[Show abstract][Hide abstract] ABSTRACT: With the increasing prevalence of sedentary behaviors during childhood, a greater understanding of the extent to which excess adiposity and aerobic fitness relate to cognitive health is of increasing importance. To date, however, the vast majority of research in this area has focused on adiposity or fitness, rather than the possible inter-relationship, as it relates to cognition. Accordingly, this study examined the differential associations between body composition, aerobic fitness, and cognitive control in a sample of 204 (96 female) preadolescent children. Participants completed a modified flanker task (i.e., inhibition) and a switch task (i.e., cognitive flexibility) to assess two aspects of cognitive control. Findings from this study indicate that fitness and adiposity appear to be separable factors as they relate to cognitive control, given that the interaction of fitness and adiposity was observed to be nonsignificant for both the flanker and switch tasks. Fitness exhibited an independent association with both inhibition and cognitive flexibility whereas adiposity exhibited an independent association only with cognitive flexibility. These results suggest that while childhood obesity and fitness appear to both be related to cognitive control, they may be differentially associated with its component processes.
Monographs of the Society for Research in Child Development 12/2014; 79(4). · 5.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Commonly reported relationships of the broad personality traits of Extraversion and Neuroticism with self-reports of physical activity (PA) have not been elaborated within motivational theory that posits how functioning of the behavioral inhibition (BIS) and activation (BAS) systems can explain or modify the influence of personality on physical activity. Whether personality predicts physical activity when it is measured objectively has not been established.
Medicine and science in sports and exercise. 11/2014;
[Show abstract][Hide abstract] ABSTRACT: Objectives
The aim of this study was to examine the relative contributions of physical activity, adiposity, lean mass and muscle quality to lower-extremity physical function (LEPF) in older women.
Cross-sectional analysis at a university research laboratory
Main Outcome Measures: Community-dwelling older women (n = 96, 73.9 ± 5.6 y, BMI = 26.5 ± 4.7 kg/m2) were assessed for body composition via dual-energy X-ray absorptiometry, leg extension power using the Nottingham power rig, muscle quality (watts/kg) as the ratio of leg extension power (watts) to lower-body mineral free lean mass (kg) and moderate-intensity physical activity via questionnaire. A composite measure of LEPF was calculated by summing Z-scores of the 6-minute walk, 8-foot up-and-go and 30-s chair stand tests.
Muscle quality and physical activity were associated with all measures of LEPF (all p < 0.01). Relative adiposity was related to the 6-minute walk and 30-s chair stand (both p < 0.01); lower-body mineral-free lean mass was not related to any measure of LEPF (p > 0.05). Hierarchical linear regression analyses revealed that muscle quality (standardized β = 0.47, p < 0.01) and relative adiposity (β = -0.33, p < 0.01) were the strongest independent predictors of composite LEPF Z-score explaining 24% and 17% of the variance, respectively.
Muscle quality and relative adiposity are the strongest independent predictors of LEPF in older women. These findings suggest that maintaining muscle quality, especially relative to adiposity, may be a critical target for interventions to prevent declines in physical function in older women.
[Show abstract][Hide abstract] ABSTRACT: This study aims were to investigate whether age differentially impacts the relationships between adiposity, muscle quality (MQ), and lower-extremity physical function in young and older women.
Menopause (New York, N.Y.) 09/2014; · 3.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The purpose of this systematic review and meta-analysis was to assess changes in body weight and relative adiposity (%FAT) during college and identify potential moderating variables.
[Show abstract][Hide abstract] ABSTRACT: This study aims to determine the sex-specific relationships of physical activity, body composition, and muscle quality with lower-extremity physical function in older men and women.
