TYPES OF SKELETAL MUSCLE:

Within our skeletal muscle we actually have 2 types of muscle fibre called fast and

slow twitch

fibres, related to the speed in which they contract.

Both these fibre types go back to when we were HUNTERS and GATHERERS Slow Fibres: Walk long distances Fast fibres: Chase our prey when needed

TYPES OF SKELETAL MUSCLE- TASK…

You will use all of the different types of muscle fibres during a game of football. However, some fibres are particularly associated with different sports.

Type I fibres are typically employed in a warm up and at the beginning of exercise.

Type IIa fibres can be used for moderate intensity exercise. They are also often used for low intensity aerobic activities when we are very fatigued and the Type I fibres are tired.

Type IIb fibres are used in explosive, powerful, fast movements. They tire very quickly.

In the space below give 5 sports that are primarily associated with each muscle fibre type.

Then give at least 2 examples of a footballer using each type of muscle fibre on match day.

TYPE 1- SLOW TWITCH FIBRES

RED in colour

, as they have a good blood supply They are suited to endurance work and are slow to fatigue vessels.

Due to having a dense network of blood They also contain many MITOCHONDRIA (Energy producing organelles within cells), using OXYGEN (O2). making them more efficient at producing energy

TYPE 2A AND TYPE 2B- FAST TWITCH FIBRES Fast twitch fibres contract twice as quickly as slow twitch fibres and THICKER in size.

They have a poor blood supply, meaning they are

whiter

in appearance and will

fatigue quicker

due to lack of OXYGEN (O2) Their FASTER, HARDER contractions make them suitable for producing fast and powerful contractions. E.G: Sprinting and Weightlifting

TYPE 2 (A) Type 2 (b)

These fibres work when a person is working close to their maximum intensity. For example a 100m runner would use these type of fibres, or an Olympic lifter performing a fast lift.

Work at slightly lower intensities, but higher than slow twitch fibres are capable of. For example a 400m runner would utilise Type 2A fibres.

TRAINING EFFECTS FOR MUSCLE FIBRES…

Type 1 and Type 2b fibres will always retain their distinctive features… However Type

Postural muscles

(muscles that keep us standing upright) like the muscles in the

back areas

time.

and will be

legs

,

abdominal

predominantly SLOW TWITCH. As they produce low forces over a long period of

2a can take on characteristics of Type 1 and Type 2b depending on the training done (they do not change their fibre type).

The type of muscles found in the legs will determine whether you are more suited to sprinting or endurance running. Your athletic performances will be a good indicator of which.

Bursztyn (1997): well trained middle- distance athletes will have 80% slow twitch fibres and well trained sprinters may have up to 75% fast twitch fibres

ANATOMY AND PHYSIOLOGY

UNDERSTANDING MUSCLE ACTION

Muscles are attached to bones by tendons.

The tendon at the non-moving (or fixed) end is known as the origin .

The tendon at the moving end is known as the insertion .

Muscles pull by contracting – they cannot push to produce the opposite movement.

Muscles are arranged in antagonistic pairs .

As one muscle contracts (shortens) its partner relaxes (lengthens). They swap actions to reverse the movement.

• • •

To cause movement, muscles must work across the joint.

– For example, the bicep works across the elbow joint causing flexion of the elbow (bending)

When the muscle contracts it pulls on the bone, causing movement. The bones act like levers, and the joints are the fulcrum.

•

The strength of the contraction depends on the amount of muscle fibres brought into use.

– This is known as muscular fibre recruitment.

The biceps and triceps work together as an antagonistic pair to move the elbow joint.

To flex the elbow, the biceps (the flexor) contracts and the triceps (the extensor) relaxes. To extend the elbow, the actions are reversed so that the triceps contracts and the biceps relaxes.

The quadriceps and hamstrings in the legs are another antagonistic pair. Can you answer the following questions?

Which joint do they move?

quadriceps

What types of movement are produced?

hamstrings

Which is the flexor and which is the extensor?

Identify the origin and insertion of each muscle.

• Each muscle involved in the movement of a specific body part has a role: •

Agonist/Prime Mover Muscle :

this is the muscle that courses the movement e.g the bicep causes the movement during a bicep curl • • •

Antagonist/Opposing Muscle :

the opposing muscle must counter the action of the primer mover muscle to allow the action to take place e.g. the triceps must relax to allow for the biceps to contract during a bicep curl.

Fixator Muscle :

this muscle works to stabilise the joint at the origin of the prime mover muscle e.g. the trapezius contracts to stabilise the origin of the biceps during the bicep curl.

Synergists :

this muscle helps the prime mover to produce the desired movement by preventing any undesirable movements, during the upward phase of the bicep curl the brachialis muscle is the synergist.

•

There are 4 main types of contraction 1. Concentric Contraction: Most common contraction, it takes place when the ends of the muscle come closer together and the muscle shortens 2. Eccentric Contraction :

The muscle ends move further away from each other

3. Isometric Contractions: A muscle exerts a force but does not change in length E.G. during a tug of war everyone is pulling the rope and your arm muscles are contracting to do this but your muscles are not shortening or lengthening. A rugby league example would be when both sides push in a scrum.

Eccentric- Involves controlling the weight on it’s way down Concentric Contraction to push weight away from the body Video of an eccentric, concentric and isometric contraction

• •

Where a muscle contracts, but does not change in length

– The muscle is active in holding a static position

This is easy to train, but soon leads to fatigue

Describe the

function

1, Type 2a, Type 2b) of the muscular system and the different

fibre types

(Type Explain the

function

system and the three

fibre types

of the muscular different muscle

Fibre types

: • • Type 1 Type 2a • Type 2b (Characteristics of both and Sports associated with each) • • • •

Movement

: Antagonistic pairs (agonist, antagonist) Fixator Synergist Types of contraction (isometric, concentric, eccentric, isokinetic) D1 builds on M1, and requires learners to

analyse

system and the different muscle fibre types.

Practical examples

provided where appropriate to support the analysis the function of the muscular should be