RESUMO
The contribution of chronological age, skeletal age (Fels method) and body size to variance in peak velocity derived from the Carminatti Test was examined in 3 competitive age groups of Brazilian male soccer players: 10-11 years (U-12, n=15), 12-13 years (U-14, n=54) and 14-15 years (U-16, n=23). Body size and soccer-specific aerobic fitness were measured. Body composition was predicted from skinfolds. Analysis of variance and covariance (controlling for chronological age) were used to compare soccer players by age group and by skeletal maturity status within of each age group, respectively. Relative skeletal age (skeletal age minus chronological age), body size, estimated fat-free mass and performance on the Carminatti Test increased significantly with age. Carminatti Test performance did not differ among players of contrasting skeletal maturity status in the 3 age groups. Results of multiple linear regressions indicated fat mass (negative) and chronological age (positive) were significant predictors of peak velocity derived from the Carminatti Test, whereas skeletal age was not a significant predictor. In conclusion, the Carminatti Test appears to be a potentially interesting field protocol to assess intermittent endurance running capacity in youth soccer programs since it is independent of biological maturity status.
Assuntos
Desempenho Atlético , Resistência Física/fisiologia , Esqueleto/fisiologia , Futebol , Adolescente , Determinação da Idade pelo Esqueleto , Antropometria , Atletas , Composição Corporal , Tamanho Corporal , Brasil , Criança , Humanos , MasculinoRESUMO
BACKGROUND/OBJECTIVE: The objective of this study is to compare the growth and physical fitness of normal, stunted and overweight/obese (owt/ob) Oaxaca children 6-13 years. SUBJECTS/METHODS: This study was a cross-sectional, included 688 school children (grades 1-3, 4-6), aged 6-13 years, from an indigenous rural community (n=361) and colonia popular (n=327) in Oaxaca, southern Mexico. MEASUREMENTS: Anthropometry-weight, height, sitting height, limb circumferences, skinfolds. Derived-body mass index, sitting height/height ratio, leg and step lengths, limb muscle areas, sum of skinfolds. Physical fitness-sit and reach, sit-ups, distance run, grip strength, standing long jump, 35 yard dash. Physical activity-steps to and from school, household chores, sports participation. ANALYSIS: Normal-not stunted, not owt/ob; stunted-not owt/ob; and owt/ob-not stunted were compared with multivariate analysis of covariance controlling for age. Two children were stunted and owt/ob, and were excluded. RESULTS: Age-adjusted means for body size, muscularity, adiposity and grip strength showed a gradient, owt/ob>normal>stunted in both sexes and grade levels (P<0.001). Relative position of stunted and owt/ob children was reversed for strength per unit mass. Stunted and normal children ran a greater distance than owt/ob children (P<0.05). Normal, stunted and owt/ob children did not differ consistently in other fitness items and indicators of activity and inactivity. CONCLUSION: Size, muscularity, fatness and strength differed significantly, owt/ob>normal>stunted, but owt/ob children had less strength per unit mass and poorer endurance. Normal and stunted children did not differ consistently in fitness. Physical activity and television time did not differ among the three groups.
Assuntos
Transtornos do Crescimento/fisiopatologia , Desnutrição/fisiopatologia , Sobrepeso/fisiopatologia , Aptidão Física , Adolescente , Fatores Etários , Antropometria , Composição Corporal , Índice de Massa Corporal , Pesos e Medidas Corporais , Criança , Estudos Transversais , Feminino , Transtornos do Crescimento/epidemiologia , Transtornos do Crescimento/etnologia , Transtornos do Crescimento/etiologia , Humanos , Indígenas Norte-Americanos , Masculino , Desnutrição/epidemiologia , Desnutrição/etnologia , México/epidemiologia , Atividade Motora , Força Muscular , Sobrepeso/epidemiologia , Sobrepeso/etnologia , Resistência Física , Prevalência , Saúde da População RuralRESUMO
Our object in this paper is to analyze the opportunity for natural selection and gene flow in an isolated Zapotec-speaking community in the valley of Oaxaca, southern Mexico, that is undergoing a secular increase in body size. Surveys were conducted in the community in 1968, 1978, and 2000, including anthropometric and census data. No secular change was found in the growth status of schoolchildren and adult height between 1968 and 1978; subsequently, major secular gains in height occurred among children and adolescents between 1978 and 2000. The 1978 household data were used to compute gene flow (3.3%) and opportunity for selection intensity (I = 1.312). Migration and other demographic information was obtained from household census data for 1978 and 2000, and mortality information was extracted from community records and archives. These data were used to compute gene flow and opportunity for natural selection. Gene flow increased from 3.3% to 4.7% and intensity of natural selection decreased from 1.312 to 0.272 from 1978 to 2000. Variance in fertility increased slightly over time (12.25 to 13.69). Opportunity for selection was dominant during the prereproductive period in 1978, but approached 0 for the mortality component in 2000, resulting in a marked decrease in the mortality component (Im) of selection (0.626 and 0.019, respectively) and total opportunity for selection (I = 1.312 and 0.272, respectively). Secular increase in height and markedly decreased opportunity for natural selection (1) were associated with better health and nutritional conditions. Genotype-environment interaction and environmental influences are apparently the predominant causes of the secular trend. If natural selection plays a role in causing the secular trend, it is a small one.
