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ABSTRACT: The postulated superior functional efficiency in association with reduced body size under conditions of chronic protein-energy undernutrition was considered in school children from rural Mexico and coastal Papua New Guinea. Grip strength and three measures of motor performance were measured in cross-sectional samples of children 6-16 years of age from a rural agricultural community in Oaxaca, Mexico, and from the coastal community Pere on Manus Island, Papua New Guinea. The strength and performance of a mixed-longitudinal sample of well nourished children from Philadelphia was used as a reference. The Oaxaca and Pere children are significantly shorter and lighter and are not as strong as the well nourished children. Motor performances of Pere children compare favorably to those of the better-nourished Philadelphia children, whereas those of the Oaxaca children are poorer. Throwing performance is more variable. When expressed relative to body size, strength is similar in the three samples, but the running and jumping performances of Pere children per unit body size are better than the relative performances of Oaxaca and Philadelphia children. Throwing performance per unit body size is better in the undernourished children. The influence of age, stature, and weight on the performance of Oaxaca and Pere children is generally similar to that for well nourished children. These results suggest that the hypothesized adaptive significance of small body size for the functional efficiency of populations living under conditions of chronic undernutrition varies between populations and with performance tasks.
American Journal of Physical Anthropology 09/1987; 73(4):489-99. · 2.82 Impact Factor
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ABSTRACT: Previous studies have reported that Blacks have 10-20% more bone mineral than Whites of the same height. Theoretically, this should mean that the lean body mass of Blacks is denser than that of Whites, such that formulas for calculating lean body mass from density in Whites will overestimate the lean body mass (and thus underestimate fatness) in Blacks. To determine if the lean body mass of Blacks is indeed denser than that of Whites, we measured density, total body water, and anthropometric dimensions in 19 white and 15 black male college students. The black and white cohorts were nearly identical in height, weight, and total body water. Among the Whites there was no significant difference between the observed density and that predicted from anthropometry, nor were there any significant differences between the dimensions of body composition calculated from total body water and from observed density. Among the Blacks, however, the observed density was significantly greater than that predicted from anthropometry, and the lean body mass calculated from observed density was significantly greater than that calculated from total body water. These results are consistent with the hypothesis that the lean body mass of the Blacks is denser than that of the Whites. Separate formulas should therefore be used for converting density to body composition. Based on our data, the correct formula for Blacks is: %fat = 100 X [(4.374/density) - 3.928]. This formula indicates a lean body density of 1.113 g/cm3 in Blacks compared with 1.100 in Whites.
Journal of applied physiology: respiratory, environmental and exercise physiology 07/1984; 56(6):1647-9. · 3.73 Impact Factor
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ABSTRACT: Young athletes of both sexes grow as well as nonathletes. The experience of athletic training and competition does not harm the physical growth and development of the youngster. The young, trained athlete has generally a lesser percentage of body weight as fat. Maturity relationships are not consistent across sports. Male athletes more often than not tend to be advanced maturationally compared with nonathletes. On the other hand, female athletes tend to be delayed in maturity, except for swimmers. Maturity-associated variation in size and body composition is thus a significant factor in comparing athletes and nonathletes, especially during the circumpuberal years.
Pediatric Clinics of North America 01/1983; 29(6):1305-23. · 2.24 Impact Factor
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Human Biology 10/1982; 54(3):609-25. · 1.31 Impact Factor
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ABSTRACT: Six skinfold measurements for male and female athletes (N=456) at the 1976 Montreal Olympic Games were analyzed to identify principal components of fatness and anatomical distribution of fat, i.e., fat patterning. As in non-athletes, two principal components were evident among the athletes. All skinfolds were correlated positively with the first component, which was termed fatness, while extremity fat measurements were correlated positively and trunk measurements were correlated negatively with the second principal component, which was termed an extremity/trunk ratio component. The two principal components accounted for about 85% of the variance. The first component was related to control variables in order of descending contribution to its variance as follows: sex (21-31%), sport (19%), ethnicity (3%), and age (1-3%). Likewise, the second component (extremity/trunk ratio) was related to the control variables: sex (20-35%), age (4-7%), ethnicity (2%), and sport (2%). Fatness is more influenced by sport and by inference training than is the anatomical distribution or patterning of fat on the extremities relative to the trunk. The latter characteristic may be more dependent on biological or environmental factors unrelated to sport and training.
Medicine & Science in Sports & Exercise 02/1982; 14(6):445-52. · 4.43 Impact Factor
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ABSTRACT: Age at menarache, family size, and birth order in 145 athletes at the Montreal Olympic Games, 1976, were determined through interview. The athletes represented 27 countries, but 76% came from Canada, Great Britain and the United States. On the average, athletes attained menarche later than the general population in their respective countries, the mean age at menarche for the sample of 139 athletes who had attained menarche at the time of the survey being 13.66 +/- 0.12 years. Six athletes had not yet attained menarche at the time of the survey. Gymnasts, runners and rowers attained menarche significantly later than swimmers, but gymnasts, runners, rowers and jumpers/hurdlers did not differ significantly among themselves in the age at menarche. Correlations between age at menarche and family size and birth order were significant, but low to moderate in magnitude. Athletes from larger families tended to have, on the average, later menarche than those from smaller families, this trend being more apparent in rowers and track and field athletes.
Medicine and science in sports 02/1979; 11(4):354-8.
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ABSTRACT: Six skinfold measurements of 92 White, Black and Mexican-American high school varsity female athletes were analysed to identify principal components of fatness and relative fat patterning. As in other athletic and non-athletic samples, two principal components were evident: a first component, accounting for 69% of the variation, was positively related to all skinfold sites, and a second principal component, accounting for 11% of the variation, was correlated positively with extremity sites (particularly lower limb sites) and negatively with trunk sites. The first component (fatness) was significantly related to sport (P less than 0.02) but not ethnicity. The second component (extremity/trunk) was significantly related to ethnicity (P less than 0.01) but not sport. These results, although tentative due to the limited sample size, support our earlier findings on Olympic athletes, i.e., fatness is more influenced by sport and by training than is fat patterning.
Annals of Human Biology 9(4):371-6. · 1.98 Impact Factor
