This study aimed to analyze the independent associations of accelerometer-determined sedentary behavior, physical activity, and steps/day with body composition variables in Brazilian children. 485 children wore accelerometers for 7 days. Variables included time in sedentary behavior and different physical activity intensities (light, moderate, vigorous, or moderate-to-vigorous) and steps/day. Body fat percentage was measured using a bioelectrical impedance scale, and BMI was calculated. Children spent 55.7% of the awake portion of the day in sedentary behavior, 37.6% in light physical activity, 4.6% in moderate physical activity, and 1.9% in vigorous physical activity. Moderate-to-vigorous physical activity and steps/day were negatively associated with body composition (BMI and body fat percentage) variables, independent of sex and sedentary behavior. Beta values were higher for vigorous physical activity than moderate physical activity. Vigorous physical activity was negatively associated with BMI (β-.1425) and body fat percentage (β-.3082; p < .0001). In boys, there were significant negative associations between moderate, vigorous, and moderate-to-vigorous physical activity and steps/day with body composition, and in girls, there was only a negative association with vigorous physical activity, independent of sedentary behavior. Moderate-to-vigorous physical activity and steps/day (in boys), but especially vigorous physical activity (in boys and girls), are associated with body composition, independent of sedentary behavior. Sedentary behavior was not related with any of the body composition variables once adjusted for moderate-to-vigorous physical activity.
Gerson Luis de Moraes Ferrari, Luis Carlos Oliveira, Timoteo Leandro Araujo, Victor Matsudo, Tiago V. Barreira, Catrine Tudor-Locke and Peter Katzmarzyk
Asunción Ferri-Morales, Marcus Vinicius Nascimento-Ferreira, Dimitris Vlachopoulos, Esther Ubago-Guisado, Ana Torres-Costoso, Augusto Cesar F. De Moraes, Alan R. Barker, Luis A. Moreno, Vicente Martínez-Vizcaino and Luis Gracia-Marco
Adolescence is characterized by rapid changes in body composition, which is attributed to the influence of a number of modifiable lifestyle factors including physical activity, diet, and sports participation ( 30 ). The assessment of body composition in young athletes, and more specifically the
Thomas W. Buford, Douglas B. Smith, Matthew S. O’Brien, Aric J. Warren and Stephen J. Rossi
The purpose of the present investigation was to examine the physiological response of collegiate wrestlers to their competitive season.
Eleven Division I collegiate wrestlers (mean ± SD; 19.45 ± 1.13 y) volunteered and completed 4 testing sessions throughout the course of the collegiate wrestling season. Testing sessions were conducted pre-, mid-, and postseason, as well as before the national tournament. Testing consisted of weigh-in, skinfold body composition testing, and a 50-rep concentric, isokinetic leg extension muscle endurance test (180°/s). Muscular performance variables measured included peak torque, peak torque at fatigue, percent decline, and peak torque/body mass ratio.
A significant increase (P < .05) of 2.9% was observed for body mass between midseason and postseason (2.38 kg). From pre- to postseason, a mean increase of 3.8% (3.1 kg) was observed for body mass. An increase (P < .05) in BF% of 2.9% was observed between prenationals and postseason. No significant differences (P > .05) were observed between consecutive time points for quadriceps peak torque; however, there was a significant increase (P < .05) between preseason and prenationals (23.39 N·m). Peak torque at fatigue was greater (P < .05) at midseason than preseason, representing an increase of 9.82 N·m. Between midseason and prenationals testing, we observed an 11% increase (P < .05) in %DCLN. Finally, we noted an increase (P < .05) from 0.6 to 0.69 in peak torque/body mass ratio between preseason and prenationals.
Our results indicate that while force values seem to suffer at midseason, the wrestlers compensated and were strongest just before their national competition.
Lenka Humenikova Shriver, Nancy Mulhollen Betts and Mark Edward Payton
Many wrestlers engage in chronic dieting and rapid “weight cutting” throughout the year to compete in a category below their natural weight. Such weightmanagement practices have a negative influence on their health and nutritional status, so the National Wrestling Coaches Association implemented a new weight-management program for high school wrestlers in 2006.
The purpose of this study was to determine whether seasonal changes in weight, body fat, and eating attitudes occur among high school wrestlers after the implementation of the new weight-management rule.
Fifteen high school wrestlers participated in the study. Their weight, body composition, and eating attitudes were measured preseason, in-season, and off-season. Body fat was assessed using dual-energy X-ray absorptiometry. Attitudes toward dieting, food, and body weight were assessed using the Eating Attitude Test (EAT).
