1. Chapter One
What is Biomechanics?
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2. Objective of Chapter One
Define the terms biomechanics, statics, dynamics, kinematics, and kinetics, and explain the ways in which they are related.
Describe the scope of scientific inquiry addressed by biomechanists.
 Distinguish between qualitative and quantitative approaches for analyzing human movement.
 Explain how to formulate questions for qualitative analysis of human movement.
 Use the 11 steps identified in the chapter to solve formal problems.
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3. Mechanic Bio What is biomechanics?
The term biomechanics combines the prefix bio, meaning “life,” with
the field of mechanics, which is the study of the actions of forces, (both internal muscle forces and external forces.) In biomechanics we analyze the mechanical aspects of living organisms.
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4. Sub-branches of biomechanics:
• statics: study of systems in constant motion, (including zero motion)
• dynamics: study of systems subject to acceleration
• kinematics: study of the appearance or description of motion
• kinetics: study of the actions of forces (Force can be thought of as a push or pull acting on a body.)
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5. What Do We Measure/Calculate?
Anatomical landmarks:
Position (displacement), velocity, acceleration, orientation (angles).
Segment parameters
Size (length, diameter, etc.), mass, centre of mass, moment of inertia, bone geometry (for muscle moment arms)
Joint kinetics
Joint reaction forces, net joint moments, joint contact forces
Muscle activity
Material properties
Bone, cartilage, muscle, tendon, ligament, fat, skin
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6. What is kinematics?
What we visually observe of a body in motion is called the kinematics of the movement. Kinematics is the study of the size, sequencing, and timing of movement, without regard for the forces that cause or result from the motion. The kinematics of an exercise or a sport skill is known, more commonly, as form or technique.
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7. Vicon Camera System
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9. What is kinetics?
Kinetics is the study of forces, including internal forces (muscle forces) and external forces (the forces of gravity and the forces exchanged by bat and ball).
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12. Finite Element Modeling
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13. Kinematics and Kinetics
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14. Anthropometry
Anthropometry: refers to the measurement of the human individual
A head-measuring tool designed for anthropological research in the early 1910s. Theodor Kocher was inventor of the craniometer
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15. Kinesiology is the study of human movement.
What is kinesiology
Kinesiology, also known as human kinetics, is the scientific study of human movement. Kinesiology addresses physiological, mechanical, and psychological mechanisms. Applications of kinesiology to human health include: biomechanics and orthopedics, strength & conditioning, sport psychology, rehabilitation, such as physical and occupational therapy, as well as sport and exercise.
Kinesiology is the study of human movement.
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16. What is sports medicine?
Sports medicine is the study and practice of medical principles related to the science of sports
Sports medicine is an umbrella term that encompasses both clinical and scientific aspects of exercise and sport.
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17. What questions or problems are studied by biomechanists?
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18. What questions are studied by biomechanists?
When not subject to gravitational force,
astronauts lose significant amounts of bone
mass. (Bone atrophies when not subjected to
forces.) Exercise, however, is known to
increase bone mass.
 So what kinds of exercise should astronauts do while in space in order to preserve as much bone as possible?
Do your own research: What is Osteoporosis?
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19. her lifting weights or lifting boxes in industry, the act of lifting
places major mechanical stress on
the low back.
What lifting kinematics (techniques) can minimize this stress?
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20. Photographs showing a subject lifting a 20-kg box with the stoop technique (first column), squat technique (second column), straddle technique (third column), and kneeling technique (last column).
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21. How do toddlers learn to balance their torsos on little legs unaccustomed to walking?
(This question spans the fields of biomechanics, motor learning, and motor development.)
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22. Pitching can lead to stress injuries of the elbow and shoulder joints.
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23. Does this actually help or hinder performance? (Increasing evidence
Recreational runners, as well as athletes in many sports, often stretch
before a work out.
Does this actually help or hinder performance? (Increasing evidence
suggests the latter…)
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24. What biomechanical elements of running technique enable some sprinters to dominate over others who are just as well trained and have just as strong physiological attributes?
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25. Qualitative vs. Quantitative
qualitative: pertaining to quality (without the
use of numbers)
 For example: strong, skillful, agile, flexible, fast
quantitative: involving numbers
 For example: running speed = 5 m/s
 height = 1.75 m mass = 68.2 kg
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26. Quantitatively, the robot missed the coffee cup by 15 cm.
Qualitatively, he malfunctioned.
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27. Coaches rely heavily on qualitative observations of athletes’
performances in formulating advice about technique.
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28. Steps in Solving Formal Quantitative Problems:
Read the problem carefully.
List the given information.
Write down what quantity is to be solved for.
Draw a diagram of the problem situation.
Select the appropriate formula to use.
Review the problem statement to determine if more information can be inferred.
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29. Substitute the given information into the formula.
Solve the equation for the unknown variable.
Do a “common sense” check of the answer.
Box in your answer, including the correct units of measurement.
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30. Example 1:
Two schoolchildren race across a playground for a ball. Ahmed starts running at a distance of 30 meters from the ball, and Walid starts running at a distance of 24 meters from the ball. If Ahmed’s average speed is 4.2 m/s and Walid’s average speed is 4.0 m/s, which child will reach the ball first? Show how you arrived at your answer.
Answer:
𝑡𝑖𝑚𝑒 = 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑠𝑝𝑒𝑒𝑑
𝑡 𝐴ℎ𝑚𝑒𝑑 = 30𝑚 4.2𝑚/𝑠 , 𝑡 𝑊𝑎𝑙𝑖𝑑 = 24𝑚 4.0𝑚/𝑠
𝑡 𝐴ℎ𝑚𝑒𝑑 = 7.2 𝑠, 𝑡 𝑊𝑎𝑙𝑖𝑑 = 6.0𝑠
7.2s > 6.0s , so Walid reaches the ball first.
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31. 𝐹𝑜𝑟𝑐𝑒 = 𝑚𝑎𝑠𝑠 𝑋 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛,
Example 2:   
A 0.25 kg ball is kicked with a force of 50 N. What is the resulting acceleration of the ball?
Answer:
  1 𝑁 = 1 𝑘𝑔 𝑚/ 𝑠 2
𝐹𝑜𝑟𝑐𝑒 = 𝑚𝑎𝑠𝑠 𝑋 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛,
𝐹 = 𝑚𝑎 𝑎 = 𝐹 𝑚
𝑎 = 50 𝑘𝑔 𝑚 𝑠 𝑘𝑔
𝑎 = 200 𝑚/ 𝑠 2
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