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.

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

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

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.

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.

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.

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.

Trapezius Triceps Pectorals Bicep Latissimus Dorsi Abdominals Hamstring Quadriceps Gastrocnemius

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

Muscle Main Action (s) Deltoid Biceps Abdominals Quadriceps Pectorals 1 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.

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.

Exam Questions

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

How can athletes do this?

Or do this?

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.

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.

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.

FAST OR SLOW TWITCH?

FAST OR SLOW TWITCH?

FAST OR SLOW TWITCH?

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?