Effect of exercise on heart-rate response to mental stress in teenagers

Purpose: We sought to determine if an exercise programme of moderate aerobic intensity would decrease the heart-rate response to mental stress in teenagers with normal hearts. Methods: Mental stress testing (50 arithmetic problems) was performed in student volunteers before and after a 5-week period of rigorous aerobic exercise training of 2.5h for 5 days/week. Results: In the baseline state, the mental stress test increased the heart rate by an average of 20 +/- 12 bpm to its observed peak at 30s of testing (p<0.001). Exercise training had a significant effect on the maximum heart rate (106 +/- 19 vs. 89 +/- 13 bpm, p<0.001) and on the maximum increase in heart rate with mental stress (20 +/- 12 pre vs. 9 +/- 15 bpm post training, p<0.001). Conclusion: Mental stress results in a marked heart response consistent with a marked neurohormonal effect. This response is effectively blunted by a 5-week moderately intensive exercise programme. These results should encourage endorsement of a regular exercise programme as an important lifestyle modification for improving maladaptive responses to stress.