Search

Carotenoids are fat-soluble phytochemicals with biological roles, including ultraviolet protective functions in skin. Spectroscopic skin carotenoid measurements can also serve as a noninvasive biomarker for carotenoid consumption. Single-nucleotide polymorphisms (SNPs) in metabolic genes are associated with human plasma carotenoid concentrations; however, their relationships with skin carotenoid concentrations are unknown.

The sensitivity of commercially available devices to detect changes in skin carotenoids is not known.

Leitch, BA, Wilson, PB, Ufholz, KE, Roemmich, JN, Orysiak, J, Walch, TJ, Short, SE, and Fitzgerald, JS. Vitamin D awareness and intake in collegiate athletes. J Strength Cond Res35(10): 2742–2748, 2021—Poor vitamin D status is a risk factor for negative health and performance outcomes in athletes, but little is known about how athletes' awareness and beliefs about vitamin D affect their consumption of vitamin D. This observational study investigated awareness of vitamin D for health and performance among collegiate athletes and evaluated the association of vitamin D awareness with its dietary intake. Fifty-two female and 29 male Division I collegiate athletes completed an online vitamin D awareness and dietary intake questionnaire between November 1, 2015, and January 30, 2016. Median intake of vitamin D was 330 International Units (IU), which is below the recommended daily allowance (RDA) of 600 IU, but was greater in male athletes (693 IU) than female athletes (263 IU, p< 0.01). The RDA for vitamin D was met by 62% of men and 30% of women. Athletes responded that vitamin D “probably” or “definitely” will play a role in their health (88.9%) and athletic performance (71.6%). However, only 23.4 and 28.4% of athletes reported concern for their vitamin D levels or believed that they were at risk for deficiency, respectively. Results showed small-to-moderate, positive correlations (r= 0.28–0.495, p< 0.05) between aspects of vitamin D awareness and vitamin D intake, particularly with supplemental forms of vitamin D. Given the lack of awareness concerning risk of vitamin D deficiency, and the links between aspects of vitamin D awareness and vitamin D intake, nutritional education programs designed to increase vitamin D awareness in athletes may be an effective strategy to reduce deficiency.

Agricultural land management may influence crop nutritional quality. However, few studies have explored potential connections between crop quality with different land management strategies. We analyzed mineral and crude protein concentrations in spring wheat grain (Triticum aestivumL.) samples from a study in Mandan, ND conducted from 2006 to 2014. The study introduced a perennial forage phase into an annual spring wheat cropping system, in three to four replicates, and previously found yield benefits and enhanced soil parameters in the perennial forage treatments. We determined whether integrating a perennial forage phase into continuous wheat would also affect crop nutritional quality by measuring wheat grain mineral and protein concentrations. Crude protein concentration was greater (p< .05) when wheat followed alfalfa (Medicago sativaL.) and increased linearly after 2–5 yr of established alfalfa. We observed comparable wheat grain crude protein and mineral concentrations between continuous annually fertilized wheat and unfertilized wheat following perennial forages. Negative correlations (p< .001) were observed between wheat grain yield and crude protein, potassium (K), magnesium (Mg), nickel (Ni), phosphorus (P), sulfur (S), and zinc (Zn) concentrations. Discriminate multivariate analyses showed, with 96% predictive accuracy, that differences in crude protein and mineral concentration were largely driven by year of wheat harvest. Differences between harvest years were likely due to timely precipitation at critical Growth Stage 3, during spikelet development. Study outcomes highlighted the important role of perennial forages and environmental factors to influence protein and mineral concentration in spring wheat grain. Perennial forages benefit annual cropping systems.Wheat grain samples were analyzed for mineral and protein concentration.Protein was greater when wheat followed alfalfa versus intermediate wheatgrass.Grain quality was similar between annual cropping and wheat following perennials.Grain mineral and protein concentrations were influenced by environmental factors.

