Echocardiographic Study of Cardiac Structure in Cyclists and Runners

Abstract

We sought to study the cardiac morphology of cyclists and runners in male and female athletes and control subjects and to find association cardiac morphological measurements with body composition measurements. Endurance training is associated with increases in both left ventricular mass (LVM) and left ventricular end-diastolic dimension (LVEDD). Cardiac morphology shows sports specific adaptations which are studied in the two groups, runners involving lower limb and cyclists involving upper limb. 28 runners and 26 cyclists were taken to do a comparison study with 38 control subjects, aged between 18-25 years of age and comprising of males and females both. All participants underwent transthoracic echocardiography and hydrostatic underwater weighing for body composition along with routine measurements. Athletes showed enlarged LV dimensions and mass (p<0.05) as compared to controls. Right ventricular and aortic root dimensions were also found to be significantly higher in athletes (p<0.05). Lean tissue mass was found to be independent predictor of LVM. Increased LV wall thickness in relation to the ventricular dimension appears to be proportionate in runners; it is disproportionate in cyclists, probably because of the isometric training component involved during upper limb training cycling. Hence runners show eccentric hypertrophy and cyclist showed mixed eccentric and concentric hypertrophy. LVM was found to be correlated only to lean tissue mass. The extent of LV remodeling (athletic heart) in trained individuals may reflect a normal physiologic response to increased lean tissue mass induced by training.