Plasticity in the growth of body segments in relation to height-for-age and maternal education in Guatemala.

OBJECTIVES: Plasticity in the growth of body segments between populations has been researched in relation to migration, temporal change and high-altitude studies. We study the within population variation in body segments, thus controlling for some of the environmental and genetic differences that could be at play in between populations studies. We test a version of the thrifty phenotype hypothesis, where the growth of head-trunk and hand are prioritized due to their functional significance over height and leg growth. MATERIALS AND METHODS: A total of 3913 Guatemalan, rural, semi-urban and urban, Maya and Ladino children 6 to 15 years old were studied. Height, sitting height, leg length, and metacarpal length were studied in relation to three proxies for living conditions: height- and leg length-for-age, and maternal education. Estimation statistics and null hypothesis significance testing were used to analyze the data. RESULTS: Metatarsal length and sitting height values were higher than height and leg length respectively. Relative metacarpal length was conserved across height-for-age groups. Females were less affected than males for metacarpal length and sitting height, but more affected for leg length. CONCLUSION: Our results agree with the thrifty phenotype hypothesis, where metacarpal and sitting height growth would be prioritized over height and leg length due to greater functional significance.

Body proportionality and adiposity are not related in 6- to 8-year-old Yucatec Maya children.

OBJECTIVE: The aim of this study was to analyze the association between relative leg length (RLL) (leg length × 100/height) and adiposity in a sample of 6- to 8-year-old children of Maya ancestry from Motul and Merida, Mexico. METHODS: This cross-sectional study included 260 children (128 girls) measured between 2011 and 2015. The RLL was used as a measure of body proportionality. Linear regression models were performed to examine the association between RLL (predictor) and three adiposity indicators (outcome variables): fat mass index (kg/m2 ), waist circumference (z-score), and sum of triceps and subscapular skinfolds (z-score). RESULTS: The prevalence of stunting was 12%, and a higher prevalence (19%) of short RLL (leg stunting) was found. The prevalence of overweight and obesity were 16% and 20%, respectively, but the highest prevalence was found for abdominal obesity (40%). None of the adiposity indicators were related to RLL (P > .05), even after adjusting for the influence of children's sex and age. CONCLUSIONS: Our results suggest that the coexistence of short RLL and high body adiposity is not observed in all populations. Our findings do not discount the possibility that a negative association between RLL and adiposity is expressed at older ages.

The application of knemometry to measure childhood short-term growth among the indigenous Shuar of Ecuador.

OBJECTIVES: Knemometry, the precise measurement of lower leg (LL) length, suggests that childhood short-term (e.g., weekly) growth is a dynamic, nonlinear process. However, owing to the large size and complexity of the traditional knemometer device, previous study of short-term growth among children has been restricted predominantly to clinical settings in industrialized Western nations. The aim of the present study is to address this limitation and promote broader understandings of global variation in childhood development by: (1) describing a custom-built portable knemometer and assessing its performance in the field; and (2) demonstrating the potential application of such a device by characterizing childhood short-term LL growth among the indigenous Shuar of Amazonian Ecuador. MATERIALS AND METHODS: Mixed-longitudinal LL length data were collected weekly from 336 Shuar children age 5-12 years old using the custom portable knemometer (n = 1,145 total observations). Device performance and Shuar short-term LL growth were explored using linear mixed effects models and descriptive statistics. RESULTS: The portable knemometer performed well across a range of participant characteristics and possesses a low technical error of measurement of 0.18 mm. Shuar childhood LL growth averages 0.47 mm/week (SD = 0.75 mm/week), but exhibits large between- and within-individual variation. DISCUSSION: Knemometry can be reliably performed in the field, providing a means for evaluating childhood short-term growth among genetically and ecologically diverse populations. Preliminary findings suggest that Shuar weekly LL growth is comparable in mean magnitude but likely more variable than reported for healthy Western children. Future work will further explore these patterns. Am J Phys Anthropol 160:353-357, 2016. © 2016 Wiley Periodicals, Inc.

Leg length and type 2 diabetes: what's the link?

PURPOSE OF REVIEW: Human leg length is determined by a complex interplay of genetics and environmental exposures during development, which may be associated with long-term metabolic disease risk. Here, we review recent literature on the link between relative leg length and type 2 diabetes in more and less economically developed societies, wherein the contextual influences on relative leg length are unique. We also hypothesize mechanisms underlying and mediating this association. RECENT FINDINGS: Evidence from more economically prosperous Western populations and contemporary adult populations in China and Brazil indicates that lower relative leg length is associated with greater risk for impaired glucose homeostasis and type 2 diabetes. In Brazil, this association was stronger among women with early menarche. Although still poorly defined and in need of further research, the potential mechanisms likely involve suboptimal early-life net nutrition that simultaneously leads to retarded growth and impaired glucose regulation. An untested hypothesis is that the association is mediated by differences in skeletal muscle mass. SUMMARY: Epidemiologic evidence from diverse settings points to humans with shorter legs relative to their stature having higher risk for type 2 diabetes. Although research is needed to test mechanistic hypotheses, the greatest potential for improving public health will come through identification of, and intervention upon, the upstream modifiable determinants of inadequate leg growth.