Menopause (New York, N.Y.) 08/2014; · 3.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Lifestyle interventions commonly measure psychosocial beliefs as precursors to positive behavior change, but often overlook questionnaire validation. This can affect measurement accuracy if the survey has been developed for a different population, as differing behavioral influences may affect instrument validity. The present study aimed to explore psychometric properties of self-efficacy and outcome expectation scales-originally developed for younger children-in a population of female college freshmen (N = 268). Exploratory principal component analysis was used to investigate underlying data patterns and assess validity of previously published subscales. Composite scores for reliable subscales (Cronbach's α ≥ .70) were calculated to help characterize self-efficacy and outcome expectation beliefs in this population. The outcome expectation factor structure clearly comprised of positive (α = .81-.90) and negative outcomes (α = .63-.67). The self-efficacy factor structure included themes of motivation and effort (α = .75-.94), but items pertaining to hunger and availability cross-loaded often. Based on cross-loading patterns and low Cronbach's alpha values, respectively, self-efficacy items regarding barriers to healthy eating and negative outcome expectation items should be refined to improve reliability. Composite scores suggested that eating healthfully was associated with positive outcomes, but self-efficacy to do so was lower. Thus, dietary interventions for college students may be more successful by including skill-building activities to enhance self-efficacy and increase the likelihood of behavior change.
[Show abstract][Hide abstract] ABSTRACT: Abstract Objective: To examine weight management barriers, using the Health Belief Model, in first-year college students. Participants: First-year college students (n = 45), with data collected in April, May, and November 2013. Methods: Nominal Group Technique sessions (n = 8) were conducted. Results: First-year students recognize benefits to weight management beyond physical attractiveness to quality of life domains including social (e.g. bonding opportunities and energy to socially engage) and mental health (e.g. stress management). Men believe weight management is important for career/financial reasons; whereas, women voiced it will allow them to live a full independent life with a high level of multi-tasking. Men believed their barriers were external (e.g. campus resources/programs) while females perceived their barriers to be internal (e.g. poor time management). Conclusions: College students are challenged by weight management and want the institution to provide resources, including curriculum, to help them manage their physical activity and nutrition behaviors.
Journal of American college health : J of ACH. 05/2014;
[Show abstract][Hide abstract] ABSTRACT: To investigate the effect of a 9-month physical activity intervention on cardiorespiratory fitness and adiposity among prepubertal children.
Prepubertal children (8- to 9-year-olds, N = 220, 103 girls) were randomly assigned to a 9-month physical activity intervention or a control group. The intervention provided 70 minutes (5 days/week) of moderate to vigorous physical activity. Maximum oxygen consumption (Vo2max percentile) and dual-energy radiograph absorptiometry measured cardiorespiratory fitness and adiposity, respectively. Intention-to-treat analysis was performed to assess baseline and follow-up cardiorespiratory fitness, percentage fat mass (%FM), percentage central fat mass (%CFM), and estimated visceral adipose tissue (VAT) area.
The intervention group increased in cardiorespiratory fitness (5.4th percentile; 95% confidence interval [CI], 1.8 to 8.9) and decreased in %FM (-0.7%; 95% CI, -1.1 to -0.4) and %CFM (-1.3%; 95% CI, -1.9 to -0.7). Reductions in %FM were evident for both nonoverweight (-0.62%; 95% CI, -1.07 to -0.17) and overweight or obese (-0.86%; 95% CI,-1.46 to -0.25) intervention participants. Conversely, the control group displayed no change in cardiorespiratory fitness while exhibiting increases in %FM (0.4%; 95% CI, 0.1 to 0.7), %CFM (0.6; 95% CI, 0.1 to 1.1), and VAT area (3.0 cm(2); 95% CI, 1.6 to 4.4). Nonoverweight control participants increased in %FM (0.52%; 95% CI, 0.13 to 0.91), and their overweight and obese counterparts increased in VAT (4.76 cm(2); 95% CI, 1.90 to 7.63).
The physical activity intervention improved cardiorespiratory fitness, reduced %FM, and prevented accumulation of %CFM among prepubertal children with varying adiposity levels. These findings provide support for daily physical activity recommendations to prevent excess fat mass accumulation in childhood.
