Sex differences in cardiovascular function during submaximal exercise in humans

Abstract

Differences in cardiovascular function between sexes have been documented at rest and maximal exercise. The purpose of this study was to examine the sex differences in cardiovascular function during submaximal constant-load exercise, which is not well understood.Thirty-one male and 33 female subjects completed nine minutes moderate and nine minutes vigorous intensity submaximal exercise (40 and 75% of peak watts determined by maximal exercise test). Measurements included: intra-arterial blood pressure (SBP and DBP), cardiac index (QI), heart rate (HR), oxygen consumption (VO2) and arterial catecholamines (epinephrine = EPI and norepinephrine = NE), and blood gases. Mean arterial pressure (MAP), stroke volume index (SVI), systemic vascular resistance index (SVRI), arterial oxygen content (CaO2), arterial to venous O2 difference (AVO2) and systemic oxygen transport (SOT) were calculated.At rest and during submaximal exercise QI, SVI, SBP, MAP, NE, CaO2, and SOT were lower in females compared to males. VO2, AVO2, EPI were lower in females throughout exercise. When corrected for wattage, females had a higher Q, HR, SV, VO2 and AVO2 despite lower energy expenditure and higher mechanical efficiency.This study demonstrates sex differences in the cardiovascular response to constant-load submaximal exercise. Specifically, females presented limitations in cardiac performance in which they are unable to compensate for reductions in stroke volume through increases in HR, potentially a consequence of a female’s blunted sympathetic response and higher vasodilatory state. Females demonstrated greater cardiac work needed to meet the same external work demand, and relied on increased peripheral oxygen extraction, lower energy expenditure and improvements in mechanical efficiency as compensatory mechanisms.

Assessment of Exercise Capacity and Oxygen Consumption Using a 6 min Stepper Test in Older Adults

“…The 6MST detected expected gender differences in performance (Wheatley et al, 2014) providing some evidence of validity.…”

Rest and exercise hemodynamic and metabolic findings in active duty soldiers referred for cardiac catheterization to exclude heart disease: Insights from past invasive cardiopulmonary exercise testing using multisensor high fidelity catheters

“…In health, it is known that exercise capacity is influenced by subject age, gender, level of conditioning, hydration status, and environmental factors . The assessment of an individual's exercise capacity is also influenced by body position and exercise protocol .…”

Acute Cardiovascular Response to Pre-Prandial and Postprandial Exercise in Active Men

“…The non-occurrence of a significant rise in systolic BP after exercise in the fasting state would suggest a dysfunction in sympathetic activity of the participants with a consequent failure to catecholamine secretion 12 . Nevertheless, HR increased significantly in both situations.…”

“…Meanwhile, the variation in plasma concentration of norepinephrine necessary for maintaining normal levels of BP is facilitated by the ingestion of glucose and the subsequent release of insulin 11 . Thus, the reduction in the concentration of this neurotransmitter may limit the activation of β-adrenergic receptor and reduce cardiac contractility 12 . Accordingly, abnormally large falls in BP after a meal (postprandial hypotension) occurs due to the absence of elevated levels of catecholamine and may indicate a dysfunction of the sympathetic nervous system 13 .…”