Sexual dimorphism in growth in the relative length of the forearm and relative knee height during adolescence

There are numerous studies concerning sexual dimorphism in body proportions, but only a few have investigated growth in the relative length of particular segments of the upper and lower limbs during adolescence. The aim of the study is an assessment of sex differences of longitudinal growth in the relative length of the forearm and knee height among adolescents. Sample involved 121 boys and 111 girls, participants of the Wroclaw Growth Study, examined annually between 8 and 18 years of age. Sexual dimorphism in six ratios: forearm length and knee height relatively to: trunk, height, and limb length were analyzed using a two‐way analysis of variance with repeated measurements. The sex and age relative to an estimate of maturity timing (3 years before, and after age class at peak height velocity [PHV]) were independent variables. All of the ratios showed significant sex differences in interaction with age relative to age at PHV. The relative length of the forearm, in boys, did not change significantly with the years relative to age at PHV, whereas in girls, was the lowest in the two first age classes and afterward significantly increased just 1 year before and during the adolescent growth spurt, remaining unchanged in further age classes. For relative knee height no clear pattern for sex differences was noticed. It is proposed that relatively longer forearms, particularly in relation to the trunk in girls, could have evolved as an adaptation to more efficient infant carrying and protection during breastfeeding.     

A survey on growth and sexual development of adolescent students in Changhua City: growth of body height and weight

In order to understand the physical growth and sexual development of contemporary adolescents, a cross-sectional survey was conducted during the period September 1983 to May 1984. The population came from all the pupils from 4th grade up, and all the junior and senior high students of Changhua City. By using stratified cluster sampling, 1419 boys and 1599 girls participated, ranging in age from 8 to 19 years. Body weight and height were measured. Growth spurt is a unique event during adolescence. It is well shown in the distance curves and pseudo-velocity curves of body height and weight. In boys, the growth spurt of height spanned from 12.0 to 14.8 years, with peak height velocity (PHV) at 13.5 years. In girls it was from 10.0 to 12.6 years and peaked at 11.5 years. The growth spurt of weight occurred from 12.0 to 15.9 years in boys with peak weight velocity (PWV) at 14.5 years, while girls had a growth spurt at 10.0-12.7 years with PWV at 11.5 years. Girls entered into the growth spurt about 2 years earlier, and also entered into PHV, PWV, two and three years earlier respectively than boys, while boys had a more intense and longer growth during the growth spurt than girls. Between 10.0-13.0 years girls were taller than boys, and between 12.0-13.0 years they were heavier than boys. However, from 13.5 years onward girls were soon surpassed by boys both in height and weight. Growth in height after 16.5 years in boys and after 15.5 in girls was minimal. Growth in weight in boys also became minimal after 16.5 years while girls weight even dropped a little bit after 16.5 years. At the mean age of 17.5 years, boys were 168.1 cm, girls were 156.2 cm in average, boys being 12 cm taller than girls after reaching their final height.     

Relation between fat mass, fat free mass and ventilatory function in children and adolescents

The aim of the present study was to evaluate the relation between fat mass (FM), fat free mass (FFM) and ventilatory function in children and adolescents. 1 174 healthy children and adolescents (583 males and 591 females) aged 10-18 years were selected from Heilongjiang Province through random sampling by means of questionnaire and physical examination, and measured for height, weight, waist to hip ratio (WHR), FM, FFM and ventilatory function. The data were analyzed by means of independent-samples t test, Pearson correlation analysis and multi-factors regression analysis. Regardless of sex, an independent positive correlation was found (P<0.001) between age and FFM index (FFMI). FM index (FMI) correlated negatively with age in males (P<0.001), but positively with age in females (P<0.001). Regardless of sex, FFMI correlated positively with forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow (PEF), forced expiratory flow at 25% of forced vital capacity (FEF25%), FEF50%, and maximal mid-expiratory flow (MMEF) (P<0.05), while negatively with FEV1/FVC (P<0.01). FFMI was correlated positively with FEF75% in males (P<0.05), but not correlated in females. In males, FMI correlated negatively with FEV1, FEV1/FVC, PEF, FEF25%, FEF50%, FEF75% and MMEF (P<0.05), but not correlated with FVC. No correlation was found between the ventilatory function indices and FMI in females. Except FEV1/FVC and FEF75% in males, the effect of FFMI in predicting ventilatory function was higher than FMI regardless of sex. Moreover, the predicting effect of FFMI was higher in males than that in females. Growth spurt of lung function occurred in the ages of 12-15 years in males, while in the ages of 12, 13 and 18 years in females. During the period of growth spurt of lung function, regardless of sex, the effect of FFMI in predicting the lung function was higher than that of age. In conclusion, regardless of sex, FFMI correlates positively with ventilatory function, as a reflection of muscle mass. The effect of FFM in predicting ventilatory function is higher in males than that in females. FM correlates negatively with ventilatory function in males, but not in females. The rapid growth of height and FFM are possibly the main reasons for growth spurt of lung function.     

