases the speed of rotation. When the rotation is around the transverse axis of the body, by coming into the tuck position, speed of rotation is increased Centripetal and Centrifugal Force: Centripetal Force: when a body is in motion in a curved or circular path the force which acts towards centre is called centripetal force Centrifugal Force: when a body is in motion in a curved or circular path the force which acts away from the centre is called centrifugal force

Implications: Bending inward in running or in cycling during executing turns helps avoid skidding Need centripetal force to move in this Path, to counter centrifugal force If velocity of cycling is high, the track should be banked(outer high edge) Sitting back against the pull of the hammer helps to resist centrifugal force There is a centripetal force acting on hammer Friction: it is external force and is a resistance to motion. Though, the force in itself resists motion, this resistance is sometimes increased to meet the demands of a specific activity

Although, it is resistive force, but in the absence of this external force the locomotion of the body or an object is not possible Similarly, a decrease in the utilization of this external force is sometimes necessary to obtain an effective performance Therefore, it is very important to know the factors upon which friction depends so that the utilization of this force may be properly channeled to produce a more effective result When a body move or tends to move over the surface of another body, the force that opposes motion is called friction or Friction is a resistance to motion created by the contact between the surfaces of the two bodies in question

When two bodies are placed one over the other, they press one another hard and with the result, a binding takes place between the atoms and molecules of the two bodies at the areas of contact The motion cannot result unless these bonds are broken Because of the pressing together of the two surfaces, deformation occurs and the contact points become ‘cold welded’ This phenomenon is called surface adhesion Force is required to rupture these tiny cold welds to set the body in motion In addition to this bonding effect, there is the effect of roughness The surface of the bodies in question are not as smooth as they appear to the necked eye There are irregularities in the surfaces

The irregularities of the two bodies in the surfaces interlock each other, when placed one over the other A certain amount of force is required to break these interlocks and to set the body/bodies in motion The other reason can be that a hard rough material may pierce holes on the surface of a soft body This resistive force created by the contact between the two bodies is called frictional force or friction Thus friction is not an isolated force but is always because of the contact between the surfaces of the two bodies Types of Friction Sliding Friction Rolling Friction

Sliding friction: when a force is applied on a body to move it over another body, it has the tendency to slide on the surface it is resting upon If the magnitude of the force applied is small, the body will not slide The force that is applied has been counteracted by the friction (as there is no motion in the body, so the friction and the force applied are equal in magnitude and opposite in direction and their algebraic sum is zero) Again, when the magnitude of the applied force is increased and yet the body does not move, it suggests that the magnitude of the friction has also increased ( at rest resultant of all the forces is zero) Thus, as the magnitude of the force applied increases, friction also keeps on increasing and stage comes when the body actually starts sliding

At this stage, when the body has started sliding, frictional force is less than the applied force and thus, it is not able to counteract the applied force Based on these considerations, sliding friction is divided into two types: Static friction Kinetic frictions Static friction: when one body tends to slide across the surface of another body, friction keeps on increasing as the force applied increases until the body actually starts sliding The friction, which is encountered before the body actually starts sliding is called static friction The maximum value of static friction at the verge of sliding is called limiting friction

Kinetic friction: when a body actually starts sliding over the surface of another body, the force of friction is called kinetic friction The value of kinetic friction is always less than limiting friction When a body tends to slide over the surface of another body, the friction is proportional to the normal reaction Factors determining sliding friction: Nature of the surface: smooth surface have less friction than the rough surfaces By a modification of the nature of the surface of one body or both the bodies, the magnitude of friction can be altered

In certain games, where bending of the body is very common, to meet the demand of the activity, there are more chances of slippage, hence there is need to increase the friction between playing surface and the shoes Furthermore, as the speed increases, friction decreases (up to certain limit), when this happens, there is a need to increase the magnitude of friction of the shoes with the playing/running surfaces Implications: The selection of shoes must be according to the playing surface and the nature of movement involved in the activity Rubber soled shoes such as those used in basketball, should fulfill bending (leaning) requirements of the body on the wooden floor

Similarly, cleats used in the football should have sufficient friction with the ground to avoid slippage because of the lean created by the body, this aspect has become more important with the introduction of artificial surfaces in many sports disciplines There is a relationship between the coefficient of friction and the angle of inclination (angle of response) on the surface in question. Sometimes the angle of inclination is also called angle of friction, as two angles are equal in magnitude If the tangent of the angle of inclination crosses the coefficient of friction, the slippage will take place. Thus, to have a higher angle of inclination or a higher degree of bending on a surface without slippage, shoes should be selected in such a way that they provide a greater coefficient of friction with the playing surface

Implications: the handle of the hockey stick, cricket bat, or racquet should be made in such a way so as to provide a proper grip to avoid the possibility of slippage. For e.g., the use of towel cloth in handles of the hockey stick or cricket bat In pole vaulting or in gymnastic exercises (where holding an apparatus is involved) which demands a firm grip, the use of chalk or resin etc., is recommended so as to increase the friction of the hands with the apparatus The base of the skies should be specially treated when manufactured, to increase the smoothness and thereby reduce the coefficient of friction with the snow Force pressing the surface together: the higher the force pressing the two surfaces together, the greater will be the friction