No significant changes in body fat were detected from preseason to off-season. Weight increased from preseason to in-season (p < .05) and off-season (p < .05). Although the EAT score did not change significantly from preseason to offseason, 60% reported “thinking about burning up calories when exercising” during preseason, and only 40% felt that way during the season (p < .05) and 47% during off-season (p < .05).
The wrestlers experienced a significant weight gain from preseason to off-season with no significant changes in body fat. Their eating attitudes did not change significantly from preseason to off-season in this study, but further research using a large sample of high school wrestlers is warranted to confirm these findings.
Jenna E. Heller, Joi J. Thomas, Bruce W. Hollis and D. Enette Larson-Meyer
Excess body fat or obesity is known to increase risk of poor vitamin D status in nonathletes but it is not known if this is the case in athletes. Furthermore, the reason for this association is not understood, but is thought to be due to either sequestration of the fat-soluble vitamin within adipose tissue or the effect of volume dilution related to obese individuals’ larger body size. Forty two US college athletes (24 men 18 women, 20.7 ± 1.6 years, 85.0 ± 28.7 kg, BMI = 25.7 ± 6.1 kg/m2) provided blood samples during the fall and underwent measurement of body composition via dual energy X-ray absorptiometry. Serum samples were evaluated for 25-hydroxyvitamin D (25(OH)D) concentration to assess vitamin D status using Diasorin 25(OH)D radioiodine assay. Serum 25(OH)D concentration was negatively associated with height (r = -0.45), total body mass (r = -0.57), BMI (r = -0.57), body fat percentage (r = -0.45), fat mass (r = -0.60) and fat-free mass (r = -0.51) (p < .05). These associations did not change after controlling for sex. In a linear regression mixed model, fat mass (coefficient -0.47, p = .01), but not fat-free mass (coefficient -0.18, p = .32) significantly predicted vitamin D status and explained approximately 36% of the variation in serum 25(OH)D concentration. These results suggest that athletes with a large body size and/or excess adiposity may be at higher risk for vitamin D insufficiency and deficiency. In addition, the significant association between serum 25(OH)D concentration and fat mass in the mixed model, which remained after controlling for sex, is in support of vitamin D sequestration rather than volume dilution as an explanation for such association.
Ina Garthe, Truls Raastad and Jorunn Sundgot-Borgen
When weight loss (WL) is needed, it is recommended that athletes do it gradually by 0.5–1 kg/wk through moderate energy restriction. However, the effect of WL rate on long-term changes in body composition (BC) and performance has not been investigated in elite athletes.
To compare changes in body mass (BM), fat mass (FM), lean body mass (LBM), and performance 6 and 12 mo after 2 different WL interventions promoting loss of 0.7% vs. 1.4% of body weight per wk in elite athletes.
Twenty-three athletes completed 6- and 12-mo postintervention testing (slow rate [SR] n = 14, 23.5 ± 3.3 yr, 72.2 ± 12.2 kg; fast rate [FR] n = 9, 21.4 ± 4.0 yr, 71.6 ± 12.0 kg). The athletes had individualized diet plans promoting the predetermined weekly WL during intervention, and 4 strength-training sessions per wk were included. BM, BC, and strength (1-repetition maximum) were tested at baseline, postintervention, and 6 and 12 mo after the intervention.
BM decreased by ~6% in both groups during the intervention but was not different from baseline values after 12 mo. FM decreased in SR and FR during the intervention by 31% ± 3% vs. 23% ± 4%, respectively, but was not different from baseline after 12 mo. LBM and upper body strength increased more in SR than in FR (2.0% ± 1.3% vs. 0.8% ± 1.1% and 12% ± 2% vs. 6% ± 2%) during the intervention, but after 12 mo there were no significant differences between groups in BC or performance.
There were no significant differences between groups after 12 mo, suggesting that WL rate is not the most important factor in maintaining BC and performance after WL in elite athletes.
