COCA CHEWING FOR EXERCISE - HORMONAL AND METABOLIC RESPONSES OF NONHABITUAL CHEWERS

To determine the effects of acute coca use on the hormonal and metabol ic responses to exercise, 12 healthy nonhabitual coca users were submi tted twice to steady-state exercise (similar to 75% maximal O-2 uptake ). On one occasion, they were asked to chew 15 g of coca leaves 1 h be fore exercise, whereas on the other occasion, exercise was performed a fter 1 h of chewing a sugar-free chewing gum. Plasma epinephrine, nore pinephrine, insulin, glucagon, and metabolites (glucose, lactate, glyc erol, and free fatty acids) were determined at rest before and after c oca chewing and during the 5th, 15th, 30th, and 60th min of exercise. Simultaneously to these determinations, cardiorespiratory variables (h eart rate, mean arterial blood pressure, oxygen uptake, and respirator y gas exchange ratio) were also measured. At rest, coca chewing had no effect on plasma hormonal and metabolic levels except for a significa ntly reduced insulin concentration. During exercise, the oxygen uptake , heart rate, and respiratory gas exchange ratio were significantly in creased in the coca-chewing trial compared with the control (gum-chewi ng) test. The exercise-induced drop in plasma glucose and insulin was prevented by prior coca chewing. These results contrast with previous data obtained in chronic coca users who display during prolonged subma ximal exercise an exaggerated plasma sympathetic response, an enhanced availability and utilization of fat (R. Favier, E. Caceres, H. Koubi, B. Sempore, M. Sauvain, and H. Spielvogel. J. Appl. Physiol. 80: 650- 655, 1996). We conclude that, whereas coca chewing might affect glucos e homeostasis during exercise, none of the physiological data provided by this study would suggest that acute coca chewing in nonhabitual us ers could enhance tolerance to exercise.