If the force applied by one body is not perpendicular to the surface but is in the lateral direction , the normal reaction will be less and the friction between the two bodies will be less Implications: during rock climbing with the use of rope, the body should be kept away from the rock to avoid slippage When the body is kept away from the rock, the feet are pressing the rock at an angle almost perpendicular to the rock, as the body is almost perpendicular to the rock. In such a position the normal reaction is higher, thus resulting in a greater amount of friction with the rock. Therefore, the chances of slippage are less when the body is perpendicular to the rock than when the body is aligned parallel with the face of the rock Shorter steps should be taken while walking on snow

While standing on surfaces that have less friction, the area of the base should not be increased more than the width of the pelvis. When the area of the base is more than the width of the pelvis, the legs are not perpendicular to the surface but they are in the slanting position. With such a position of the legs, the normal reaction is less ( as there is a lateral component of the force) thus, the friction decreases which may result in slippage Rolling Friction: when a body (ball) rolls or tends to roll over a second body (surface of the ground) the force opposing the motion is called rolling friction. When a body tends to roll on the surface of another body, deformation occurs in the surface of the body/bodies

For e.g., in the wheel of a motor deformation occurs when it rolls on the road. A certain force is required to set the wheel in motion due to this deformation The force required is called rolling friction. The rolling friction is always less than the sliding friction Factors determining rolling friction: Nature of the ball and the surface (ground) involved: if the surface of the ball or the playing surface is rough, the friction is more and vice-versa Weight of the ball: the greater the weight of the ball the more will be normal reaction and thus there will be greater friction and vice-versa Diameter of the ball: the larger the diameter of the ball more will be friction and vice-versa

Air pressure in the ball: the higher the air pressure, less will be the deformation and less will be the friction and vice-versa Implications: playing style should be changed according to the nature of playing surface In sports the nature, the weight, and the diameter of the ball are fixed by the rules of the game. Furthermore, a player has to play on the available playing surface, which may also be fixed by the rules. In such situations, the playing style may be changed. In cricket, for e.g., if the grass is long, thick, and wet, the ball should remain in contact with the ground for the shortest possible time. The same holds true for hockey played on grass and for golf

UNIT-IV: INVESTIGATIONAL PROCEDURES IN SPORTS BIOMECHANICS
Anthropometric procedures: Experimental procedure and analytical procedures Kinematic Methods: Determination of angular distance: Goniometry Measurement of time Determination of velocity and acceleration Imaging Measurement Technique: Cinematography, Single plate methods, Video, Optoelectronic technique Kinetic Methods: Dynamometry

INVESTIGATIONAL PROCEDURES IN SPORTS BIOMECHANICS
There is a high degree of relationship between the progress made in the field and the measurements techniques or investigational procedures in that field The same relationship exists in sports It is becoming more and more important to evaluate sports performances on scientific basis and to find the ways and the means for further improvement in athletic performances In this regard many scientific disciplines like physiology, psychology, biochemistry, anthropometry, sports medicine, biomechanics etc., are playing vital role There is a lot of progress being made in the measurement techniques of various sports disciplines to increase the accuracy of measurement, to make these more sports specific, with minimum interference to the performer and to be applicable under actual playing conditions

In these days of automation, a lot of progress has been made in the telemetric devices and in the computer techniques Investigational procedures of many scientific disciplines of sports are using more and more of these techniques in the evaluation of sports performances As the sports biomechanics studies the mechanical movement of the living beings, thus it requires the measurement of various mechanical values The procedures in sports biomechanics can be grouped under two categories kinematic procedures and kinetic procedures Besides these two categories, there is a special group of procedures , which deals with the determination of various body segment parameters or anthropometric measures i.e., anthropometric procedures

Anthropometric Procedures: these procedures deal with the determination of lengths of different body segments, their partial masses, moment of inertia, mass centres of body segments, and centre of gravity (C.G) of the whole body. The information about these parameters is required to compute various kinematic and kinetic parameters In physics, a center of gravity of a material body is a point that may be used for a summary description of gravitational interactions. In a uniform gravitational field, the center of mass serves as the center of gravity. This is a very good approximation for smaller bodies near the surface of Earth, so there is no practical need to distinguish "center of gravity" from "center of mass" in most applications, such as engineering and medicine

Determination of length, mass centre and moment of inertia: the height of an individual (body length) and the length of various segments of the body between two anatomical markers can be determined by using stadiometer, or anthropometric rod and calipers As far as the determination of mass of whole body is concerned general method i.e., using balance or a weighing machine is well accepted procedure. However estimation of different body parts (partial masses of body segments), mass centers of different body segments, moment of inertia of different body segments and centre of gravity of whole body (mass centre of whole body) requires special procedures These procedure can be classified into two Experimental and Analytical Procedures Experimental Procedures: these procedures are classified into two types: technique with cadavers and techniques with living subjects

ANTHROPOMETRIC ROD STADIOMETER

Caliper Digital Caliper

Skin fold caliper

Technique with cadavers: mass, mass centre of different body segments and their moment of inertia around an axis passing through their mass centre can be estimated by using cadavers or dead bodies The cadavers are cut into different body segments between two anatomical land marks. The mass of each segment can be found out by using weighing machine. The position of centre of mass is estimated by balancing the body segment on a knife-edge. The moment of inertia is found by suspending a body segment as a free swinging pendulum and recording the period of oscillation. Many workers have used these procedures to obtain information on body segment parameters However, a limited number of cadavers were used in these studies The main objection to this approach is whether the data on cadavers can be applied to living subjects Further, the data, which is available in literature, is not only on limited number of subjects but also on few selected races

