A condition most commonly seen in runners and endurance athletes, in which they regularly develop pain localised to a particular muscle or muscle group after a set amount of exercise, which is relieved by rest. It is caused by muscle swelling confined by tight surrounding FASCIA leading to increased pressure obstructing blood flow. Treatment may be by bracing, stretching or the use of anti-inflammatory medication but, if they are to return to full activity, surgical measures may be needed to release the tight fascia.