Dexamethasone in resting and exercising men. I. Effects on bioenergetics, minerals, and related hormones
Journal of applied physiology
Dexamethasone in resting and exercising men. I. Effects on bioenergetics, minerals, and related hormones. J. Appl. Physiol. 87(1): 175-182, 1999.-A placebo and a low and a high dose of dexamethasone (Dex) were administered for 4.5 days, at 3-wk intervals, to 24 healthy men, following a double-blind, random-order, crossover procedure. After the last dose the subjects performed a maximal cycling exercise, during which respiratory exchanges, electrocardiogram, and blood pressures were monitored.
... s were monitored. Blood was sampled just before and after each exercise bout. Dex showed no significant effect on fitness, sleep, exhaustion during exercise, maximal O 2 consumption, ventilatory threshold, maximal blood lactate, or rest and exercise blood pressures. On the contrary, both doses of Dex significantly decreased heart rate at rest and during maximal exercise. Blood glucose at rest was higher after both doses of Dex than after placebo; the opposite was found during exercise. Blood levels of ACTH, ␤-endorphin, cortisol, and cortisol-binding globulin were lowered by Dex at rest and after exercise. Dex stimulated the increase in atrial natriuretic factor during exercise and lowered rest and postexercise aldosterone. Finally, no difference between "fit or trained" and "less fit or untrained" subjects could be found with respect to Dex effects. dexamethasone suppression test; performance; aldosterone; atrial natriuretic factor; ␤-endorphins CORTICOSTEROIDS, the use of which is restricted by the International Olympic Committee to local applications and sprays (6) , are probably also used per os or intravenously as doping agents because of their supposed stimulating, analgesic, and anxiolytic effects. On the other hand, if therapeutic and side effects of corticosteroids are well known in humans at rest, to our knowledge no study has been conducted on their effects on or during muscular exercise. Exercise is one of the strongest physiological stimuli, for which nervous, cardiovascular, respiratory, and several hormonal systems are solicited to fulfill the energetic demand and the necessary elimination of metabolites. Steroids inhibit the hypothalamic-pituitary-adrenal system, which is highly solicited during exercise and partly regulates the renin-angiotensinaldosterone system (RAAS) and atrial natriuretic factor (ANF) secretions via pro-opiomelanocortin, the common precursor of ACTH and endorphins (18).