Browsing by Autor "Lawrence P. Greksa"

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Effect of altitude on the lung function of high altitude residents of European ancestry
(Wiley, 1988) Lawrence P. Greksa; Hilde Spielvogel; M Paz-Zamora; Esperanza Cáceres; Luis Paredes‐Fernández
The forced vital capacity (FVC), forced expiratory volume in one second (FEV), and ratio of FEV to FVC (%FEV) of 161 male and 158 female youths of European ancestry who were born at high altitudes and who were residing in La Paz, Bolivia (average altitude of 3,600 m) were examined and compared with those for lowland Europeans and highland Aymara Amerindians. FVC and FEV were significantly larger (p less than .001) in the La Paz Europeans than in two lowland control samples of European ancestry, with the relative differences between samples varying from small (1.5-4.1%) to moderate (7.7-11.9%). It could not be determined whether the enhanced lung volumes of the La Paz European children were acquired through an accelerated development of lung volumes relative to stature during adolescence, as is the case for Amerindian highlanders. After controlling for body and chest size, FVC and FEV were significantly smaller in the La Paz Europeans than in highland Aymara (p less than .001), suggesting that the lung volumes of the Aymara are influenced by factors other than simply growth and development at high altitude. Finally, as found in Amerindians, chest size is an important determinant of intra-individual variation in lung function among highland Europeans.
Effect of altitude on the physical growth of upper-class children of European ancestry
(Informa, 1985) Lawrence P. Greksa; Hilde Spielvogel; Esperanza Cáceres
The physical growth of 351 upper-socioeconomic-status children (9-20 years) of European ancestry residing in La Paz, Bolivia (altitude 3600 m) is described and compared with that of lowland children of similar background. The purpose is to evaluate the independent effect of continual exposure to atmospheric hypoxia during the period of growth and development on linear growth. The data presented here indicate that the effect of hypoxia on achieved stature ranges from minimal in males and none in females to a maximum of 3 cm in both sexes. The magnitude of this effect is relatively small compared to the potential effect of other factors which affect the growth of highland children.
Lung function of young Aymara highlanders
(Informa, 1987) Lawrence P. Greksa; Hilde Spielvogel; Esperanza Cáceres; Luis Paredes‐Fernández
The patterns of development of FVC, FEV and %FEV are examined in 217 male and 195 female youths of Aymara ancestry residing in La Paz, Bolivia (altitude 3600 m). The data provide some evidence of an acceleration in the development of lung function relative to stature in Aymara children, beginning during early adolescence, and also indicate that there is a strong relationship between lung function and chest dimensions in Aymara children. Similar patterns have been observed among Quechua youth. However, despite the general similarity between Quechua and Aymara youths in the development of lung function, there are potentially important differences between them. In particular, the magnitude of the acceleration of lung volumes relative to stature among Aymara children appears to be considerably less than is exhibited by highland Quechua children. In addition, shorter Quechua boys have FVC values similar to those of shorter Aymara boys, despite having significantly larger chests, while taller Quechua boys have considerably larger FVC values than taller Aymara boys, without a corresponding increase in chest size relative to stature. Thus, although lung volumes and chest dimensions are closely related in both groups, the development of lung function to chest size of Quechua boys appears to be somewhat different from that of Aymara boys and, in particular, to be amplified during adolescence in response to factors other than simply an increase in chest size.
Maximal aerobic power in high-altitude runners
(Informa, 1993) Lawrence P. Greksa; Hilde Spielvogel; Luis Paredes‐Fernández
Maximal aerobic power (VO2max) was assessed in seven male and one female middle- and long-distance recreational runners residing in La Paz, Bolivia (3600 m). All runners were born and raised at high altitudes (> 2500). Mean VO2max in the male runners was 60.8 ml/kg/min while VO2max in the female runner was 55.5 ml/kg/min. These values are higher than in any previously reported sample of either trained or untrained high-altitude natives. In addition, mean VO2max in the La Paz male runners and VO2max in the La Paz female runner were very similar to those found in comparable low-altitude samples of recreational athletes, suggesting that the cardiorespiratory systems of both normally active and highly active native Andean highlanders are capable of successfully responding to the stress of hypobaric hypoxia. This ability may have both developmental and genetic components.
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.
Maximal exercise capacity in adolescent European and Amerindian high‐altitude natives
(Wiley, 1985) Lawrence P. Greksa; Hilde Spielvogel; Luis Paredes‐Fernández
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.
Skin reflectance of children and young adults of Aymara ancestry
(Wiley, 1991) Lawrence P. Greksa; Hilde Spielvogel; John D. Driscoll
The skin reflectance of 556 Andean Indians of Aymara ancestry (305 males, 251 females; 10.0-29.9 yr) residing in La Paz, Bolivia (average altitude of about 3,600 m) is described. Reflectances were measured at three wavelengths (425 nm, 545 nm, and 685 nm) on two different sites, the medial surface of the upper arm and forehead. Males tended to be significantly darker than females on both the upper arm and forehead (P < .05). Female Aymara tended to lighten significantly in skin color with age on both the upper arm and forehead, while males tended to lighten significantly with age only on the upper arm (P < .05). The results of comparisons between three categories based on paternal and maternal surnames (two Aymara surnames, one Aymara and one Spanish surname, and two Spanish surnames) were consistent with the hypothesis that the possession of Spanish surnames is positively related to the degree of European admixture in urban Aymara. However, the extent of admixture within each surname category may differ between rural and urban Aymara, making classification by surnames problematic for rural-urban comparisons.
The physical growth of urban children at high altitude
(Wiley, 1984) Lawrence P. Greksa; Hilde Spielvogel; Luis Paredes‐Fernández; M Paz-Zamora; Esperanza Cáceres
The physical growth of urban Aymara children residing in La Paz, Bolivia (3,600 m) is described and compared with Amerindian children residing at low and high altitudes and with low-altitude U.S. children. The sample consists of 227 males (10.6-19.7 yr) and 219 females (11.2-19.8 yr). The urban La Paz children were taller at all ages than rural high altitude Amerindian children but similar in stature to urban high altitude children from Peru. The variation in stature among the high altitude populations was considerable, amounting to average differences between the tallest and shortest samples of about 10 cm in males and 8 cm in females. In addition, stature in the two urban high altitude samples was similar to that of rural low-altitude Amerindians. This overlapping of the distributions of stature in high- and low-altitude populations could easily confound comparisons designed to determine the effects of hypoxia on physical growth. La Paz Aymara children had considerably smaller chest sizes relative to stature than high-altitude Quechua children. However, the available data indicates that relative chest sizes are similar in Aymara and Quechua adults, suggesting that the process by which large chests are achieved may differ between these Andean populations.
Total lung capacity in young highlanders of Aymara ancestry
(Wiley, 1994) Lawrence P. Greksa; Hilde Spielvogel; Esperanza Cáceres
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 larger 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. © 1994 Wiley‐Liss, Inc.
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.