Acute muscle soreness is the pain felt in muscles during and immediately after strenuous physical exercise. The pain appears within a minute of contracting the muscle and disappears within two or three minutes or up to several hours after relaxing it.
The following causes have been proposed for acute muscle soreness:
- Accumulation of chemical end products of exercise in muscle cells, such as H+
- Tissue edema caused by the shifting of blood plasma into the muscle tissue during contraction
- Muscle fatigue (the muscle tires and cannot contract any more)
Acute muscle soreness is one form of exercise-induced muscle damage, the other being delayed onset muscle soreness, which appears between 24 and 72 hours after exercise.