Short-term aerobic physical training induced resting bradycardia and increased VO2 at anaerobic threshold (P<0.05) in healthy men, but did not significantly change heart rate variability.
Does short-term aerobic physical training improve heart rate variability and cardiorespiratory responses in young and middle-aged healthy sedentary men?
Short-term aerobic exercise training induces resting bradycardia likely through intrinsic sinus node adaptations rather than changes in autonomic modulation, while improving cardiorespiratory fitness.
The purpose of the present study was to evaluate the effects of aerobic physical training (APT) on heart rate variability (HRV) and cardiorespiratory responses at peak condition and ventilatory anaerobic threshold. Ten young (Y: median = 21 years) and seven middle-aged (MA = 53 years) healthy sedentary men were studied. Dynamic exercise tests were performed on a cycloergometer using a continuous ramp protocol (12 to 20 W/min) until exhaustion. A dynamic 24-h electrocardiogram was analyzed by time (TD) (standard deviation of mean R-R intervals) and frequency domain (FD) methods. The power spectral components were expressed as absolute (a) and normalized units (nu) at low (LF) and high (HF) frequencies and as the LF/HF ratio. Control (C) condition: HRV in TD (Y: 108, MA: 96 ms; P<0.05) and FD - LFa, HFa - was significantly higher in young (1030; 2589 ms2/Hz) than in middle-aged men (357; 342 ms2/Hz) only during sleep (P<0.05); post-training effects: resting bradycardia (P<0.05) in the awake condition in both groups; VO2 increased for both groups at anaerobic threshold (P<0.05), and at peak condition only in young men; HRV in TD and FD (a and nu) was not significantly changed by training in either groups. The vagal predominance during sleep is reduced with aging. The resting bradycardia induced by short-term APT in both age groups suggests that this adaptation is much more related to intrinsic alterations in sinus node than in efferent vagal-sympathetic modulation. Furthermore, the greater alterations in VO2 than in HRV may be related to short-term APT.
Catai et al. (Sat,) conducted a other in Healthy sedentary men (n=17). Aerobic physical training (APT) vs. Pre-training baseline was evaluated on Heart rate variability (HRV) and cardiorespiratory responses. Short-term aerobic physical training induced resting bradycardia and increased VO2 at anaerobic threshold (P<0.05) in healthy men, but did not significantly change heart rate variability.
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