Fascia is the gristle that envelopes muscle. In the lower leg there are 4 muscular compartments, the anterior, lateral, superficial and deep posterior. Compartment syndrome develops when a muscle cannot expand within its fascial compartment and begins to cut off blood supply and compress the nerves innervating that particular muscular compartment. An entity called “chronic exertional compartment syndrome” can occur as well which is a lot less urgent/emergent than acute compartment syndrome, though the principle is the same in that the muscles in the compartment are unable to expand.
Acute compartment syndrome can often happen after traumatic injury and bleeding into the compartment. Rhabdomyolysis, or the breakdown of muscle components that can be associated with extreme exercise, can cause muscle edema and compartment syndrome. Certain supplements that increase muscle bulk may predispose to compartment syndrome.
With chronic exertional compartment syndrome, the most common compartments involved are the anterior and lateral and these present with pain along the outside shin. Typically the pain can be a numb, tingling sensation that develops consistently at a certain time during exercise. The condition may get severe to the point where there is foot drop. It may take an hour or so of rest for the pain and weakness to go away. There may be visible bulging of muscle through a fascial layer.
There has been limited success treating this condition with Botox injections, however, Botox by design paralyzes/weakens the muscle so this may not be an option for elite level athletes. Persistent chronic exertional compartment syndrome may require surgical intervention.