Techniques with living subjects: keeping in view the limitations of the results obtained on cadavers, certain techniques have been proposed on living subjects Each technique has its own advantages and limitations Reaction change method: this method is used to estimate the position of mass center or centre of gravity (C.G) of whole body and determination of the mass of distal body segments Estimation of C.G., of the body: this procedure is experimental method and is also called board-and-scale method. This is based on principle that when a body is in equilibrium the sum of moments acting on the body is zero In this procedure a large board, the one edge of which is supported on a knife-edge and the second edge on a scale (weighing machine) is used

The scale reading is noted (initial reading)
The scale reading is noted (initial reading). To determine the position of C.G., in vertical direction the subject lies supine on the board with the heels pressing a foot-rest (axis) away from the scale and the second or the final scale reading is noted The moment acting on the board about the foot-rest (axis) will be due to the reaction force acting at the opposite end. As the system is in equilibrium state, the sum of clockwise moments will be equal to the sum of anti clockwise moments Thus with this approach we are able to determine the position of C.G., above the soles of the feet Using the same procedure when the subject acquires the upright position the location of C.G., can be determined in the frontal (front to back) and the lateral (right to left) directions axes.

The assumption is that change from supine position to upright posture will not shift the position of C.G., However, due to the shift of the body fluids in the downwards direction the position of C.G., is little lower in the upright position than in the supine position In another approach that involves the use of large board, the location of C.G., can be determined simultaneously in two directions and in different body postures In this adaption, a triangular board is used which is supported on one end on a knife-edge and its other two ends are supported on the scales. If a rectangular board is used then its three ends are supported on the scales The initial scale readings are noted on both the scales when the board is not loaded. Again the final scale readings are noted when person lies on the board

The moments along the two axes are computed as follows:
X= (Raf-Rai) distance of C.G., from the edge of board W Y= (Rbf-Rbi) distance of C.G., from the edge of board Scale A and scale B In the case of triangular board that is equilateral, s1 and s2 (length and breadth of the board) are equal and these represents the altitude of the triangle For analysis purpose the subject is filmed during the execution of the movement. The frame, which is to be analyzed, is projected on the board with image size equal to the life size(1:1).

Boundaries are drawn to make the figure representing the body posture and the subject assumes the required position on the reaction board. The main limitation of this method are that it is very time consuming and requires the continuous presence of the subject Determination of mass of the body segment: in this case, the subject lies supine on the reaction board and the scale reading is noted. The desired distal segment for example arm or leg is lifted to a near vertical position so that the mass centre of the arm or leg and the joint centre lie in a line and the scale reading is noted The mass of the segment is computed as follows: W= (Rf- Ri)l Xi-xf The main limitation of this procedure is that to compute the mass of a body segment the position of its mass center should be known by some other method

Secondly, the method is applicable to determine the mass centre of extremities or distal segments
Immersion technique: this technique is based on the Archimedes principle. In this technique, a body segment is immersed in a tank or cylinder of water and the weight/volume of the water displaced is recorded which is equal to the volume of body segment The volume of the body segment, when multiplied by its density gives the mass of the body segment The density of the body is either taken as 1 gm/ml( density of water at 4 degree C) or the values of the density reported in literature While using this technique error is encountered while recording the overflow of water and also due to the movement of body segment when being immersed in water

To minimize these sources of errors modification of this basic technique have been proposed in which two cylinders, one measurement and other supply cylinders are used (Drillis and Contini, 1966) Certain workers have used the immersion technique to estimate the position of mass center of a body segment by recording the difference in the weights of the body segment in the air and water Radiation technique: this technique is based on the principle that the gamma rays through a body is dependent upon the mass of the body and is independent of its elemental composition In this technique, gamma rays of known intensity are focused on a small part of a body segment, and transmitted rays are monitored

The beams of the rays are focused on a small portion of a body segment in a small increment of distance i.e., scanning of a body segment with simultaneous recording of the coordinates With this the mass of the body segment, mass centre and moment of inertia can be computed Using this procedure Zatsiorsky and Seluyanov (1986) have studied 100 subjects and have reported body segment parameters along with regression equations to predict body segment parameters on the basis of height and weight of a person

Analytical Procedures: as it is not possible to obtain experimentally the estimates of body segment parameters for each and every subject, analytical procedure have been used to obtain the estimate of mass and inertial characteristics

Estimation of body segment parameters: the most common approach is to assume that fixed relationship exist between the mass of the body segment, and that of the mass of whole body. These relationships have been determined mainly from the existing cadaver data. On this basis the appropriate segmental mass proportions have been computed for different body segments As in this approach the total body mass is a single variable to predict segmental masses, certain workers have included various anthropometric measurements to minimize the magnitude of error Based on similar logic, relationships have been computed between the length of a body segment and the position of its mass centre. Usually in biomechanics, the body landmarks are taken as the end points of a segment and the mass centre is assumed to be on the longitudinal axis of the line joining these points

Similarly, based on the cadaver data on segmental lengths and segmental masses, relationships have been computed to determine moment of inertia. The usual practice is to determine radii of gyration from moment of inertia expressed as proportion of segmental length The moment of inertia of different body segments around an axis passing through the mass centre of segment and perpendicular to the long axis of the body segment is presented in table To compute moment of inertia around any other axis not necessarily passing through mass center is computed by parallel axis theorem Parallel axis theorem: this theorem is useful to calculate the moment of inertia of body segment/segments about various joints. The data on moment of inertia of different body segments about axes passing through their mass centres is available in literature

