Absence of Work Efficiency Differences During Cycle Ergometry Exercise in Bolivian Aymara

Abstract

This study tested the hypothesis that Andean natives are adapted to high altitude (HA) via high work efficiency during exercise in hypoxia. A total of 186 young males and females were tested in Bolivia, comprising eight different subject groups. Groups were identified based on gender, ancestry (Aymara vs. European), altitude of birth (highlands vs. lowlands), and the altitude where tested (420, 3600, 3850 m). This design allows partitioning of ancestral (i.e., genetic) and developmental effects. To minimize measurement error, subjects were given two submaximal exercise tests on a cycle ergometer (on separate days). Each test consisted of four 5-min work bouts (levels), each separated by a 5-min rest period. For all groups, the oxygen consumption (V(O2))-work rate relationship was not different from the sea-level reference. Gross and net efficiencies (GE and NE) were not different between groups at any work level, with the exception of European men born in the lowlands and acclimatized and tested at 3600 m. These men showed slightly lower V(O2) at high work output, but this may be due to a nonsteady-state V(O2) kinetic, rather than to an altered steady-state V(O2)-work rate relationship per se. There were no significant group differences in delta efficiency (DE). In sum, these results provide no support for the hypothesis of energetic advantage during submaximal work in Andean HA natives. A review and analysis of the literature suggest that the same is true for HA natives in the Himalayas.

Why Are High-Altitude Natives So Strong at Altitude? Maximal Oxygen Transport to the Muscle Cell in Altitude Natives

“…In brief, however, one of the better studies addressing the question investigated 186 men and women that were distinguished by ethnicity, place of birth, and testing environment. In this study there was no evidence of higher work effi ciencies in Aymara [ 8 ]. Also when analyzing multiple data obtained from independent investigations no trend was observed toward higher work effi ciencies in high-altitude natives from around the world [ 7 ].…”

High Altitude Adaptation in Tibetans

“…However, a recent study in Bolivian Aymara Indians has questioned the hypothesis of increased efficiency of locomotion in altitude populations (Brutsaert et al, 2004). These authors recruited Aymara in Bolivia with different degrees of genetic admixture of European origin, as well as acclimatized Europeans, and measured gross and net efficiency, comparing the results to reference data obtained in lowlanders.…”

Developmental Effects Determine Submaximal Arterial Oxygen Saturation in Peruvian Quechua

“…The only study that has supported a developmental effect on submaximal Sao 2 was reported by the same research group (Brutsaert et al, 2004). They reported a *5% contribution of development in determining higher Sao 2 during exercise in Quechua natives born and raised in the highlands compared to lowland-born individuals.…”

“…Ancestry informative markers (AIMs) have been used to give a measure of Quechua ancestry by some studies. However, ancestry was not associated to exercise Sao 2 in Andeans (Brutsaert et al, 2004;2005). Additionally, the I-allele of the Insertion/Deletion (I/D) polymorphism of the ACE genotype has been associated with higher Sao 2 in Andeans (Bigham et al, 2008).…”

“…The ''Developmental Adaptation Hypothesis'' is based on the plasticity of structural and functional systems in the individual at sensitive periods in their life (Frisancho, 2009). It is well-known that larger pulmonary volumes are strongly determined by developmental exposure to hypoxia in Andean populations (Greksa, 1990;Frisancho et al, 1997;Brutsaert et al, 2004;Kiyamu et al, 2012) in Tibetans (Droma et al, 1991), and in non-native populations who were born and raised at the highlands (Greksa, 1990). Moreover, there are a handful of studies suggesting the role of lifelong exposure to hypoxia on a more efficient gas exchange system (Dempsey et al, 1971;Zhuang et al, 1996;Brutsaert et al 2000;Wagner et al, 2002).…”