[Show abstract][Hide abstract] ABSTRACT: Objectives: To investigate the impact of body mass index (BMI) (normal weight, overweight, obese) on the relationship between muscle quality (MQ) and physical function in community-dwelling older women. Design: Cross-sectional study. Setting: University research laboratory. Participants: Community-dwelling older women (n = 94, 73.6 ± 5.4 y) stratified by BMI (normal weight: 20.0-24.9 kg/m2; overweight: 25.0-29.9 kg/m2; obese: ≥ 30.0 kg/m2). Measurements: Body mass index using height and weight, leg extension power via the Nottingham power rig, body composition using dual-energy X-ray absorptiometry, and physical function (6-minute walk, 8-foot up-and-go, 30-second chair stand). Muscle quality was defined as leg power (watts) normalized for lower-body mineral-free lean mass (kg). Results: Following adjustments for covariates, muscle quality was significantly higher in women of normal BMI compared to overweight (10.0 ± 0.4 vs 8.7 ± 0.4 watts/kg, p = 0.03). Muscle quality was a significant predictor of performance on the 6-minute walk and 8-foot up-and-go in normal and overweight women (all p < 0.05) and performance on the 30-second chair stand in normal and obese women (both p < 0.05). Body mass index did not significantly impact the association between MQ and physical function (all p > 0.05). Conclusions: Muscle quality varies by BMI, yet the relationship to physical function is not significantly different across BMI groups. The results imply that interventions that increase MQ in older women may improve physical function, regardless of BMI.
The Journal of Nutrition Health and Aging 01/2014; 18(4):378-82. · 2.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND AND OBJECTIVES:The prevalence of obesity and diabetes is increasing among children, adolescents, and adults. Although estimates of the efficacy of exercise training on fasting insulin and insulin resistance have been provided, for adults similar estimates have not been provided for youth. This systematic review and meta-analysis provides a quantitative estimate of the effectiveness of exercise training on fasting insulin and insulin resistance in children and adolescents.METHODS:Potential sources were limited to peer-reviewed articles published before June 25, 2013, and gathered from the PubMed, SPORTDiscus, Physical Education Index, and Web of Science online databases. Analysis was limited to randomized controlled trials by using combinations of the terms adolescent, child, pediatric, youth, exercise training, physical activity, diabetes, insulin, randomized trial, and randomized controlled trial. The authors assessed 546 sources, of which 4.4% (24 studies) were eligible for inclusion. Thirty-two effects were used to estimate the effect of exercise training on fasting insulin, with 15 effects measuring the effect on insulin resistance. Estimated effects were independently calculated by multiple authors, and conflicts were resolved before calculating the overall effect.RESULTS:Based on the cumulative results from these studies, a small to moderate effect was found for exercise training on fasting insulin and improving insulin resistance in youth (Hedges' d effect size = 0.48 [95% confidence interval: 0.22-0.74], P < .001 and 0.31 [95% confidence interval: 0.06-0.56], P < .05, respectively).CONCLUSIONS:These results support the use of exercise training in the prevention and treatment of type 2 diabetes.
[Show abstract][Hide abstract] ABSTRACT: Persons with multiple sclerosis (MS) have reduced physical activity (PA) and lower-limb physical function and potentially disordered body composition compared with their peers without MS. The aim of this study was to determine whether PA and body composition were differentially associated with lower-limb physical function in persons with MS compared with controls. Females with MS and age- and body mass index-matched female controls (n = 51; average age 48.1 +/- 9.7 yr) were measured for PA with daily step counts, relative fat mass (%Fat), and leg lean mass (LM-LEG) via dual energy X-ray absorptiometry and for lower-limb physical function with objective performance tests. Persons with MS had 12.5% to 53% poorer lower-limb physical function than controls (all p < 0.05). PA, %Fat, and LM-LEG to body mass ratio (LM-LEG/BM) were associated with lower-limb physical function in both persons with MS and controls (all p < 0.05). Based on median splits, higher %Fat, lower LM-LEG/BM, and MS conferred poorer lower-limb physical function (all p < 0.05). PA, %Fat, and LM-LEG/BM were associated with lower-limb physical function, suggesting that body composition, specifically reducing adiposity and increasing lean mass and/or increasing PA levels, may be a potential target for MS interventions.