However, the body segment rotate about the joints and not about their mass centers. According to this theorem the moment of inertia about any axis, which is parallel to an axis passing through mass centre, can be calculated as follows: I= I0-mx2, I0 is moment of inertia about the mass centre, m is mass of the body segment, x is distance between an axis passing through mass centre and a parallel axis I is moment of inertia about a parallel axis Thus with the help of this theorem we can calculate the moment of inertia of a body segment/ segments about various joints. For example if we want to compute the moment of inertia of a kicking leg about the hip joint, which is the axis of rotation in kicking we can utilize this equation as follows:

I1= I0t+mt(xt)2 + I0s+ ms(xs)2 + Iof+ mf (xf)2
I1= moment of inertia of the leg around hip axis Iot= moment of inertia of the thigh around its mass centre Ios= moment of inertia of the shin around its mass centre Iof= moment of inertia of the foot around its mass centre mt= mass of thigh ms= mass of shin mf= mass of foot Xt= distance between an axis passing through mass centre of thigh and hip joint Xs= distance between an axis passing through mass centre of shin and hip joint Xf= distance between an axis passing through mass centre of foot and hip joint

Estimation of position of C. G
Estimation of position of C.G., of the body: this procedure is also called segmental method. In contrast to the experimental method, it does not require the presence of the performer when the measurements are taken. In this procedure the location of C.G., in two axes can be determined on a photograph or on a desired frame in the film, thus making it suitable to determine the location of the C.G., in various body positions during the execution of a movement This procedure is also based on the principle of moments The sum of moments of individual body segments about two arbitrary axis (X and Y) is equal to the resultant moment of total body about the same axes. To compute the moments of individual body segments, masses of these segments and their mass centres (segmental C.G) should be known

As to obtain data on segmental masses and their mass centers for every individual is very time consuming usually the ratio or percentages are taken. These values have been obtained from various methods In this approach, two arbitrary axes are drawn on a photograph or desired frame of the film. The various joints of the body are marked and the straight lines connecting the body joints are drawn. The length of each body segment is measured and the positions of mass centres of various body segments are marked. The distance of mass centre from the chosen X and Y axes are measured for each body segment and are recorded These distances are multiplied by the relative masses of the respective body segment to compute the partial moments

The summation of these partial moments is equal to the moment of the whole body about these arbitrary axes. when this is divided by the total mass of the body 1(in case of relative mass are taken) or it will be 100 ( if the relative masses are taken in percentages) gives the distance between the position of C.G and the arbitrary axes. Usually a table is used to calculate the position of C.G. In a modification to the above procedure, the force acting on the mass centre of each segment is divided into two parts, each force acting on the proximal and the distal joints. In place of partial mass, the forces acting on two adjacent joints are used and the moments are computed about the two arbitrary axes by multiplying the forces with the distances from the axes

The measurement and the computation procedure are similar to the previous method. This procedure is called joint point method in contrast to the previous method as the main point method. As in the previous method, a table is used to record and calculate the position of C.G. In situations where the performer holds an implement the common C.G., (performer and the implement) is calculated by knowing the mass and the mass centre of the implement. This is calculated by the following formula: X= ( a x W1) (W+ Wi) Y= (b x Wi)

X= displacement of C.G., in horizontal direction
Y= displacement of C.G., in vertical direction A= distance between the horizontal line passing through the C.G., of the athlete and the implement B= distance between the vertical line passing through the C.G., of the athlete and the implement W= weight of the athlete Wi= weight of the implement The manual computation to determine the position of C.G., by this procedure is time consuming as it involves a lot of measurements and calculations. In practice, film motion analyzers are used with inbuilt X-Y coordinate systems and the digitizer To further facilitate each digitized point is fed to computer and by using special computer program, the position of C.G., can be determine instantaneously

Further, the path of C.G., in any moment can be determined and can be presented in a graphical form. In case of video films, the images after grabbing to the computer are digitized and using special software the position of C.G., can be determined in each frame of video Kinematic Methods: distance and time are the two basic values and from these two basic values, various kinematic values such as velocity, acceleration can be derived Determination of distance: the common method to measure distance is by using a tape or a scale. However, in the technique evaluation these cannot be used as the distances to be measured are small and the body is not stationary but is in motion. Usually imaging measurement techniques are used

Determination of angular distance: usually the imaging measurement techniques are used to measure the angular distance. Besides this, goniometry, a direct method to record angles is also used to measure angular distance Goniometry: a goniometer is a device to measure the joint angle. A simple goniometer has two arms and a protractor. One arm of the goniometer is fixed with protractor and the second arm is free moveable. These two arms are called fixed arm and moveable arm or wiper arm. The centre of the protractor or the axis of the goniometer is aligned to the centre of joint axis. The two arms of the goniometer are strapped to the two adjacent limbs e.g., forearm and the upper arm. When the angle at the body joint changes as during the bending of arm, the angle covered or the angular distance can be obtained by taking the reading on the protractor

Usually electrogoniometers are used
Usually electrogoniometers are used. By using electrogoniometers the change in the angular displacement with the time can be recorded. In an electrogonimeter, a potentiometer is attached to the two arms of the goniometer. A constant voltage is applied across the potentiometer and the wiper arm picks up the fraction of voltage The magnitude of this fraction of voltage is proportional to the angle at the joint. This voltage can be displayed or recorded. The advantage of goniometry is that data regarding the angular distance or the angle at a joint is immediately available. The disadvantage is that these are to be strapped with the body segments along with the wires in the case of electrogoniometers, thus restricting the movement.