Pubertal growth of the short normal girl

OBJECTIVES: To determine the timing, magnitude and duration of the pubertal spurt for short normal and average height girls, to compare these with Tanner's standard and to investigate predictors of pubertal growth. METHODS: The growth of 46 short normal and 55 control girls, identified at school entry, was monitored throughout puberty. Height and weight were measured at 6-month intervals from which body mass index (BMI) was derived. Annual velocities were calculated and used to estimate the age and magnitude of peak height velocity (PHV). Age of menarche was recorded to the nearest month. Parents provided information on the child's medical and social history. RESULTS: The mean age at PHV, the magnitude of PHV and age at menarche were similar for both groups and close to Tanner's 50th centile values. Pre-pubertal BMI predicted age at menarche for short and control girls, accounting for 17% of the variance. There was a tendency for early maturing girls of average stature to have greater PHV. However, this relationship was not observed in short girls, nor did any other variable, genetic or environmental, predict the timing or magnitude of their pubertal spurt. CONCLUSIONS: Delayed puberty in short normal girls is unlikely and their growth during puberty is comparable to girls of average height. The pubertal variables measured remain close to Tanner's original standards for both groups, suggesting the lack of a secular trend towards earlier puberty in girls. The onset of menstruation is influenced by pre-pubertal BMI. However, the clinician should be aware that short normal girls have normal pubertal growth and that no genetic or environmental variable can predict the timing or magnitude of their growth spurt.     

The Diabetes Alert study: growth, fatness, and fat patterning, adolescence through adulthood in Mexican Americans

Diabetes Alert is a multidisciplinary genetic and epidemiological study of Type II (non insulin-dependent) diabetes in Texas Mexican Americans. We report the anthropometry of 1,155 individuals 10 to 70 or more years with particular reference to overweight, fatness, and anatomical fat patterning in the sample. Children ages 10-18 of both sexes are growing at the 50th percentile of the reference data (U.S. Health and Nutrition Examination Survey-1) for height, Wt/Ht2, and triceps and subscapular skinfolds. Adults are well below median height but well above median Wt/Ht2 and skinfolds. Prevalence of obesity (Wt/Ht2 greater than or equal to 30) among adults is typically 30% or higher by age 30. Diabetics compared to age/sex-matched non diabetics have shorter sitting heights, have more upper body fat (subscapular skinfold), have less lower body fat (lateral calf skinfold), and were heavier at maximum weight and at age 18. The ratio of lower to upper body fat distribution decreases over the life cycle, being highest at adolescence and lowest at ages 40-50 in both sexes. Our results show a precipitous weight gain after maturity in the sample and an association of diabetes with differences in anatomical fat patterning. The age-related changes in fat patterning need to be explained in terms of their ecological and genetic influences.     

Relationship of fat patterning to coronary artery disease risk in obese adolescents

Fatness and fat patterning of 27 male and 33 female obese adolescents were identified by principal-components analysis of five skinfolds (triceps, subscapular, iliac, abdominal, and thigh). Correlations were computed between the component scores, based on the eigen vectors, and anthropometric and physiological variables. Overall fatness, component I, was highly correlated with all anthropometric and body composition variables. Also, component I significantly correlated with fasting insulin and VO2 max for both sexes and with basal metabolism and HDL-cholesterol for females and males, respectively. Extremity fat patterning, component II, was poorly correlated with all the anthropometric and physiological variables except diastolic blood pressure for the females. Upper-lower body fat patterning, component III, was correlated with the fewest physiological variables.     

