Published:  2008-01-01

No Effect of Training State on Ambulatory Measures of Cardiac Autonomic Control

Authors:  Annebet Goedhart, Marije Vries, Jeroen Kreft, Frank Bakker, Eco Geus


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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.