Correction to: Tanner-Whitehouse Skeletal Ages in Male Youth Soccer Players: TW2 or TW3?

An Online First version of this article was made available online at https://link.springer.com/article/10.1007%2Fs40279-017-0799-7 on 29 October 2017. Errors were subsequently identified in the article, and the following corrections should be noted.

Correlates of physical activity and inactivity in urban Mexican youth.

OBJECTIVES: To evaluate correlates of physical activity in Mexico City school youth. METHODS: A cross-sectional survey was conducted with 1,004 school youth (490 males and 514 females), 9-18 years of age resident in Mexico City. Age, height, body mass index (BMI), socioeconomic status (SES), time viewing television and playing video games (physical inactivity), and perceived sport/physical activity status of mother and father were evaluated as potential correlates of physical activity [Physical Activity Questionnaire (PAQ)]. Multiple linear regression analyses (backward elimination) by age group and sex were used. RESULTS: Physical activity declined in older adolescents, while differences between the two younger age groups were minimal. Television time showed a similar tendency. Overall, fathers were perceived as being active in sport/physical activity more frequently than mothers. Significant predictors of activity differed by age group and sex. For the total sample, age (negative) and perceived sport/activity status of the mother (positive) were significant predictors of the PAQ in boys, and age and the BMI (negative) and height and perceived sport/activity status of both parents (positive) were significant predictors for girls. Age (negative) was the main predictor for inactivity in both males and females. CONCLUSIONS: Potential correlates of physical activity and inactivity considered in this analysis were limited and accounted for relatively little of the variance in physical activity. The role of perceived sport/activity of the parents, especially among younger boys and girls, is particularly of interest and merits more detailed study. Nevertheless, many other variables also need to be considered.

Age and secular effects on muscular strength of indigenous rural adults in Oaxaca, Southern Mexico: 1978-2000.

PURPOSE: To evaluate age and secular changes in strength of rural Zapotec adults in Oaxaca between 1978 and 2000. METHODS: Grip strength, height and weight were measured in 1978 (n = 247, 19-82 years) and 2000 (n = 407, 19-89 years); 35 males and 52 females were measured in both years. MANCOVA was used for comparisons by age and year. RESULTS: Grip strength and strength/height decline with age; the slope is greater after 40-49 years. Both are significantly greater in 2000 compared to 1978 only in males 19-29 and 30-39 years and in females 30-39 years. Strength and strength/height decline at a slightly faster rate in females than males during young adulthood, but at similar rates in both sexes during middle age. Strength/mass is greater in 1978 than 2000, but differences are not significant in most age groups. Strength/mass declines linearly with age and rates do not differ between young and older adults of both sexes. Left grip strength/left mid-arm muscle circumference shows a pattern across age similar to strength/mass in both sexes. CONCLUSION: Grip strength and strength per unit size declined with age. Strength and strength/height tended to increase between 1978 and 2000, while the opposite occurred for strength/weight. Results likely reflected in changes in habitual physical activity patterns associated with the transition from subsistence agriculture to less economic dependence upon agriculture.

Community well-being and growth status of indigenous school children in rural Oaxaca, southern Mexico.

OBJECTIVE: To evaluate the relationship between community well-being based on an index of marginalization and growth status of indigenous rural school children in Oaxaca. METHODS: Heights and weights of a cross-sectional sample of 11,454 children, 6-14 years, from schools for indigenous rural children (escuelas albergue) in 158 municipios in Oaxaca were measured in 2007. Tertiles of an index of marginalization were used to classify the 158 municipios into three categories of community well-being: lowest (highest marginalization), low, and moderate (lowest marginalization). Multivariate analysis of covariance, controlling for age, relative isolation and population size, was used to compare body size of children by category of community well-being. Contributions of marginalization, isolation and population size to variation in body size were estimated with sex-specific linear regression. RESULTS: Children from municipios lowest in well-being were shorter and lighter than children from municipios low and moderate in well-being. Marginalization and relative isolation accounted for 23% (boys) and 21% (girls) of the variance in height and for 21% of the variance in weight of girls. Marginalization was the predictor of weight in boys (23%). CONCLUSION: Community well-being was reflected in the growth status of rural indigenous school children. Compromised growth status was consistent with poor health and nutritional conditions that were and are characteristic of rural areas in the state of Oaxaca.

Secular change in muscular strength of indigenous rural youth 6-17 years in Oaxaca, southern Mexico: 1968-2000.

