Structural heart adaptations in triathletes

To perform a triathlon in aerobic conditions, a variety of cardiovascular, haemodynamic and metabolic adaptations are required. The heart is the central concern and also the most important limiting factor. In this study we investigate the structural and functional heart adaptations of a group of triathletes.

A group of 52 male triathletes was divided into 4 subgroups in function of their athletic results and compared with a control group of 22 healthy, very active but no athletic men. The groups had comparable anthropometric and general physical characteristics. Very significant differences in cardiac structure and cardiac function were observed between the groups. In the triathletes, we registered distinct signs of significantly mixed eccentric and concentric hypertrophy. Unlike the findings in a pathological left ventricular hypertrophy, the diastolic left ventricular function in triathletes was completely normal and even better than in the control group. The late passive diastolic filling period of the triathlete, in particular, seemed to have specific characteristics. The comparison between the subgroups of triathletes shows us that genetic factors probably play an important role in the cardiac adaptations in triathletes.

In our opinion the "athletic heart" in triathletes is not a specific "physiological entity" but is a transitional phase to a dilated hypertrophic cardiomyopathy. Our study yields some arguments for the following proposition: "People are born as elite athletes, with specific characteristics of the left ventricle and with a specifically supernormal diastolic left ventricular function."