The Influence of Exercise Intensity on Postexercise Baroreflex Sensitivity.

PURPOSE

The purpose of this study was to investigate the influence of exercise intensity on postexercise supine and tilt baroreflex sensitivity (BRS).

METHOD

Nine healthy, active men performed 2 conditions of interval cycling of 40% maximal work rate (WR) and 75% WR of matched work done and a control condition of no exercise in a counterbalanced order. BRS outcome measures were determined at preexercise and postexercise up to +24 hr in supine and tilt positions. R-R interval and blood pressure data were collected over consecutive 10-min periods and were analyzed by Fast Fourier transformation analysis.

RESULTS

A fully repeated analysis of variance revealed a significant interaction (p < .05) between time and condition in supine for BRS, F(3, 134) = 5.19, p < .05, ES = .39, and BRS, F(3, 134) = 5.65, p < .05, ES = .41, and in tilt for BRS, F(3, 134) = 3.54, p < .05, ES = .31, BRS, F(3, 134) = 5.94, p < .05, ES = .43, BRS, F(4, 134) = 6.23, p < .05, ES = .44, and BRS, F(4, 134) = 9.22, p < .05, ES = .54. There were significant differences (p < .05) between condition comparisons at +15 min and between control and 75% WR and between the 40% WR and 75% WR conditions at +60 min. At +15 min, BRS was lower in the 75% WR condition compared with the 40% WR condition and the control condition, and it was lower in the 40% WR condition than in the control condition.

CONCLUSION

The findings demonstrate an intensity-dependent relationship in the BRS response following exercise.