Anterior compartment syndrome is a problem in runners that is more appropriately called chronic exertional compartment syndrome in which the anterior tibial muscle expands in a tight fascial compartment when exercising resulting in symptoms.
The symptoms of anterior compartment syndrome are most commonly described as an aching, tightening, cramping or squeezing pain on the front and outside area of the leg. The pain mostly occurs during exercise and tends to go away when you stop exercising. The pain gradually disappears after exercise as the muscle volume and, therefore, pressure within the anterior compartment fascia returns to normal. The swelling may cause the compression of a nerve that passes through the compartment and may also cause a numbness between the big and second toes and a weakness in the leg.