**1. Introduction**

The detrimental event on a muscular level, founds one of the most recurring traumatic insults in sporting environment. The entity of the lesion can go from simple sprain, often associated with the breakage of small vessels, with appearance of pain and swelling, to complete muscular tear. The consequences for the athlete, which appear linked with the entity of the lesion, are always unpleasant and involve suspension, more or less long, of sporting activity, not to mention suitable therapy.

In this chapter we will try to clear up the different physiological aspects which normally characterize the traumatic event and to describe, even if only summarize, the mechanism of muscular repair.
