Spanish genetic admixture is associated with larger V̇o2 maxdecrement from sea level to 4,338 m in Peruvian Quechua

Abstract

Quechua in the Andes may be genetically adapted to altitude and able to resist decrements in maximal O2consumption in hypoxia (ΔV̇o2 max). This hypothesis was tested via repeated measures of V̇o2 max(sea level vs. 4,338 m) in 30 men of mixed Spanish and Quechua origins. Individual genetic admixture level (%Spanish ancestry) was estimated by using ancestry-informative DNA markers. Genetic admixture explained a significant proportion of the variability in ΔV̇o2 maxafter control for covariate effects, including sea level V̇o2 maxand the decrement in arterial O2saturation measured at V̇o2 max(ΔSpO2 max) ( R2for admixture and covariate effects ∼0.80). The genetic effect reflected a main effect of admixture on ΔV̇o2 max( P = 0.041) and an interaction between admixture and ΔSpO2 max( P = 0.018). Admixture predicted ΔV̇o2 maxonly in subjects with a large ΔSpO2 max( P = 0.031). In such subjects, ΔV̇o2 maxwas 12–18% larger in a subgroup of subjects with high vs. low Spanish ancestry, with least squares mean values (±SE) of 739 ± 71 vs. 606 ± 68 ml/min, respectively. A trend for interaction ( P = 0.095) was also noted between admixture and the decrease in ventilatory threshold at 4,338 m. As previously, admixture predicted ΔV̇o2 maxonly in subjects with a large decrease in ventilatory threshold. These findings suggest that the genetic effect on ΔV̇o2 maxdepends on a subject's aerobic fitness. Genetic effects may be more important (or easier to detect) in athletic subjects who are more likely to show gas-exchange impairment during exercise. The results of this study are consistent with the evolutionary hypothesis and point to a better gas-exchange system in Quechua.