Epidemiology of early and late growth in height, leg and trunk length: findings from a birth cohort of Brazilian males.

BACKGROUND/OBJECTIVE: To investigate socioeconomic, gestational and early life exposures as potential determinants of total height, leg and trunk length. SUBJECTS/METHODS: Male subjects from the 1982 Pelotas Birth Cohort Study were examined in 1986 at home, and in 2000 when registering at the local army base. The follow-up rate was 79%. Standing and sitting heights were measured on both occasions. Leg length was calculated as the difference between standing and sitting heights. Outcome measures were height, leg and trunk length at 4 and 18 years and growth in this period. Complete data were obtained for 2012 participants, representing 71% of all eligible male subjects. RESULTS: Mean (s.d.) height, trunk length and leg length at 18 years were 173.4 (6.8), 96.0 (3.5) and 77.5 cm (4.5), respectively. The mean (s.d.) change in height from 1986 to 2000 was 75.4 cm (5.2) and for leg and trunk length 35.4 (3.9) and 40.0 cm (2.9), respectively. Of 11 independent variables analyzed, only maternal height and birthweight were associated with all three variables of growth. Gestational age showed no associations with growth or attained size. CONCLUSIONS: Early growth plays a pivotal role in determining attained height and its components. Both biological and socioeconomic variables strongly influence determinants of height, though socioeconomic factors appear to be more important in early growth. Leg and trunk length contribute almost equally to differences in overall height, regardless of the independent variable influencing the difference. Public health strategies designed to improve chronic disease profiles should focus on the early growth period.

Prediction of adult height using maturity-based cumulative height velocity curves.

OBJECTIVE: To validate and demonstrate how adult height can be predicted by using reference values obtained from maturity and sex-specific cumulative height velocity curves. STUDY DESIGN: Serial height measurements were taken on 224 boys and 120 girls. Individuals were classified as early, average, or late maturers, depending on their age of peak height velocity. Maturity and sex-specific cumulative height velocity curves were developed for early, average, and late maturers, and the area under these curves were used to develop reference values to predict adult height. RESULTS: This method can predict adult height within +/-5.35 cm 95% of the time in boys and +/-6.81 cm 95% of the time in girls. CONCLUSIONS: The technique is a valid, nonintrusive, inexpensive, and simple method of predicting adult height in adolescent children, free of growth limiting diseases.

Side effects of 2 different dexamethasone courses for preterm infants at risk of chronic lung disease: a randomized trial.

OBJECTIVE: We hypothesized that a pulsed course of dexamethasone would result in better linear growth than a 42-day reducing course in preterm infants at risk for chronic lung disease of prematurity. STUDY DESIGN: Forty infants with a birth weight of < or =1,250 g who required mechanical ventilation at 7 days of age were randomly assigned to a repeatable 3-day pulse course of dexamethasone commencing immediately or a 42-day (long) course commencing at 14 days of age if they still required mechanical ventilation and supplemental oxygen. The primary outcome measure was linear growth at 36 weeks' postmenstrual age measured by knemometry. RESULTS: There was no difference in lower leg length at 36 weeks' postmenstrual age. Infants receiving the pulse course had lower rises in blood pressure, less myocardial hypertrophy, and less adrenal suppression. However, more infants required supplemental oxygen at 28 days' postnatal age (14/18 vs 8/21, P < .05) and 36 weeks' PMA (8/16 vs 5/20, P = .12). CONCLUSION: In preterm infants at risk for chronic lung disease, a pulsed course of dexamethasone has fewer side effects than a long course but may be less effective at preventing chronic lung disease.

Linear growth of Zapotec schoolchildren: growth status and yearly velocity for leg length and sitting height.

The growth status and yearly growth velocity for sitting height and leg length of mild-to-moderately undernourished Zapotec schoolchildren from Oaxaca, Mexico, are described and compared with well-nourished black and white North American boys and girls. Zapotec children between 6 and 13 years of age are significantly smaller than their North American counterparts. Differences in sitting height between the three samples are maintained throughout the age range; their yearly growth increments are comparable. Yearly growth velocity in leg length of the Zapotec children is lower, which increases variation in growth status with age. Age-specific relative leg length (leg length/stature) for the Zapotec sample is 1-5% smaller than well-nourished North American children. The results show that statural growth differences between Zapotec and North American schoolchildren are accounted for by diminished growth rates of leg length.

Leg growth following umbilical artery catheter-associated thrombus formation: a 4-year follow-up.

Fourteen children were re-examined 4 years following the radiographic demonstration of umbilical artery catheter associated thrombus formation. Positive correlations could not be established between radiographically determined femoral and/or tibial lengths, length differences, pulse pressure differences, and the location of thrombi noted on the 1971 aortograms.