Isolation by Distance Between Spouses and its Effect on Boys’ Maturational Timing

Heterosis is thought to be an important contributor to human growth and development. Marital distance (distance between parental birthplaces) is commonly considered as a factor favoring the occurrence of heterosis and can be used as a proximate measure of its level. It has already been shown that marital distance appears to be an independent and important factor influencing the height of offspring. However, there is no study showing this effect on maturational timing in boys. The aim of the study was to assess the effect of marital radius on age at peak height velocity in boys, controlling for midparental height and the socioeconomic status of family. Longitudinal, annual height measurements on 740 boys from 11 to 15 years of age from Ostrowiec Świętokrzyski, Poland, were analyzed along with sociodemographic data from their parents. Midparental height was calculated as the average of the reported heights of the parents. The SITAR model was applied to the longitudinal data of height in order to assess the age at peak height velocity (APHV). As the measurements were incomplete, the APHV was successfully estimated in only 298 boys. Multiple Linear regression showed the small, but significant effect of Marital distance on the maturation rate of boys (standardized beta=-0.14; p<0.05). According to the ‘‘isolation by distance’’ hypothesis, a greater distance between parental birthplaces may increase heterozygosity, potentially promoting heterosis. We propose that these conditions may result in reduced metabolic costs of growth among heterozygous individuals, and hence a lowered velocity of growth

Early-life influences on body composition, metabolic economy, and age at menarche

Prenatal energy balance and postnatal psychosocial experiences have been linked by separate literatures to maturational timing, adult body composition (e.g., height, skeletal muscle mass), and life-long differences in metabolic physiology. This dissertation examines the potential influences of prenatal energy balance and postnatal psychosocial experiences in simultaneous analyses designed to test whether they exert additive or interacting influences on adult body composition (chapters 2 and 4), metabolic physiology (chapter 3), and age at menarche (chapter 4) among samples of U.S. men and women. Evolutionary models that address human developmental plasticity are explored as possible explanations for the observed relationships

Maturational timing and overweight prevalence in US adolescent girls

OBJECTIVES: This study examined the relation of age at menarche to overweight in US adolescent girls. METHODS: Effects of age at menarche and race/ethnicity on overweight were estimated via logistic regression, after adjustment for sociodemographic characteristics, in a sample of 6507 Hispanic, Black, White, and Asian American girls who participated in wave 2 of the National Longitudinal Study of Adolescent Health. RESULTS: Overweight prevalence rates were significantly higher in early maturing adolescents of all racial/ethnic groups but highest (57.5%) among early maturing Black girls. Early maturation nearly doubled the odds of being overweight (body mass index at or above the 85th percentile). CONCLUSIONS: Greater public health attention should be focused on the high prevalence of overweight, particularly among minority female adolescents

The Influences of Growth, Maturational Timing and Physical Activity on Adult Bone Structural Strength at the Proximal Femur

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Putting pubertal timing in developmental context: Implications for prevention

This article examines selected findings regarding the consequences of difference in timing of pubertal onset in order to build an explanatory model of puberty in context. We also seek to shed light on possible prevention efforts targeting adolescent risk. To date, there is substantial evidence supporting early onset effects on both internalizing and externalizing problems during the adolescent decade and possibly beyond. However, such effects do not directly speak to preventive intervention. The biological, familial, and broader relationship contexts of puberty are considered along with unique contexts for early maturing girls versus boys. Finally, we identify potential strategies for intervention based on these explanatory models

Racial differences in central adiposity in a longitudinal cohort of black and white adolescent females

<p>Abstract</p> <p>Background</p> <p>Central adiposity is related to chronic disease risk in adolescents. Racial differences in waist circumference have been identified using cross-sectional data from this age group. We tested for racial differences in age-related growth in waist circumference in a longitudinal cohort of black and white adolescent girls.</p> <p>Methods</p> <p>We analyzed 9 years of publicly available data from the National Heart, Lung, and Blood Institute Growth and Health Study, for 2379 girls (1213 black and 1166 white) enrolled at age 9-10 years in 1987-1988 and followed annually. Individual growth trajectories of waist circumference were constructed for girls with >3 annual measures. Mixed models were used to compare changes in waist circumference during adolescence between black and white females. BMI and age at menarche were included in the models.</p> <p>Results</p> <p>At each age, black females had significantly higher waist circumference. Mean annual increase in waist circumference was significantly higher for black females compared to white females (1.46 cm/yr vs. 1.36 cm/yr, respectively). After adjusting for BMI, the mean annual increase in waist circumference for white females was significantly higher than for black females (0.08 cm/yr vs. -0.07 cm/yr, respectively). These relationships remained significant after adjusting for age at menarche.</p> <p>Conclusions</p> <p>Black females had significantly steeper increases in waist circumference over adolescence than white females. After adjusting for BMI and age at menarche, however, the annual increase in waist circumference for black females was significantly shallower than for their white peers. These data suggest racial differences in the deposition of fat over the adolescent period.</p

Maturational timing, physical self-perceptions and physical activity in UK adolescent females: Investigation of a mediated effects model

Background: Advanced (early) biological maturation may be a risk factor for inactivity among adolescent girls. The aim of the present paper was to test the mediational effects of body attractiveness and physical self-worth on the relationship between biological maturity and accelerometer assessed moderate-to-vigorous physical activity (MVPA) in a large multi-ethnic sample of girls from the Midlands area in the UK (11-14 years). Methods: Biological maturity (predicting age at peak height velocity (APHV)); self-perceptions of body attractiveness, physical self-worth, and minutes spent in MVPA were assessed in 1062 females aged 11 to 14 years. Results: Structural equation modeling using maximum likelihood estimation and boot- strapping procedures supported the hypothesized model. Later maturation predicted higher perceptions of body attractiveness (β=.25, p<.001) which, in turn, predicted higher perceptions of physical self-worth (β=.91, p<.001) and, significantly higher MVPA (β=.22, p<.001). Examination of the bootstrap-generated bias-corrected confidence intervals suggested that perceptions of body attractiveness and physical self-worth partially mediated a positive association between predicted APHV and MVPA (β=.05, p Conclusions: Greater biological maturity (i.e. early maturity) in adolescent girls is associated with less involvement in MVPA and appears to be partly explained by lower perceptions of body attractiveness and physical self-worth. Physical activity interventions should consider girls perceptions of their pubertal related physiological changes during adolescence, particularly among early maturing girls. </p