Sex Differences in Autonomic Function Following Aerobic Exercise

Abstract

Heart rate variability (HRV), blood pressure variability (BPV) and baroreceptor sensitivity (BRS) provides insight into cardiovascular regulation in different physiological settings. Pre-menopausal females have been shown to exhibit a cardioprotective autonomic profile compared to males following maximal exercise, but it is unknown if there are sex differences in autonomic recovery following submaximal aerobic exercise. PURPOSE: To determine the effects of sex on autonomic function at rest and following an acute bout of submaximal aerobic exercise. METHODS: Forty-three (males n=22, age = 22 ± 1 yrs, BMI = 25.9 ± 0.7 kg/m2; females n=21, age = 22 ± 1 yrs, BMI = 23.7 ± 0.5 kg/m2) healthy, normotensive participants completed a 45-min moderate intensity aerobic exercise session. Beat-to-beat BP was recorded using finger plethysmography for 5 min prior to exercise (REST), at 30 min (P30), 60 min (P60) and 90 min (P90) following exercise. Frequency domain measurements of HRV and BRV were calculated. The low frequency power of BPV (BPV_LF) was used as an estimation of sympathetic vasomotor tone and the ratio of low- (LF) and high-frequency (HF) bands in HRV (LF/HF) has been used to quantify the degree of sympathovagal balance. BRS was estimated by the alpha coefficient method (Alpha_LF). Repeated measures analysis of variance (ANOVA) (2 x 4; sex x time-point) was performed. RESULTS: Data were presented in Table 1 as mean ± standard error. CONCLUSION: Forty-five min of submaximal aerobic exercise results in sustained disturbance of cardiovascular homeostasis as manifested by elevated sympathovagal balance and increased cardiovagal baroreceptor sensitivity 90 min after exercise. In addition, young, healthy women exhibited lower sympathetic tone at rest and during recovery from aerobic exercise compared to age-matched males.Table 1: Autonomic function variables at rest and 30,60, and 90 mins following aerobic exercise