Assuntos
Estatura/genética , Genética Populacional/tendências , Seleção Genética , Adolescente , Adulto , Coeficiente de Natalidade , Criança , Mortalidade da Criança/tendências , Pré-Escolar , Feminino , Fertilidade/genética , Humanos , Masculino , México , População Rural/estatística & dados numéricosRESUMO
OBJECTIVE: The study used path analysis to estimate genetic and environmental determinants of familial similarity in anthropometric characteristics among children from a rural subsistence agrarian community in the Valley of Oaxaca in southern Mexico. METHODS: Anthropometric dimensions included height, weight, arm circumference and triceps skinfold; the BMI was calculated. Parent-offspring pairs (n = 34) were constructed from pedigrees and prior studies using listwise case deletion for parent-male child and parent-female child, respectively. Path coefficients for genetic and environmental effects were computed using linear regression. Age effects were held constant by computing residuals after parameter regression on age and age2. Environmental effects were analysed using a previously published factor analysis of village ecology. RESULTS: By path analysis, the paternal effect was low-to-moderately strong on males (0.21-0.57) but low on females (0.13-0.23). Maternal effects were low, inconsistent and negligible on males (-0.16-0.09), but high on females (0.57-0.81), except for height (0.19). Estimated environmental effects on sibling similarity were low (0.12-0.27). CONCLUSION: The environment exerts a relatively consistent effect on growth status, and probably accounts for the low path coefficients (i.e. sibling correlations, parent-offspring regressions). Sex-specific effects are apparent in a strong paternal influence on male offspring height and moderate influences on weight, triceps skinfold, and arm circumference. Maternal influences are small on the anthropometric characteristics of males, but are exceptionally large on female weight, triceps skinfold and arm circumference. Estimated environmental effects on sibling similarity are low-to-moderately high.
Assuntos
Tamanho Corporal/genética , Adulto , Índice de Massa Corporal , Tamanho Corporal/etnologia , Tamanho Corporal/fisiologia , Criança , Meio Ambiente , Feminino , Humanos , Indígenas Norte-Americanos , Modelos Lineares , Masculino , México , Núcleo Familiar , População RuralRESUMO
OBJECTIVE: To evaluate secular changes in height, sitting height and estimated leg length between 1968 and 2000 in residents in a rural Zapotec-speaking community in Oaxaca, southern Mexico. MATERIALS AND METHODS: Height and sitting height were measured in school children 6-13 years (1968; 1978, 2000), in adolescents 13-17 years (1978, 2002) and adults 19-29 years (1978, 2000). Leg length was estimated as height minus sitting height. The sitting height/ height ratio was calculated. Subjects were grouped by sex into four age categories: 6-9, 10-13, 13-17 and 19-29 years for analysis. The Preece-Baines Model I growth curve was fitted to cross-sectional means for 1978 and 2000. RESULTS: There were no differences between children 6-9 and 10-13 years in 1968 and 1978 with the exception of the sitting height ratio in girls 6-9 years. Children of both sexes 6-13 years and adolescent boys 13-17 years were significantly larger in the three dimensions in 2000 compared to 1978; adolescent girls differed only in height and sitting height. Adult males in 2000 were significantly taller with longer legs than those in 1978, but the samples did not differ in sitting height and the ratio. Adult females in 1978 and 2000 did not differ significantly in the three dimensions. Rates of secular change in height and sitting height between 1978 and 2000 were reasonably similar in the three age groups of male children and adolescents, but the rate for estimated leg length was highest in 10-13-year-old boys. Secular gains were smaller in adult males, but were proportionally greater in estimated leg length. Girls 6-9 and 10-13 years experienced greater secular gains in height, sitting height and estimated leg length than adolescent and young adult females, while secular gains and rates decreased from adolescent girls to young adult women. Ages of peak velocity for height, sitting height and estimated leg length declined in boys, while only ages of peak velocity for height and estimated leg length declined in girls. CONCLUSIONS: There are major secular increases in height, sitting height and estimated leg length of children and adolescents of both sexes since 1978. Secular gains in height are of similar magnitude in boys and girls 6-13 years, but are greater in adolescent and young adult males than females. The secular increase in height of young adults of both sexes is smaller than that among adolescents. Estimated leg length accounts for about 60% of the secular increase in height in children of both sexes. Estimated leg length and sitting height contribute equally to the secular increase in height in adolescent boys, whereas estimated leg length accounts for about 70% of the secular increase in height in young adult males. Sitting height contributes about two-thirds of the secular increase in height in adolescent and young adult females.
