EXERCISE TRAINING IMPROVES LEFT-VENTRICULAR SYSTOLIC FUNCTION IN OLDER MEN

To determine whether endurance exercise training can improve left ventricular systolic function in older men, 10 healthy sedentary men (64 +/- 3 years old; mean +/- SD0 were studied. Training consisted of endurance exercise 4 +/- 0.3 days per week for 11.8 +/- months at a progressively increasing intensity of 60-80% of maximal O2 uptake (Vo2max0 with additional brief bouts of exercise equal to 93 +/- 13% of Vo2max increased from 29.6 +/- 4.1 to 37.2 +/- ml/kg/min (p < 0.001). Percent body fat was decreased (17.8 +/- 3.6% versus 15.6%; p < 0.001). Before training, left ventricular ejection fraction, determined by electrocardiographic-gated equilibrium blood pool imaging, increased only modestly during exercise (from 66.3 +/- 6.7% at rest to 70.6 +/- 6.9% at peak exercise). After training, the increase in ejection fraction during exercise was significantly greater (from 67 +/- 4.8% at rest to 77.6 +/- 7.5% at peak exercise) than that observed before training and was similar to that in young sedentary men (64 +/- 7% at rest versus 74 +/- 9% at peak exercise). Although the changes in systolic pressure from rest to exercise were similar, end-systolic volume decreased significantly at peak exercise after (51 +/- versus 38 +/- 13 ml; p < 0.005) but not before (46 +/- versus 43 +/- versus 43 +/- ml; p = NS) training with a shift in the end-systolic volume-systolic blood pressure relation to the left compatible with enhanced inotropic state. Exercise training induced proportional increases in left ventricular end-diastolic diameter and posterior wall thickness, measured echocardiographically, with no change in the wall thickness-to-radius ratio (0.27 +/- 0.04 versus 0.28 +/- 0.03), suggestive of volume-overload hypertrophy. End-diastolic volume at rest was increased (138 +/- 0.03), suggestive of volume-overload hypertrophy. End-diastolic volume at rest was increased (138 +/- 11 versus 155 +/- 26 ml; p < 0.05). Stroke volume was significantly greater at peak exercise in response to training (110 +/- 17 ml before versus 132 +/- ml after training; p < 0.05). The differences in end-diastolic volume and stroke volume at peak exercise between the trained and untrained states correlated strongly (r = 0.95). At a given increase in end-diastolic volume during exercise, the increase in stroke volume was more after than before training. Furthermore, at a given change in end-systolic volume from rest to exercise, the subjects attained a higher systolic blood pressure after than before training. These data suggest that endurance exercise training of sufficient intensity can improve left ventricular systolic performance in older men.