Background: Insufficient compensation for energy from sugar-sweetened beverages (SSBs) consumed prior to meals may promote greater overall energy intake. If so, ability to compensate for prior energy intake may account for difference in adiposity between adolescents with and without overweight. Studies of fraternal siblings discordant for weight status control for some genetic and shared within-family factors, which allows for testing how putative non-shared factors, such as parental control of feeding, predicts sibling weight differences.Aim: To determine whether same-sex weight-discordant (one with, one without overweight) adolescent siblings differ in ability to compensate for prior energy intake.Methods: Same-sex biological sibling pairs (mean age = 15.4; 95% confidence interval (CI) 15.1, 15.7) (n= 38 pairs; 21 male pairs) consumed a sugar-sweetened (450 kcal) or a non-nutritive-sweetened (10 kcal) liquid preload of equal volumes on separate days, followed by an ad libitumlunch. Multilevel models examined ability to compensate, dietary restraint, and parental control of child’s feeding.Results: Siblings showed insufficient compensation and overate (with overweight = 44 kcal; without overweight = 32 kcal). Siblings shared little within-family similarity in compensation (intra-class correlation coefficient (ICC) = 0.20). Compensation was predicted by parental restriction and general restriction (p= 0.02) Differences in siblings’ BMI z-scores were associated with differences in dietary restraint (p= 0.04) not with differences in compensation.Conclusion: Sibling differences in compensation for energy from sweetened beverages were not associated with differences in their adiposity. Compensation may be determined by a constellation of factors, including age, parental feeding practices, and food characteristics.

Preservation of fat-free mass (FFM) during intentional weight loss is challenging yet important to maintain a resting metabolic rate. A balanced protein distribution of 25–30 g per meal improves 24-h muscle protein synthesis, which may promote FFM maintenance and greater reductions in fat mass (FM) during weight loss in women.

We present a protocol for a study investigating the effect of food price changes on purchasing decisions among individuals participating in federal food assistance programs and among those not participating in these programs. We use a laboratory-based grocery store design, which provides greater control over factors influencing food purchasing than in situexperiments in actual grocery stores. We focus primarily, but not exclusively, on eggs because they are highly nutritious, easy to prepare, can be included in many different dishes, and are a part of a wide range of cultural food menus. The primary aim of this study is to compare the own-and cross-price elasticity of eggs between individuals participating in federal food assistance programs and those not participating in these programs. Our secondary aims are to 1) compare the own- and cross-price elasticity of eggs between overweight/obese individuals and non-overweight/obese individuals, 2) examine whether delay discounting moderates the effect of income on own- and cross-price elasticity, 3) examine whether subjective social status moderates the effect of participation in federal food assistance programs on the purchase of high nutrient-dense foods, and 4) examine whether usual psychological stress level moderates the effect of subjective social status on the purchase of high-nutrient dense foods. The results of this study will provide information about the drivers of food demand among low-income adults. A better understanding of these drivers is needed to develop effective nutrition interventions for this large population.

OBJECTIVE To investigate the notion of indicated prevention—helping overweight or obese youth attain non-overweight status to prevent adult obesity—by examining weight-for-height changes needed to normalize weight status in youth who are growing. DESIGN We determined the amount of weight-for-height change necessary for overweight or obese youth to achieve non-overweight status using linear mixed modeling of longitudinal growth patterns and using Centers for Disease Control and Prevention weight thresholds corresponding to the age- and sex-adjusted body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) below the 85th percentile. Mean weight changes among children who achieved nonoverweight status at 1 and 2 years after treatment were calculated. SETTING Weight control programs at 3 research institutions. PARTICIPANTS A total of 669 overweight or obese children aged 8 to 13 years. INTERVENTION Family-based behavioral weight control treatment. MAIN OUTCOME MEASURE Weight. RESULTS Relatively small weight changes (range, −7.55 to +3.90 kg) were necessary for children to achieve nonoverweight status after 1 year; this was most pronounced among younger children (range, −2.90 to +3.36 kg for children aged 8-10 years) and children closer to the 85th BMI percentile (range, +2.44 to +3.90 kg for children at the 90th BMI percentile). Observed weight changes of children who achieved nonoverweight status following treatment were similar to estimates based on Centers for Disease Control and Prevention normative data. CONCLUSIONS Attaining nonoverweight status in childhood is possible with modest weight loss or, in some circumstances, by slowing weight gain, and may help prevent adult obesity. Future research should investigate how much intervention is needed to shift the growth trajectory to nonoverweight status and how much weight-for-height change is needed to improve other health outcomes in adulthood.

Objective: Children with cerebral palsy (CP) are smaller than normally growing children. The association between the growth hormone (GH) axis and growth in children with CP during puberty is unknown. We compared growth and markers of the GH axis in pre-pubertal and pubertal children with moderate to severe CP and without CP over a three-year period. Study design: Twenty children with CP, ages 6–18, Gross Motor Function Classification System levels III-V, were compared to a group of sixty-three normally growing children of similar age. Anthropometry, Tanner stage, bone age, and laboratory analyses were performed every six months for three years. Laboratory values included spontaneous overnight GH release, fasting IGF-1 and IGFBP-3. Repeated measures models were used to evaluate interactions among Tanner stage and group (children with CP vs. reference children), taking into account gender, age, and nutritional status.Results: Children with CP grew more slowly than those without CP at all Tanner stages (p< 0.01). Patterns of IGF-1 and GH secretion in children with CP were similar to those of the reference group; however, the concentrations of IGF-1 (p< 0.01) and GH (p< 0.01) were lower in girls with CP, with a similar trend for boys (p=0.10 and 0.14, respectively). Conclusions: Diminished circulating IGF-1 and GH concentrations may explain the differences in growth between the two groups.