Now a day biaxial and triaxial electrogonimeters are available and by using these angular displacement in different axes at a joint can be obtained simultaneously. The output is stored in the memory card of portable data logger (recording unit) and is downloaded to computer Measurement of time: time is a basic quantity by which other mechanical quantities such as velocity, acceleration etc., are computed by differentiation, if the distance covered are known. Similarly, distance or velocity can be computed by integration from the acceleration-time data. The time data is also utilized to obtain average velocity over a certain distance The simplest approach to measure time is by the use of stopwatches or timers. However, this approach is useful only when intervals of time recorded are large

To record short intervals of time manually by a stopwatch or a timer leads to a large measurement errors. The major source of error is the reaction time of the individual using the watch. Besides inter-individual differences, reaction time will vary in same individual in different trials. Thus, to overcome this source of error the watches (timers) should be started and stopped automatically. The most common approach is to use light barriers or optoelectronic devices The light barriers consists of a light source, reflector, and a photoelectric cell. The light source and the reflector are placed opposite to each other in a path of motion may be on the two sides of the track, and the photoelectric cell that acts as a receiver is usually in the same unit with the light source.

In a normal situation, the reflected lights is registered by the photoelectric cell and a certain amount of current is registered. When the athlete or an object come in between the light source and the reflector, the reflected light does not fall on the photoelectric cell and the current is not registered. Such a change in current can act as a trigger to switch on or to switch off a timer. Normally such light barriers are put in series and are attached to a multi-channel timer. With such a serial arrangement of the light barriers, the partial or split timings over a certain distance can be recorded. Usually in place of ordinary light the infrared light sources with appropriate reflectors and photoelectric cells are used so that recordings can be made during day light

In case of symmetrical objects, there are no problems to place such light barriers to record partial or split lights. The light barriers are put to such a height so that the objects comes in between the light source and reflector during course of its motion. However, in case of human body, any body part may come in between the light source and the reflector to give a trigger to the timer. The barriers, which are put in series, should be put in such a way that each barrier is triggered by the same body part. Thus, the height of the light barrier is of crucial importance and this is especially important when the measuring path is small. The chest level is not ideal to record time in running as the swinging arms may also trigger these barriers.

Usually these are placed at the head level
Usually these are placed at the head level. However this problem has been overcome with the availability of double beam and triple beam barriers. Sometimes the timer can also be triggered with the sound of the starting gun and subsequently triggered on and off with the light barriers. In another approach to record short interval of time micro switches with appropriate make and break circuits are connected to multi-timer. These switches are usually event regulated. Foe example at the first contact of the foot on the ground at take off, the timer may be switched on, and when the foot leaves the ground, the timer may be switched off. Similarly in other activities, these switches may give trigger to the timer on the important phases of the movement

As it is not permitted to use the above approach to record time in the competitions, the imaging measurement techniques are used. Furthermore, when the path of motion is very small or time interval to be recorded is small, imaging measurement techniques are preferred Determination of velocity: there are various approaches to determine velocity. In an indirect approach, average velocity can be determined by the time taken to cover a certain distance. This can be achieved by using multi channel timer, triggered by the photocells pr by electromechanical switches. The velocity can also be determine by Doppler radar For direct registration of velocity, speedograph is used. In this approach, a cable is attached to a fixed part of the body of the performer or the implement. When the movement of the performer pulls the cable the rotation of the pulley takes place.

The revolving speed or the angular velocity is proportional to the linear velocity of the performer or of the implement. The angular speed of the pulley is determined by using a techogenretor. The techogenretor gives a voltage proportional to the angular velocity of the pulley, which in turn is proportional to the linear velocity. The advantage of this of this procedure is the direct registration of velocity instantaneously. However, there are problems to maintain the linear conditions. For example, when the distance covered is large, there are problems of vibrations in the cable. Further, when the motion is not rectilinear, as is in the common case in sports movements the linear conditions will not be maintained and this will result in an errors.

Further, as a cable is attached to the performer there are bound to be the interference to the movement of the performer. This method is applicable only in certain movements e.g., in sprint start, weight-lifting etc. However this approach is no longer used for sports movements and is of only historical importance The most widely used procedure in sports biomechanics to determine velocity is the use of imaging measurement techniques. In this approach, the velocity in any direction is computed by dividing the distance covered in any direction by the time taken to cover that distance. Usually small intervals of distance and small intervals of time are taken in the computation Determination of angular velocity: angular velocity is computed by dividing the angular distance or the angle covered by the time taken. The most common approach to find the angular distance and time is the use of imaging measurement techniques

Determination of acceleration: when a force acts on a body, it produces acceleration in the body. Further, acceleration in a body is equal to rate of change of velocity. Based on these, there are two methods or approaches to determine acceleration. In the first approach the force exerted by a constant mass when being accelerated is measured. The mass is accelerated against a force transducer that gives a voltage signal proportional to the force. As the mass is constant, the force exerted is proportional to the acceleration. Thus, a voltage signal proportional to the acceleration is obtained. The signal can be displayed by using oscilloscope, or can be recorded by using an X-Y recorder or can be fed to a computer using analog digital card (ADC) for further computation

