PROLONGED EXERCISE INCREASES PERIPHERAL PLASMA ACTH, CRH, AND AVP IN MALE-ATHLETES

We wished to determine whether the increased ACTH during prolonged exe rcise was associated with changes in peripheral corticotropin-releasin g hormone (CRH) and/or arginine vasopressin (AVP). Six male triathlete s were studied during exercise: 1 h at 70% maximal oxygen consumption, followed by progressively increasing work rates until exhaustion. Dat a obtained during the exercise session were compared with a nonexercis e control session. Venous blood was sampled over a 2-h period for cort isol, ACTH, CRH, AVP, renin, glucose, and plasma osmolality. There wer e significant increases by ANOVA on log-transformed data in plasma cor tisol (P = 0.002), ACTH (P < 0.001), CRH (P < 0.001), and AVP (P < 0.0 3) during exercise compared with the control day. A variable increase in AVP was observed after the period of high-intensity exercise. Plasm a osmolality rose with exercise (P < 0.001) and was related to plasma AVP during submaximal exercise (P < 0.03) but not with the inclusion o f data that followed the high-intensity exercise. This indicated an ad ditional stimulus to the secretion of AVP. The mechanism by which ACTH secretion occurs during exercise involves both CRH and AVP. We hypoth esize that high-intensity exercise favors AVP release and that prolong ed duration favors CRH release.