Aerobic power and pubertal peak height velocity in Belgian boys

To determine the cardiorespiratory response to maximal exercise before, during and after the pubescent growth spurt, thirty boys were tested at yearly intervals over a period of six consecutive years. For each individual, peak height velocity (PHV) was determined. The age at PHV (X = 13.6 years) was taken as a standard of maturation. The results from all subjects at 1.5 and 0.5 years before and 0.5 and 1.5 years after PHV are presented. The highest oxygen uptake (VO2) obtained during an incremental bicycle ergometer test to voluntary exhaustion was taken as peak oxygen uptake (VO2 peak). Across each of the four years studied, mean VO2 peak (min = 49.6; max = 52.5 ml.kg-1.min-1) and mean heart rate (HR) at VO2 peak (min = 190; max = 192) did not change significantly as a function of PHV. On the other hand, the respiratory quotient at VO2 peak increased considerably from mean minima and maxima of 0.99 and 1.01 before PHV to 1.07 and 1.10 after PHV. Ventilatory equivalent for VO2 (VE/VO2), taken as an indicator of ventilatory economy, seemed to be unaffected by the maturation process. The steepest increase in circumpubertal oxygen pulse was found one year after PHV. Average stability coefficients (r), calculated from the inter-years correlations were high for height (r = 0.95), weight (r = 0.92), HR at VO2 peak (r = 0.74), VO2 peak in 1/min (r = 0.71), oxygen pulse (r = 0.68) and tidal volume (r = 0.64).     

Stunting at 2 Years in Relation to Body Composition at 9 Years in African Urban Children**

Objective: To determine whether African urban children who were stunted at 2 years of age demonstrated an altered body composition by the end of childhood, before entering puberty, at 9 years of age. Research Methods and Procedures: This was a mixed‐longitudinal study of 330 prepubertal African children (182 boys) from Soweto‐Johannesburg, South Africa. Anthropometric data at 2 years of age were compared with anthropometric, DXA‐determined body composition and fat patterning in late childhood (7 to 9 years). Results: Children who had been stunted at 2 years were significantly shorter and lighter than non‐stunted children at 7 to 9 years, but there were no differences in their BMI or centralization of body fat. Previously stunted status significantly predicted reduced weight and height at 7 to 9 years but did not predict BMI, body composition, or fat patterning after controlling for potential confounding factors. The odds ratio for stunting at 2 years as a predictor of overweight at 7 to 9 years was not significant at 1.09 (95% confidence limits: 0.30, 3.98). Discussion: Greater BMI in stunted infants does not demonstrate a tendency toward overweight or obesity but is a reflection of the greater reduction in height rather than weight in stunted children. Stunted children may be programmed to accumulate greater body fat at central sites during adolescence, but we have been unable to show that these changes are evident before the initiation of pubertal development.     

Socioeconomic status, sex, age, and ethnicity as determinants of body fat distribution for Guatemalan children

The distribution of subcutaneous fat at the triceps and subscapular skinfold sites is described for four groups of children living in Guatemala. These groups are high socioeconomic status (SES) children of Ladino (mixed Spanish and Indian) ancestry, high SES children of European ancestry, low SES Ladino children, and very low SES Indian children. The method of Healy and Tanner (1981) is used, employing regression and principal components analysis of log transformed skinfold values to divide "fatness" into two uncorrelated variables: size (amount of fat) and shape (fat pattern). Significant differences exist between groups in size, with lower SES groups having less fat than higher SES groups. No significant difference in fat pattern exists between the high SES Ladino and high SES European children. Significant differences do exist between the high SES groups and the low SES groups. The relative amount of subscapular fat increases from the high SES Ladinos and high SES Europeans, to the low SES Ladinos, to the very low SES Indians. In the high SES European and high SES Ladino samples, girls have significantly more arm fat than boys. There is no significant difference in fat patterning between boys and girls in the two low SES samples. Finally, the relative amount of subscapular fat tends to increase with age in all four samples. These results indicate that fatness and fat patterning are independent anatomical characteristics, SES influences fat patterning; low SES children of both Ladino and Indian ancestry show greater reductions in arm fat than in trunk fat compared to high SES children, sexual dimorphism in fat patterning is SES dependent.(ABSTRACT TRUNCATED AT 250 WORDS)     