In the second approach rate of change of velocity is computed which is equal to acceleration. Usually imaging measurement techniques are used to compute acceleration. In this approach, velocity of moving body is computed at different intervals of time and acceleration is computed by taking the differences in the velocity and the time Imaging Measurement Techniques: the Chinese proverb ‘a picture is more than ten thousand words’ gives a very important message to bio mechanists. The imaging measurement techniques give description of human movement in a very purposeful manner i.e., presentation of the body position or of the body part in space and time Under this, there are four techniques: Cinematography, Single plate methods, Video, and Optoelectronic technique

Cinematography: is the art or science of motion picture photography
Cinematography: is the art or science of motion picture photography. It is the technique of movie photography, including both the shooting and development of the film. It has been used more frequently than any other procedures for the quantitative analysis of human motion. Though, other photographic and non-photographic methods have been applied for the evaluation of technique but it has many advantages over the others. It has better resolution than any other photographic method. In contrast to non-photographic methods it is non-contact, remote process of recording data and allows full freedom of action to the subject and can be utilized during the competition situations even without the knowledge of the performer and without any physical and mental interference to the performer Conduct of cinematographic study:

Cine cameras: these are available in 8mm, super 8, 16mm, 35mm, 70mm (depending upon the film which these employ). Though 8mm, super 8, are least expensive but the image size is small and also these have become obsolete. The 35mm, and 70 mm, cameras offer a large image size but are expensive. Usually 16 mm cameras are used for biomechanical research purpose as these offers a compromise between the cost and the image size Characteristics of a cine camera: It must have stabilized frequency It must provide a range of frequency between frames per second (f.p.s or fps). The preferable upper limit is 500 fps It should provide time information on the film itself It should synchronize with another cameras or the other measurement device e.g., dynamometric platform or electrogonoimeters

Types of cameras: there are three types of cine cameras i. e
Types of cameras: there are three types of cine cameras i.e., intermittent pin-registered, rotating prism and streak cameras Intermittent pin-registered: the film in this camera is moved into the exposure gate by a pull down claw, which inserts into one of the perforations at the edge of the film. When the film is in position, the pull down claw retracts and the pin inserts into the film perorations in order to hold it steadily while the shutter opens to expose the film. The result of this action is a constant stop and start (or intermittent motion of the film) This type of mechanical movement puts constraints on the maximum possible speed of these cameras. Usually these cameras operate up to 500 frames per second. The advantage of these cameras is that these produce extremely high resolution

Rotating prism cameras: it provide a frequency up to 2500 fps with a short exposure time. The disadvantage of these cameras is the poor resolution than the intermittent cameras Streak cameras: these are used to study the self-luminous events in the linear motion. The camera does not record the picture of the event but a streak is recorded of the moving light. These cameras operate in the range of pictures per second up to 1 million pictures per second For evaluation of techniques in sports, usually pin registered cameras are used as these give good resolution as well as the range of camera speed is sufficient for most of the events encountered in sports. These cameras may be spring driven or motor drive type. Usually motor driven cameras are preferred as these have better consistency to maintain speed or frame rate. The speed of the camera is not much affected by the environmental conditions in contrast to the spring driven type

Lens: the choice of the lens depends upon the purpose and the filming situations but there are certain important factors, which gives guidelines for selecting lens for a given situation Distance from the object: usually the distance between the object and the camera is kept large to keep distortion or the perspective error to the minimum. Thus, preference goes towards a tele lens Recording area: depending upon the movement and the purpose of the study, field of view or the area to be covered is chosen, and accordingly the selection of the lens Usually zoom lenses are used as with zoom lens desired area can be obtained by keeping the camera and the object distance large Camera speed: the selection of the speed of the camera or its frequency (fps) depends upon the movement to be recorded

When the object moves across the field of view of the camera, it produces a blur on the film and the degree of blur depends upon the velocity of the object, duration of exposure and the image magnification. Usually the blur is confined to 0.005cm. As a rule, faster the speed of the movement, higher is the requirement of the operating speed of the camera, otherwise the resolution will be poor. Furthermore, it depends upon the purpose or what are the parameters to be obtained from the recorded film. Usually the camera is operated between 80 fps to 200 fps but for special purpose higher speeds are also used. If the camera is operated at a higher frequency than the required, then it is not only wastage of film but error (noise) also increase and the data reduction becomes more time consuming and complex

Exposure time: it is dependent upon the frame rate and the shutter opening. Usually exposure meters are used to find the desired exposure time and to select the aperture under the light conditions, frame rate, speed of the film(film rating) and the selected shutter angle Camera position: for biomechanical evaluation, camera should be placed perpendicular to the plane of motion of the object. In case it is not possible to position the camera perpendicular to the plane of motion then a necessary correction should be made using trigonometric rules. Camera and subject distance should be kept large to minimize the perspective error. Lens should be selected in such a way that at such a distance sufficiently large image size is available for easy and accurate analysis. To shoot from a large distance tele photo lenses are used

Camera should be mounted on a tripod
Camera should be mounted on a tripod. Tripod should be strong and sturdy enough so that there is no vibration or movement of camera during its operation. Furthermore, under normal conditions for biomechanical evaluation panning of the camera is not recommended. In case camera is not placed perpendicular to the plane of motion and camera is panned or tilted during the course of movement, then mathematical procedures are used in the analysis. Now a days with the availability of commercial software, the cameras are panned and tilted during the recording, and the software itself makes the necessary correction during analysis Measurement of time: to obtain various kinematic values, displacement and the time information are the basic requirement. High speed films are of little value unless the time spectrum in which the motion occurs is known

