1. Unit 1 Task 2.B 1

2. Functions of the muscular system
Antagonist pairs: Antagonist muscle pairs work together to create movement. When the prime mover the agonist contracts the antagonist relaxes. These types of muscles work in pairs such as the biceps and the triceps in the arm and the quadriceps and hamstring in the leg.
Synergist: Synergist contractions in a muscle stabilises a joint that movement is occurring in. example in a bicep curl the synergists help stabilise the elbow joint and help movement take place. It is the brachioradialis and brachialis that help stabilise the joint in a bicep curl.
Fixator:The fixator muscles stabilize a section of the body when another section moves. The muscle allows the antagonist muscles to move effectively during normal movement or exercise Some muscles attach to one or more bones. When a person performs a bicep curl, for example, 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. 2

3. Types of contraction
Isometric: Isometric contractions occur when there is no change in the length of the contracting muscle. This can occur when you are carrying an object in front of you as the weight of the object is pulling your arms down but your muscles are contracting to hold the object at the same level .The amount of force a muscle is able to produce during an isometric contraction depends on the length of the muscle at the point of contraction.
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. Concentric contractions are the most common type of muscle contraction and occur frequently in daily and sporting activities.
Eccentric: Eccentric contractions are the opposite of concentric and occur when the muscle lengthens as it contracts. This is less common and usually involves the control or deceleration of a movement being initiated by the eccentric muscles agonist. For example, when kicking a football, the Quadriceps muscle contracts concentrically to straighten the knee and the Hamstrings contract eccentrically to decelerate the motion of the lower limb.
Isokinetic: Isokinetic contractions are similar to isotonic in that the muscle changes length during the contraction, where they differ is that Isokinetic contractions produce movements of a constant speed. 3

4. Fibre Types
Type 1: Type 1 muscle fibres are known as slow twitch fibres. They contain high amounts of myoglobin, oxygen and mitochondria having high amounts of these make the muscles more resistant to fatigue. This means that type 1 muscle fibres are best suited to long distance sports such as running or cycling because they don't fatigue as fast as other muscle types.
Type 2a: Type 2a fibre types are known as fast twitch oxydative fibres. These fibres contain a large number of mitochondria and Myoglobin similar to type one fibres but without the oxygen. They manufacture and split Adenosine triphosphate at a fast rate by utilising both aerobic and anaerobic metabolism and so produce fast, strong muscle contractions, although they are more prone to fatigue than type I fibres. Type 2a fibres are in the middle of fast twitch fibres and slow twitch fibres. They are best suited to sports such as 400/800m as they don't fatigue as fast and they can maintain speed they cant go as long as fast twitch fibres.
Type 2b: Type 2b fibres are known as fast twitch glycolytic fibres which means that they fatigue fast. They produce ATP at a slow rate by anaerobic metabolism and break it down very quickly This results in short, fast bursts of power and rapid fatigue. 4