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Gene Variant Predicts Heart Function in Ultra-Marathon

Study also confirms 'cardiac fatigue' phenomenon

FRIDAY, July 28 (HealthDay News) -- A variant of the angiotensin-converting enzyme (ACE) gene can predict the extent to which the heart will tire following prolonged exercise, according to a study of athletes in a 300-mile endurance race published in the Aug. 1 issue of the Journal of the American College of Cardiology.

Euan A. Ashley, M.D., Ph.D., of Stanford University School of Medicine in Stanford, Calif., and colleagues studied 86 athletes who participated in the Adrenaline Rush Adventure Race. Only about half of the original entrants finished the race and they had a differential decline in left ventricular function as measured by fractional shortening from before the race (39.6 percent) to after the race (32.2 percent), confirming the "cardiac fatigue" phenomenon.

The researchers found that subjects homozygous for an insertion/deletion polymorphism of intron 16 of the ACE gene pumped 13 percent less blood at the end of the race, compared with 8 percent less blood among athletes without this genetic variation. Heterozygotes had an intermediate decline in fractional shortening. The ACE genotype predicted the extent of exercise-induced decline in systolic left ventricular function, but not diastolic function. All changes were reversible.

"The ACE genotype…is associated with a differential post-activity augmentation of sympathetic nervous system function" that may explain the findings, the authors conclude.

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