OBJECTIVE To assess the effects of reducing television viewing and computer use on children's body mass index (BMI) as a risk factor for the development of overweight in young children. DESIGN Randomized controlled clinical trial. SETTING University children's hospital. PARTICIPANTS Seventy children aged 4 to 7 years whose BMI was at or above the 75th BMI percentile for age and sex. INTERVENTIONS Children were randomized to an intervention to reduce their television viewing and computer use by 50% vs a monitoring control group that did not reduce television viewing or computer use. MAIN OUTCOME MEASURES Age- and sex-standardized BMI (zBMI), television viewing, energy intake, and physical activity were monitored every 6 months during 2 years. RESULTS Children randomized to the intervention group showed greater reductions in targeted sedentary behavior (P &lt; .001), zBMI (P &lt; .05), and energy intake (P &lt; .05) compared with the monitoring control group. Socioeconomic status moderated zBMI change (P = .01), with the experimental intervention working better among families of low socioeconomic status. Changes in targeted sedentary behavior mediated changes in zBMI (P &lt; .05). The change in television viewing was related to the change in energy intake (P &lt; .001) but not to the change in physical activity (P =.37). CONCLUSIONS Reducing television viewing and computer use may have an important role in preventing obesity and in lowering BMI in young children, and these changes may be related more to changes in energy intake than to changes in physical activity. TRIAL REGISTRATION clinical trials.gov Identifier: NCT00065052Arch Pediatr Adolesc Med. 2008;162(3):239-245--

Our objective was to compare three BMI‐based adiposity measures to assess change in pediatric weight control: LMS z‐BMI, BMI sympercent, and percent overBMI. Comparison 1 presents changes of +1.0, −1.0, and −2.0 BMI units for 36 hypothetical children (7‐, 11‐, and 15‐year‐old children with BMI values from 19–39 kg/m2). Comparison 2 presents effect sizes over 12 months and the relationship between baseline and change for 140 8–12‐year‐old children with BMI values ranging from 21 to 37 kg/m2. Comparison 1 showed smaller changes in z‐BMI than BMI sympercent or percent overBMI for equal changes in BMI when initial BMI values are greater. Comparison 2 showed similar effect sizes for the three measures, since there is a reduction in both standard deviation and magnitude of LMS z‐BMI values as the BMI values increase. The three measures perform differently when considering the relationship of initial value to change. Initial percent overBMI shows a negative relationship with change, as heavier children show larger changes, LMS z‐BMI shows a positive relationship, as children with lower baseline values show larger changes, and BMI sympercent changes were inconsistently related to baseline BMI sympercent values. Although all three measures result in similar effect sizes when evaluating treatment over time, we conclude that LMS z‐BMI is less appropriate for comparing individuals and percent overBMI is the only measure that shows heavier children have greater change. Am. J. Hum. Biol. 19:487–494, 2007. © 2007 Wiley‐Liss, Inc.

Objective: Better adherence to treatment strategies in family‐based behavioral weight control programs may lead to greater weight reduction and improved weight maintenance in youth. This study assessed the influence of child and parent self‐reported adherence to behavioral strategies on changes in 2‐year child and parent percentage overweight. Research Methods and Procedures: Participants included 8‐ to 12‐year‐old children in ≥ 85th BMI percentile and their parents from 110 families taking part in two family‐based randomized controlled weight control studies. This study examined whether self‐reported adherence to behavioral strategies measured at 24 months increased prediction of child and parent percentage overweight change through 24‐month follow‐up after accounting for other factors that may influence weight change. Results: Child adherence to weighing and to preplanning for celebrations where high‐fat foods are served and parent adherence to praising the child and modeling healthy eating habits predicted 24‐month child percentage overweight change (p< 0.001). Child adherence to recording food and calories and parent adherence to modeling healthy eating habits predicted 24‐month parent percentage overweight change (p< 0.001). In hierarchical regression models, child weighing and preplanning and parent modeling were significant (p< 0.01) incremental predictors (r2of 24.8%) of 24‐month child percentage overweight. Child recording and parent modeling were significant (p< 0.01) incremental predictors (r2of 14%) of parent 24‐month percentage overweight change. Discussion: Child and parent adherence to specific components of family‐based behavioral weight control treatment are independent predictors of long‐term child and parent percentage overweight change.