The Journal of Rehabilitation Research and Development 12/2013; 50(8):1139-48. · 1.78 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aging process leads to adverse changes in body composition, (increases in fat mass and decreases in skeletal muscle mass), declines in physical function (PF), and ultimately increased risk for disability and loss of independence. Specific components of body composition or muscle capacity (strength and power) may be useful in predicting PF; however, findings have been mixed regarding the most salient predictor of PF. The development of a conceptual model potentially aids in understanding the interrelated factors contributing to PF with the factors of interest being physical activity, body composition, and muscle capacity. This review also highlights sex differences in these domains. Finally, factors known to impact PF, such as sleep, depression, fatigue, and self-efficacy are discussed. Development of a comprehensive conceptual model is needed to better characterize the most salient factors contributing to PF and to subsequently inform the development of interventions to reduce physical disability in older adults.
[Show abstract][Hide abstract] ABSTRACT: To assess reliability/validity of psychosocial surveys and explore health beliefs across weight status in female freshmen.
Participants (N = 259) completed Weight Efficacy Lifestyle Questionnaire and Eating Among Teens-II survey; results evaluated by weight status (Cronbach α; principal components analysis; Mann-Whitney U).
Factor structures generally differed by weight group but "trigger situations" and "social pressure" were consistent. For comparable constructs with Cronbach α ≥ .70, scores were neutral or slightly positive for self-efficacy, emotional eating, and social pressure. Scores did not differ between weight groups.
Surveys demonstrated reliability but could benefit from further development to accurately evaluate psychosocial variables by weight status.
American journal of health behavior 07/2013; 37(4):502-16. · 1.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Adiposity, lean mass, and physical activity (PA) are known to influence physical function in older adults although the independent influences are not completely characterized. Older adults (N = 156, M age = 68.9 ± 6.7 yrs, 85 men) were assessed for body composition via dual energy x-ray absorptiometry, PA by accelerometer, and physical function via Timed Up and Go (UP&GO), 30-second chair stand, 6-minute walk (6 min WALK), and Star-Excursion Balance Test (STAR). In the absence of %Fat by PA interactions (p > 0.05), main effects existed such that higher %Fat was associated with poorer performance in UP&GO, 30 second chair stand, and 6 min WALK (p < 0.05). No significant main effects were found for PA and functional performance. Adiposity explains 4.6-11.4% in physical functional variance (p < 0.05). Preventing increases in %Fat with age may help older adults maintain functional independence.
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVES: To investigate the association between lean soft tissue (LST) and fat mass (FM) on bone health variables in women across the lifespan, while taking into account the influence of objectively measured habitual physical activity (PA). STUDY DESIGN: A total of 104 women, 37 young (23.3±2.6 years), 28 middle-age (49.2±5.4 years), and 39 old (68.3±6.4 years) participated in this cross-sectional study. All underwent a DXA scan and wore a pedometer for 7 days. MAIN OUTCOME MEASURES: Bone mineral content (BMC) and BMD of the whole body (WB), lumbar spine (LS) and proximal femur (PF), and body composition (FM and LST) were assessed with DXA and PA (steps/day) was assessed from 7 day pedometer counts. RESULTS: LST was significantly and positively associated with PF and LS BMD (r=0.34; 0.67, p<0.05), and WB, PF and LS BMC (r range=0.41-0.59, p<0.05) in all age groups and WB BMD in the middle-age group (r=0.72, p<0.05) independent of PA, FM, and hormonal status. FM was not positively associated with any bone variable in any age group when adjusted for PA, LST, and hormonal status. PA was significantly associated with WB BMD in the middle-age group (r=0.60, p<0.05), independent of LST, FM, and hormonal status. CONCLUSIONS: LST contributes more to bone health in women across the lifespan than FM, independent of PA and hormonal status.
