[Effects of physical training on autonomic nerve activity in patients with acute myocardial infarction]

The effects of early physical training on heart rate variability and autonomic nerve activity in acute myocardial infarction were studied in 20 patients (men, mean age 57 +/- 11 years) successfully treated by direct coronary angioplasty. Patients were randomly divided into the physical training group (training group: 10 patients) and conventional rehabilitation group (non-training group: 10 patients). Exercise tolerance (VO2 peak and anaerobic threshold: AT), heart rate variability indices, serum levels of catecholamines, and 24-hour urinary excretion of catecholamines were measured on the 14th and 28th days. The conventional cardiac rehabilitation program was followed by each group, and the training group patients were also instructed to follow a training program using the bicycle ergometer (80% AT, 10 min, 2 times a day) for 2 weeks from the 15th day. Autonomic nerve activity was assessed by non-spectral (24-hour averaged normal RR intervals: mean NN, standard deviation of normal RR intervals over 24 hours: SDNN and standard deviation of the mean RR intervals for each 5 min periods over 24 hours: SDANN) and spectral [high frequency power (HF) 0.15-0.40 Hz; represents parasympathetic activity, and the low/high frequency power (L/H ratio); represents sympathetic activity] indices of heart rate variability. There were no cardiac events during physical training. Comparison of the 14th and 28th day in the training group showed that the VO2 peak and VO2 AT significantly increased, SDNN and SDANN significantly increased, HF (82.5 +/- 56.2 to 131.1 +/- 99.8 msec2) increased and the L/H ratio (3.9 +/- 2.2 to 2.6 +/- 1.3) decreased significantly during the night-time, and serum noradrenalin concentration (0.47 +/- 0.11 to 0.35 +/- 0.13 ng/ml) and urinary noradrenalin excretion (195.6 +/- 130.7 to 139.6 +/- 73.3 micrograms/day) significantly decreased. In contrast, the non-training group showed no significant changes. These results suggest early physical training may be safe and improves the autonomic nerve balance and exercise tolerance in patients with acute myocardial infarction.