Effects of exercise training on the recovery of the autonomic nervous system and exercise capacity after acute myocardial infarction.

Abstract

This study investigated the effects of aerobic exercise training on the early phase of the recovery process following acute myocardial infarction (AMI) in terms of the autonomic nervous system, cardiac function and exercise capacity. Twenty-eight patients in the first week after the onset of AMI were assigned randomly to either a training group or a control group. The training group performed aerobic exercise for 2 weeks. Cardiopulmonary exercise testing was performed 3 times during the 3 months after the onset. Heart rate variability, plasma norepinephrine (NE) levels, and cardiac index (CI) during exercise were measured. In the training group, plasma NE level and deltaCI (peak CI-rest CI) were significantly improved from 1 to 3 weeks after the onset, and the high frequency of heart rate variability and peak oxygen uptake were significantly increased up to 3 months after the onset. In the control group, the plasma NE level and the deltaCI during the 1-3 weeks post-AMI, the high frequency of heart rate variability and the peak oxygen uptake showed a tendency to improve up to 3 months after the onset. These results indicate that sympathetic nervous activity improves soon after the onset of AMI, in conjunction with improvement in cardiac function, and that this improvement is not affected by exercise training. In contrast, the recovery of parasympathetic nervous activity requires a longer period, along with the recovery of exercise capacity, which is facilitated by even short-term aerobic exercise training.