The Oporto mixed-longitudinal growth, health and performance study. Design, methods and baseline results.

BACKGROUND: Studies concerning child and adolescent growth, development, performance and health aimed at the multiple interactions amongst this complex set of variables are not common in the Portuguese speaking countries. AIM: The aim of this paper is to address the key ideas, methodology and design of the Oporto Growth, Health and Performance Study (OGHPS). SUBJECTS AND METHODS: The OGHPS is a multidisciplinary mixed-longitudinal study whose main purpose is to examine the multiple interactions among biological, environmental and lifestyle indicators that affect growth, development, health and performance of Portuguese adolescents aged 10-18 years old. RESULTS: This study briefly presents baseline results for growth, physical fitness and lifestyle behaviours for those participating in the cross-sectional sample (n ≈ 8000). Approximately 30% were over-fat or obese. On average, boys were more physically fit and active than girls. Few adolescents meet the guidelines for sleep duration (≈10%) and eating habits (16.2-24.8%), while 76-85% meet the recommended levels of moderate-to-vigorous physical activity. CONCLUSIONS: The OGHPS has an innovative approach due to its mixed-longitudinal design and the broad array of variables. Furthermore, subsequent analyses of the longitudinal data will enable a detailed exploration of important factors affecting the growth trajectories of health and performance variables and will also help to identify some of the most opportune times for interventions in terms of health behaviours.

Birthweight, body composition, and motor performance in 7- to 10-year-old children.

AIM: The aim of this study was to analyse the influence of birthweight on motor performance and body composition in children. Further, we investigated whether associations between birthweight and motor performance changed after adjustment for current height, body mass index (BMI), fat-free mass (FFM), and % body fat. METHOD: A total of 483 children (251 males and 232 females) aged 7 to 10 years (mean 8.78, SD 1.0y) born in Vitória Santo Antão (northeast Brazil) were sampled. Motor performance was operationalized using different physical fitness components and gross motor coordination. Physical fitness was measured by handgrip strength, muscle endurance, explosive power, flexibility, agility, running speed, and maximal oxygen consumption (VO2max). Gross motor coordination was evaluated by means of the Körper Koordination Test für Kinder (KTK). RESULTS: Positive correlations between birthweight and height, BMI, and FFM were found. Birthweight was positively correlated with handgrip strength and negatively correlated with 20-meter sprint time, even after controlling for age, height, BMI, FFM, and % body fat. Birthweight was negatively associated with relative VO2max (mL/kg/min); however, the association was no longer significant after inclusion of BMI or FFM in the model. INTERPRETATION: Birthweight significantly predicted height, BMI, FFM, and performance in strength and velocity tests, but did not influence gross motor coordination.

Secular trends in physical fitness of Mozambican school-aged children and adolescents.

OBJECTIVE: This study presents information about secular trends in physical fitness (PF) levels among Mozambican youth. METHODS: The sample comprises 3,851 subjects (1,791 boys; 2,060 girls) aged 8-15 years who were evaluated at three time points (1992, 1999, 2012). PF tests included handgrip strength, 10 m × 5 m shuttle-run, sit-and-reach, and 1-mile run/walk. Biological maturity was assessed by sexual characteristics, and percentage body fat was predicted using triceps and subscapular skinfolds. ANCOVA (controlling for age, maturity status, and percentage body fat) was used to compare mean differences in PF tests among the three time points, by sex. RESULTS: Children in 1992 were more flexible than those from 2012; boys handgrip strength increased from 1992 to 2012, while girls decreased their handgrip strength; youth in 1992 were faster and more agile than their 2012 peers; and a decrease was observed in cardiorespiratory fitness between 1992 and 1999 and between 1992 and 2012 for both sexes. CONCLUSIONS: A negative secular trend among Mozambican children's PF was observed over the last two decades, suggesting that socio-political, educational, and economical changes occurring during this period had a relevant effect on their PF. This negative trend suggests that development of intervention programs/strategies to improve PF among youth is warranted.

Zygosity Differences in Height and Body Mass Index of Twins From Infancy to Old Age: A Study of the CODATwins Project.

