1. 1.2.4 – Active lifestyles and your muscular system
Learning objectives
To understand the three muscle types and their functions
To be able to label the important voluntary muscles in our body
To be able to define and explain muscle tone and posture
To understand the difference between fast and slow twitch muscle fibres and the relevance to the sportsperson.

2. MUSCLES
Muscles are used in everyday life all the time. Sportspeople are reliant on the power of muscles to compete.

3. Muscle classification
Muscles are involved in every movement in your body.
Muscle is a special type of tissue made up of fibres that contract (shorten) and relax (lengthen).
There are three types of muscle fibre.
Image © 2006 Jupiterimages Corporation

4. 1. Voluntary Voluntary Muscles
These are attached to bones and they work whenever we want them to. e.g. Biceps, Quadriceps, etc
It is attached to bones.
It moves these bones under
your conscious control.

5. 2. Involuntary Involuntary muscle
These are found on the walls of the internal organs and they contract in waves. Food travels through the digestive system and blood through the blood vessels in this way.
It works without you consciously controlling it, or even being aware of it.

6. 3. Cardiac muscle
Cardiac muscle is a special type of muscle that forms the walls of the heart chambers.
It is a type of involuntary muscle, as it contracts without conscious thought or effort.
It works non-stop without ever tiring.
When it contracts it pumps blood out of the heart and around the body.

7. All three types of muscle are important in physical activity:
Voluntary muscle enables movement.
Involuntary muscle is essential in maintaining body systems.
Cardiac muscle is vital in sport because it makes the heart pump.
Fitness training will strengthen cardiac muscle making the heart more efficient at pumping blood around the body.

8. Trapezius
Triceps
Pectorals
Bicep
Latissimus Dorsi
Abdominals
Hamstring
Quadriceps
Gastrocnemius

9. Muscle Main Action (s) Deltoid Biceps Abdominals Quadriceps Pectorals
Complete the grid below: (pupils to try contact the muscles to see effect on limb)
Muscle
Main Action (s) 1
Deltoid 2
Biceps 3
Abdominals 4
Quadriceps 5
Pectorals 6
Latissimus Dorsi 7
Trapezius 8
Triceps 9
Gulteals 10
Hamstring 11
Gastrocnummius

10. Muscle Main Action (s) Deltoid Biceps Abdominals Quadriceps Pectorals1
Deltoid 2
Biceps 3
Abdominals 4
Quadriceps 5
Pectorals 6
Latissimus Dorsi 7
Trapezius 8
Triceps 9
Gulteals 10
Hamstring 11
Gastrocnummius
Raises your arm sideways at the shoulder (abduction)
Bends your arm at the elbow (Flexion)
Flex your trunk so you can bend forward.
Straighten your leg at the knee. (extension)
Draws arm across your chest. Raises arm at shoulder.
Pulls arm down at shoulder. Draws it behind your back
Holds & rotates your shoulders. Moves head back & sideways
Straightens your arm at the elbow joint. (extension)
Answers
Pull leg back at hip. Raise it sideways.
Bend your leg at the knee. (flexion)
Straightens the ankle joint so you can stand on tiptoes.

11. Muscle tone and posture
Muscles almost never fully relax.
Muscle tone – “muscle fibres in a state of partial tension”.
Poor muscle tone leads to poor posture and slouching.

12. Exam Questions

13. Muscle twitch fibres
Muscle twitch fibres occur in different proportions in different people.
This proportion is mainly to do with the genes you inherit but can be altered by training.
Suggested answer:
Marathon runner 75% slow twitch / 25% fast twitch
Wrestler 75% fast twitch / 25% slow twitch

14. How can athletes do this?

15. Or do this?

16. There are two main types of muscle fibres:
SLOW TWITCH MUSCLE FIBRES – Small in size.
These fibres take a relatively long time to contract.
- Have a good oxygen supply and is why they are deep red in colour. - They contract slowly, but can work for long periods.

17. FAST TWITCH MUSCLE FIBRES - Large in size.
These fibres contract quickly and powerfully.
- Fast twitch fibres are paler in colour and have limited oxygen supply. - They contract quickly and powerfully, but tire easily.

18. 60% Slow twitch 40% Fast twitch fibres An average person possesses:
Elite endurance athletes possess a high percentage of slow twitch fibres.
Elite explosive athletes possess a high percentage of fast twitch muscle fibres.

19. FAST OR SLOW TWITCH?

20. FAST OR SLOW TWITCH?

21. FAST OR SLOW TWITCH?

22. Task:
1. Name some sporting activities that require more slow twitch fibres:
2. Name some sporting activities that require more fast twitch fibres:
3. What percentage of fast twitch and slow twitch muscle fibres would a midfield football player need and why?