LEFT-VENTRICULAR PERFORMANCE DURING PROLONGED EXERCISE AND EARLY RECOVERY IN HEALTHY-SUBJECTS

The effect of semi-supine long lasting exercise to exhaustion [61 (SD 10) min] on left ventricular systolic performance was studied by echocardiography in 16 young healthy volunteers. During the incremental phase of exercise, the ejection fraction increased from 65.2 (SD 4.1)% to 80.1 (SD 4.8)% (P<0.0001), then it levelled off up to the end of exercise [81.7 (SD 4.4)%, P < 0.0001 vs rest]. During recovery, the ejection fraction rapidly and steadily decreased to a value similar to that at rest [66.1 (SD 5.0)%, n.s.). A similar pattern was shown by the systolic blood pressure/end-systolic volume coefficient, which rose from 3.2 (SD 0.8) mmHg.ml(-1) to 7.5 (SD 2.7) mmHg.ml(-1) (P < 0.0001) in the initial phase and subsequently did not change until the end of exercise [7.0 (SD 2.2) mmHg.ml(-1), P < 0.0001 vs rest], to fall sharply after the cessation of exercise [2.9 (SD 1.1) mmHg.ml(-1) at the 10th min, n.s. vs rest]. Exercise and recovery indices of left ventricular performance were not correlated with exercise duration, maximal heart rate and increase in free fatty acids. The present results indicated that, after the initial increase, left ventricular performance remained elevated during prolonged high intensity exercise and that conclusions on exercise cardiac performance drawn from postexercise data can be misleading.