A trend toward greater body size in dizygotic (DZ) than in monozygotic (MZ) twins has been suggested by some but not all studies, and this difference may also vary by age. We analyzed zygosity differences in mean values and variances of height and body mass index (BMI) among male and female twins from infancy to old age. Data were derived from an international database of 54 twin cohorts participating in the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins), and included 842,951 height and BMI measurements from twins aged 1 to 102 years. The results showed that DZ twins were consistently taller than MZ twins, with differences of up to 2.0 cm in childhood and adolescence and up to 0.9 cm in adulthood. Similarly, a greater mean BMI of up to 0.3 kg/m2 in childhood and adolescence and up to 0.2 kg/m2 in adulthood was observed in DZ twins, although the pattern was less consistent. DZ twins presented up to 1.7% greater height and 1.9% greater BMI than MZ twins; these percentage differences were largest in middle and late childhood and decreased with age in both sexes. The variance of height was similar in MZ and DZ twins at most ages. In contrast, the variance of BMI was significantly higher in DZ than in MZ twins, particularly in childhood. In conclusion, DZ twins were generally taller and had greater BMI than MZ twins, but the differences decreased with age in both sexes.

The CODATwins Project: The Cohort Description of Collaborative Project of Development of Anthropometrical Measures in Twins to Study Macro-Environmental Variation in Genetic and Environmental Effects on Anthropometric Traits.

For over 100 years, the genetics of human anthropometric traits has attracted scientific interest. In particular, height and body mass index (BMI, calculated as kg/m2) have been under intensive genetic research. However, it is still largely unknown whether and how heritability estimates vary between human populations. Opportunities to address this question have increased recently because of the establishment of many new twin cohorts and the increasing accumulation of data in established twin cohorts. We started a new research project to analyze systematically (1) the variation of heritability estimates of height, BMI and their trajectories over the life course between birth cohorts, ethnicities and countries, and (2) to study the effects of birth-related factors, education and smoking on these anthropometric traits and whether these effects vary between twin cohorts. We identified 67 twin projects, including both monozygotic (MZ) and dizygotic (DZ) twins, using various sources. We asked for individual level data on height and weight including repeated measurements, birth related traits, background variables, education and smoking. By the end of 2014, 48 projects participated. Together, we have 893,458 height and weight measures (52% females) from 434,723 twin individuals, including 201,192 complete twin pairs (40% monozygotic, 40% same-sex dizygotic and 20% opposite-sex dizygotic) representing 22 countries. This project demonstrates that large-scale international twin studies are feasible and can promote the use of existing data for novel research purposes.

Skeletal maturation, fundamental motor skills and motor coordination in children 7-10 years.

Relationships between skeletal maturation and fundamental motor skills and gross motor coordination were evaluated in 429 children (213 boys and 216 girls) 7-10 years. Skeletal age was assessed (Tanner-Whitehouse 2 method), and stature, body mass, motor coordination (Körperkoordinations Test für Kinder, KTK) and fundamental motor skills (Test of Gross Motor Development, TGMD-2) were measured. Relationships among chronological age, skeletal age (expressed as the standardised residual of skeletal age on chronological age) and body size and fundamental motor skills and motor coordination were analysed with hierarchical multiple regression. Standardised residual of skeletal age on chronological age interacting with stature and body mass explained a maximum of 7.0% of the variance in fundamental motor skills and motor coordination over that attributed to body size per se. Standardised residual of skeletal age on chronological age alone accounted for a maximum of 9.0% of variance in fundamental motor skills, and motor coordination over that attributed to body size per se and interactions between standardised residual of skeletal age on chronological age and body size. In conclusion, skeletal age alone or interacting with body size has a negligible influence on fundamental motor skills and motor coordination in children 7-10 years.

Multi-level modelling of physical activity in nuclear families.

BACKGROUND: Few studies focus on the different dyadic relations among family members to study physical activity (PA) levels. AIM: The aim was to investigate predictors and sources of variance of PA levels in nuclear families using multi-level modelling. SUBJECTS AND METHODS: The sample consisted of 2661 Portuguese four-member nuclear families (10 644 subjects). PA was measured using a questionnaire and socioeconomic status (SES) was assessed by parental occupation. Height and weight were measured in children, while parents self-reported their values. RESULTS: The results showed that intra-generational similarities were higher than inter-generational, with correlation values of 0.26 and 0.10, respectively. SES was unrelated to any family members' PA level. Being male (ß = 0.26, t = 21.77), being older (ß = -0.36, t = -4.73) and greater BMI for mothers (ß = 0.02, t = 2.55) had effects on individuals' PA. CONCLUSION: These results suggest a strong dyadic resemblance in PA, showed different effects of gender, age and BMI on individuals' PA and demonstrated that multi-level modelling is a useful strategy to study PA in families.