Background:The influence of weight loss on insulin resistance was determined in severely overweight (BMI Z-score: 7.3 ± 0.9 z-units) hyperinsulinemic (mean fasting serum insulin concentration: 33.0 ± 6.7 μIU/mL) youth.Methods:Eight overweight youth and obese parents were studied at baseline and then at 6 and 12 months after behavioral weight loss therapy. Non-treated lean youth (n= 8) served as controls for normal interval growth. The groups were matched for sex, race, age (10.2 versus 10.1 years), and pubertal maturation, and evaluated for weight, height, blood pressure, and the homeostasis model of insulin resistance (HOMA-IR).Results:Overweight youth had reductions (p≤ 0.05) in % overBMI (BMI – BMI at 50th percentile)/BMI at 50thpercentile * 100), HOMA-IR, and systolic blood pressure after 6 months of treatment. These were sustained until the 12-month follow-up, while the control group did not change. Youth with the greatest reduction in % overBMI had the greatest reduction in HOMA-IR (r= 0.59, p≤ 0.05), and HOMA-IR was directly related (r= 0.56, p= 0.03) to the change in systolic blood pressure. Parents of overweight youth had reductions (p≤ 0.05) in % overBMI. There was a robust relationship between child and parent % overBMI change (r= 0.82, p≤ 0.05).Conclusions:Insulin resistance can be reduced in severely overweight youth following 6 months of weight loss therapy and maintained for 12 months. The relationship between child and parent weight change supports the role of the parent in modeling appropriate weight loss behaviors and restructuring the environment so that weight loss is possible.

Objective: Rapid synaptic dopamine transport or reduced brain dopamine receptor signaling may influence energy intake. Methylphenidate, a dopamine reuptake inhibitor, increases brain synaptic dopamine and produces anorexia, suggesting that it may reduce energy intake. We investigated the effects of two doses of short‐acting methylphenidate on energy intake over one meal in obese adult males. Research Methods and Procedures: Nine obese males (>85th BMI percentile) ingested a placebo or a moderate dose (0.5 mg/kg) or a high dose (1.0 mg/kg) of methylphenidate in a within‐subject double‐blind acute laboratory study. One hour after ingestion, pizza consumption was measured in a naturalistic laboratory setting. Results: Participants reduced energy intake by 23% for the moderate dose vs. the placebo (p< 0.02), but there was no significant difference for the high dose vs. the moderate dose (p> 0.05). Participants consumed 34% fewer kilocalories after ingesting the lowest effective dose of methylphenidate compared with placebo (725.7 ± 404.5 vs.1095 ± 271.1 kcal, p< 0.01). Seven of nine subjects responded to the moderate dose. The increase in perceived drug effect above placebo was correlated with the reduction in energy intake for both the moderate (r= −0.85, p= 0.004) and the high (r= −0.75 p= 0.021) doses. Hunger scores were not different across drug doses or placebo before drug administration. Discussion: Methylphenidate reduced energy intake of a highly palatable food over one meal by one‐third in obese adult males. Dopamine transport inhibition may be an effective component of a comprehensive treatment for obesity.

Objective: To determine whether interpersonal stress reduces youths’ motivation to exercise in a laboratory setting. Research Methods and Procedures: Physical activity and sedentary behavior were measured in boys and girls across a control day, after reading children's magazines, and on a stress day, after giving a videotaped speech. For one analysis, children were divided into low (n= 12) and high (n= 13) heart‐rate reactivity groups based on changes in heart rate to stress. In a second analysis, children were divided into low and high perceived level of stress based on changes in perceived stress. To determine differences in choice of exercise or sedentary behavior across the control and stress conditions, subjects chose either to exercise for progressively longer periods to earn a monetary reinforcer or to engage in a high‐rated sedentary behavior. Results: The choice to exercise was influenced by stress reactivity differently in the stress and control conditions. Low heart‐rate reactive children participated in similar (p> 0.50) amounts of exercise on the stress and control days, but high heart‐rate reactive children participated in less (p< 0.01) exercise (22.0 ± 2.5 vs. 26.3 ± 2.2 minutes) on the stress than control days. When grouped by change in perceived stress, there were no group differences, but subjects exercised longer (p< 0.01) on the control day than the stress day. Discussion: Interpersonal stress decreased exercise in children susceptible to interpersonal stress. Stress‐induced alterations in health behaviors may lead to weight gain in children.

