||No Effect of Training State on Ambulatory Measures of Cardiac Autonomic Control
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||Journal of Psychophysiology
||exercise, detraining, heart rate, autonomic control, sympathetic, vagal
||We examined the effect of training state on cardiac autonomic control in a naturalistic setting. Twenty-four vigorous exercisers
were compared to age- and sex-matched sedentary controls. The regular exercisers were subjected to a 6-week training program after
which they were randomized to 2 weeks of continued training or 2 weeks of detraining. Cardiac autonomic control was measured over
a 24-h period by ambulatory recording, using the preejection period (PEP) and respiratory sinus arrhythmia (RSA). Nonexercising controls
had a significantly higher ambulatory heart rate (HR) compared to the regular exercisers but comparable 24-h levels of PEP and RSA.
In regular exercisers, 2 weeks of detraining did not significantly change the 24-h levels of HR, PEP, or RSA. We conclude that the
bradycardia in healthy regular exercisers is the result of a lower intrinsic heart rate rather than a shift in cardiac autonomic balance from
sympathetic to vagal control.