Browsing by Autor "Jere D. Haas"

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Absence of Work Efficiency Differences During Cycle Ergometry Exercise in Bolivian Aymara
(Mary Ann Liebert, Inc., 2004) Tom D. Brutsaert; Jere D. Haas; Hilde Spielvogel
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.
Altitude and infant growth in Bolivia: A longitudinal study
(Wiley, 1982) Jere D. Haas; Geraldine Moreno‐Black; Edward A. Frongillo; A. Javier Pabon; L. Gerardo Pareja; U. Jorge Ybarnegaray; G. Luis Hurtado
The growth of 79 healthy, well-nourished lowland (400 M) and highland (3600 M) Bolivian infants was analyzed in a longitudinal study through the first postnatal year. Compared to low altitude infants, the high altitude infants were found, by analysis of covariance controlling for size at the previous exam, to be significantly shorter at birth, 1 and 6 months, while they were significantly lighter only at birth and 1 year. Recumbent length gain was slower in the high altitude infants in the early months of life, while weight gain did not differ between altitudes. The observed lower weights at high altitude throughout the first year appear to be due to a persistence of lower weights seen at birth and not to postnatal growth retardation. Significantly greater triceps and subscapular skinfold thickness measurements were found in the highland group, despite their smaller length and weight. The possible causes and implications of the greater fat accumulation in the highland infants are discussed.
Effect of developmental and ancestral high altitude exposure on chest morphology and pulmonary function in Andean and European/North American natives
(Wiley, 1999) Tom D. Brutsaert; Rudy Soria; Esperanza Cáceres; Hilde Spielvogel; Jere D. Haas
Chest depth, chest width, forced vital capacity (FVC), and forced expiratory volume (FEV1) were measured in 170 adult males differing by ancestral (genetic) and developmental exposure to high altitude (HA). A complete migrant study design was used to study HA natives (Aymara/Quechua ancestry, n = 88) and low altitude (LA) natives (European/North American ancestry, n = 82) at both altitude (La Paz, Bolivia, 3,600 m) and near sea level (Santa Cruz, Bolivia, 420 m). HAN and LAN migrant groups were classified as: N(th) generation migrants, born and raised in a non-native environment; child migrants who migrated during the period of growth and maturation (0-18 yrs); and adult migrants who migrated after 18 years of age. Chest depth, FVC, and FEV1 measures were larger with increasing developmental exposure in both HAN migrants at LA and LAN migrants at HA. Developmental responses were similar between HAN and LAN groups. FVC and FEV1 measures were larger in HANs vs LANs born and raised at HA to suggest a genetic effect, but were similar in HANs and LANs born and raised at LA. The similarity of HAN and LAN groups at LA suggests that the genetic potential for larger lung volumes at HA depends upon developmental exposure to HA. Additional data for females (HANs at HA, n = 20, and LAN adult migrants to HA, n = 17) show similar differences as those shown between male HAN and LAN groups. Am. J. Hum. Biol. 11:383-395, 1999. Copyright 1999 Wiley-Liss, Inc.
Effect of developmental and ancestral high-altitude exposure on ??O2peak of Andean and European/North American Natives
(Wiley, 1999) Tom D. Brutsaert; Hilde Spielvogel; Rudy Soria; Esperanza Cáceres; Giliane Buzenet; Jere D. Haas
Peak oxygen consumption (VO(2)peak) was measured in 150 adult males (18-35 years old) in Bolivia, using a complete migrant study design to partition developmental from ancestral (genetic) effects of high-altitude (HA) exposure. High-altitude natives (HANs, Aymara/Quechua ancestry, n = 75) and low-altitude natives (LANs, European/North American ancestry, n = 75) were studied at high altitude (3,600-3,850 m) and near sea level (420 m). HAN and LAN migrant groups to a nonnative environment were classified as: multigeneration migrants, born and raised in a nonnative environment; child migrants who migrated to the nonnative environment during the period of growth and development (0-18 years old); and adult migrants who migrated after 18 years of age. Variability in VO(2)peak due to high-altitude adaptation was modeled by covariance analysis, adjusting for fat-free mass and physical activity (training) differences between groups. A trend for increased VO(2)peak with increasing developmental high-altitude exposure in migrant groups did not reach statistical significance, but low statistical power may have limited the ability to detect this effect. HANs and LANs born, raised, and tested at high altitude had similar VO(2)peak values, indicating no genetic effect, or an effect much smaller than that reported previously in the literature. There was no functional correlation between forced vital capacity and VO(2)peak, within or across groups. These results do not support the hypothesis that Andean HANs have been selected to express a greater physical work capacity in hypoxia.
