5 research outputs found
Coca chewing for exercise: hormonal and metabolic responses of nonhabitual chewers
No full text Favier, Roland, Esperanza Caceres, Laurent Guillon, Brigitte Sempore, Michel Sauvain, Harry Koubi, and Hilde Spielvogel. Coca chewing for exercise: hormonal and metabolic responses of nonhabitual chewers. J. Appl. Physiol. 81(5): 1901–1907, 1996.—To determine the effects of acute coca use on the hormonal and metabolic responses to exercise, 12 healthy nonhabitual coca users were submitted twice to steady-state exercise (∼75% maximal O2 uptake). On one occasion, they were asked to chew 15 g of coca leaves 1 h before exercise, whereas on the other occasion, exercise was performed after 1 h of chewing a sugar-free chewing gum. Plasma epinephrine, norepinephrine, insulin, glucagon, and metabolites (glucose, lactate, glycerol, and free fatty acids) were determined at rest before and after coca chewing and during the 5th, 15th, 30th, and 60th min of exercise. Simultaneously to these determinations, cardiorespiratory variables (heart rate, mean arterial blood pressure, oxygen uptake, and respiratory gas exchange ratio) were also measured. At rest, coca chewing had no effect on plasma hormonal and metabolic levels except for a significantly reduced insulin concentration. During exercise, the oxygen uptake, heart rate, and respiratory gas exchange ratio were significantly increased in the coca-chewing trial compared with the control (gum-chewing) 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 submaximal 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 glucose homeostasis during exercise, none of the physiological data provided by this study would suggest that acute coca chewing in nonhabitual users could enhance tolerance to exercise. </jats:p
Lactate and epinephrine during exercise in altitude natives
No full text Kayser, Bengt, Roland Favier, Guido Ferretti, Dominique Desplanches, Hilde Spielvogel, Harry Koubi, Brigitte Sempore, and Hans Hoppeler. Lactate and epinephrine during exercise in altitude natives. J. Appl. Physiol. 81(6): 2488–2494, 1996.—We tested the hypothesis that the reported low blood lactate accumulation ([La]) during exercise in altitude-native humans is refractory to hypoxia-normoxia transitions by investigating whether acute changes in inspired O2 fraction ([Formula: see text]) affect the [La] vs. power output (W˙) relationship or, alternatively, as reported for lowlanders, whether changes in [La] vs. W˙ on changes in[Formula: see text] are related to changes in blood epinephrine concentration ([Epi]). Altitude natives [ n = 8, age 24 ± 1 (SE) yr, body mass 62 ± 3 kg, height 167 ± 2 cm] in La Paz, Bolivia (3,600 m) performed incremental exercise with two legs and one leg in chronic hypoxia and acute normoxia (AN). Submaximal one- and two-leg O2 uptake (V˙o 2) vs.W˙ relationships were not altered by[Formula: see text]. AN increased two-leg peak V˙o 2 by 10% and peakW˙ by 7%. AN paradoxically decreased one-leg peak V˙o 2 by 7%, whereas peak W˙ remained the same. The [La] vs. W˙ relationships were similar to those reported in unacclimatized lowlanders. There was a shift to the right on AN, and maximum [La] was reduced by 7 and 8% for one- and two-leg exercises, respectively. [Epi] and [La] were tightly related (mean r = 0.81) independently of[Formula: see text]. Thus normoxia attenuated the increment in both [La] and [Epi] as a function of W˙, whereas the correlation between [La] and [Epi] was unaffected. These data suggest loose linkage of glycolysis to oxidative phosphorylation under influence from [Epi]. In conclusion, high-altitude natives appear to be not fundamentally different from lowlanders with regard to the effect of acute changes in[Formula: see text] on [La] during exercise. </jats:p
Effets du jeûne intermittent sur l'utilisation des substrats énergétiques au cours de l'exercice chez le rat
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