ACE activity and endurance performance during the South African Ironman triathlons

The insertion allele of the angiotensin-converting enzyme (ACE) gene has been associated with endurance performance. Since a large portion of the variance seen in circulatory ACE levels is unaccounted for by the insertion/deletion polymorphism it is likely that the ACE phenotype would serve as a more informative marker in assessing elite endurance performance. The aim of this study was to correlate plasma ACE activity with performance of a homogenous population of South African-born Caucasian male triathletes. Plasma ACE activity was determined in 145 triathletes, representing the fastest and slowest subgroups who completed either the 2000 or 2001 South African Ironman Triathlon. There was a trend for lower mean plasma ACE activity in the fastest (28.85±8.60 mU/ml) when compared to the slowest finisher subgroup (31.65±8.75 mU/ml, P=0.055). There was a significant positive correlation between plasma ACE activity and overall finishing time within the participants who completed the event in under 15 h (r=0.192, P=0.029). There was also a positive correlation with cycle (r=0.195, P=0.034) and run (r=0.184, P=0.040) stages but not the swim stage (r=0.084, P=0.353). In conclusion, this is the first study to report a relationship between plasma ACE activity and endurance performance in humans.