Assuntos
Tamanho Corporal , População Rural/tendências , Adolescente , Adulto , Estatura , Criança , Feminino , Humanos , Masculino , México , Estudos RetrospectivosRESUMO
OBJECTIVE: To evaluate secular change in the age at menarche between 1978 and 2000 in residents of a rural Zapotec-speaking community in Oaxaca, southern Mexico, using status quo and retrospective methods. MATERIALS AND METHODS: Status quo menarcheal status of girls 9-18 years of age in 1978 (n= 101) and 2000 (n=238) and retrospective ages at menarche of adult women 19+ years of age in 1978 (n = 228) and 2000 (n = 246) were obtained via interview. Probit analysis was used to estimate median ages at menarche and 95% confidence intervals (CI) for the status quo data. Analysis of variance and linear regression was used to compare the retrospective data across surveys. RESULTS: The median ages at menarche of adolescents are 14.8+/-1.2 years (0.24 year, 95% CI 14.2-15.4 years) in 1978 and 13.0+/-1.0 years (0.10 year, 95% CI 12.7-13.3 years) in 2000. Age at menarche has declined by 1.8 years over about 23 years, 0.78 year/decade (95% CI = 0.65-0.91 year/decade). Recalled ages at menarche do not differ by age group in the 1978 survey, but differ significantly by age group in the 2000 survey (p <0.001). Within the 2000 survey, the two youngest age groups (< 29, 30-39 years) do not differ, but attain menarche earlier than women in the four older age groups (p < 0.05), who do not differ from each other in age at menarche. The estimated rates of secular decline in age at menarche in adult women vary between 0.38 and 0.42 years/decade (0.26-0.56 year/decade). CONCLUSIONS: There is a major secular decline in the age at menarche of adolescent girls and young adult women between 1978 and 2000. The estimated rate of decline in adult women is about one-half of that in adolescent girls. The secular decline in age at menarche is consistent with corresponding secular gains height, sitting height and estimated leg length of children and adolescents in the community; corresponding secular gains are smaller in young adults 19-29 years.
