Weight loss and wrestling training: effects on growth-related hormones

Roemmich, James N., and Wayne E. Sinning. Weight lossand wrestling training: effects on growth-related hormones.J. Appl. Physiol. 82(6):1760-1764, 1997.Adolescent wrestlers(n = 9, 15.4 yr) and recreationallyactive control males (n = 7, 15.7 yr)were measured before, at the end of, and 3.5-4 mo after acompetitive 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-likegrowth 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 freetestosterone (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 elevationsin 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 differbecause of exercise-dietary practices of wrestlers. In-seasonelevations in GH, with concomitant reductions in GHBP and IGF-I, thatwere reversed during the postseason suggest a reduction in GH receptor number and partial GH resistance during the season. Nonelevated LH withreduced T levels suggests a central hypothalamic-pituitary-gonadal (H-P-G) axis impairment. In conclusion, undernutrition may lead toaltered H-P-G and GH-IGF-I axes function in adolescent wrestlers. However, only the wrestlers' late-season Free-T concentrations wereoutside the normal range, and the hormone axis impairments were quicklyreversed. The present data do not address hormonal axis responses toseveral years of wrestling and weight loss.

     

Alterations in growth and body composition during puberty. I.Comparing multicompartment body composition models

Roemmich, James N., Pamela A. Clark, Arthur Weltman, andAlan D. Rogol. Alterations in growth and body composition duringpuberty. 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 acriterion to determine the accuracy of three-compartment (3C) andtwo-compartment (2C) models to estimate percent body fat (%BF) inprepubertal 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-densitymodels, dual-energy X-ray absorptiometry, the Lohman age-adjustedequations, the Slaughter et al. skinfold equations, and the Houtkooperet al. and Boileau bioelectrical impedance equations wereevaluated. Agreement with the 4C model increased with thenumber of compartments (i.e., body water, bone mineral) measured.Except for the 3C-H₂O model, thelimits of agreement were large and did not perform well forindividuals. 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 equationsperformed better than did the Houtkooper et al. and Boileaubioimpedance 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 densityof 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 and3C-H₂O models should be used ascriterion methods for body composition validation in children andadolescents.

     

Increasing healthy eating vs. reducing high energy-dense foods to treat pediatric obesity

Objective: The objective was to compare targeting increased eating of healthy foods vs. reducing intake of high energy‐dense foods within the context of a family‐based behavioral weight control program. Methods and Procedures: Forty‐one 8–12 year‐old children >85th BMI percentile were randomly assigned to a 24‐month family‐based behavioral treatment that targeted increasing fruits and vegetables and low‐fat dairy vs. reducing intake of high energy‐dense foods. Results: Children in the increase healthy food group showed greater reduction in zBMI compared to children in the reduce high energy‐dense food group at 12‐ (?0.30 zBMI units vs. ?0.15 zBMI units, P = 0.01) and 24‐ (?0.36 zBMI units vs ?0.13 zBMI units, P = 0.04) month follow‐up. Parents in the increase healthy food group showed greater reductions in concern about child weight (P = 0.007), and these changes were associated with child zBMI change (P = 0.008). Children in the reduce high energy‐dense group showed larger sustained reductions in high energy‐dense foods (P < 0.05). Baseline levels of high energy‐dense foods (P < 0.05), parent food restraint (P = 0.01), parent concern over parent weight (P = 0.01) and parent acceptance of the child (P < 0.05) moderated child zBMI change, with greater sustained reductions in zBMI for children in the increase healthy food group for each measure. Parent zBMI change followed the same pattern as child changes, and parent and child zBMI changes were correlated (P < 0.001). Discussion: Focusing on healthy food choices within an energy restricted diet may be useful in family‐based weight control programs.     

The Relationship Between Parent and Child Self‐Reported Adherence and Weight Loss

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 (r² of 24.8%) of 24‐month child percentage overweight. Child recording and parent modeling were significant (p < 0.01) incremental predictors (r² of 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.     

Pubertal alterations in growth and body composition. V. Energy expenditure, adiposity, and fat distribution

We determined whether activity energy expenditure (AEE, from doubly labeled water and indirect calorimetry) or physical activity [7-day physical activity recall (PAR)] was more related to adiposity and the validity of PAR estimated total energy expenditure (TEE(PAR)) in prepubertal and pubertal boys (n = 14 and 15) and girls (n = 13 and 18). AEE, but not physical activity hours, was inversely related to fat mass (FM) after accounting for the fat-free mass, maturation, and age (partial r = -0.35, P < or = 0.01). From forward stepwise regression, pubertal maturation, AEE, and gender predicted FM (r(2) = 0.36). Abdominal visceral fat and subcutaneous fat were not related to AEE or activity hours after partial correlation with FM, maturation, and age. When assuming one metabolic equivalent (MET) equals 1 kcal. kg body wt(-1). h(-1), TEE(PAR) underestimated TEE from doubly labeled water (TEE bias) by 555 kcal/day +/- 2 SD limits of agreement of 913 kcal/day. The measured basal metabolic rate (BMR) was >1 kcal. kg body wt(-1). h(-1) and remained so until 16 yr of age. TEE bias was reduced when setting 1 MET equal to the measured (bias = 60 +/- 51 kcal/day) or predicted (bias = 53 +/- 50 kcal/day) BMR but was not consistent for an individual child (+/- 2 SD limits of agreement of 784 and 764 kcal/day, respectively) or across all maturation groups. After BMR was corrected, TEE bias remained greatest in the prepubertal girls. In conclusion, in children and adolescents, FM is more strongly related to AEE than activity time, and AEE, pubertal maturation, and gender explain 36% of the variance in FM. PAR should not be used to determine TEE of individual children and adolescents in a research setting but may have utility in large population-based pediatric studies, if an appropriate MET value is used to convert physical activity data to TEE data.     

