Lactate and epinephrine during exercise in altitude natives

Kayser, Bengt, Roland Favier, Guido Ferretti, DominiqueDesplanches, Hilde Spielvogel, Harry Koubi, Brigitte Sempore, and HansHoppeler. Lactate and epinephrine during exercise in altitudenatives. J. Appl. Physiol. 81(6):2488-2494, 1996.We tested the hypothesis that the reported lowblood lactate accumulation (La]) during exercise inaltitude-native humans is refractory to hypoxia-normoxia transitions byinvestigating whether acute changes in inspiredO₂ fraction(FI_O2) affect theLa] vs. power output ()relationship or, alternatively, as reported for lowlanders, whetherchanges in La] vs. on changes inFI_O2 are related tochanges 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 twolegs and one leg in chronic hypoxia and acute normoxia (AN). Submaximalone- and two-leg O₂ uptake (O₂) vs. relationships were not altered byFI_O2. AN increased two-legpeak O₂ by 10% and peak by 7%. AN paradoxically decreasedone-leg peak O₂ by 7%,whereas peak remained the same. TheLa] vs. relationships were similar tothose reported in unacclimatized lowlanders. There was a shift to theright on AN, and maximum La] was reduced by 7 and 8% forone- and two-leg exercises, respectively. Epi] andLa] were tightly related (mean r = 0.81) independently ofFI_O2. Thus normoxiaattenuated the increment in both La] and Epi]as a function of , whereas the correlation betweenLa] and Epi] was unaffected. These data suggest loose linkage of glycolysis to oxidative phosphorylation under influence from Epi]. In conclusion, high-altitudenatives appear to be not fundamentally different from lowlanders with regard to the effect of acute changes inFI_O2 on La] during exercise.