Objective:To determine whether dietary restraint modifies stress‐induced eating in youth. Research Methods and Procedures:Snacking was measured in boys (9.5 ± 0.3 years) and girls (9.0 ± 0.3 years), with and without dietary restraint, across a control day after reading children's magazines and/or coloring, and on a stress day after giving a videotaped speech, with order of conditions counterbalanced. Children were divided into four groups based on dietary restraint and changes in perceived stress: low‐restraint/low‐reactive (n= 9), low‐restraint/high‐reactive (n= 13), high‐restraint/low‐reactive (n= 10), and high‐restraint/high‐reactive (n= 8). Body composition was estimated by skinfolds. Results:Energy intake of snack foods was influenced differently by dietary restraint and stress reactivity in the stress and control conditions (p< 0.01). After being stressed, low‐restraint/low‐reactive children ate fewer snacks and high‐restraint/high‐reactive children ate more snacks compared with the control condition. After covarying for percentage of body fat, the interactions remained (p< 0.01). Girls ate less than boys (p< 0.001), but sex did not influence eating in control and stress conditions. Discussion:Dietary restraint occurs in children and may influence the effect of stress on eating. Interpersonal stress decreases snacking in low dietary restrained youth but increases snacking in high dietary restrained children, perhaps because of stress‐induced disinhibition.

EPSTEIN, L.H., and J.N. ROEMMICH. Reducing sedentary behavior role in modifying physical activity. Exerc. Sport Sci. Rev., Vol. 29, No. 3, pp 103–108, 2001. Decreased physical activity is associated with the increased incidence of obesity. Behavioral economic research demonstrates that reducing sedentary behaviors in children increases physical activity. Understanding how people choose physical or sedentary activities can aid in developing public health initiatives that increase access to physical activity, while reducing access to sedentary behaviors.

In adults, abdominal visceral adiposity is related to an increased risk of cardiovascular diseases, Type 2 diabetes mellitus, and stroke. The antecedents of these conditions likely begin with the alterations in body fat distribution during childhood and adolescence. The sexually dimorphic alterations in fat distribution are influenced by sex differences in hormone concentrations, anatomical differences in the number and density of specific hormone receptors, capillary blood flow, and the activity of enzymes promoting lipid synthesis or degradation. Hormones influencing the amount and regional distribution of adipose tissue during puberty include cortisol, insulin, growth hormone, and the sex steroids. Cortisol and insulin promote fat deposition while the sex steroids and GH stimulate lipolysis. An overly sensitive hypothalamic–pituitary–adrenal axis may exist in obesity and disrupt the balance between the lipogenic effects of cortisol and insulin and the lipolytic effects of sex steroids and growth hormone. Leptin is released from the adipocytes and may act as a metabolic signal to the hypothalamic areas controlling satiety, energy expenditure, and the regulation of cortisol, insulin, sex steroid and growth hormone release. The complex issues of the hormonal control of alterations in body fat distribution during puberty are developed and a working model is proposed. Am. J. Hum. Biol. 11:209–224, 1999. © 1999 Wiley-Liss, Inc.

In adults, abdominal visceral adiposity is related to an increased risk of cardiovascular diseases, Type 2 diabetes mellitus, and stroke. The antecedents of these conditions likely begin with the alterations in body fat distribution during childhood and adolescence. The sexually dimorphic alterations in fat distribution are influenced by sex differences in hormone concentrations, anatomical differences in the number and density of specific hormone receptors, capillary blood flow, and the activity of enzymes promoting lipid synthesis or degradation. Hormones influencing the amount and regional distribution of adipose tissue during puberty include cortisol, insulin, growth hormone, and the sex steroids. Cortisol and insulin promote fat deposition while the sex steroids and GH stimulate lipolysis. An overly sensitive hypothalamic–pituitary–adrenal axis may exist in obesity and disrupt the balance between the lipogenic effects of cortisol and insulin and the lipolytic effects of sex steroids and growth hormone. Leptin is released from the adipocytes and may act as a metabolic signal to the hypothalamic areas controlling satiety, energy expenditure, and the regulation of cortisol, insulin, sex steroid and growth hormone release. The complex issues of the hormonal control of alterations in body fat distribution during puberty are developed and a working model is proposed. Am. J. Hum. Biol. 11:209–224, 1999. © 1999 Wiley‐Liss, Inc.