Nutritional status and its association with physical fitness, physical activity and parasitological indicators in youths from rural Mozambique.

BACKGROUND: Little information exists about the relationship of nutritional status and motor performance conditional on asymptomatic parasitemia in rural African children. AIMS: The aims of this study were to (1) determine if malnourished youths from rural African areas have lower levels of physical fitness (PF) and physical activity (PA) compared to normal weight youths, (2) verify the biological relevance of anthropometric criteria used to classify nutritional status in youth, and (3) determine the prevalence of parasitological indicators, and its association with nutritional status and PF. METHODS: The sample comprised 794 youths (6-17 years) from Calanga, a rural community in Mozambique. PF tests were selected from standardized test batteries, and PA was estimated by accelerometry. Nutritional status was defined according to WHO recommendations for stunting, wasting and normal weight. Parasitological indicators were determined based on stool specimens' analysis. RESULTS: In general terms the normal group out-performed the other nutritional groups (stunted and wasted) for PF. However, no significant differences were found for PA among nutritional groups. There were also no significant differences in prevalence of intestinal parasites. CONCLUSIONS: Nutritional status was not associated with PA levels or the prevalence of parasitological indicators in youth, but was related to physical performance.

Physical activity, physical fitness, gross motor coordination, and metabolic syndrome: focus of twin research in Portugal.

A very brief history of Portuguese twin research in sport and human movement sciences is presented. Recruitment procedures, zygosity determination, and phenotypes are given for twins and their parents from the mainland, and Azores and Madeira archipelagos. Preliminary findings are mostly related to physical activity, health-related physical fitness, gross motor coordination, neuromotor development, and metabolic syndrome traits.

Physical activity, fitness and the metabolic syndrome in rural youths from Mozambique.

BACKGROUND: Except for North America and Europe, few studies have reported the association among physical activity (PA), cardiorespiratory fitness (CRF) and metabolic syndrome (MetS) in youths, especially for rural African youth. AIM: The aims of this study were to determine the prevalence of PA levels, CRF, MetS and its indicators, and examine the association between these variables in a school-aged sample of youth from rural Mozambique. SUBJECTS AND METHODS: The sample included 209 children and adolescents aged 7-15 years old from Calanga, a rural community in Mozambique. PA was estimated with a culturally-specific questionnaire. CRF was determined by 1-mile run test. Indicators of the MetS included fasting glucose, triglycerides, total cholesterol, blood pressure and body mass index. A continuous metabolic risk score was computed. RESULTS: Results showed high levels of PA and CRF and a low prevalence of MetS ( < 2%) among children and adolescents from Calanga. However, there was a moderately high prevalence of elevated blood pressure (81.8%) and triglycerides (18.7%), respectively. There were no significant associations between PA, CRF and MetS. CONCLUSION: Youths from Calanga are physically active and possess high CRF and their lifestyle may be a protective effect against MetS.

Genetics of physical activity and physical inactivity in humans.

Emerging evidence suggests that physical activity and sedentary behavior [reflected in physical inactivity (PI)], might be two different phenotypes that may have distinct underlying physiological mechanisms. The purpose of this review is to summarize the existing literature on the genetic determinants of PA and PI phenotypes in humans, considering them as distinct behaviors. Completed in January 2011, this review includes family studies, twin studies, association studies, genome-wide linkage studies and genome-wide association scan (GWAs) reporting different physical activity/inactivity-related phenotypes. In regards to PA, familial aggregation studies resulted in heritability estimates ranging from 0 to 60 %, and twin studies yielded heritability estimates (a(2)) and shared environment (c(2)) scores for PA phenotypes ranging from 0.00 to 0.85 and 0.00 to 0.84, respectively. Unique environmental (e(2)) results are well dispersed from 0.12 to 0.72. Suggestive linkages were found with markers nearby different activity-related genes: EDNRB, MC4R, UCP1, FABP2, CASR, SLC9A9. Significant associations with PA phenotypes were found for Ace, Gln223ARrg, MC4R and DRD2 genes. We found one GWAs that reported novel SNPs in the PAPSS2 gene on chromosome 10q23.2 and in two intergenic regions on chromosomes 2q33.1 and 18p11.32. Heritability estimates for PI ranged from 25 to 60 % and linkage studies recorded higher LOD scores for PI versus PA. The ACE genotype was strongly associated with PI. There are potentially different genetic influences on PA versus PI phenotypes. Future studies should focus on the different genetic influences on PA and PI to improve our understanding of underlying determinants of these behaviors.

