Exercise-induced muscle damage (second phase)

In the second phase of exercise-induced muscle damage, an inflammatory process takes place in which certain genetic variants may contribute to more or less muscle damage.

Certain gene variations, or polymorphisms, have been associated with exercise-induced muscle damage, i.e., individuals with certain genotypes experience greater muscle damage and require longer recovery after strenuous exercise.

In the initial phase of muscle damage, mechanical damage occurs. The second phase is a consequence of the first and consists of an inflammatory response. The products originating from the damaged muscle tissue attract immune cells (a process known as chemotaxis) which will initiate the inflammatory process. In addition, the release of certain molecules, known as cytokines (mainly IL1B, IL6 and TNF) that enhance the inflammatory process occurs.

Variants in the genes coding for these cytokines appear to be involved in the development of this second inflammatory phase of muscle damage.