To determine how accurately the Roche-Wainer-Thissen (RWT), Tanner-Whitehouse (TW2), and Bayley-Pinneau (BP) prediction models estimated adult height, serial height predictions were made for 23 healthy boys (mean initial age 10.4 ± 1.1 years) every 8 months from 8–15 years of age. The RWT model was tested using Greulich-Pyle (RWT-GP) and Fels (RWT-Fels) bone ages. Stature was measured every 4 months until near final height was attained (growth rate &lt;1cm · 8 mo−1). Mean age at near final height was 18.4 ± 1.4 years. To assure that the predictions were as accurate and precise as possible, bone age assessments were made by experts in each method. To investigate the influence of maturation on the predictions, the boys were grouped by Fels bone ages: &lt;11 yr, 11–13.99 yr, and 14–14.99 yr. Comparison of the prediction bias and of the root mean square errors (RMSE) showed that the TW2 model gave the most accurate results, followed by the RWT and BP models. The adult height was generally underpredicted by the TW2 model and overpredicted by the RWT and BP models. The RMSE was reduced for each of the models as the bone age approached maturity. The TW2 model had the smallest average RMSE in all bone age groups. In the &lt;11 yr bone age group, the RWT-Fels, RWT-GP, and BP models produced RMSEs that were 16.4%, 18.4%, 62.1%, respectively, greater than the TW2 model. For the 11–13.99 yr group, RMSE by the RWT-Fels, RWT-GP, and BP models were 7.5%, 18.0%, and 15.2%, respectively, greater than the TW2 model. In the 14–14.99 yr group the RWT-GP model had a 45.5% greater RMSE than the TW2 model, whereas the RWT-Fels model produced a RMSE only 15.2% greater than TW2. The RWT-Fels model produced a lower RMSE than the RWT-GP model for all bone age groups. Although the data are probably as accurate and precise as presently possible, biologically significant error remains, especially with overprediction of adult height in normally growing boys by the BP and RWT models. It is recommended that regardless of the prediction model implemented, caution be used when advising patients of their predicted adult height since all of the models tested had outlying predictions. Am. J. Hum. Biol. 9:371–380, 1997. © 1997 Wiley-Liss, Inc.

The measurement of body composition has become important in clinical endocrinology and endocrine research because often it is necessary to assess the metabolic effects of hormones on bone, adipose, and lean tissues. All human body composition methods are based on prediction models that indirectly estimatethe true body composition with various amounts of error. Prediction error can be minimized if the investigator understands the assumptions of each model. When the assumptions are violated, large errors of estimation may occur. Accurate body composition assessments are difficult to achieve during puberty. For instance, despite its popularity as a clinical body composition model, dual-energy x-ray absorptiometry has not been shown to accurately predict the body composition of children and adolescents. The measurement of total body water to estimate the body composition of children is often used inappropriately because the investigator assumes that the fat-free mass of a child has a proportional water content equivalent to that of an adult. This article reviews the assumptions and validity of body composition models commonly used in endocrinology. As highlighted in a review of recent research on the relationships between body composition and leptin, growth hormone, and insulin resistance, inaccurately estimating the body composition makes it difficult to describe precisely the relationship between body composition and hormone release or the metabolic effects of hormone therapy. The use of inaccurate body composition models also makes it difficult to compare the results of various studies.

Proper groupings of children for physical activity and sport is important for injury prevention and competition. Several of the classification systems presently used are reviewed, as are the physiologic underpinnings of pubertal growth and development as they relate to the accrual of strength and power. It is during adolesence that the greatest physiologic differences exist, mainly because of the wide variations in the timing and tempo of the pubertal growth spurt in normally growing boys and girls. Maturity-based categorization, especially in contact and collision sports, would heighten the competition and may lessen rates of injury.

Roemmich, James N., Pamela A. Clark, Arthur Weltman, and Alan D. Rogol. Alterations in growth and body composition during puberty. I. Comparing multicompartment body composition models.J. Appl. Physiol.83(3): 927–935, 1997.—A four-compartment (4C) model of body composition was used as a criterion to determine the accuracy of three-compartment (3C) and two-compartment (2C) models to estimate percent body fat (%BF) in prepubertal and pubertal boys (genital I & II,n= 17; genital III & IV,n= 7) and girls (breast I & II, n= 8; breast III & IV,n= 15). The 3C water-density (3C-H2O) and 3C mineral-density models, dual-energy X-ray absorptiometry, the Lohman age-adjusted equations, the Slaughter et al. skinfold equations, and the Houtkooper et al. and Boileau bioelectrical impedance equations were evaluated. Agreement with the 4C model increased with the number of compartments (i.e., body water, bone mineral) measured. Except for the 3C-H2O model, the limits of agreement were large and did not perform well for individuals. The mean %BF by dual-energy X-ray absorptiometry (23.6%) was greater than that of the criterion 4C method (21.7%). For the field methods, the Slaughter et al. skinfold equations performed better than did the Houtkooper et al. and Boileau bioimpedance equations. The hydration of the fat-free mass decreased (genital I & II = 75.7%, genital III & IV = 74.8%, breast I & II = 75.5%, breast III & IV = 74.4%) and the mineral content increased (genital I & II = 4.9%, genital III & IV = 5.0%, breast I & II = 5.1%, breast III & IV = 5.7%) with maturation. The density of the fat-free mass also increased (genital I & II = 1.084 g/ml, genital III & IV = 1.087 g/ml, breast I & II = 1.086 g/ml, breast III & IV = 1.091 g/ml) with maturation. All of the models reduced the %BF overprediction of the Siri 2C model, but only the 4C and 3C-H2O models should be used as criterion methods for body composition validation in children and adolescents.

