Obesity does not Impair Ambulatory Cardiovascular and Autonomic Responses Post-exercise

Abstract

This study aimed to assess whether obesity and/or maximal exercise can change 24 h cardiac autonomic modulation and blood pressure in young men. Thirty-nine men (n: 20; 21.9±1.8 kg·m−2, and n: 19; 32.9±2.4 kg·m−2) were randomly assigned to perform a control (non-exercise) and an experimental day exercise (after maximal incremental test). Cardiac autonomic modulation was evaluated through frequency domain heart rate variability (HRV). Obesity did not impair the ambulatory HRV (p>0.05), however higher diastolic blood pressure during asleep time (p=0.02; group main effect) was observed. The 24 h and awake heart rate was higher on the experimental day (p<0.05; day main effect), regardless of obesity. Hypotension on the experimental day, compared to control day, was observed (p<0.05). Obesity indicators were significantly correlated with heart rate during asleep time (Rho=0.34 to 0.36) and with ambulatory blood pressure(r/Rho=0.32 to 0.53). Furthermore, the HRV threshold workload was significantly correlated with ambulatory heart rate (r/Rho=− 0.38 to−0.52). Finally, ambulatory HRV in obese young men was preserved; however, diastolic blood pressure was increased during asleep time. Maximal exercise caused heart rate increase and 24h hypotension, with decreased cardiac autonomic modulation in the first hour, regardless of obesity.

Parasympathetic modulation during sleep time is reduced after maximal exercise, correlated with aerobic fitness in young women

“…Previously, a parasympathetic modulation reduction during the sleep period after intense exercise in physically active men has been reported 1,10,15 . On the other hand, a recent study 12 verified attenuated parasympathetic nervous modulation only in the first hour post maximal exercise, while and another study 13 observed that the nighttime period was more responsive to the positive effects of moderate-intensity exercise on cardiac autonomic modulation. However, both studies 12,13 were performed in the morning and with men.…”

“…On the other hand, a recent study 12 verified attenuated parasympathetic nervous modulation only in the first hour post maximal exercise, while and another study 13 observed that the nighttime period was more responsive to the positive effects of moderate-intensity exercise on cardiac autonomic modulation. However, both studies 12,13 were performed in the morning and with men. The differences in subject characteristics such as physical fitness and sex, the varied duration and intensity of exercise protocols, may also contribute to the differing results reported.…”

“…The parasympathetic and sympathetic influence on HR is mediated via cholinergic vagal nerve fibers and by catecholamines, respectively. Although differences in cardiac autonomic modulation between the sexes are well established 11,14 , most studies analyze cardiac autonomic modulation exclusively in men 1,10,12,13,15 or trained women 7,20 . To our knowledge, there is no information about ambulatory cardiac autonomic modulation responses to maximal exercise in women, especially those with little aerobic fitness, who represent the majority of the population 21 .…”

“…One previous study 10 has reported an attenuated parasympathetic nervous modulation in sleep time after high-intensity exercise. On the other hand, a recent study 12 verified attenuated parasympathetic nervous modulation only in the first-hour post maximal exercise. A third study 13 observed that the nighttime period was more responsive to the positive effects of moderate-intensity exercise on cardiac autonomic modulation.…”

“…Considering that sex is a significant predictor of differences in HRV 14 , that the responsiveness to exercise might be dependent on the resting status, and that several studies analyzed only men 1,10,12,13,15 , we suggest here that studies to understand all the risks associated with recovery from maximum exercise be designed to specifically consider sex in order to increase their ecological validity. This study aimed to verify whether maximal exercise alters the ambulatory cardiac autonomic modulation in untrained women and whether aerobic fitness is correlated to cardiac autonomic modulation.…”