OBJECTIVE: The study compared the grip strength of indigenous school youth 6-17 years of age in Oaxaca, southern Mexico, who were surveyed in 1968, 1978 and 2000. METHODS: Grip strength (Smedley/Stoelting) was measured to 0.5 kg in 1280 children and adolescent, 621 males and 659 females, in the three surveys. Height and weight were also measured. Strength of the right and left hands was summed to provide a general estimate of muscular strength. Summed grip strength was also expressed per unit body mass (kg/kg) and height (kg/m). Subjects were classified into four age groups: 6-8 years (childhood), 9-11 years (transition in adolescence), 12-14 years (early adolescence) and 15-17 years (later adolescence). Children 6-14 years were surveyed in 1968, 1978 and 2000 while adolescents 15-17 years were surveyed in 1978 and 2000. Sex-specific MANCOVAs were used for comparisons among years within age groups. RESULTS: Changes in grip strength between 1968 and 1978 among children 6-14 years were small and significant only in girls. Grip strength increased, on average, between 1978 and 2000 in boys 6-17 years but only in girls 6-14 years; adolescent girls 15-17 years in 1978 were stronger than those in 2000. Secular gains in muscular strength were generally proportional to secular gains in body weight and height. CONCLUSION: The data demonstrate secular changes in muscular strength in indigenous rural youth in a community in the process of transition from subsistence level agriculture to an economy less dependent upon agriculture.

Secular change in heights of indigenous adults from a Zapotec-speaking community in Oaxaca, southern Mexico.

Secular change in adult height of residents in a rural indigenous community in the Valley of Oaxaca was evaluated. Subjects were measured in 1971 (49 males, 26 females 19-70 years), 1978 (128 males, 124 females 19-82 years) and 2000 (155 males, 255 females 19-89 years). Heights were adjusted for estimated loss with age using two protocols; height at 21 years of age was also estimated. The effects of age and secular factors on measured and adjusted heights were evaluated through segmented linear regressions for three birth periods, <1930, 1930 through 1959 and >or=1960 which approximate significant periods in Mexican history. Secular increase in height occurred but estimated rates varied over time and between sexes. Males born before 1930 showed a secular increase in height but females did not. Adults of both sexes born 1930-1959 showed secular gains and estimated rates did not differ. The secular gain in height continued among those born 1960 and later and estimated rates were similar in both sexes. Estimated height at 21 years of age increased in males (not significant) but not in females born before 1930, showed little or no change in those born between 1930-1959, and increased (not significant) in those born 1960 and later. Combining observations on adults with those for youth in the community indicated several phases of secular change in height that varied with years of birth.

Socioeconomic variation in the growth status of urban school children 6-13 years in Oaxaca, Mexico, in 1972 and 2000.

Socioeconomic variation in the growth status of urban school children 6-13 years of age in 1972 and 2000 was compared. The children were resident in the city of Oaxaca and were students in the same primary school in each year. Socioeconomic status (SES) was based on parental occupation. Height, sitting height, estimated leg length, weight, and the body mass index in 218 boys and 191 girls in 1972 and 173 boys and 166 girls in 2000 were compared. Sex-specific MANCOVA was used to evaluate SES differences within each year, while sex- and SES-specific MANCOVA was used to evaluate differences between years. The prevalence of stunting, overweight and obesity was estimated. There were no SES differences among boys and girls in 1972 and boys in 2000; low-middle and middle SES girls were significantly taller and heavier with longer legs than low SES girls in 2000. Within each SES group, children in 2000 were significantly larger in body size and segment lengths except for sitting height in low SES children of both sexes. Estimated secular gains increased from low to low-middle to middle SES in both sexes. Inequitable gains by SES contributed to an increase in the magnitude of differences between SES groups, especially between low SES children on one hand and low-middle and middle SES children on the other hand. The prevalence of stunting declined while the prevalence of overweight and to a lesser extent in obesity increased from 1972 to 2000, more so in low-middle and middle SES than in low SES children.

Physical activity in youth from a subsistence agriculture community in the Valley of Oaxaca, southern Mexico.

Observations of activities of contemporary subsistence agricultural communities may provide insights into the lifestyle of youth of 2 to 3 generations ago. The purpose of this study was to document age- and sex-associated variation in household activities and daily steps walking to school of youth 9-17 years in an indigenous subsistence agricultural community in Oaxaca, southern Mexico. Activities during leisure were also considered. A cross-sectional survey of a rural Zapotec-speaking community was undertaken, and respondents included 118 boys and 152 girls, aged 8.7-17.9 years. Household and leisure activities were documented by questionnaire and subsequent interview. Household activities were classified by estimated intensity for before and after school and on the weekend, and an estimate of METS per day accumulated while doing chores was derived. Number of steps from home to school was estimated. Contingency table analysis and MANCOVA controlling for age was used to evaluate results. Household activities tended to cluster at light and moderate intensities in girls and at moderate to moderate-to-vigorous intensities in boys. Estimated METS per day in approximately 2 h of chores differed significantly by sex. Secondary school girls expended significantly more METS per day in chores than primary school girls, but there was no difference by school level in boys. The daily round trip from home to school was approximately 2400 steps for primary students and approximately 2700 and approximately 3100 steps for secondary boys and girls, respectively. Television viewing and participation in sports were major leisure activities for boys and girls. Daily household chores, walking, and leisure activities suggest moderately active and moderately-to-vigorously active lifestyles in girls and boys, respectively, in this indigenous subsistence agricultural community.

