Sports Science

Muscles

In order for our framework (skeleton) to have moving parts we need muscles. Muscles are arranged around joints and can create movement by contacting. When muscle cells are stimulated, by an electrical impulse from a nerve, they contract. Contraction of the muscle creates a force that pulls on the bone to produce movement.

Since muscles can only contract and relax they have to be pulled back to their original length. For this reason most muscles act in pairs, called antagonistic pairs. An antagonist acts in the opposite way to its partner. Consider the arm. As seen in the animation on the right, the biceps muscle will contract and bend the arm at the elbow. While the biceps muscle is contracting the triceps muscle is relaxed. When the arm needs to be straightened the opposite occurs. The triceps muscle contracts pulling the biceps back to its original length.

Muscles are attached to bones by bands of fibrous tissue called tendons. Tendons are very tough and are composed mainly of strong, flexible collagen fibres and special cells called fibroblasts. All the force generated by the muscle to move bones against a resistance is transmitted through the tendon. The tendon is not elastic and often tears when put under severe strain. Warm-up periods are very important before exercise. Warm-up exercises increase the blood flow to the muscle tissue in preparation for the ensuing sporting activity.

 
As we will see later, muscle can be made to increase in size through specialised training and diet.

How does muscle tissue contract?

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