Assuntos
Menarca , População Rural/tendências , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Análise de Variância , Criança , Dieta/tendências , Feminino , Nível de Saúde , Humanos , México , Pessoa de Meia-Idade , Estudos RetrospectivosRESUMO
OBJECTIVES: The growth status of school children resident in an urban colonia and in a rural indigenous community in Oaxaca, southern Mexico, was considered in the context of two objectives, current status and the magnitude of urban-rural differences over a span of about 30 years. Both communities were initially surveyed in 1968 and 1972. MATERIALS AND METHODS: Height, body mass, segment lengths, skeletal breadths, limb circumferences, and subcutaneous fatness were taken on 361 rural (177 boys, 184 girls) and 339 urban (173 boys, 166 girls) school children, aged 6-13 years. Additional variables were derived. RESULTS: Height and body mass were significantly greater in urban compared with rural children. Sitting height, estimated leg length and skeletal breadths on the trunk were also larger in urban than in rural school children, but only the difference in skeletal breadths was significant after age and body size were statistically controlled. Urban and rural children did not consistently differ in skeletal breadths on the extremities and limb circumferences. Subcutaneous fatness was more variable. After controlling for age and body size, rural girls had thicker skinfolds. The magnitude of the urban-rural difference in boys in 2000 was greater for body mass, BMI and triceps skinfold, and reduced for height, sitting height, leg length, and arm and estimated arm muscle circumferences compared with 1970. The magnitude of the urban-rural difference in girls was greater in 2000 than 30 years earlier for body mass, height, sitting height, leg length and BMI. Urban-rural differences for arm and arm muscle circumferences and the triceps skinfold were slightly smaller over the interval. CONCLUSIONS: Children resident in an urban colonia were taller and heavier than children resident in a rural indigenous community. After controlling for age and body size, urban-rural differences in skeletal breadths and limb circumferences were reduced or eliminated, but skinfold thicknesses were greater in rural girls. The magnitude of urban-rural differences in body size has decreased over approximately 30 years in boys, but has increased in girls.
Assuntos
Crescimento , População Rural , População Urbana , Adolescente , Estatura , Índice de Massa Corporal , Peso Corporal , Criança , Escolaridade , Feminino , Humanos , Masculino , MéxicoRESUMO
In previous studies, environmental stress has been associated with increased structural asymmetry, indicating differential rates of development on either side of the median plane. To analyse the effect of environmental stress upon anthropometric asymmetry, six bilateral measurements and one derived measurement were compared between chronically mild-to-moderately undernourished school children (7-13 years of age) and a well-nourished control sample (5-35 years of age). The undernourished sample was from a subsistence agricultural community in Southern Mexico. The well-nourished comparison (control) sample was middle class, White children and young adults in Texas. Anthropometric asymmetry of the skeleton was not consistently increased in the undernourished school children compared to the well-nourished controls. Arm and estimated mid-arm muscle circumferences had significantly increased asymmetry, but these differences are likely due more to laterality in function or physical work than to undernutrition. Genetic influences are hypothesized to underlie skeletal asymmetry (i.e. differences in development on either side of the median plane).
Assuntos
Transtornos da Nutrição Infantil/patologia , Adolescente , Adulto , Antropometria , Constituição Corporal , Estudos de Casos e Controles , Criança , Pré-Escolar , Feminino , Humanos , Masculino , México , TexasRESUMO
PRIMARY OBJECTIVES: The purposes of the study are to assess the growth status of urban Mexican children living in different geographic areas of the country, to estimate the prevalence of overweight and obesity, and to explore secular trends in body size. DESIGN: Cross-sectional surveys of 293 children 6-11 years from Sonora in the north-west of the country (155 boys, 138 girls), and 356 children 7-12 years from Veracruz on the Gulf Coast (194 boys, 162 girls) were undertaken in 1992 and 1993, respectively. PROCEDURES: Height and weight were measured; the body mass index (BMI, kg m(-2)) was calculated. Growth status was compared to USA reference data and to samples of Mexican children in 1926 and 1975. The prevalence of overweight (BMI > or = 85th and < 95th percentiles) and obesity (BMI > or = 95th percentile) was estimated. RESULTS: Girls and boys from Sonora and Veracruz do not differ in height, weight and the BMI. Mean heights are at (girls) or below (boys) the medians of USA growth charts, while mean weights are at (boys) or just below (girls) the 75th percentiles at most ages. As a result, mean BMIs are above (boys) and below (girls) the 75th percentiles over the age range studied. The prevalence of overweight and obesity is 40% in boys and 35% in girls, whereas the prevalence of obesity per se is 23% in boys and 17% in girls. Compared to urban Mexican children in the Federal District surveyed in 1926, children in the present sample are taller and heavier, but the secular trend in body weight is more pronounced since the mid-1960s. Heights of the current samples are similar to those of well-off children in Mexico City in the early 1970s, but weights are heavier. CONCLUSIONS: The gap in height between well-off and lower socioeconomic status children in different regions of Mexico has been reduced, but there is an increase in the prevalence of overweight and obesity.