There are various methods used to obtain time information
There are various methods used to obtain time information. The time spectrum can be obtained from the operating speed of the camera. Usually the operating speed of the camera is not consistent. This variability is much more pronounced in the case of old spring cameras. The camera frequency is affected by many factors e.g., general condition of the cameras, battery voltage, temperature, film material etc. in the earlier approach, to know the operating speed of the camera an object was dropped from a known height and was filmed. Time was calculated using the equations of uniform accelerated motion By counting the number of frames filmed and the time elapsed, the camera speed was calculated. In another approach a running stopwatch was filmed either before or after the execution of the movement and from this camera speed was computed. In certain situations, a large timer, preferably a luminous one was placed in the field of view of the camera and from this time information was obtained at every frame of the film

In the modern cameras the timing information is recorded on the edge of the photographic film itself by using a tiny built-in-lamp (neon lamp or light emitting diode). The lamp is flashed at a constant rate with a timing light generator. From the number of flashes on fixed number or flashes on fixed number of frames and the flashing rate, camera speed can be computed. This is the most widely used approach in the modern cameras. This approach is more appropriate than other methods as information about frequency fluctuations from frame to frame can be observed. Distance calibration factor: to know the actual distance transversed by an object, the relationship between the true length and apparent length on the film is found out. This is achieved by filming a known distance placed in the photographic field either before or after the execution of the movement

The well-known distance is placed in the plane of motion
The well-known distance is placed in the plane of motion. Usually a bar painted alternatively black and grey paint is used. Sometimes at the ends of the bar, rectangular boards are fixed. In many situations various apparatus or implements used by the performer are also used to get this relationship. These may be hurdle, pommel horse, or javelin as used in the competitions Reference axes: Horizontal axis and the vertical axis must be available on the recorded film to compute various goniometric and kinematic parameters. Furthermore, certain points must be available on the film, which during the course of the movement remain stationary to study the relative motion This is usually obtained by placing boards on both the sides near the performance area and in the photographic field

In certain cases, a building or stem of a tree or an apparatus or any other stationary structure depending upon the prevailing conditions may be used. The main consideration is that reference point or object should not move during the execution of the movement and should be visible at every frame of film Three dimensional cinematography: usually the sports movements do not occur in two dimensions but they are executed in three planes or in the three dimensions. For detailed analysis many a times three-dimensional information is required or in other words all the three X, Y, Z coordinates should be available for any point during the course of its motion. Various approaches have been used by different workers to obtain the spatial coordinates. These are:

Using a single camera and noting the angular displacement by the ratio of the true length and the observed length and using the trigonometric relationship, using a large mirror to obtain the second image, using stereo metric cameras, and using multiple cameras Because of the limitations of the various methods using one camera to obtain the three coordinates, most of the workers are of the view that more than one camera should be used if the three dimensional information is required Certain workers have used two synchronized cameras placed perpendicular to each other. The two cameras are synchronized as they start with the trigger of flash. However, there is time lag so good cameras are gen locked

With the availability of commercial software and fast computers it is not necessary to keep the cameras perpendicular to each other. Furthermore, the cameras can be panned and tilted. The point visible in both the cameras is used to drive the three orthogonal coordinates. To obtain distance calibration factor, in place of filming a know distance as in two dimensional cinematography the cube of known dimensions is used. Most of the workers however prefer three synchronized cameras placed perpendicular to each other in order to obtain three spatial coordinates Analysis: once a film is exposed keeping in view the calibration of the camera, distance calibration scale, fixed points, and the reference axis, after development it can be used for biomechanical analysis.

This film is projected on an analyzing projector having a frame counter, and the facility to advance the film in cine mode as well as frame by frame. The X Y coordinates of a point, body joint or an implement under consideration are measured in the desired frame. The process is repeated by advancing the film frame by frame. The process of measuring the X and Y coordinates manually is time consuming and hence film motion analyzers are used. With the film motion analyzers X and Y coordinates values along with the frame number are fed to a computer directly by using a suitable interface. The stored data can be further computed and the results can be further printed and plotted. The computer programs are used to compute and plot various biomechanical parameters

Before computing various kinematic parameters, the data is to be smoothed to minimize noise. There are various smoothing procedures such as digital filtering and spline functions and these are usually part of the computer programs or software. Multiple Exposure or Single Plate Methods: in these methods, unlike the cinematography whole movement is recorded on a single picture (or frame). A still camera is used and its shutter always remains open and special procedures are employed for controlling the light passing through the lens. These are stroboscopy or flash light photography, rotary slit shutter or chronocyclo photography, light streak photography, and interrupted light photography or impulse light photography

However these approaches are of historical importance and are not used in these days as these approaches have many inherent limitations and are mainly suitable for qualitative analysis. Video: video and the cinematography have many similarities among them. The filming procedure is the similar in both the cases. The major advantages of video over cinematography is its capability of instant replay. The difference between video and cinematography is that unlike cinematography video camera has a fixed frame rate. The normal television camera having a frequency of fields per seconds (Hz) is useful for qualitative analysis but not for quantitative analysis as the field rate is not sufficient for most of the athletic events.