Testing Seefeldt's Proficiency Barrier: A Longitudinal Study.

The idea that proficiency in the fundamental movement skills (FMS) is necessary for the development of more complex motor skills (i.e., the proficiency barrier) and to promote health-enhancing physical activity and health-related physical fitness levels is widespread in the literature of motor development. Nonetheless, to the best of our knowledge, there is no study assessing whether children presenting proficiency below a specified proficiency barrier would demonstrate difficulty in improving performance in more complex skills-even when subjected to a period of practice in these complex skills. The present study tested this. Eighty-five normal children (44 boys) aged 7 to 10 years participated in the study. The intervention took place during 10 consecutive classes, once a week, lasting 40 min each. Six FMS (running, hopping, leaping, kicking, catching and stationary dribbling) and one transitional motor skill (TMS) (speed dribbling skill) were assessed. The results showed that only those who showed sufficient proficiency in running and stationary dribbling before the intervention were able to show high performance values in the TMS after intervention. In addition, in line with recent propositions, the results show that the basis for development of the TMS was specific critical components of the FMS and that the barrier can be captured through a logistic function. These results corroborate the proficiency barrier hypothesis and highlight that mastering the critical components of the FMS is a necessary condition for motor development.

Genetic and environmental influences on human height from infancy through adulthood at different levels of parental education.

Genetic factors explain a major proportion of human height variation, but differences in mean stature have also been found between socio-economic categories suggesting a possible effect of environment. By utilizing a classical twin design which allows decomposing the variation of height into genetic and environmental components, we tested the hypothesis that environmental variation in height is greater in offspring of lower educated parents. Twin data from 29 cohorts including 65,978 complete twin pairs with information on height at ages 1 to 69 years and on parental education were pooled allowing the analyses at different ages and in three geographic-cultural regions (Europe, North America and Australia, and East Asia). Parental education mostly showed a positive association with offspring height, with significant associations in mid-childhood and from adolescence onwards. In variance decomposition modeling, the genetic and environmental variance components of height did not show a consistent relation to parental education. A random-effects meta-regression analysis of the aggregate-level data showed a trend towards greater shared environmental variation of height in low parental education families. In conclusion, in our very large dataset from twin cohorts around the globe, these results provide only weak evidence for the study hypothesis.

Familial aggregation and heritability of markers of metabolic risk, physical activity, and physical fitness in nuclear families from Muzambinho (Minas Gerais, Brazil).

OBJECTIVE: This study investigated the familial aggregation and heritability of markers of metabolic risk, physical activity, and physical fitness in nuclear families from Muzambinho (Minas Gerais, Brazil). SUBJECTS AND METHODS: The study included members of 139 families, comprising 97 fathers (aged 40 ± 7 years), 129 mothers (35 ± 6 years), 136 sons (12 ± 4 years), and 121 daughters (12 ± 5 years). Evaluated markers included (A) body mass index, waist circumference, glycemia, and cholesterolemia, as metabolic risk markers; (B) total weekly volume of physical activity, as a physical activity marker; and (C) relative muscle strength, as a physical fitness marker. Correlations between family members and heritability (h2) were estimated using the software S.A.G.E. RESULTS: Significant familial correlations were obtained between parents-offspring for glycemia and cholesterolemia (both ρ = 0.21, p < 0.05) and relative muscle strength (ρ = 0.23, p < 0.05), and between siblings for waist circumference, glycemia, total weekly volume of physical activity, and relative muscle strength (ρ variation 0.25 to 0.36, p < 0.05). Heritability values were significant for almost all variables (h2 variations: 20% to 57% for metabolic risk markers, 22% for the total weekly volume of physical activity, and 50% for relative muscle strength), except for waist circumference (h2 = 15%, p = 0.059). CONCLUSION: The presence of significant correlations between family members and/or significant heritability strengthens the possible genetic and/or common familial environment influence on metabolic risk markers, total weekly volume of physical activity, and relative muscle strength.

