Reducing psychosocial stress: a novel mechanism of improving survival from exercise training.

BACKGROUND: Exercise training reduces mortality in patients with coronary artery disease. Behavioral characteristics, including depression, hostility, and overall psychosocial stress, have been shown to be independent risk factors for recurrent myocardial infarction and death in these patients. Exercise training can reduce these high-risk behaviors, but it remains uncertain as to what extent the health benefits of exercise training can be attributed to improving these behaviors.
METHODS: We evaluated the impact of exercise training during cardiac rehabilitation on mortality in 53 patients with coronary artery disease with high levels of psychosocial stress and in 469 patients with coronary artery disease with low levels of psychosocial stress and compared them with 27 control patients with high psychosocial stress who did not undergo formal cardiac rehabilitation and exercise training.
RESULTS: Mortality was approximately 4-fold greater in patients with high psychosocial stress than in those with low psychosocial stress (22% vs 5%; P = .003). Exercise training decreased the prevalence of psychosocial stress from 10% to 4% (P<.0001) and similarly improved peak oxygen uptake in patients with high and low psychosocial stress. Mortality in patients who improved exercise capacity by>or=10% (high exercise change) was 60% lower than in patients who had<10% improvement in exercise capacity (low exercise change) (P=.009). Mortality was lower in patients with high psychosocial stress with high exercise change compared with patients with high psychosocial stress with low exercise change (0% vs 19%; P=.009). In contrast, there was no significant improvement in mortality in patients with high versus low exercise change with low psychosocial stress (4% vs 8%; P=.14).
CONCLUSION: Psychosocial stress is an independent risk factor for mortality in patients with coronary artery disease, and exercise training can effectively reduce its prevalence. Exercise training reduces mortality in patients with coronary artery disease, and this effect seems to be mediated in part because of the salutary effects of exercise on psychosocial stress.