Roemmich, James N., and Wayne E. Sinning. Weight loss and wrestling training: effects on growth-related hormones.J. Appl. Physiol.82(6): 1760–1764, 1997.—Adolescent wrestlers (n= 9, 15.4 yr) and recreationally active control males (n= 7, 15.7 yr) were measured before, at the end of, and 3.5–4 mo after a competitive wrestling season to assess the influence of dietary restriction on growth-related hormones. Wrestlers had significant elevations preseason to late season for morning serum concentrations (mean of 8 serial samples) of growth hormone (GH; 2.9 ± 0.7 vs. 6.5 ± 1.4 ng/ml) and sex hormone-binding globulin (SHBG; 16.1 ± 2.3 vs. 27.9 ± 6.9 nmol/l) and significant reductions in GH-binding protein (GHBP; 178 ± 19 vs. 109 ± 17 pmol/l), insulin-like growth factor I (IGF-I; 332 ± 30 vs. 267 ± 34 ng/ml), testosterone (T; 4.9 ± 0.4 vs. 3.6 ± 0.4 ng/ml), and free testosterone (Free-T; 22.4 ± 3.6 vs. 15.7 ± 2.8 pg/ml). Wrestlers had significant postseason reductions in GH (3.44 ± 1.30 ng/ml) and SHBG (10.43 ± 4.13 nmol/l) but elevations in GHBP (66.7 ± 23.8 pmol/l), IGF-I (72.9 ± 25.1 ng/ml), T (2.10 ± 0.46 ng/ml), and Free-T (9.76 ± 3.01 pg/ml). Concentrations of luteinizing hormone (LH), estradiol, prolactin, cortisol, insulin, and thyroid hormones did not differ because of exercise-dietary practices of wrestlers. In-season elevations in GH, with concomitant reductions in GHBP and IGF-I, that were reversed during the postseason suggest a reduction in GH receptor number and partial GH resistance during the season. Nonelevated LH with reduced T levels suggests a central hypothalamic-pituitary-gonadal (H-P-G) axis impairment. In conclusion, undernutrition may lead to altered H-P-G and GH-IGF-I axes function in adolescent wrestlers. However, only the wrestlers’ late-season Free-T concentrations were outside the normal range, and the hormone axis impairments were quickly reversed. The present data do not address hormonal axis responses to several years of wrestling and weight loss.

Roemmich, James N., and Wayne E. Sinning. Weight loss and wrestling training: effects on nutrition, growth, maturation, body composition, and strength. J. Appl. Physiol.82(6): 1751–1759, 1997.—Adolescent wrestlers (n= 9, 15.4 yr) and recreationally active control adolescent males (n= 7, 15.7 yr) were measured before, at the end (late season), and 3.5–4 mo after a wrestling season to assess the influence of dietary restriction on growth, maturation, body composition, protein nutrition, and muscular strength. Controls consumed adequate amounts of energy, carbohydrate (CHO), protein, and fat, and demonstrated normal gains in weight, fat mass (FM) and fat-free mass (FFM). Wrestlers consumed a high-CHO (61 ± 2% kcal), low-fat (24 ± 2% kcal) diet during the season but did not consume adequate energy (24.7 ± 3.5 kcal ⋅ kg−1⋅ day−1) or protein (0.9 g ⋅ kg−1⋅ day−1). Deficient dietary intake reduced prealbumin levels (26.0 ± 1.9 vs. 20.2 ± 0.9 mg/dl) and slowed the accrual of lean arm and thigh cross-sectional muscle areas (AXSECT, TXSECT, respectively). For wrestlers, dietary deficiency also decreased weight (60.3 ± 3.5 to 58.0 ± 3.3 kg), relative fat (9.9 ± 0.5 to 8.0 ± 0.7%), and FM (6.0 ± 0.5 to 4.7 ± 0.6 kg). Postseason, wrestlers and controls consumed similar diets, and wrestlers had significant increases in prealbumin, AXSECT, and TXSECT. Wrestlers also increased their weight (6.1 ± 0.6 kg), FFM (3.0 ± 0.6 kg), and FM (3.2 ± 0.5 kg) postseason. Rates of bone maturation and segmental growth were not different between the groups. The wrestlers had reductions in elbow and knee strength from preseason to late season but increases postseason. Lean tissue changes were associated with the changes in strength and power (r= 0.72–0.91, P< 0.001). After covariance for FFM or limb-specific cross section, few significant changes remained. In conclusion, dietary restriction reduced protein nutrition and muscular performance but produced little effect on linear growth and maturation. Prealbumin levels and the rate of lean tissue accrual were positively related (r= 0.43, P≤ 0.05).