[Show abstract][Hide abstract] ABSTRACT: The global epidemic of childhood obesity has become a major public health concern. Yet, evidence regarding the association between childhood obesity and cognitive health has remained scarce. This study examined the relationship between obesity and cognitive control using neuroelectric and behavioral measures of action monitoring in preadolescent children. Healthy weight and obese children performed compatible and incompatible stimulus-response conditions of a modified flanker task, while task performance and the error-related negativity (ERN) were assessed. Analyses revealed that obese children exhibited a longer reaction time (RT) relative to healthy weight children for the incompatible condition, whereas no such difference was observed for the compatible condition. Further, obese children had smaller ERN amplitude relative to healthy weight children with lower post-error response accuracy. In addition, healthy weight children maintained post-error response accuracy between the compatible and incompatible conditions with decreased ERN amplitude in the incompatible condition, whereas obese children exhibited lower post-error response accuracy for the incompatible relative to the compatible condition with no change in ERN amplitude between the compatibility conditions. These results suggest that childhood obesity is associated with a decreased ability to modulate the cognitive control network, involving the prefrontal cortex and anterior cingulate cortex, which supports action monitoring.
[Show abstract][Hide abstract] ABSTRACT: To examine whether childhood obesity is associated with inhibitory control, we compared healthy weight and obese preadolescent children's task performance along with the N2 and P3 components during a Go/NoGo task. Results indicated that obese children exhibited lower response accuracy relative to healthy weight children during the NoGo task requiring greater amounts of inhibitory control, whereas no such difference was observed during the Go task. Neuroelectric data indicated that healthy weight children exhibited a more frontal distribution for the NoGo P3 relative to the Go P3, whereas obese children had similar topographic distributions between the Go P3 and NoGo P3. Further, obese children had larger NoGo N2 amplitude relative to the Go N2, whereas this difference was not observed for healthy weight children. These findings suggest that childhood obesity is negatively and selectively associated with prefrontal inhibitory control.
[Show abstract][Hide abstract] ABSTRACT: Limited data on sex differences in body composition changes in response to higher protein diets (PRO) compared to higher carbohydrate diets (CARB) suggest that a PRO diet helps preserve lean mass (LM) in women more so than in men.
To compare male and female body composition responses to weight loss diets differing in macronutrient content.
Twelve month randomized clinical trial with 4mo of weight loss and 8mo weight maintenance.
Overweight (N = 130; 58 male (M), 72 female (F); BMI = 32.5 ± 0.5 kg/m2) middle-aged subjects were randomized to energy-restricted (deficit ~500 kcal/d) diets providing protein at 1.6 g.kg-1.d-1 (PRO) or 0.8 g.kg-1.d-1 (CARB). LM and fat mass (FM) were measured using dual X-ray absorptiometry. Body composition outcomes were tested in a repeated measures ANOVA controlling for sex, diet, time and their two- and three-way interactions at 0, 4, 8 and 12mo.
When expressed as percent change from baseline, males and females lost similar amounts of weight at 12mo (M:-11.2 ± 7.1 %, F:-9.9 ± 6.0 %), as did diet groups (PRO:-10.7 ± 6.8 %, CARB:-10.1 ± 6.2 %), with no interaction of gender and diet. A similar pattern emerged for fat mass and lean mass, however percent body fat was significantly influenced by both gender (M:-18.0 ± 12.8 %, F:-7.3 ± 8.1 %, p < 0.05) and diet (PRO:-14.3 ± 11.8 %, CARB:-9.3 ± 11.1 %, p < 0.05), with no gender-diet interaction. Compared to women, men carried an extra 7.0 ± 0.9 % of their total body fat in the trunk (P < 0.01) at baseline, and reduced trunk fat during weight loss more than women (M:-3.0 ± 0.5 %, F:-1.8 ± 0.3 %, p < 0.05). Conversely, women carried 7.2 ± 0.9 % more total body fat in the legs, but loss of total body fat in legs was similar in men and women.
PRO was more effective in reducing percent body fat vs. CARB over 12mo weight loss and maintenance. Men lost percent total body fat and trunk fat more effectively than women. No interactive effects of protein intake and gender are evident.