Age and sex differences in physical activity of Portuguese adolescents.

PURPOSE: This study sought to examine sex- and age-associated variations in physical activity (PA) among Portuguese adolescents aged 10-18 yr. METHODS: A total of 12,577 males and females at the primary or secondary education level were sampled across four regions of Portugal. PA was assessed by a questionnaire, producing four different indexes: work/school (WSI), sport (SI), leisure time (LI), and total physical activity index (PAI). We examined sex and age differences by using two-way analysis of variance. RESULTS: Males had higher mean values of PA than did females. In both sexes, mean values for all four PA indexes increased from ages 10 to 16 yr. After age 16, females decreased their mean values, whereas males continued to increase their values (except for LI). In both sexes, the average annual rate of change for the mean values of all four PA indexes correspond to three sensitive age periods (10-13, 13-16, and 16-18 yr). Until age 16, average mean changes for females ranged from +0.7 to +1.6% per year, except for SI in the youngest group (a modest decrease). For males under 16 yr, the pattern was similar, with increases ranging from 0.4 to 1.9% per year. After age 16, females experienced decreases of 1-2.1% per year for the four PA indexes, whereas males showed an increase for three indexes and an average decrease of 1.3% per year for LI. CONCLUSIONS: These results suggest that it is important to consider sex differences in PA levels among Portuguese adolescents. Unlike their male counterparts, Portuguese females may reduce much of their PA during late adolescence.

Relationship between physical activity, physical fitness and multiple metabolic risk in youths from Muzambinho's study.

Negative associations between physical activity (PA), physical fitness and multiple metabolic risk factors (MMRF) in youths from populations with low PA are reported. The persistence of this association in moderately-to highly active populations is not, however, well established. The aim of the present study was to investigate this association in a Brazilian city with high frequency of active youths. We assessed 122 subjects (9.9 ± 1.3 years) from Muzambinho city. Body mass index, waist circumference, glycaemia, cholesterolaemia, systolic and diastolic blood pressures were measured. Maximal handgrip strength and one-mile walk/run test were used. Leisure time PA was assessed by interview. Poisson regression was used in the analysis. The model explained 11% of the total variance. Only relative muscular strength and one-mile walk/run were statistically significant (p < .05). Those who needed more time to cover the one-mile walk/run test had an increased in metabolic risk of 11%, and those with greater strength reduced the risk by about 82%. In conclusion, children and youths from an active population who need less time to cover the one-mile walk/run test or who had greater muscular strength showed a reduced metabolic risk. These results suggest that even in children and youths with high leisure time PA, a greater aerobic fitness and strength might help to further reduce their MMRF.

Developmental and physical-fitness associations with gross motor coordination problems in Peruvian children.

The aims of this cross-sectional study were to examine the developmental characteristics (biological maturation and body size) associated with gross motor coordination problems in 5193 Peruvian children (2787 girls) aged 6-14 years from different geographical locations, and to investigate how the probability that children suffer with gross motor coordination problems varies with physical fitness. Children with gross motor coordination problems were more likely to have lower flexibility and explosive strength levels, having adjusted for age, sex, maturation and study site. Older children were more likely to suffer from gross motor coordination problems, as were those with greater body mass index. However, more mature children were less likely to have gross motor coordination problems, although children who live at sea level or at high altitude were more likely to suffer from gross motor coordination problems than children living in the jungle. Our results provide evidence that children and adolescents with lower physical fitness are more likely to have gross motor coordination difficulties. The identification of youths with gross motor coordination problems and providing them with effective intervention programs is an important priority in order to overcome such developmental problems, and help to improve their general health status.

Skeletal Maturation, Body Size, and Motor Coordination in Youth 11-14 Years.

