Higher exercise performance and lower VO2max in Tibetan than Han residents at 4,700 m altitude

Ge, Ri Li; Chen, Q. H.; Wang, L. H.; Gen, Ding; Yang, Pearl; Kubo, Keishi; Fujimoto, Keisaku; Matsuzawa, Y.; Yoshimura, Kazuhiko; Takeoka, Michiko; al, et

doi:10.1152/jappl.1994.77.2.684

Cited by 74 publications

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“…In contrast, both Sherpas and Andean Quechuas show evidence for enhanced cardiac glucose uptake at the tissue level (50), and in Sherpas, the decreased ratio of phosphocreatine to ATP in cardiac myocytes suggests a greater reliance on glucose for ATP production (51). However, neither Quechuas nor Sherpas exhibit enhanced maximal aerobic capacities compared with lowlanders at similar fitness levels (52,53), suggesting that human patterns of metabolic adjustment may be optimized to enhance O 2 economy rather than maximal aerobic capacity (54).…”

Section: Discussionmentioning

confidence: 99%

Regulatory changes contribute to the adaptive enhancement of thermogenic capacity in high-altitude deer mice

Cheviron

Bachman

Connaty

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

170

226

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In response to hypoxic stress, many animals compensate for a reduced cellular O 2 supply by suppressing total metabolism, thereby reducing O 2 demand. For small endotherms that are native to high-altitude environments, this is not always a viable strategy, as the capacity for sustained aerobic thermogenesis is critical for survival during periods of prolonged cold stress. For example, survivorship studies of deer mice (Peromyscus maniculatus) have demonstrated that thermogenic capacity is under strong directional selection at high altitude. Here, we integrate measures of whole-organism thermogenic performance with measures of metabolic enzyme activities and genomic transcriptional profiles to examine the mechanistic underpinnings of adaptive variation in this complex trait in deer mice that are native to different elevations. We demonstrate that highland deer mice have an enhanced thermogenic capacity under hypoxia compared with lowland conspecifics and a closely related lowland species, Peromyscus leucopus. Our findings suggest that the enhanced thermogenic performance of highland deer mice is largely attributable to an increased capacity to oxidize lipids as a primary metabolic fuel source. This enhanced capacity for aerobic thermogenesis is associated with elevated activities of muscle metabolic enzymes that influence flux through fatty-acid oxidation and oxidative phosphorylation pathways in high-altitude deer mice and by concomitant changes in the expression of genes in these same pathways. Contrary to predictions derived from studies of humans at high altitude, our results suggest that selection to sustain prolonged thermogenesis under hypoxia promotes a shift in metabolic fuel use in favor of lipids over carbohydrates.functional genomics | RNA-seq | thermoregulation | transcriptomics D uring cold stress, homeothermic endotherms maintain a constant body temperature by increasing metabolic heat production. In small endotherms like mice that have high thermoregulatory demands, thermogenic capacity influences survival in cold environments and therefore has a clear connection to Darwinian fitness (1, 2). Indeed, thermogenic capacity in freeranging deer mice (Peromyscus maniculatus) is subject to strong directional selection at high altitude (3).Sustaining maximal thermogenic capacities during prolonged periods of cold stress requires a high rate of O 2 flux through oxidative pathways, and this requirement presents a unique challenge for endothermic animals that live under conditions of chronic O 2 deprivation at high altitude. The reduced partial pressure of O 2 (PO 2 ) at high altitude imposes well-documented constraints on aerobic metabolism (4-8), thereby exacerbating the increased thermoregulatory demands faced by endothermic animals that are native to cold, alpine environments.In rodents, aerobic thermogenesis is accomplished through both shivering and nonshivering mechanisms, and in deer mice, shivering accounts for roughly 35-50% of total thermogenic capacity (9). As with other forms of strenuous exerci...

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Section: Discussionmentioning

confidence: 99%

Regulatory changes contribute to the adaptive enhancement of thermogenic capacity in high-altitude deer mice

Cheviron

Bachman

Connaty

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

170

226

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“…After resting 30 min while seated, subjects performed the exercise test on an electronically braked cycle ergometer (Ergo-Oxyscreen, Jaeger, Wü rzburg, Germany), as previously described (12) to estimate V O 2 max , which is equivalent to V O 2 max at a steady-state condition, at a maximal exercise condition. The gas analyzers were calibrated before each measurement of expired gas by using ambient air and a gas mixture of 15% O 2 -5% CO 2 -80% N 2 that had been previously measured by using the Scholander technique.…”

Section: Methodsmentioning

confidence: 99%

“…This is due to the reduction of ambient O 2 pressure at high altitude. Although comparative studies of V O 2 max between high altitude natives and lowland residents at high-altitude have been done, the conclusions are controversial (10)(11)(12)(13)30). High-altitude adult natives in either Andean or Himalayan populations have higher exercise performance and maintain better arterial O 2 saturation (Sa O 2 ) during exercise compared with newcomers (17,20,30,38).…”

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confidence: 99%

Exercise performance of Tibetan and Han adolescents at altitudes of 3,417 and 4,300 m

