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 echoc ardiography in 16 young healthy volunteers. During the incremental pha se 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 exer cise [81.7 (SD 4.4)%, P < 0.0001 vs rest]. During recovery, the ejecti on 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 sys tolic 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 t he initial phase and subsequently did not change until the end of exer cise [7.0 (SD 2.2) mmHg.ml(-1), P < 0.0001 vs rest], to fall sharply a fter the cessation of exercise [2.9 (SD 1.1) mmHg.ml(-1) at the 10th m in, n.s. vs rest]. Exercise and recovery indices of left ventricular p erformance were not correlated with exercise duration, maximal heart r ate and increase in free fatty acids. The present results indicated th at, 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 m isleading.