The feral goats of Raoul Island,and some effects of hunting on their body size and population density

Abstract

A campaign to eradicate goats (Capra hircus L.) was begun in August–October 1972 on Raoul Island, Kermadec group, 1000 km north-east of New Zealand. Of a total of 1286 animals killed, 155 were examined and dissected. The coat colour of 88% was pradominandy black, and of these 80% were patterned with white and/or brown. The hair was short in 85% of the goats, but a few males were shaggy all over. No throat tassels or other features of improved breeds were seen. Both sexes were fecund by 1 year of age. Conceptions occurred up to the winter solstice, but none was recorded for at least 4 months after it. Older females conceived earlier than young ones. Females more than 2 years old were 53% of all fecund females, and produced 66% of all kids born. Productivity was estimated to be 83 or 94 kids per year per 100 females of breeding age, depending on the criteria used. Eviscerated body weight, body length, shoulder height, and horn length all showed clear sexual dimorphism, and all increased with age up to 3 years. Kidney fat increased with age only in males. At the time of sampling, female fatness was not related to reproductive state. In areas which had been hunted during the past decade the population was least dense, there was a higher proportion of young animals, the growth rate up to 1 year old was greater, and adults were larger, age for age, than elsewhere on the island.     

A Longitudinal Study of Income Differences in the Height-BMI Relation among U.S. Children Ages 6 to 14

Previous work has shown a positive height-obesity association in U.S. children that is more pronounced in those from lower-income families than in those from higher-income families. That work has been limited to cross-sectional analysis. This study evaluates income differentials in the inter-temporal associations between childhood height and obesity in U.S. children ages 6 to 14. Pooled samples of 9,670 female and 10,110 male children from the U.S. Early Childhood Longitudinal Study—Kindergarten Cohort (ECLS-K) were evaluated in multilevel mixed effects models. The results indicated a modest height-income interaction such that the concurrent height-obesity association was weaker at higher incomes. This strengthened into adolescence for females and weakened for males. With respect to height growth, for lower-income males, being shorter before the typical start of the growth spurt (≈ 9 years) and experiencing faster later growth (between 11 and 14 years) were attributes less strongly associated with subsequent obesity. There were no indicated income interactions with height growth in females.     

Body composition and fat distribution among older Jat females: A rural–urban comparison

The aim of the present cross-sectional study is to describe and compare age related changes in body composition and fat patterning among rural and urban Jat females of Haryana State, India. A total of 600 females (rural = 300, urban = 300), ranging in age from 40 to 70 years were selected by the purposive sampling method. Body weight, height, two circumferences (waist and hip) and skinfold thickness at five different sites (biceps, triceps, calf, subscapular, and supra-iliac) were taken on each participant. To study total adiposity, indices such as body mass index (BMI), grand mean thickness (GMT), total body fat and percentage fat were analyzed statistically. The fat distribution pattern was studied using waist/hip ratio, subscapular/triceps ratio and responsiveness of five skinfold sites towards accumulation of fat at different sites with advancing age. Results indicate a decline in almost every dimension including level of fatness between the mid-fourth and mid-fifth decades of life in both rural and urban females. Urban Jat females were heavier (57.36 kg vs. 56.07 kg, p > 0.05) and significantly taller (1553.3 mm vs. 1534.5 mm, p < 0.001) than their rural counterparts. Urban females also exhibited higher mean values for both the circumferences, five skinfold thicknesses as well as for lean body mass, total fat and percentage fat than the rural females. This is also evident from their higher mean values for body mass index and grand mean thickness. Waist/hip ratio values in rural and urban females showed upper body fat predominance, with urban females having relatively more abdominal fat. Results of subscapular/triceps ratio showed that rural and urban females gained proportionally similar amounts of subcutaneous fat at trunk and extremity sites until 45 years of age. Subsequently trunk skinfolds increased relatively more in thickness. The magnitude of this increase was comparatively greater in rural females up to 55 years and among urban females from 55 to 70 years. The profiles of subcutaneous fat accumulation and sensitivity of each skinfold site also revealed more fat deposition in the trunk region compared to extremities in both rural and urban females. The present study demonstrated differential rates of fat redistribution among rural and urban females.     