Assuntos
Estatura/fisiologia , Peso Corporal/fisiologia , Crescimento/fisiologia , Constituição Corporal , Índice de Massa Corporal , Criança , Estudos Transversais , Feminino , Humanos , Masculino , México , Valores de Referência , Fatores SocioeconômicosRESUMO
This study focused on levels of physical activity (PA) in adolescents from Niterói, Rio de Janeiro. Adolescents (n = 325) from the public school system filled out the physical activity questionnaire (PAQ-C) developed by Crocker et al. (1997). Anthropometric data (body mass, stature, and body mass index) and television (TV) viewing time were also assessed. Mean PAQ-C scores were 2.3+/-0.6 and 2.0+/-0.6 for males and females, respectively (p < 0.01). Mean TV times were 4.4 h/day and 4.9 h/day for males and females, respectively. The most popular PA was soccer for boys and soccer and walking for girls. Adolescents in the sample tended to be more active on weekends as compared to weekdays. PAQ-C scores classified 85% of boys and 94% of girls as inactive individuals. These results pose a concern as to the high prevalence of inactivity in this age group, which increases the probability of inactive adults. However, other studies are needed to investigate PA throughout adolescence and the determinants of PA in Brazilian adolescents.
Assuntos
Comportamento do Adolescente , Exercício Físico , Adolescente , Análise de Variância , Estatura , Índice de Massa Corporal , Brasil , Criança , Feminino , Humanos , Masculino , Inquéritos e Questionários , TelevisãoAssuntos
Índice de Massa Corporal , Etnicidade , Obesidade/diagnóstico , Adolescente , Adulto , Negro ou Afro-Americano , Asiático , Áustria , População Negra , Composição Corporal , Criança , Feminino , Hispânico ou Latino , Humanos , Masculino , México/etnologia , Obesidade/epidemiologia , Ontário , Fatores de Risco , Dobras Cutâneas , Estados Unidos , População BrancaRESUMO
The estimated prevalence of obesity in North American children and youth (6 to 17 years) in the 1960s through the 1980s is reported. Use of the triceps skinfold and BMI independently and in combination as indicators of obesity provides different estimates of prevalence due to ethnicity. With the triceps skinfold as the indicator, there is an increase in the prevalence of obesity and a reduction in variation between Black and White children and youth from the 1960s to 1980; however, with the BMI as the indicator, there is no change in the prevalence of obesity and negligible ethnic difference in these national data sets. On the other hand, the prevalence of obesity has increased over time in Mexican American and American Indian children and youth. Data for American children and youth of Asiatic ancestry are limited.
Assuntos
Obesidade/etnologia , Adolescente , Negro ou Afro-Americano , Asiático , Índice de Massa Corporal , Criança , Feminino , Hispânico ou Latino , Humanos , Indígenas Norte-Americanos , Masculino , México/etnologia , Quebeque , Dobras Cutâneas , Estados Unidos , População BrancaRESUMO
Gene flow is associated with differences in craniofacial and postcranial dimensions among indigenous populations of southern Mexico. This study compares four craniofacial dimensions in 322 children from families which have an average inbreeding coefficient of 0.01 and 36 children from families which have an inbreeding coefficient of zero (more heterozygous) in a Zapotec speaking community. In addition, two indices were computed. With sex and chronological age constant, there is a statistically significant difference between more and less heterozygous children in bizygomatic diameter. Differences in biparietal diameter and fronto-occipital length reflect the same tendency. The differences probably reflect more an effect of heterozygosity on these dimensions than facial dissimilarity of the populations from which the new genetic materials were drawn because gene flow was from related groups of Indians (e.g., Mixtec) in southern Mexico. Hence, midface growth and overall normal size appear to be affected by fluctuation in level of heterozygosity.
Assuntos
Ossos Faciais/anatomia & histologia , Heterozigoto , Áreas de Pobreza , Crânio/anatomia & histologia , Análise de Variância , Cefalometria , Criança , Consanguinidade , Frequência do Gene , Variação Genética , Humanos , México , Seleção GenéticaRESUMO
Sibling similarity in annual growth increments was analysed in schoolchildren, aged 6-13 years, from a Zapotec-speaking, subsistence agricultural community in the Valley of Oaxaca in southern Mexico. Sibling correlations for 44 brother-brother, 44 sister-sister, and 110 unlike sex pairs were computed for 17 dimensions holding constant environmental effects, age difference between siblings, and the growth status of each sibling for the dimension. Correlations are negative or close to zero. The lack of similarity between siblings in annual growth increments perhaps reflects age-specific variation in a genotype-environment interaction with chronic undernutrition, the important mediating environmental variable.
