EFFECTS OF ENDURANCE TRAINING ON LEFT-VENTRICULAR DIMENSIONS IN HEALTHY-MEN

Echocardiography was employed to measure the serial effects of jogging on resting left ventricular dimensions and function. Twelve men were exercised (mean age 36.8 yr) and 10 served as controls (mean age 34.8 yr). Increases of 14 and 18% were observed for predicted aerobic capacity in the training group (TG) after 3 and 6 mth of training, respectively; the control group (CG) displayed a small detraining effect. Echocardiographic findings included a significant (P < 0.05) reduction in resting heart rate and a moderate increase in stroke volume (SV) in the TG compared to the CG. The increased SV appeared to be due to increased end-diastolic dimensions (LVIDd, LVEDV), secondary to greater ventricular filling rather than a more vigorous ventricular contraction. Posterior wall thickness, septal thickness, and calculated left ventricular muscle mass were not significantly increased in the TG compared to CG after either 3 or 6 mth training. It was concluded that left ventricular structure and resting contractile status are not altered by 6 mth of jogging training in healthy, previously sedentary men.