Fat patterning in Papua New Guineans: effects of age, sex and acculturation

For the renewed interest in fat patterning to be fruitful, more information on the biology of fat patterning, particularly normative data are required. Nine skinfold thicknesses were measured in 2312 coastal and highland Papua New Guineans of all ages undergoing acculturation. Principal component analysis of the skinfold data revealed components of fatness and fat patterning. First component scores were typical of the changes in fatness with age and the sex differences expected in these populations. Second component scores of limb-trunk fat patterning showed marked changes with age in both sexes but they stabilised in adulthood. This pattern seemed more affected by maturity although it is usually thought to be a sex-specific pattern. The third component, upper-lower body patterning, was more sexually dimorphic in adults. Marked differences were not observed between the two communities but over a 15-year period fatness levels increased slightly and subcutaneous fat tended to be deposited more centrally.     

人工饲养条件下根田鼠肥满度的研究

实验室条件下,利用根田鼠1～70日龄体重和体长数据,计算其肥满度指数,目的在于分析其生长发育的基本规律。结果表明,根田鼠1～70日龄肥满度存在性别差异且随日龄增加而增大;雌雄个体的发育不同步;常见曲线回归模型对根田鼠1～70日龄的肥满度不能准确拟合,根据其生长发育状况,将其划分为3个阶段(其中幼体和成体阶段各含2个阶段)。     

Forty years trends in timing of pubertal growth spurt in 157,000 Danish school children

Background

Entering puberty is an important milestone in reproductive life and secular changes in the timing of puberty may be an important indicator of the general reproductive health in a population. Too early puberty is associated with several psychosocial and health problems. The aim of our study was to determine if the age at onset of pubertal growth spurt (OGS) and at peak height velocity (PHV) during puberty show secular trends during four decades in a large cohort of school children.

Methods and Findings

Annual measurements of height were available in all children born from 1930 to 1969 who attended primary school in the Copenhagen Municipality. 135,223 girls and 21,612 boys fulfilled the criteria for determining age at OGS and age at PHV. These physiological events were used as markers of pubertal development in our computerized method in order to evaluate any secular trends in pubertal maturation during the study period (year of birth 1930 to 1969). In this period, age at OGS declined statistically significantly by 0.2 and 0.4 years in girls and boys, respectively, whereas age at PHV declined statistically significantly by 0.5 and 0.3 years in girls and boys, respectively. The decline was non-linear with a levelling off in the children born between 1940 and 1955. The duration of puberty, as defined by the difference between age at OGS and age at PHV, increased slightly in boys, whereas it decreased in girls.

Conclusion

Our finding of declining age at OGS and at PHV indicates a secular trend towards earlier sexual maturation of Danish children born between 1930 and 1969. Only minor changes were observed in duration of puberty assessed by the difference in ages at OGS and PHV.     

Longitudinal analysis of adolescent growth of ladino and Mayan school children in Guatemala: effects of environment and sex.

The rate of growth in height and the timing of adolescent growth events are analyzed for two samples of Guatemalan children. One sample includes Mayan school children, 33 boys and 12 girls between the ages of 5.00 to 17.99 years, living under poor conditions for growth and development. The second sample includes ladino children, 78 boys and 85 girls of the same age range, living under favorable conditions for growth. The Preece-Baines model I function is used to estimate mean values for rates and timing of childhood and adolescent growth events for the two groups. Significant statistical contrasts (t-tests) of these means show Mayan boys reach the age of "take-off" (TO; the onset of the adolescent growth spurt) 1.45 years later, achieve peak height velocity (PHV) 1.68 years later, and continue growing for about 2.0 years longer than do the ladino boys. Despite the Mayan boys' increased duration for growth they grow significantly more slowly than the ladinos. Mayan boys are 6.60 cm shorter than ladinos at the age of TO and are estimated to be 7.71 cm shorter than the ladinos at adulthood. Mayan girls reach the age of TO 0.93 years later than do the ladina girls, but the two groups do not differ in the age at PHV or the age at adulthood. The mean height of Mayan girls is significantly less than that of ladinas at the age of TO (6.5 cm), and this difference increases to an estimated 11.14 cm at adulthood. Possible causes of these ethnic and sex-related differences in amounts and rates of growth are discussed in relation to hypotheses about the genetic and environmental determinants of human development.     

