The effect of aerobic training and cardiac autonomic regulation in young adults.

OBJECTIVES We tested the effect of aerobic exercise on autonomic regulation of the heart in healthy young adults. METHODS Healthy, sedentary young adults (n = 149; age = 30.4 +/- 7.53 years) were randomized to receive 12 weeks of either aerobic conditioning or strength training. Primary outcomes were heart rate and RR interval variability (RRV) measured before and after training and after 4 weeks of sedentary deconditioning. RRV, a noninvasive index of cardiac autonomic regulation, reflects variability in the intervals between consecutive R waves of the electrocardiogram. RESULTS Aerobic conditioning but not strength training led to a significant increase in aerobic capacity (3.11 mL/kg/min), a decrease in heart rate (-3.49 beats per minute), and an increase in high-frequency RRV (0.25 natural log msec2), each of which returned to pretraining levels after deconditioning. Significant 3-way interactions, however, revealed autonomic effects only in men. CONCLUSIONS In sedentary, healthy young adults, aerobic conditioning but not strength training enhances autonomic control of the heart, but post hoc analyses suggested that gender plays a significant role in this exercise-related cardioprotection.