Effects of aerobic exercise training on sympathetic and renal responses to mental stress in humans

Abstract

The effects of aerobic exercise training (ET) on muscle sympathetic nerve activity (MSNA) and renal vascular responses to mental stress (MS) have not been determined in humans. We hypothesized that aerobic ET would reduce MSNA and renal vasoconstriction during MS. MSNA, mean arterial pressure (MAP), heart rate, renal blood flow velocity (RBFV), and peak oxygen uptake (V(O2peak)) were recorded in 23 healthy adults. Fourteen subjects participated in 8 wk of aerobic ET, while nine subjects served as sedentary controls (Con). ET significantly increased V(O2peak) (Delta18 +/- 1%; P < 0.001) and decreased RBFV at rest (60 +/- 4 to 48 +/- 3 cm/s; P < 0.01), whereas Con did not alter V(O2peak) or RBFV. ET did not alter resting MSNA (11 +/- 1 to 9 +/- 1 bursts/min) or MAP (84 +/- 2 to 83 +/- 2 mmHg), and these findings were similar in the Con group. MS elicited similar increases in MSNA (approximately Delta2 bursts/min; P < 0.05), MAP (approximately Delta15 mmHg; P < 0.001), and heart rate (approximately Delta20 beats/min; P < 0.001) before and after ET, and the responses were not different between ET and Con. Likewise, MS elicited similar decreases in RBFV and renal vascular conductance before and after ET, and the responses were not different between ET and Con. Perceived stress levels during MS were similar before and after the 8-wk study in both ET and Con. In conclusion, ET does not alter MSNA and renal vascular responses to MS in healthy humans.

Fig. 1.

Changes in heart rate (HR) and mean arterial pressure (MAP) during mental stress (MS) after 8 wk of exercise training or sedentary control. MS increased HR and MAP in both our exercise training and control groups, and these increases were similar before (Pre) and after (Post) the 8-wk training study in both groups. Base, baseline; Rec, recovery; bpm, beats/min. Values are reported as means ± SE; n, number of subjects.

Fig. 2.

Changes in muscle sympathetic nerve activity (MSNA) during MS after 8 wk of exercise training or sedentary control. MS increased MSNA burst frequency in our exercise training group, and these increases were similar before and after training. AU, arbitrary units. Values are reported as means ± SE; n, number of subjects.

Fig. 3.

Renal blood flow velocity (RBFV) and renal vascular conductance (RVC) during MS after 8 wk of exercise training or sedentary control. Aerobic exercise training significantly reduced RBFV at rest and during MS, but the magnitude of these responses (i.e., change in RBFV and RVC) was similar before and after the 8-wk study in both groups. RVC was calculated using MAP measurements obtained from the Finometer. There was only a small difference observed between blood pressure at rest obtained using a cuff and that of the Finometer. Values are reported as means ± SE; n, number of subjects. *P < 0.05 vs. baseline; †P < 0.05 vs. corresponding pretraining value.