Later, we will see how the junction between a muscle and its tendon is a frequent site of damage. Types of Contractions M uscle contractions are generally classified into three different types. This is important to understand since one particular type of contraction tends to be responsible for most injuries. Concentric contractions occur when a muscle shortens in order to exert force. For example, the biceps muscle does a concentric contraction in order to do an arm curl.
Isometric contractions are when the muscle exerts a force but there is no movement in the limb.
Eccentric contractions are the contractions we rely on the most. These are contractions that occur in a muscle while it is lengthening . For example, as a person lowers the curl bar in a biceps curl, the biceps are performing eccentric contractions in order to slow the descent of the bar. The muscle is getting longer, but it is still exerting force. I t is widely accepted that muscle strain injuries occur more frequently with eccentric muscle contractions.