Catecholamine, renin-aldosterone, and glucoregulatory responses to maximal exercise in humans: Effects of prolonged bedrest

The catecholamine, renin-aldosterone, and glucose-insulin responses to maximal exercise were studied in 18 young, healthy male subjects. Eight of these subjects agreed to further undergo an 18-day period of bedrest, following which the exercise protocol was repeated. Bedrest deconditioning elicited a decrease (P < .05) in maximal oxygen consumption and exercise duration. Upright resting epinephrine, norepinephrine, and dopamine levels and their responses to maximal exercise were not significantly altered by the bedrest period. Upright resting renin and aldosterone levels tended (P < .1) to increase after the bedrest period, but their responses to maximal exercise were not affected. The bedrest period elicited a decrease (P < .05) in resting glucose concentrations but did not alter the elevation in glucose during maximal exercise. In contrast, the mean resting insulin level was not significantly altered by bedrest. The drop (P < .05) in insulin concentration from rest to maximal exercise noted before the bedrest period was not observed after bedrest. While the catecholamine responses are minimally affected, prolonged bedrest elicits alterations of the renin-aldosterone and glucose-insulin systems at rest and during maximal exercise.

Duke Scholars

Author Michael Hugh Sketch Jr. Medicine, Cardiology