Postexercise hemodynamics: Interactions of sex, training status, and fluid regulation

Abstract

In general, postexercise hypotension is characterized by a sustained increase in systemic vascular conductance that is not completely offset by ongoing increases in cardiac output. These hemodynamic changes are present immediately after a single bout of moderate-intensity dynamic exercise in healthy (sedentary and endurance exercise-trained) and hypertensive humans. The mechanisms underlying this postexercise hypotension are currently under investigation; however, the overall hemodynamic response may be altered in response to different factors related to sex, training status, and fluid regulation. The purpose of this dissertation was to investigate the contribution of endogenous hormones associated with the normal menstrual cycle and training status and sex on postexercise hemodynamics and to better understand how fluid replacement and heat-stress affect postexercise hemodynamics in a group of highly trained men. In Chapter IV, the contribution of the menstrual cycle and sex to postexercise hemodynamics was investigated. The results showed that postexercise hemodynamics are largely unaffected by sex and factors associated with the menstrual cycle. In Chapter V, the role of heat-stress and fluid replacement on the postexercise cardiac hemodynamics in a group of endurance exercise-trained men was investigated. These data suggest that fluid replacement and heat-stress mitigate the previously observed fall in cardiac output during exercise recovery in trained men. In Chapter VI, the study investigated the hemodynamic profile in well-hydrated sedentary and trained men and women during recovery from exercise. In contrast to previous research, the results showed a lack of variation in the postexercise hemodynamic response across categories of subjects as there was no evidence of a sex and training interaction. Thus, it appears that factors such as heat-stress and fluid replacement can alter postexercise hemodynamics in trained men; however, factors such as menstrual cycle, sex, and training status do not seem to influence the hemodynamic recovery profile. Yet substantial variation in the postexercise response across individuals remains unexplained.

This dissertation contains my previously published and my co-authored material.