Does 5-month low- and high-intensity endurance training improve resting heart rate, HRV, and BRS in sedentary, middle-aged persons?
Five months of aerobic training improves resting heart rate and exercise capacity but does not modify cardiac vagal outflow (HRV or BRS) in sedentary middle-aged individuals.
Endurance-trained athletes have increased heart rate variability (HRV), but it is not known whether exercise training improves the HRV and baroreflex sensitivity (BRS) in sedentary persons. We compared the effects of low- and high-intensity endurance training on resting heart rate, HRV, and BRS. The maximal oxygen uptake and endurance time increased significantly in the high-intensity group compared with the control group. Heart rate did not change significantly in the low-intensity group but decreased significantly in the high-intensity group (-6 beats/min, 95% confidence interval; -10 to -1 beats/min, exercise vs. control). No significant changes occurred in either the time or frequency domain measures of HRV or BRS in either of the exercise groups. Exercise training was not able to modify the cardiac vagal outflow in sedentary, middle-aged persons.
Loimaala et al. (2000) studied this question.