Usual energy intake mediates the relationship between food reinforcement and BMI

The relative reinforcing value of food (RRV(food)) is positively associated with energy consumed and overweight status. One hypothesis relating these variables is that food reinforcement is related to BMI through usual energy intake. Using a sample of two hundred fifty-two adults of varying weight and BMI levels, results showed that usual energy intake mediated the relationship between RRV(food) and BMI (estimated indirect effect = 0.0027, bootstrapped 95% confidence intervals (CIs) 0.0002-0.0068, effect ratio = 0.34), controlling for age, sex, minority status, education, and reinforcing value of reading (RRV(reading)). Laboratory and usual energy intake were correlated (r = 0.24, P < 0.001), indicating that laboratory energy intake could provide an index of eating behavior in the natural environment. The mediational relationship observed suggests that increasing or decreasing food reinforcement could influence body weight by altering food consumption. Research is needed to develop methods of modifying RRV(food) to determine experimentally whether manipulating food reinforcement would result in changes in body weight.     

Influence of Methylphenidate on Eating in Obese Men

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.     

Stress reactivity and adiposity of youth

Objective: The relationship between stress reactivity and total or central adiposity in children has not been widely studied. Data from two studies were combined to determine the relationship between reactivity to interpersonal stress and the adiposity of children. Research Methods and Procedures: Stress reactivity to an interpersonal stressor (speech) was measured in 36 boys (9.8 ± 1.3 years of age) and 27 girls (9.3 ± 1.3 years of age). Total adiposity (percentage body fat) was estimated from skinfolds and central adiposity from the abdominal girth. Multiple regression was used to establish the associations of change in perceived stress and heart rate reactivity with adiposity. Age, sex, ethnicity, and baseline perceived stress and heart rate served as covariates for total adiposity. Fat mass was included as an additional covariate for the prediction of log abdominal girth (central adiposity). Results: Based on adjusted β‐weights, change in perceived stress (β = 1.13, p ≤ 0.001) and heart rate reactivity (β = 0.14, p ≤ 0.03) independently predicted percentage body fat. Heart rate reactivity (β = 0.002, p ≤ 0.04) independently predicted log abdominal girth. Discussion: Reactivity to psychological stress may initiate the antecedents of cardiovascular disease before adolescence by increasing total and central adiposity. Future studies should determine whether stress reactivity increases the adiposity of youth by increasing their consumption of energy‐dense snack foods and decreasing their willingness to be physically active.     

Gait variability magnitude but not structure is altered in essential tremor

Essential tremor (ET) is a common tremor disorder affecting postural/action tremor of the upper extremities and midline. Recent research revealed a cerebellar-like deficit during tandem gait in persons with ET, though spatiotemporal variability during normal gait in ET has been relatively ignored. The first purpose of this study was to investigate gait variability magnitude and structure in ET as compared to healthy older adults (HOA). To address this issue, 11 ET and 11 age-matched HOAs walked on a treadmill for 5 min at preferred walking speeds. HOAs walked for an additional minute while speed-matched to an ET participant. The second purpose was to describe the clinical correlates of gait variability in this population. To address this aim, 31 persons with ET walked on a treadmill for 5 min and completed the Fahn–Tolosa–Marin Tremor Rating Scale. Gait variability magnitude was derived by calculating coefficients of variation in stride length, stride time, step length, step time, and step width. Gait variability structure was derived using a detrended fluctuation analysis technique. At preferred walking speeds, ET participants walked significantly slower with significantly increased variability magnitude in all five spatiotemporal gait parameters. At speed-matched walking, ET participants exhibited significantly higher step width variability. Gait variability structure was not different between groups. We also observed that gait variability magnitude was predicted by severity of upper extremity and midline tremors. This study revealed that self-selected gait in ET is characterized by high variability that is associated with tremor severity in the upper extremity and midline.     

Weight loss and wrestling training: effects on nutrition, growth, maturation, body composition, and strength

Roemmich, James N., and Wayne E. Sinning. Weight lossand wrestling training: effects on nutrition, growth, maturation, bodycomposition, and strength. J. Appl.Physiol. 82(6): 1751-1759, 1997.Adolescentwrestlers (n = 9, 15.4 yr) andrecreationally 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 toassess the influence of dietary restriction on growth, maturation, bodycomposition, protein nutrition, and muscular strength. Controlsconsumed adequate amounts of energy, carbohydrate (CHO), protein, andfat, and demonstrated normal gains in weight, fat mass (FM) andfat-free mass (FFM). Wrestlers consumed a high-CHO (61 ± 2% kcal),low-fat (24 ± 2% kcal) diet during the season but did not consumeadequate energy (24.7 ± 3.5 kcal · kg¹ · day¹)or protein (0.9 g · kg¹ · day¹).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(A_XSECT,T_XSECT, respectively). Forwrestlers, dietary deficiency also decreased weight (60.3 ± 3.5 to58.0 ± 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 hadsignificant increases in prealbumin,A_XSECT, andT_XSECT. 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 hadreductions in elbow and knee strength from preseason to late season butincreases postseason. Lean tissue changes were associated with thechanges in strength and power (r = 0.72-0.91, P < 0.001). Aftercovariance for FFM or limb-specific cross section, few significantchanges remained. In conclusion, dietary restriction reduced proteinnutrition and muscular performance but produced little effect on linear growth and maturation. Prealbumin levels and the rate of lean tissueaccrual were positively related (r = 0.43, P  0.05).