Left ventricular inotropic response during weight lifting in untrained, weight trained, and endurance trained men: Evaluation by echocardiography.

摘要

This research was designed to measure the cardiac inotropic response of men trained by resistive exercise and by endurance exercise, and to compare these responses to a group of untrained, anthropometrically-matched, male controls. Subjects for this study were recruited from the Jackson, Mississippi and Hattiesburg, Mississippi areas. All subjects were properly informed of the risks involved during the data collection process, and each subject presented with no known medical malady which was prohibitive to his participation in the project. The data collection process involved two days; one to assess each subject's biometric parameters and to familiarize and perform the strength test, and another to perform the exercise echocardiographic assessment. A second phase of this process was needed to derive the cardiac measures from the hard-copy M-mode echocardiograms with the aid of a cardiologist blind to the subjects' training history. As revealed by a one way ANOVA with repeated measures procedure, the groups were similar on all echocardiographic contractility indices (velocity of circumferential fiber shortening and shortening fraction). It was further demonstrated that the endurance trained men were able to recover faster than the other groups on two hemodynamic measures (heart rate and rate pressure product). Finally, each group had equal end-systolic diameter measures, as this measure tends to parallel cardiac contractility. Aside from the formalized stated hypotheses of the study, there were other interesting findings of this investigation. The discovery of a lower diastolic blood pressure following acute resistive exercise warrants further study on the time course of this phenomenon. In addition, this study enhanced our understanding of the acute response of left ventricular function during maximal, dynamic weight lifting. The observation that both end-diastolic and end-systolic diameters decrease during this form of exercise, which contradicts findings from other studies utilizing other forms of resistive exercise, helps clarify our thinking on this important subject. Finally, it was demonstrated that high intensity weight lifting has a positive inotropic effect regardless of the previous training history.