However, with the introduction of high speed video cameras and the analysis units these are now used for quantitative analysis. The availability of the digital cameras has replaced the conventional cameras and VCR and the cost have also come down. Further the images from the cameras can be directly grabbed to computer or to a laptop. The size and weight of digital cameras is very small and its compatibility with the laptop has made the recording unit very portable. As no celluloid film is used in the video cameras the running cost is negligible. Hence three dimensional video systems have almost replaced the cinematography Optoelectronic Techniques: in these techniques, special tiny light bulbs are placed on the desired body parts/joints or on the implement.

The lights are flashed at controlled rate
The lights are flashed at controlled rate. The X and Y coordinates are picked up and are fed to a computer. The most widely approach is to pick up X and Y coordinates on the diodes using special cameras. Kinetic Methods: Dynamometry: to measure kinetic values, the procedures of dynamometry are used. The force measuring device is called force transducer. There are two basic requirements for any force transducer. These are as follows: There should be proportional dependence of the force applied and the measured value The measured value should show a simultaneous change to the changing force and force-timer curve should be distortion free

The first requirement is the prerequisite for any measurement device
The first requirement is the prerequisite for any measurement device. The second requirement is for the dynamic transmission or for the measurement of dynamic values. This requirement is very important in sports biomechanics as the force applied by the human body keeps on changing during the course of any movement The earlier types of transducers were made on mechanical basis but now a day these are made on electrical basis. The basic principle behind these transducers is that it give electrical signal proportional to the applied force, these may be inductive, capacitive, piezoelectric, or piezoresistive types. In biomechanical investigations, mostly strain gauge and piezoelectric types are used

The strain gauge transducer consists of a thin resistance wire attached to a body in foil. When a force is applied on the body it results in a change in the electrical resistance of the wire. This change in the electrical resistance is proportional to the applied force. By using wheat stone bridge circuit and voltage amplifier, a voltage proportional to the force is obtained which can be displayed using a oscilloscope or can be recorded using a X-Y recorder or the signals can be fed to a computer using ADC for further computations The principle of piezoelectric transducer is that when a force is applied on certain crystals it results in the development of electric charge on the surface of the crystal. The magnitude of the electric charge is proportional to the force applied

Moreover, the magnitude of electric charge along any surface of the crystal is dependent upon the component of force acting along that surface. The most commonly used crystal is quartz. The electrical charges are so small that these cannot be measured directly. These are amplified by using charge amplifiers, and finally voltage proportional to the force applied are obtained, which can be displayed or fed to computer using ADC The piezoelectric types of transducers are more favorable than the strain gauge types in the measurement of force in biomechanics as these have better dynamic transmission characteristics . However in sports biomechanics both types of transducers are widely used The proper cutting of these crystals and the proper arrangement of the transducers can measure the force in different directions

Besides the force distribution, the data regarding the time of support, time of flight, frequency and other parameters regarding gait analysis can also be obtained. The data from the data logger is downloaded to the computer and commercial software computes the same. The goniometer and electromyographic electrodes can also be attached to the data logger unit so simultaneous data regarding force distribution; angular changes at the joint and muscular strength can be obtained. Such a system is called computerized dynograph The measurement of ground reaction force is important in many activities as in jumping, running, walking, throwing etc. This is measured by using force platform or dynamometric platform

In the force platform, tri-axial transducers are used to measure force in all the three directions i.e., vertical, anterior posterior, and lateral directions. Besides the magnitude of force the point of application of force can also be obtained by the force platform

Torque is a measure of how much a force acting on an object causes that object to rotate. The object rotates about an axis, which we will call the pivot point, and will label 'O'. We will call the force 'F'. The distance from the pivot point to the point where the force acts is called the moment arm, and is denoted by 'r'. Note that this distance, 'r', is also a vector, and points from the axis of rotation to the point where the force acts. (Refer to Figure 1 for a pictoral representation of these definitions.) Angular motion is the motion of a body about a fixed point. The motion of pendulums and planets are examples of angular motion. Angular motion can also be used to describe the angle made during the motion of a body about a fixed axis.

Linear motion (also called rectilinear motion) is a motion along a straight line, and can therefore be described mathematically using only one spatial dimension. Curvilinear motion is defined as motion that occurs when a particle travels along a curved path. The curved path can be in two dimensions (in a plane), or in three dimensions. This type ofmotion is more complex than rectilinear (straight-line) motion. In physics, circular motion is a movement of an object along the circumference of a circle or rotation along a circular path. It can be uniform, with constant angular rate of rotation and constant speed, or non-uniform with a changing rate of rotation.

In rigid-body dynamics, the terms circular motion and rotational motion both describe the motion of a body about a fixed point, but there is a difference between the two motions. The main difference between circular motion and rotational motion is that circular motion is a special case of rotational motion, where the distance between the body’s centre of mass and the axis of rotation remains fixed. Rotation or Rotational Motion refers to the motion about a fixed point. An axis of rotation is a line passing through this fixed point, perpendicular to the plane in which the body is moving. The term rotational motion can be used to describe the rotation around a fixed axis, precession (where the orientation of the axis of rotation changes), and nutation (where the axis of rotation wobbles).

fully automatic timing camera system
Light beam timing system

Cinemtography

Distance calibration

Videography Optoelectronic

Dynamometry

force transducer

Sports Biomechanics and Kinesiology

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