Examples of isotonic reactions include concentric and eccentric contractions. Isotonic contractions are those that the muscles have the same tension throughout the movement. Typically, the muscles maintain the same tone even while shortening.
Concentric contractions allow the muscles to shorten during contraction. A good example is when a person is flexing the elbow. This type of contraction occurs daily as a person engages in different activities. Eccentric contractions make it possible for the muscles to lengthen during the contraction. This contraction is necessary for deceleration of movements. It is less common, and it is associated with different injuries, as stated by Teach PE.