An effort-related compartmental syndrome is a condition in which increased pressure in a muscle compartment impedes blood flow and compromises metabolic demands of the tissues within that space. One can clinically distinguish acute irreversible and chronic reversible types. The aetiology relates in most instances to a limiting noncompliant fascia surrounding the affected muscle compartment. Sports activity leads to increased muscle volume and if there is a noncompliant fascia this will result in an excessive intracompartmental pressure which interferes with muscle blood flow. As a consequence of a reduced intracompartmental blood flow a reversible (recurrent) or irreversible (acute) exercise ischaemia, a so-called 'compartmental syndrome' occurs. A compartment syndrome is typically encountered in the lower leg, but it can be also observed in the upper leg and even in the forearm. Clinical history plays a key role in the diagnosis. Pain, muscle tightness and cramp-like feeling are the most common complaints. Weakness, paralysis and numbness are seen, especially in the acute syndrome. Symptoms appear at a certain intensity of activity and disappear at rest in the chronic compartment syndrome, but in the acute type pain will persist and will be severe. It is clearly an effort-related pain syndrome. Physical examination is not always useful in diagnosing a recurrent syndrome, but in the acute syndrome one will find high sensitivity to pressure and tenseness over the involved muscle compartment. Decreased or loss of active motion and sensation in the involved compartment are frequently seen. Tissue pressure monitoring can confirm the diagnosis for both types.(ABSTRACT TRUNCATED AT 250 WORDS)