Natural selection and demographic transition in a Zapotec-speaking genetic isolate in the Valley of Oaxaca, southern Mexico.

OBJECTIVE: The study analyzed the potential for natural selection and the demographic transition in an isolated Amerindian population in the process of secular change in body size. SETTING: A genetically isolated, Zapotec-speaking community located in the Valley of Oaxaca, southern Mexico, has been studied regularly from the mid-1960s to 2000. Children, adolescents and young adults have experienced a recent secular increase in body size since 1978 after a major period of no change. METHODS: Potential for natural selection and the demographic transition were analyzed over a 100-year period, ca 1900-2000. National census data, results from anthropological surveys and community archives and reports were used. RESULTS: Opportunity for natural selection changed markedly over the last century. Demographic transition to Stage II occurred ca 1955 and preceded a secular increase in body size. The crossover between curves for mortality (I(m)) and fertility (I(f)) occurred at approximately the time of onset of the secular trend among children, adolescents and young adults, i.e. those born since the early 1970s. CONCLUSIONS: The 'classic' demographic transition occurred in the mid-1950s and preceded the secular increase in body size. A 'critical mass' of environmental improvement appears to be necessary to activate secular improvements in growth status, possibly turning on a gene complex that interacts with the improved environmental conditions. The lead time from the onset of demographic transition phase II to beginning of the secular trend is approximately 25 years (one generation) in this community.

Overweight and obesity in a rural Amerindian population in Oaxaca, Southern Mexico, 1968-2000.

The purpose of this study was to evaluate secular change in the prevalence of overweight and obesity in a rural Zapotec Indian community in southern Mexico between 1968 and 2000. Cross-sectional surveys of children 6-13 years, adolescents 13-17 years, and adults 19 years of age and older resident in a rural community in Oaxaca were conducted in 1968/1971, 1978, and 2000. Individuals present in the 1968, 1978, and 2000 surveys provided a small longitudinal component. Height and weight were measured; the BMI was calculated. International criteria for overweight and obesity were used. Overweight and obesity were virtually absent in school children 6-13 years in 1968 and 1978 and in adolescents in 1978. Small proportions of children (boys, 5%; girls, 8%) and adolescents (boys, 3%; girls, 15%) were overweight in 2000; two children (1%) and no adolescents were obese. Among adults, 7% of males and 19% of females were overweight and <1% of males and 4% of females were obese in 1971/1978, but 46% of males and 47% of females were overweight; and 5% of males and 14% of females were obese in 2000. The trends for children, adolescents, and adults were confirmed in the longitudinal subsamples. In conclusion, overweight and obesity are not presently a major problem in children and adolescents in this rural Zapotec community. Overweight, in particular, and to a lesser extent obesity have increased in prevalence among adults since the late 1970s. The results suggest adulthood as a critical period for onset of overweight and obesity in this sample.

Relative fat distribution: Relationship to skeletal maturation, growth status, and motor fitness of boys 8-11 years of age.

Skeletal maturia (Tanner-Whitehouse II [TW II]), growth status, and motor fitness were compared in boys having high and low trunk/extremity skinfold ratios (T/E ratio). The T/E ratio was based on the sums of the subscapular and midaxillary, and the triceps and medial calf skinfolds. The sample included 80 boys, age 8 through 11 years, who represented the highest and lowest quartiles of the distribution of the T/E ratio (10 boys per quartile in each age group). Chronological and skeletal ages did not differ between boys in the highest and lowest quartiles, with the exception of the 10-year-old sample in the highest quartile, in whom skeletal age was significantly advanced. Boys in the highest quartile tended to be slightly taller, but especially heavier and fatter (sum of four skinfolds). They thus had a higher body mass index (BMI), which was elevated in part due to increased muscle mass as reflected in a larger estimated midarm muscle circumference. In contrast, boys in the lowest quartile tended to perform better, both absolutely and per unit body mass, in the three motor tests (run, jump, throw), while there were no consistent differences in absolute strength. However, boys in the lowest quartile tended to be stronger and to perform better per unit body mass. The results thus suggest that more centrally distributed subcutaneous fat may have a negative effect on the motor fitness of children, and this effect is mediated in part through excess fatness. © 1994 Wiley-Liss, Inc.