Statural growth in known-age African elephants (Loxodonta africana)

The shoulder heights of 224 females and 170 males, and hindfoot length of 236 female and 217 male known-age African elephants ( Loxodonta africana ) were measured, and growth curves constructed for each measure of size. A linear relationship between foot length and shoulder height was confirmed in simultaneous measures of 97 males and 110 females. Growth curves demonstrated the typical sexual dimorphism in both foot length and shoulder height, with males growing more rapidly than females from birth onwards. The size dimorphism in foot length and shoulder height becomes marked by the age of 10 years, with males on average being 60–70 cm taller than females at 65 years. This size dimorphism is produced through faster growth which continues for longer than does that of females. The variance in growth rates is slightly greater for females than for males. It is proposed that female growth after puberty is affected by a trade-off between growth and reproduction, while males who deviate markedly from typical patterns of growth may be subject either to mortality or energetic constraints limiting their potential variance.     

Sex differences in the distribution of subcutaneous and internal fat

One-hundred twenty-one male and 93 female subjects, aged 18-23 years, were selected for an investigation of the proportion of subcutaneous to total fat in the whole body. Body fat mass was calculated from body density using the Siri equation. Subcutaneous fat mass was calculated by measuring skinfold thickness at 15 sites and using a modification of the equation derived by Skerjl, Brozek, and Hunt. The main modification to this equation was the introduction of a midlayer area of subcutaneous tissue that is multiplied by fat thickness to give fat volume. The outermost body surface area, which has been utilized in previous research, results in an overestimation of the true subcutaneous fat mass. The average percentages of fat situated subcutaneously (PFSSs) were calculated as 53.7% for males and 62.6% for females. This sex difference is also seen in correlation-regression analysis of PFSS and percentage of fat. In females PFSS decreases with increasing total percentage of fat, whereas in males there is no significant relationship between PFSS and total percentage of fat. This suggests that the proportion of subcutaneous to total fat distribution is negatively related to fatness in females.     

Estimating Body Composition in Adolescent Sprint Athletes: Comparison of Different Methods in a 3 Years Longitudinal Design

A recommended field method to assess body composition in adolescent sprint athletes is currently lacking. Existing methods developed for non-athletic adolescents were not longitudinally validated and do not take maturation status into account. This longitudinal study compared two field methods, i.e., a Bio Impedance Analysis (BIA) and a skinfold based equation, with underwater densitometry to track body fat percentage relative to years from age at peak height velocity in adolescent sprint athletes. In this study, adolescent sprint athletes (34 girls, 35 boys) were measured every 6 months during 3 years (age at start = 14.8 ± 1.5yrs in girls and 14.7 ± 1.9yrs in boys). Body fat percentage was estimated in 3 different ways: 1) using BIA with the TANITA TBF 410; 2) using a skinfold based equation; 3) using underwater densitometry which was considered as the reference method. Height for age since birth was used to estimate age at peak height velocity. Cross-sectional analyses were performed using repeated measures ANOVA and Pearson correlations between measurement methods at each occasion. Data were analyzed longitudinally using a multilevel cross-classified model with the PROC Mixed procedure. In boys, compared to underwater densitometry, the skinfold based formula revealed comparable values for body fatness during the study period whereas BIA showed a different pattern leading to an overestimation of body fatness starting from 4 years after age at peak height velocity. In girls, both the skinfold based formula and BIA overestimated body fatness across the whole range of years from peak height velocity. The skinfold based method appears to give an acceptable estimation of body composition during growth as compared to underwater densitometry in male adolescent sprinters. In girls, caution is warranted when interpreting estimations of body fatness by both BIA and a skinfold based formula since both methods tend to give an overestimation.