Grant: Travel Awards - Institute Community Support

Recent reports on maladaptive changes in heart tissue structure in athletes have raised concerns that high-volume "excessive" exercise may be bad for health. This study looked at the relationship between heart tissue mass and a measure of tissue structure from cardiac imaging (cardiac MRI) in middle-aged endurance athletes (EA) and recreationally-active (RA) adults with a minimum of 10 years of exercise history. Participants completed a maximal exercise test and a standardized cardiac MRI with novel techniques to assess heart tissue structure in the left heart chamber (known as the left ventricle, LV). Among 68 participants (average age=54+/-5 years old, maximal volume of oxygen consumed per kg of body mass per minute, VO2max in EA vs. RA: 50+/-7 vs. 37+/-9 ml/kg/min p<0.0001, left heart chamber mass indexed to body surface area: 63+/-11 vs. 50+/-12 g/m2, extracellular volume fraction: 23.7+/-4.6 vs. 27.8+/-7.6%, p<0.05 for all), a higher exercise capacity (VO2max) was associated with a greater amount of left heart chamber mass (r=0.54, p<0.0001), left heart chamber volumes (r=0.59 and 0.55, p<0.0001), and a lower extracellular volume fraction (r=-0.39, p=0.001). Greater heart chamber mass was not associated with the presence of maladaptive changes in heart tissue structure as measured by ECV (r=-0.16, p=0.19). Study findings suggest that increases in heart cell and left heart chamber volume are present in middle-aged endurance athletes without a maladaptive change in heart tissue structure. This imaging technique should be explored further, especially in athletes with significant heart remodeling, as a method for distinguishing between normal adaptation to exercise and maladaptations whenever more traditional heart test results remains inconclusive.