Endurance training is thought to contribute to improved heart health. However, a recent study suggests that too much training may have the opposite effect. Published online ahead of print in the Journal of Applied Physiology (2011; doi: 10.?1152/?japplphysiol.?01280.?2010), the study had the purpose of determining the cardiac structure and function of veteran endurance athletes. The study subjects included three sets of men: 12 older endurance athletes (aged 50–67), 20 older controls (aged 52–69) and 17 younger endurance athletes (aged 26–40). The participants underwent cardiac magnetic resonance imaging to assess heart structure and function. Tests to determine myocardial fibrosis—abnormal thickening of the heart valves—
were also administered. According to the data, evidence of myocardial fibrosis was not present among the young athletes or the older-adult controls. It was present in 50% of the veteran athletes; there was no association based on age. The study authors stated that myocardial fibrosis “was significantly associated with the number of years spent training and number of competitive marathons and ultra-endurance marathons completed. This data suggests a link between lifelong endurance exercise and myocardial fibrosis that
requires further investigation.”