Endurance and the ACE I/D polymorphism.

A variant of the angiotensin-converting enzyme (ACE) gene, which we all carry, is known as the insertion, or I allele, due to the presence of a 287 base pair DNA fragment. This variant, or polymorphism, is associated with reduced levels of serum and tissue ACE. This intriguing polymorphism has been associated with various physiological and pathological states from diabetic renal disease to coronary heart disease. There have been conflicting reports regarding its association with some aspects of enhanced endurance performance in elite athletes. This review aims to examine the evidence for and against an association of the I allele with endurance and highlight some of the possible mechanism that might be involved. It is concluded that an association seems likely and that it is probably due to a local muscle effect rather than a central cardiorespiratory mechanism.