1. Unit 1: The Body in Sport
2. Understanding the muscular system and how it is affected by exercise
In this section you will learn how the skeletal and muscular systems are linked in the creation of movement during sports activities. You will also learn about the structure of joints and levers in the production of movement.

2. Classification of muscles
All sports performers need to be able to move. Movement is possible through the use of muscles, but not all muscles bring about movement.
There are three different types of muscle tissue that make up the muscular system.
Can you name them?

3. The three different types of muscle tissue are:
Cardiac muscle, which is only found in the heart.
Smooth muscle, also known as involuntary muscle.
Skeletal muscle, also known as voluntary muscle
The structure and function of each of these muscle tissues are very different, and they are controlled by different methods

4. Cardiac Muscle
This type of muscle is only found in the heart, and is a special form of involuntary muscle in that we have no direct conscious control over it. It also differs from voluntary muscle in that it does not tire, but continues to contract and relax throughout our lives.

5. Involuntary or Smooth Muscle
Examples of this type of muscle can be found in parts of the digestive tract propelling food through the digestive system and the blood vessels that aid blood flow away from the heart to all parts of the body.

6. Skeletal or Voluntary Muscle
This type of muscle is attached to the skeleton of the human body and is responsible for bringing about movement and maintaining body posture. These muscles are controlled by the central nervous system and we move these muscles with conscious thought.

7. Your body has over 600 muscles to enable it to move.
You are going to concentrate on just 11. Can you name any muscles?
Hamstrings
Quadriceps
Triceps
Deltoid
Latissimus dorsi
Gastrocnemius
Bicep
Pectoral
Gluteus maximus / Gluteals
Trapezius
Abdominals

8. Anterior View of the muscular system

9. Posterior view of the muscular system

10. Muscle and Sporting action
Triceps - Extends lower arm at the elbow
Volleyball player has arms outstretched to block the
ball
Biceps - Flexes arm at the elbow
Tennis serve – racket preparation, when racket is
behind head
Deltoids - Abducts upper arm at the shoulder
Preparation for a cartwheel in gymnastics
Pectorals - Adduction of upper arm at the shoulder
Arm action in front crawl (pull)
Trapezius - Adducts and rotate scapula, rotation of
head at atlas and axis
Lifting of the head to watch the flight of the shuttle
in badminton

11. Muscle and Sporting action
Gluteals - Extends the leg at the hip
Running action, one leg is left stretched back
behind the other
Quadriceps - Extends the leg at the knee
Follow through after kicking a ball in football
Hamstrings - Flexes the leg at the knee
Taking the leg back in preparation to strike the ball
in rugby
Gastrocnemius - Plantar flexion of the foot
Going up onto toes prior to take off in a diving
competition
Latissimus dorsi - Adducts and rotates the
humerus at the shoulder
Pulling the arm back in archery
Abdominals - Flexes and rotates the trunk
Forward action in sit ups

12. Structure and function of skeletal muscle
Skeletal muscles are
made up of many
thousands of fibres.
These in turn are
made of even
smaller fibres called
myofibrils. It is
within these smallest
fibres that the
contraction of the
muscle takes place.

13. Muscle movement
Skeletal muscle has a vast supply of nerve and blood vessels. Skeletal muscle is also termed voluntary muscle because movement is created via conscious thought process. Muscles pull to produce movement. In other words, the cells of the muscle tissue contract and then relax to their original size.

14. How Muscles Work: When you move a part of your body
your muscles will either:
CONTRACT – Bulge (get fatter) and shorten
Or:
RELAX – Return to their original length

15. Muscle Contraction
Muscles work (contract and shorten) when stimulated (told to do so) by the central nervous system (CNS). The brain sends messages via the spinal cord to the muscles it wishes to move. The spinal cord acts like a telephone wire.
Muscular tissue has the ability to contract (shorten and bulge) and then return to its original length because it has ELASTICITY.
Voluntary / Skeletal muscles usually works across a joint. They are attached to both bones by strong cords called Tendons.
Tendons are white, flexible, very strong and are different shapes depending upon the muscle.
In other words Tendons are the cords that connect Muscles to Bone so a muscle has tendons at both ends.

16. Antagonistic Pairs
Muscles work in pairs to provide movement for physical activity, for example the biceps and triceps work together to create movement.

17. Antagonistic pairs Prime movers – these muscles determine the
movement of an action via
contraction. For example
during the bicep curl, the
prime mover during the
flexion phase is the bicep.
Antagonistic – this muscle
works together with the
prime mover but creates an
opposition action. Using the
example of the bicep curl
again, during the flexion
phase the triceps enable the
arm to bend at the elbow
joint for the bar to move
towards the shoulder girdle.

18. Antagonistic pairs During the downward phase
of the bicep curl the opposite
occurs. For example the
prime mover (Agonist) is the
triceps and the antagonistic
muscle is the bicep.

19. Origins and Insertion Muscles PULL on Bones – muscles are
attached to two different bones with
tendons.
To make a joint move – one of these
bones will move but not the other
ORIGIN –attached to the STATIONARY bone
INSERTION – attached to the MOVING bone

20. Origins and insertion

21. Muscle Contraction
Muscles contract to produce movement. There are three main types of muscle contraction: two where obvious movement occurs and one where no obvious movement is visible.
Isometric contraction is where the muscle stays the same length during contraction, or when the activity is being carried out. Tension occurs in the muscle but the distance between the ends stay the same

22. Muscle Contraction
Isotonic concentric contraction is when the muscle shortens when performing an action. There is obvious movement when the ends of the muscle move closer together.
Isotonic eccentric contraction occurs when the muscles lengthen under tension. The ends of the muscle move further away during an action.