1. function of the muscular system and the different fibre types

2. Antagonist pairs
Antagonist and agonist muscles often occur in pairs, called antagonistic pairs. As one muscle contracts, the other relaxes.
An example of an antagonistic pair is the biceps and triceps; to contract - the triceps relaxes while the biceps contracts to lift the arm.

3. Synergist
synergist muscles performs, or helps perform, the same set of joint motion as the agonist. Synergists muscles act on movable joints. Synergists are sometimes called neutralizers because they help cancel out, or neutralize, extra motion from the agonists to make sure that the force generated works within the desired plane of motion.
In the bicep curl the synergist muscles are the brachioradialis and brachialis which assist the biceps to create the movement and stabilise the elbow joint

4. Fixator
These muscles provide the support to assist in holding the rest of the body in place while the movement occurs, they are also called stabilizers.
When you do I bicep curl, the bicep flexes the elbow. The bicep connects to the bone in two places, and the fixator allows one area to move during the curl. As the bicep contracts, the radius and scapula come together. The fixator muscle prevents the scapula from moving in order to achieve full movement of the radius area. Most fixator muscles surround the hip and shoulder bones

5. Types of contraction: isometric
Isometric contractions occur when there is no change in the length of the contracting muscle.
An example is when you grip a tennis racket. . There is no movement in the joints of the hand, but the muscles are contracting to provide a force sufficient enough to keep a steady hold on the racket.

6. Concentric
Concentric contractions are those which cause the muscle to shorten as it contracts.
An example is bending the elbow from straight to fully flexed, causing a concentric contraction of the Biceps Brachii muscle. Concentric contractions are the most common type of muscle contraction and occur frequently in daily and sporting activities.

7. Eccentric
When the muscle lengthens under tension each of the muscles move further away during an action
For example, when kicking a football, the Quadriceps muscle contracts concentrically to straighten the knee. The Hamstrings contract eccentrically to decelerate the motion of the lower limb. This type on contraction puts strain on the muscles and can lead to injury.

8. Fibre type 1
Type I fibres are also known as slow twitch fibres. They are red in colour. Due to this fact they are very resistant to fatigue and are capable of producing repeated low-level contractions
athletes such as marathon runners have a high number of this type of fibre, partly through genetics, partly through training.

9. Fibre type 2a
Type 2a fibres are also sometimes known as fast oxidative fibres and are a hybrid of type 1 and 2 fibres.
Type 2a produce fast, strong muscle contractions, although they are more prone to fatigue than type 1 fibres. Resistance training can turn type 2b fibres into type 2a.

10. Fibre type 2b
 they are white in colour . They are short, fast bursts of power and rapid fatigue. this type of fibre can be turned into type 2a fibres by resistance training. This is a positive change due to the increased fatigue resistance of type 2a fibres. These fibres are found in large quantities in the muscles of the arms.