HORSWILL, C. A., S. H. PARK, and J. N. ROEMMICH. Changes in the protein nutritional status of adolescent wrestlers. Med. Sci. Sports Exerc., Vol. 22, No. 5, pp. 599–604, 1990. The protein nutritional status of adolescent wrestlers was studied to determine whether changes occur during a season of competition and weight loss. Subjects (N18) were measured prior to the start of the season (PRE), twice in the midseason, and once during late season (LATE) for weight, percent body fat, and height. At each of these times, a venous blood sample was obtained from the subjects, who were fasted, and analyzed for concentrations of albumin, prealbumin, retinol binding protein (RBP), blood urea nitrogen (BUN), hemoglobin, hematocrit, and 23 amino acids. Diet records were kept by subjects to assess daily energy, protein, fat, and carbohydrate intake. Data were analyzed by repeated measures ANOVA. Results showed that wrestlers decreased weight by an average of 6.6 ± 0.9 and that percent body fat, fat-free weight, plasma levels of prealbumin and RBP, the ratio of total essential amino acids to total amino acids, and dietary energy nutrient intakes were significantly lower at LATE compared to PRE. RBP decreased during midseason and averaged (± SE) 3.21 ± 0.15 mg·100 ml−1at LATE; prealbumin was significantly lower at LATE with a mean value of 19.8 ± 1.0 mg·100 ml−1. Total energy intake decreased from PRE values by 35, to approximately 27 kcal·kg−1·d−1during the season. In conclusion, in these high school wrestlers who lost approximately 6.6 of weight, there were adverse effects on some of the indices of protein nutritional status.

To determine how accurately the Roche‐Wainer‐Thissen (RWT), Tanner‐Whitehouse (TW2), and Bayley‐Pinneau (BP) prediction models estimated adult height, serial height predictions were made for 23 healthy boys (mean initial age 10.4 ± 1.1 years) every 8 months from 8–15 years of age. The RWT model was tested using Greulich‐Pyle (RWT‐GP) and Fels (RWT‐Fels) bone ages. Stature was measured every 4 months until near final height was attained (growth rate <1cm · 8 mo−1). Mean age at near final height was 18.4 ± 1.4 years. To assure that the predictions were as accurate and precise as possible, bone age assessments were made by experts in each method. To investigate the influence of maturation on the predictions, the boys were grouped by Fels bone ages: <11 yr, 11–13.99 yr, and 14–14.99 yr. Comparison of the prediction bias and of the root mean square errors (RMSE) showed that the TW2 model gave the most accurate results, followed by the RWT and BP models. The adult height was generally underpredicted by the TW2 model and overpredicted by the RWT and BP models. The RMSE was reduced for each of the models as the bone age approached maturity. The TW2 model had the smallest average RMSE in all bone age groups. In the <11 yr bone age group, the RWT‐Fels, RWT‐GP, and BP models produced RMSEs that were 16.4%, 18.4%, 62.1%, respectively, greater than the TW2 model. For the 11–13.99 yr group, RMSE by the RWT‐Fels, RWT‐GP, and BP models were 7.5%, 18.0%, and 15.2%, respectively, greater than the TW2 model. In the 14–14.99 yr group the RWT‐GP model had a 45.5% greater RMSE than the TW2 model, whereas the RWT‐Fels model produced a RMSE only 15.2% greater than TW2. The RWT‐Fels model produced a lower RMSE than the RWT‐GP model for all bone age groups. Although the data are probably as accurate and precise as presently possible, biologically significant error remains, especially with overprediction of adult height in normally growing boys by the BP and RWT models. It is recommended that regardless of the prediction model implemented, caution be used when advising patients of their predicted adult height since all of the models tested had outlying predictions. Am. J. Hum. Biol. 9:371–380, 1997. © 1997 Wiley‐Liss, Inc.