[1] Generally, the muscle or tendon overstretches and partially tears, under more physical stress than it can withstand, often from a sudden increase in duration, intensity, or frequency of an activity.

Typical signs and symptoms of a strain include pain, functional loss of the involved structure, muscle weakness, contusion, and localized inflammation.

Chronic strains typically result from repetitive movement of the muscles and tendons over a long period of time.

[11] A new treatment for acute strains is the use of platelet rich plasma (PRP) injections which have been shown to accelerate recovery from non-surgical muscular injuries.

[12] It is recommended that the person injured should consult a medical provider if the injury is accompanied by severe pain, if the limb cannot be used, or if there is noticeable tenderness over an isolated spot.