Lactate and epinephrine during exercise in altitude natives

Bengt Kayser, Roland Favier, Guido Ferretti, Dominique Desplanches, Hilde Spielvogel, Harry Koubi, Brigitte Sempore, and Hans Hoppeler Département de Physiologie, Centre Médical Universitaire, 1211 Geneva 4; Anatomisches Institut, Universität Bern, 1000 Berne, Switzerland; Unité de Recherche Associé 1341, Centre National de la Recherche Scientifique, Laboratoire de Physiologie, Université Claude Bernard, 69373 Lyon Cedex 08, France; and Instituto Boliviano de Biología de Altura, Universidad Mayor de San Andrés, Casilla 717, La Paz, Bolivia Received 12 March 1996; accepted in final form 23 July 1996. 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 O 2 fraction (F I O 2 ) affect the [La] vs. power output ( ) relationship or, alternatively, as reported for lowlanders, whether changes in [La] vs. on changes in F I O 2 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 O 2 uptake ( O 2 ) vs. relationships were not altered by F I O 2 . AN increased two-leg peak O 2 by 10% and peak by 7%. AN paradoxically decreased one-leg peak O 2 by 7%, whereas peak remained the same. The [La] vs. 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 F I O 2 . Thus normoxia attenuated the increment in both [La] and [Epi] as a function of , 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 F I O 2 on [La] during exercise. lactate paradox; energetics 0161-