Browsing by Autor "Greksa, Lawrence P"

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Maximal exercise capacity in adolescent european and amerindian high-altitude natives
(Facultad de Medicina, Enfermería, Nutrición y Tecnología Médica, 1985) Greksa, Lawrence P
ABSTRACT Forty-seven highland natives were given maximal exercise tests on a treadmill ergometer at 3,600 m. The subjects were grouped into four subsamples on the basis of ethnicity (European vs. Aymara) and age (young vs. old adolescent). Two-way ANOVA indicated that VO2max adjusted for body size did not differ significantly between ethnic groups but was significantly larger in older than younger boys within each ethnic group (p less than .05). This finding does not support the hypothesis that Amerindian highland natives have adapted genetically to hypoxia but is consistent with the hypothesis that the relatively high VO2max's of highlanders are acquired by developmental adaptation. Several measures of ventilation and oxygen transport capacity differed significantly between ethnic groups, suggesting that growing European and Aymara boys may respond somewhat differently to the stress of high-altitude hypoxia. However, despite these differences, VO2max, an integrated measure of the overall functional capacity of the oxygen transport system, did not differ significantly between ethnic groups, suggesting that both groups are equally capable of meeting the body's oxygen requirements during maximal exercise at high altitude.
Total lung capacity in Andean highlanders
(Facultad de Medicina, Enfermería, Nutrición y Tecnología Médica, 1994) Greksa, Lawrence P
ABSTRACT. Total lung capacity (TLC), residual volume (RV), and vital capacity (VC), as well as related measures of pulmonary function, were assessed in a sample of 39 male and 23 female native highlanders of Aymara ancestry (20.1- 28.8 years) who were residing in La Paz, Bolivia (average altitude of about 3,600 m). After controlling for body and chest size, most measures of respiratory function were significantly larger in males than females (P < .05). Absolute TLC (1 BTPS) was significantly larger in the La Paz Amara males than in highland Peruvian or Tibetan males (P < .05) but, after controlling for body size, TLC was only 1 and 4% larger in the La Paz Aymara than in highland Peruvians or Tibetans, respectively. Also, comparison of the body size-adjusted percentage increases in TLC, VC and RV above U.S. sea-level reference values in selected highland populations indicated that the enhanced TLCs of highlanders are primarily due to an enhancement of RV and secondarily due to an enhancement of VC.
Total lung capacity in young highlanders of Aymara ancestry
(Facultad de Medicina, Enfermería, Nutrición y Tecnología Médica, 1994) Greksa, Lawrence P
ABSTRACT. Total lung capacity (TLC) and its components, including residual volume (RV) and vital capacity (VC), are described in a sample of 164 male and 143 female youths of Aymara ancestry (10.0-19.9 years) who were born and raised at high altitudes (>2,500 m) and who were residing in La Paz, Bolivia (average altitude of about 3,600 m). The hypothesis was tested that the enhanced lung volumes of adult highlanders are attained during the period of growth and development. As found in adult male highlanders, TLC in young highlanders was significantly Iarger than in lowlanders of the same sex and body size, primarily as a result of increases in RV and secondarily through increases in VC. In addition, estimates of the magnitude of the effect of chronic hypobaric hypoxia on all of the measures of pulmonary function, including TLC, RV, and VC, were positively related to age. This finding suggests that growth and development at high altitude is associated with a constant increase in TLC and other measures of pulmonary function relative to those of lowlanders, a finding which is consistent with the expectations of the developmental adaptation hypothesis. However, although these relationships were statistically significant in males, they were not significant in females. Thus, although the magnitude of the estimated effects of chronic hypobaric hypoxia on TLC, RV, and VC were similar in males and females, the developmental pattern by which these enhanced volumes are achieved may differ between sexes.