PURPOSE: The objective of this study is to estimate the relative contribution of biological maturation to variance in the motor coordination (MC) among youth and to explore gender differences in the associations. METHODS: Skeletal maturation (Tanner-Whitehouse 3), stature, body mass, and MC (Körperkoordinationstest für Kinder) were assessed in 613 youths, 284 boys and 329 girls 11-14 yr of age. Standardized residuals of skeletal age on chronological age were used as the estimate of skeletal maturity status independent of chronological age. Hierarchical multiple regression analyses were used to analyse associations between skeletal maturity status and MC. RESULTS: Skeletal maturity status by itself, i.e., standardized residuals of skeletal age on chronological age (step 3) explained a maximum of 8.1% of the variance in MC in boys (ΔR3 in the range of 0.0%-8.1%) and 2.8% of the variance in girls (ΔR3 in the range of 0.0%-2.8%), after controlling for stature, body mass and interactions of the standardized residuals of skeletal age on chronological age with stature and body mass. Corresponding percentages for the interactions of the standardized residuals of skeletal age and stature and body mass, after adjusting for stature and body mass (step 2) were 8.7% in boys (ΔR2 in the range of 0.3%-8.7%) and 7.1% in girls (ΔR2 in the range of 0.1%-7.1%). Chow tests suggested structural changes in ß-coefficients in the four MC tests among boys and girls, 12-13 yr. CONCLUSION: The percentage of variance in the four MC tests explained by skeletal maturation was relatively small, but the relationships differed between boys and girls. By inference, other factors, e.g., neuromuscular maturation, specific instruction and practice, sport participation, and others may influence MC at these ages.

An evaluation of a nurse-led rehabilitation programme (the ProBalance Programme) to improve balance and reduce fall risk of community-dwelling older people: A randomised controlled trial.

OBJECTIVE: This study aims to assess the effect of a nurse-led rehabilitation programme (the ProBalance Programme) on balance and fall risk of community-dwelling older people from Madeira Island, Portugal. DESIGN: Single-blind, randomised controlled trial. SETTING: University laboratory. PARTICIPANTS: Community-dwelling older people, aged 65-85, with balance impairments. Participants were randomly allocated to an intervention group (IG; n=27) or a wait-list control group (CG; n=25). INTERVENTION: A rehabilitation nursing programme included gait, balance, functional training, strengthening, flexibility, and 3D training. One trained rehabilitation nurse administered the group-based intervention over a period of 12 weeks (90min sessions, 2 days per week). A wait-list control group was instructed to maintain their usual activities during the same time period. OUTCOME: Balance was assessed using the Fullerton Advanced Balance (FAB) scale. The time points for assessment were at zero (pre-test), 12 (post-test), and 24 weeks (follow up). RESULTS: Changes in the mean (SD) FAB scale scores immediately following the 12-week intervention were 5.15 (2.81) for the IG and -1.45 (2.80) for the CG. At follow-up, the mean (SD) change scores were -1.88 (1.84) and 0.75 (2.99) for the IG and CG, respectively. The results of a mixed between-within subjects analysis of variance, controlling for physical activity levels at baseline, revealed a significant interaction between group and time (F (2, 42)=27.89, p<0.001, Partial Eta Squared=0.57) and a main effect for time (F (2, 43)=3.76, p=0.03, Partial Eta Squared=0.15), with both groups showing changes in the mean FAB scale scores across the three time periods. A significant main effect comparing the two groups (F (1, 43)=21.90, p<0.001, Partial Eta Squared=0.34) confirmed a clear positive effect of the intervention when compared to the control. CONCLUSION: This study demonstrated that the rehabilitation nursing programme was effective in improving balance and reducing fall risk in a group of older people with balance impairment, immediately after the intervention. A decline in balance was observed for the IG after a period of no intervention. CLINICAL TRIAL REGISTRATION NUMBER: ACTRN12612000301864.

Genetic and environmental influences on height from infancy to early adulthood: An individual-based pooled analysis of 45 twin cohorts.

Height variation is known to be determined by both genetic and environmental factors, but a systematic description of how their influences differ by sex, age and global regions is lacking. We conducted an individual-based pooled analysis of 45 twin cohorts from 20 countries, including 180,520 paired measurements at ages 1-19 years. The proportion of height variation explained by shared environmental factors was greatest in early childhood, but these effects remained present until early adulthood. Accordingly, the relative genetic contribution increased with age and was greatest in adolescence (up to 0.83 in boys and 0.76 in girls). Comparing geographic-cultural regions (Europe, North-America and Australia, and East-Asia), genetic variance was greatest in North-America and Australia and lowest in East-Asia, but the relative proportion of genetic variation was roughly similar across these regions. Our findings provide further insights into height variation during childhood and adolescence in populations representing different ethnicities and exposed to different environments.