ObjectiveTo determine whether a relationship exists between left ventricular morphology and aerobic capacity in large numbers of male university students with a physically inactive and active life style.DesignA prospective study.SettingSports medicine research center.ParticipantsEleven sedentary normal-weight university students, 17 sedentary overweight university students, and 215 university athletes.Main Outcome MeasuresAfter the echocardiographic examination, an incremental treadmill exercise test until exhaustion was performed to measure peak oxygen uptake (VO2).ResultsIn sedentary students, absolute peak VO2in the overweight students was slightly higher than that in normal-weight students (3,024 vs. 2,912 ml/min). Relative peak VO2(ml/min/kg) was highly negatively correlated with body mass index (kg/m2) in a total of 28 sedentary students. The correlation between absolute peak VO2and left ventricular dimension was weak in the sedentary overweight students; however, a correlation coefficient of 0.55 was obtained in athletic students. A stepwise multiple regression showed significant determinants of absolute peak VO2in athletic students for body surface area (45%), left ventricular dimension (7%), and certain sports (6%).ConclusionsA physically active life style plays a role in increasing both aerobic capacity and left ventricular enlargement. Body size appeared to be a potent stimulus to left ventricular enlargement.