Higher arterial oxygen saturation during submaximal exercise in Bolivian Aymara compared to European sojourners and Europeans born and raised at high altitude
(Wiley, 2000) Tom D. Brutsaert; Mauricio Araoz; Rudy Soria; Hilde Spielvogel; Jere D. Haas
Arterial oxygen saturation (SaO(2)) was measured at 3,600-3,850 m by pulse oximetry at rest and during submaximal exercise in three study groups: 1) highland Aymara natives of the Bolivian altiplano (n = 25); 2) lowland European/North American sojourners to the highlands with at least 2 months of acclimatization time to 3,600 m (n = 27); and 3) subjects of European ancestry born and raised at 3,600 m (n = 22). Aymara subjects maintained approximately 1 percentage point higher SaO(2) during submaximal work up to 70% of their maximal work capacity, and showed a smaller rate of decline in SaO(2) with increasing work compared to both European study groups. The higher-exercise SaO(2) of Aymara compared to Europeans born and raised at 3,600 m suggests genetic adaptation. The two European study groups, who differed by exposure to high altitude during their growth and development period, did not show any significant difference in either resting or exercise SaO(2). This suggests that the developmental mode of adaptation is less important than the genetic mode of adaptation in determining exercise SaO(2). A weak correlation was detected (across study groups only) between the residual forced vital capacity (FVC) and the residual SaO(2) measured at the highest level of submaximal work output (P = 0.024, R = 0.26). While firm conclusions based on this correlation are problematic, it is suggested that a part of the higher SaO(2) observed in Aymara natives is due to a larger lung volume and pulmonary diffusion capacity for oxygen. Results from this study are compared to similar studies conducted with Tibetan natives, and are interpreted in light of recent quantitative genetic analyses conducted in both the Andes and Himalayas.
Higher arterial oxygen saturation during submaximal exercise in Bolivian Aymara compared to European sojourners and Europeans born and raised at high altitude
(Wiley, 2000) Tom D. Brutsaert; Mauricio Araoz; Rudy Soria; Hilde Spielvogel; Jere D. Haas
Arterial oxygen saturation (SaO2) was measured at 3,600–3,850 m by pulse oximetry at rest and during submaximal exercise in three study groups: 1) highland Aymara natives of the Bolivian altiplano (n = 25); 2) lowland European/North American sojourners to the highlands with at least 2 months of acclimatization time to 3,600 m (n = 27); and 3) subjects of European ancestry born and raised at 3,600 m (n = 22). Aymara subjects maintained ∼1 percentage point higher SaO2 during submaximal work up to 70% of their maximal work capacity, and showed a smaller rate of decline in SaO2 with increasing work compared to both European study groups. The higher-exercise SaO2 of Aymara compared to Europeans born and raised at 3,600 m suggests genetic adaptation. The two European study groups, who differed by exposure to high altitude during their growth and development period, did not show any significant difference in either resting or exercise SaO2. This suggests that the developmental mode of adaptation is less important than the genetic mode of adaptation in determining exercise SaO2. A weak correlation was detected (across study groups only) between the residual forced vital capacity (FVC) and the residual SaO2 measured at the highest level of submaximal work output (P = 0.024, R = 0.26). While firm conclusions based on this correlation are problematic, it is suggested that a part of the higher SaO2 observed in Aymara natives is due to a larger lung volume and pulmonary diffusion capacity for oxygen. Results from this study are compared to similar studies conducted with Tibetan natives, and are interpreted in light of recent quantitative genetic analyses conducted in both the Andes and Himalayas. Am J Phys Anthropol 113:169–181, 2000. © 2000 Wiley-Liss, Inc.
Maximal aerobic power in trained youths at high altitude
(Informa, 1982) Lawrence P. Greksa; Jere D. Haas; Thomas L. Leatherman; Hilde Spielvogel; Megan Zamora; Luis Paredes Fernández; Geraldine Moreno‐Black
The sample for this study consisted of 25 males and 19 females between the ages of 8.8 and 19.5 years. The subjects were healthy, well nourished and trained swimmers residing in La Paz, Bolivia (mean altitude 3700 m). The purpose of this study was to provide normative values for the work capacity of high-altitude youths. Mean VO2 max was 46.9 ml/kg/min in males and 39.3 ml/kg/min in females. VO2max increased significantly with age in males but not in females. Mean VO2max tended to be 10-20% lower in the swimmers than in sea-level athletes.
Pulmonary Diffusing Capacity in Young Andean Highland Children
(Karger Publishers, 1982) Enrique Vargas; John Beard; Jere D. Haas; L. Cudkowicz
Lung diffusing capacities for carbon monoxide were measured in 125 highland Andean children between 4 and 6 years of age in La Paz, Bolivia (3,650 m), using a steady-state technique. Male children had a significantly lower DLC0 (13.2 ± 2.7) compared to females (14.2 ± 1.9; p < 0.05), despite similar body size Hemoglobin concentration was significantly greater than published values for low-altitude children and this also changes pulmonary diffusing capacities and supports the concept of early developmental adaptation in pulmonary function to environmental stressors as well as a sexual dimorphism in this type of adaptation.
Work performance of high-altitude Aymara males
(Informa, 1984) Lawrence P. Greksa; Jere D. Haas; Thomas L. Leatherman; R. Brooke Thomas; Hilde Spielvogel
The sample for this study consisted of 28 Aymara males between the ages of 15 and 43 years. The subjects were rural high-altitude natives who were temporarily working as porters in La Paz, Bolivia (3700 m). Mean VO2max was 46 X 5 ml/kg/min. There was a significant negative relationship between VO2max and age in adult porters . However, there was also a significant positive relationship between maximal work output and age and a significant negative relationship between VO2 during submaximal exercise and age. Relative work intensity (VO2/VO2max) during submaximal exercise did not change significantly with age. Thus, even though VO2max decreased significantly with age, these data suggest that there may not be a substantial decrease with age in the adaptive status of these men. Minimal support was found for the hypothesis that chest size in Andean highlanders influences the effectiveness of the oxygen transport system.