Chen

Wang

et al. 1997

Journal of Applied Physiology

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Yoshimura. Exercise performance of Tibetan and Han adolescents at altitudes of 3,417 and 4,300 m. J. Appl. Physiol. 83(2): 661-667, 1997.-The difference was studied between O 2 transport in lifelong Tibetan adolescents and in newcomer Han adolescents acclimatized to high altitude. We measured minute ventilation, maximal O 2 uptake, maximal cardiac output, and arterial O 2 saturation during maximal exercise, using the incremental exercise technique, at altitudes of 3,417 and 4,300 m. The groups were well matched for age, height, and nutritional status. The Tibetans had been living at the altitudes for a longer period than the Hans (14.5 6 0.2 vs. 7.8 6 0.8 yr at 3,417 m, P , 0.01; and 14.7 6 0.3 vs. 5.3 6 0.7 yr at 4,300 m, P , 0.01, respectively). At rest, Tibetans had significantly greater vital capacity and maximal voluntary ventilation than the Hans at both altitudes. At maximal exercise, Tibetans compared with Hans had higher maximal O 2 uptake (42.2 6 1.7 vs. 36.7 6 1.2 ml · min 21 ·kg 21 at 3,417 m, P , 0.01; and 36.8 6 1.9 vs. 30.0 6 1.4 ml · min 21 ·kg 21 at 4,300 m, P , 0.01, respectively) and greater maximal cardiac output (12.8 6 0.3 vs. 11.4 6 0.2 l/min at 3,417 m, P , 0.01; 11.5 6 0.5 vs. 10.0 6 0.5 l/min at 4,300 m, P , 0.05, respectively). Although the differences in arterial O 2 saturation between Tibetans and Hans were not significant at rest and during mild exercise, the differences became greater with increases in exercise workload at both altitudes. We concluded that exposure to high altitude from birth to adolescence resulted in an efficient O 2 transport and a greater aerobic exercise performance that may reflect a successful adaptation to life at high altitude. cardiac output; maximal oxygen consumption; ventilation; developmental adaptation; genetic adaptation MAXIMAL O 2 UPTAKE (V O 2 max ), an integrated index of the overall functional capacity of the O 2 transport system, invariably decreases with altitude during both acute and chronic exposure to high altitude in lowland adults (31,34). This is due to the reduction of ambient O 2 pressure at high altitude. Although comparative studies of V O 2 max between high altitude natives and lowland residents at high-altitude have been done, the conclusions are controversial (10-13, 30). High-altitude adult natives in either Andean or Himalayan populations have higher exercise performance and maintain better arterial O 2 saturation (Sa O 2 ) during exercise compared with newcomers (17,20,30,38). These characteristics, which are associated with more efficient pulmonary gas exchange (38) and better adaptation to high-altitude stress, are acquired through many generations of lifelong high-altitude exposure. The Tibetans are believed to have lived at high altitude longer than other highaltitude residents. The effects of high-altitude hypoxia on the physiological responses of Tibetan and Han adolescents to exercise have never been reported. Whether the pulmonary adaptations in humans are determined purely by environment or relate to genetic character...

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“…9 Another study concluded that Tibetans born at low altitude do not seem to differ from lowlanders with regard to their metabolic response whereas their ventilatory response to exercise is greater. 10 Hence we conclude in our study that, though both Indian born Tibetan male youths and Indian male youths share similar environmental challenges, this difference in PEFR and MVV has shown that Indian born Tibetan male youths have retained better respiratory parameters as their ancestors which could be due to their inheritance of genetic factors which favour the Tibetans to survive at high altitude.…”

Section: Discussionmentioning

confidence: 52%

A Comparative Study of Pefr and MVV Between Indian Born Tibetan Youths and Indian Youths

Shindhe¹,

Shindhe²,

Kammar³

et al. 2015

jemds

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BACKGROUND AND OBJECTIVE: Tibetans are the oldest population living permanently at high altitude (4000m). This ethnic group along with Sherpas may have been living at high altitude for longer than any other population. Previous research has shown Tibetans living at high altitude to have superior pulmonary functions. The size of the lungs relative to the size of the person varies depending on ethnic group and a host of environmental factors. Peak expiratory flow rate (PEFR) measurement is the easiest and cheapest method to evaluate respiratory functions. MVV tests the overall functioning of the respiratory system, the respiratory muscles, airway resistance and compliance of lungs and chest wall. So, the study was carried out to evaluate PEFR and MVV of healthy Tibetans youths born and brought up in India and compare their values with healthy Indian youths, to know whether Tibetans born and brought up in India (sea level) retain better respiratory parameters as their ancestors (born at high altitude). MATERIALS AND METHOD: A comparative study was conducted in which the PEFR and MVV of 50 Tibetan male youths born and brought up in Mundgod, North Karnataka district, Hubli, in the age group of 20-30yrs were compared with 50 Indian male youths matched for age and sex as controls. The PEFR and MVV were measured with spiroanalyser SPL-95. The obtained data was analysed using unpaired student's't' test. RESULTS: The Indian born Tibetan male youths had a PEFR (L/sec) of value 8.18 2.47 where as the corresponding value for Indian male youths was 4.86 1.89. The PEFR was higher in Indian born Tibetan male youths than Indian male youths. This was statistically highly significant at (P<0.001). The Tibetan youths had a MVV (L/min) of value 116.16 25.78 whereas the corresponding value for Indian youths was 101.49 19.21.The MVV was less in Indian youths than Tibetan youths. This was statistically significant at p<0.01. CONCLUSION: Though both Indian born Tibetan male youths and Indian male youths share similar environmental challenges, this difference in PEFR and MVV has shown that Indian born Tibetan male youths have retained better respiratory parameters as their ancestors.

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Higher exercise performance and lower VO2max in Tibetan than Han residents at 4,700 m altitude

Cited by 74 publications

References 0 publications

Regulatory changes contribute to the adaptive enhancement of thermogenic capacity in high-altitude deer mice

Regulatory changes contribute to the adaptive enhancement of thermogenic capacity in high-altitude deer mice

Exercise performance of Tibetan and Han adolescents at altitudes of 3,417 and 4,300 m

A Comparative Study of Pefr and MVV Between Indian Born Tibetan Youths and Indian Youths

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