Assuntos
Constituição Corporal/genética , Família , Crescimento , Somatotipos , Adolescente , Fatores Etários , Antropometria , Constituição Corporal/fisiologia , Criança , Feminino , Humanos , Masculino , México , População Rural , Fatores Sexuais , Dobras Cutâneas , Fatores de TempoRESUMO
Adult Zapotecs are among the shortest Indians in Mexico. This study investigated whether reduced body size was an effect of genetic selection or a developmental effect of very poor nutrition and health. Fertility, offspring survival, and offspring prereproductive mortality were regressed on stature and weight of 205 multiparous adults (ages 20 to 72). The statistical analyses suggest that the exceptionally short stature of Zapotec Indians in this community is due to poor environmental conditions and not to genetic selection or adaptation.
Assuntos
Estatura , Distúrbios Nutricionais/complicações , Seleção Genética , Adulto , Feminino , Humanos , Masculino , México , Pessoa de Meia-Idade , População RuralRESUMO
Genetic drift and natural selection were analyzed in a genetically isolated Zapotec-speaking community in the Valley of Oaxaca, southern Mexico. Moderately intense genetic drift and selection potentials were found. Potential for drift was related to (1) the small effective size of the population, and (2) the exceptionally low number of migrants into the population. Potential for selection was due to (1) an unusually high variance in fertility, and (2) a high contribution of prereproductive mortality. Significant potential for genetic evolution was found due to genetic drift and natural selection.
Assuntos
Frequência do Gene , Seleção Genética , Adolescente , Adulto , Fatores Etários , Idoso , Evolução Biológica , Criança , Pré-Escolar , Feminino , Fertilidade , Humanos , Indígenas Norte-Americanos/genética , Lactente , Recém-Nascido , Masculino , México , Pessoa de Meia-Idade , Mortalidade , Fatores Sexuais , MigrantesRESUMO
Gene flow and rate of inbreeding (delta F) were calculated from demographic data for a community previously reported to be isolated from outside genetic influences of immigration. Significant child growth differences caused by gene flow among children born to native parents (n = 287) and offspring of native-immigrant matings (n = 38) were found in fatness (triceps skinfold), body proportions (sitting height ratio), and size (leg length). No differences were found between the two groups in height, weight, sitting height, and arm circumference. Variation in absolute and relative leg length in this population parallels previously reported differences in adult body size and proportion associated with increased heterozygosity caused by gene flow in other populations in southern Mexico.
Assuntos
Desenvolvimento Infantil , Genética Populacional , Heterozigoto , População Rural , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , México , Pessoa de Meia-IdadeRESUMO
Socioeconomic variation in estimated growth velocities (annual growth increments) of several anthropometric dimensions was considered in schoolchildren from a rural, subsistence agricultural community in the Valley of Oaxaca in southern Mexico. The children (114 males, 99 females), 6-13 years of age, were measured twice, approximately one year apart. Annual growth increments were computed by subtracting measurements taken in the fall of 1978 from those taken in the fall of 1979. Information on household land holdings and appliances and parental occupation was used to compute an index of socioeconomic status (SES). Analysis of annual increments among upper SES (65 males, 45 females) and lower (49 males, 54 females) children indicated negligible differences. The results suggest that growth deficits evident in the children at school age occurred in infancy and early childhood so that there was little, if any, SES variation in growth rate at the school ages.
Assuntos
Antropometria , Desenvolvimento Infantil , Adolescente , Criança , Feminino , Humanos , Masculino , México , População Rural , Fatores SocioeconômicosRESUMO
The literature on the motor development and performance of American children from several racial and ethnic groups is reviewed. The evidence suggests that Black infants are advanced in motor development during the first two years of life, and that Black children of school age, particularly boys, perform consistently better than White and Mexican-American children in running speed (dashes) and the vertical jump, with somewhat less consistent results for the standing long jump and softball throw for distance. In contrast, differences in the motor development and performance of Mexican-American and White children are generally inconsistent and slight. Environmental factors are most often cited as underlying racial or ethnic variation, but have not been systematically investigated. A biocultural approach is essential if an understanding of racial and ethnic variation in motor performance is to be attained.