Nidia Rodriguez-Sanchez and Stuart D.R. Galloway
Dual energy x-ray absorptiometry (DXA) is a popular tool to determine body composition (BC) in athletes, and is used for analysis of fat-free soft tissue mass (FFST) or fat mass (FM) gain/loss in response to exercise or nutritional interventions. The aim of the current study was to assess the effect of exercise-heat stress induced hypohydration (HYP, >2% of body mass (BM) loss) vs. maintenance of euhydration (EUH) on DXA estimates of BC, sum of skinfolds (SF), and impedance (IMP) measurements in athletes. Competitive athletes (23 males and 15 females) recorded morning nude BM for 7 days before the first main trial. Measurements on the first trial day were conducted in a EUH condition, and again after exercise-heat stress induced HYP. On the second trial day, fluid and electrolyte losses were replaced during exercise using a sports drink. A reduction in total BM (1.6 ± 0.4 kg; 2.3 ± 0.4% HYP) and total FFST (1.3 ± 0.4 kg), mainly from trunk (1.1 ± 0.5 kg), was observed using DXA when participants were HYP, reflecting the sweat loss. Estimated fat percent increased (0.3 ± 0.3%), however, total FM did not change (0.1 ± 0.2 kg). SF and IMP declined with HYP (losses of 1.5 ± 2.9% and 1.6 ± 3% respectively) suggesting FM loss. When EUH was maintained there were no significant changes in BM, DXA estimates, or SF values pre to post exercise, but IMP still declined. We conclude that use of DXA for FFST assessment in athletes must ensure a EUH state, particularly when considering changes associated with nutritional or exercise interventions.
Julia Aparecida Devide Nogueira and Teresa Helena Macedo da Costa
Body weight and composition are determined by genotype, environment, and energy balance. Physical activity or sedentary behavior have different associations with body weight, fat mass, and fat-free mass, a relationship that is not clear in adolescents. The aim of this study was to test the associations between gender, physical activity, sedentary behavior, and body composition in physically active adolescents.
Weight, height, and skinfold thickness were measured in 326 physically active boys and girls age 11 to 15 years. All subjects answered a questionnaire assessing their usual daily activities for the last month. Time spent on each activity was used to estimate the physical activity level (PAL).
PAL was associated with body composition after adjustment for age and maturation, with differences between genders. For boys, PAL was positively and significantly associated with body mass index (BMI) and fat-free mass index (β= 0.14 and 0.15, respectively). For girls, PAL was negatively and significantly associated with BMI and fat mass index (β= −0.11 and −0.75, respectively). Sedentary behavior, expressed by hours of TV, videogame, and computer use, was not associated with any body-composition outcome for either gender.
The accumulated amount of physical activity, but not of sedentary behavior, was related to body composition in active adolescents.
Chad R. Straight, Leah R. Dorfman, Kathryn E. Cottell, Julie M. Krol, Ingrid E. Lofgren and Matthew J. Delmonico
Community-based interventions that incorporate resistance training (RT) and dietary changes have not been extensively studied in overweight and obese older adults. The purpose of this investigation was to determine the effects of a community-based RT and dietary intervention on physical function and body composition in overweight and obese older adults.
Ninety-five overweight and obese (BMI = 33.4 ± 4.0 kg/m2) older adults aged 55–80 years completed an 8-week RT and dietary intervention at 4 Rhode Island senior centers. Participants performed RT twice-weekly using resistance tubing, dumbbells, and ankle weights. Participants also attended 1 weekly dietary counseling session on a modified Dietary Approaches to Stop Hypertension diet. Outcome measurements included anthropometrics, body composition, and physical function.
There were small changes in body mass (–1.0 ± 1.8 kg, P < .001), waist circumference (–5.2 ± 3.8 cm, P < .001), and percent body fat (–0.5 ± 1.4%, P < .001). In addition, significant improvements were observed in knee extensor torque (+7.9 ± 19.1 N-m, P < .001), handgrip strength (+1.2 ± 2.5 kg, P < .001), and 8-foot up-and-go test time (–0.56 ± 0.89 s, P < .001).
Community-based RT and dietary modifications can improve body composition, muscle strength, and physical function in overweight and obese older adults. Future investigations should determine if this intervention is effective for long-term changes.
Richard Larouche, Travis John Saunders, Guy Edward John Faulkner, Rachel Colley and Mark Tremblay
The impact of active school transport (AST) on daily physical activity (PA) levels, body composition and cardiovascular fitness remains unclear.
A systematic review was conducted to examine differences in PA, body composition and cardiovascular fitness between active and passive travelers. The Medline, PubMed, Embase, PsycInfo, and ProQuest databases were searched and 10 key informants were consulted. Quality of evidence was assessed with GRADE and with the Effective Public Health Practice Project tool for quantitative studies.
Sixty-eight different studies met the inclusion criteria. The majority of studies found that active school travelers were more active or that AST interventions lead to increases in PA, and the quality of evidence is moderate. There is conflicting, and therefore very low quality evidence, regarding the associations between AST and body composition indicators, and between walking to/from school and cardiovascular fitness; however, all studies with relevant measures found a positive association between cycling to/from school and cardiovascular fitness; this evidence is of moderate quality.
These findings suggest that AST should be promoted to increase PA levels in children and adolescents and that cycling to/from school is associated with increased cardiovascular fitness. Intervention studies are needed to increase the quality of evidence.