Bruce W. Bailey

Physical activity across the curriculum: year one process evaluation results

BackgroundPhysical Activity Across the Curriculum (PAAC) is a 3-year elementary school-based intervention to determine if increased amounts of moderate intensity physical activity performed in the classroom will diminish gains in body mass index (BMI). It is a cluster-randomized, controlled trial, involving 4905 children (2505 intervention, 2400 control).MethodsWe collected both qualitative and quantitative process evaluation data from 24 schools (14 intervention and 10 control), which included tracking teacher training issues, challenges and barriers to effective implementation of PAAC lessons, initial and continual use of program specified activities, and potential competing factors, which might contaminate or lessen program effects.ResultsOverall teacher attendance at training sessions showed exceptional reach. Teachers incorporated active lessons on most days, resulting in significantly greater student physical activity levels compared to controls (p < 0.0001). Enjoyment ratings for classroom-based lessons were also higher for intervention students. Competing factors, which might influence program results, were not carried out at intervention or control schools or were judged to be minimal.ConclusionIn the first year of the PAAC intervention, process evaluation results were instrumental in identifying successes and challenges faced by teachers when trying to modify existing academic lessons to incorporate physical activity.

Effects of dairy intake on weight maintenance

BackgroundTo compare the effects of low versus recommended levels of dairy intake on weight maintenance and body composition subsequent to weight loss.Design and MethodsTwo site (University of Kansas-KU; University of Tennessee-UT), 9 month, randomized trial. Weight loss was baseline to 3 months, weight maintenance was 4 to 9 months. Participants were maintained randomly assigned to low dairy (< 1 dairy serving/d) or recommended dairy (> 3 servings/d) diets for the maintenance phase. Three hundred thirty eight men and women, age: 40.3 ± 7.0 years and BMI: 34.5 ± 3.1, were randomized; Change in weight and body composition (total fat, trunk fat) from 4 to 9 months were the primary outcomes. Blood chemistry, blood pressure, resting metabolism, and respiratory quotient were secondary outcomes. Energy intake, calcium intake, dairy intake, and physical activity were measured as process evaluation.ResultsDuring weight maintenance, there were no overall significant differences for weight or body composition between the low and recommended dairy groups. A significant site interaction occurred with the low dairy group at KU maintaining weight and body composition and the low dairy group at UT increasing weight and body fat. The recommended dairy group exhibited reductions in plasma 1,25-(OH)2-D while no change was observed in the low dairy group. No other differences were found for blood chemistry, blood pressure or physical activity between low and recommended dairy groups. The recommended dairy group showed significantly greater energy intake and lower respiratory quotient compared to the low dairy group.ConclusionWeight maintenance was similar for low and recommended dairy groups. The recommended dairy group exhibited evidence of greater fat oxidation and was able to consume greater energy without greater weight gain compared to the low dairy group. Recommended levels of dairy products may be used during weight maintenance without contributing to weight gain compared to diets low in dairy products.Trial RegistrationClinicalTrials.gov NCT00686426

Minimal resistance training improves daily energy expenditure and fat oxidation.

UNLABELLED Long-term resistance training (RT) may result in a chronic increase in 24-h energy expenditure (EE) and fat oxidation to a level sufficient to assist in maintaining energy balance and preventing weight gain. However, the impact of a minimal RT program on these parameters in an overweight college-aged population, a group at high risk for developing obesity, is unknown. PURPOSE We aimed to evaluate the effect of 6 months of supervised minimal RT in previously sedentary, overweight (mean +/- SEM, BMI = 27.7 +/- 0.5 kg x m(-2)) young adults (21.0 +/- 0.5 yr) on 24-h EE, resting metabolic rate (RMR), sleep metabolic rate (SMR), and substrate oxidation using whole-room indirect calorimetry 72 h after the last RT session. METHODS Participants were randomized to RT (one set, 3 d x wk(-1), three to six repetition maximums, nine exercises; N = 22) or control (C, N = 17) groups and completed all assessments at baseline and at 6 months. RESULTS There was a significant (P < 0.05) increase in 24-h EE in the RT (527 +/- 220 kJ x d(-1)) and C (270 +/- 168 kJ x d(-1)) groups; however, the difference between groups was not significant (P = 0.30). Twenty-four hours of fat oxidation (g x d(-1)) was not altered after RT; however, reductions in RT assessed during both rest (P < 0.05) and sleep (P < 0.05) suggested increased fat oxidation in RT compared with C during these periods. SMR (8.4 +/- 8.6%) and RMR (7.4 +/- 8.7%) increased significantly in RT (P < 0.001) but not in C, resulting in significant (P < 0.001) between-group differences for SMR with a trend for significant (P = 0.07) between-group differences for RMR. CONCLUSION A minimal RT program that required little time to complete (11min per session) resulted in a chronic increase in energy expenditure. This adaptation in energy expenditure may have a favorable impact on energy balance and fat oxidation sufficient to assist with the prevention of obesity in sedentary, overweight young adults, a group at high risk for developing obesity.

Neural response to pictures of food after exercise in normal-weight and obese women.

PURPOSE This study examined the effect of a bout of moderate-to-vigorous (MV) exercise on the neural response to pictures of food (used to index food motivation) in normal-weight and obese women. Secondary outcomes included energy intake and physical activity (PA) over 24 h. METHODS Using a crossover design, 18 normal-weight and 17 obese women completed a morning-time, 45-min exercise bout (treadmill at 3.8 mph; 0% grade) and were subsequently followed for 24 h. This was counterbalanced by a control day with no exercise bout. To assess the effect of exercise on food motivation, participants were shown pictures of food and flowers (control) after exercise. Neural activity was concurrently monitored using electroencephalogram for the late positive potential (LPP) component of the event-related potential (ERP) and compared with the LPP response on the nonexercise day. After testing, weighed food records were kept for the duration of each day. PA was monitored, via accelerometry, over each day. RESULTS There was not a significant body mass index (BMI) group × exercise condition × picture-type interaction for LPP amplitude; however, when participants were pooled, the exercise condition resulted in lower LPP amplitude waveforms in response to food pictures than the nonexercise condition (F = 4.25, P = 0.048). There were no differences in energy or macronutrient intake (P > 0.05). The exercise condition resulted in significantly more PA than the nonexercise condition, and there was a significant BMI group × exercise condition interaction for MV PA (F = 4.48, P = 0.043) with obese women showing less MV PA. CONCLUSIONS A bout of MV exercise decreases neurologically determined food motivation (i.e., the LPP event-related potential), but the effect of BMI is unclear. In addition, a morning-time exercise bout significantly increases 24-h PA; 24-h MV PA differed according to BMI.

A Prospective Study of Physical Activity Intensity and Change in Adiposity in Middle-Aged Women

Purpose. To determine the extent to which objectively measured intensity of physical activity (PA) predicts change in body fat (BF%) in women. Design. Prospective cohort study of PA intensity and body composition in middle-aged women. Setting. The study took place in a metropolitan Mountain West community. Subjects. Two hundred and twenty-eight women participated in two assessment periods separated by 20 months. Measures. Each assessment period consisted of seven consecutive days of monitoring, followed by body composition testing. Analysis. The general linear model using partial correlations and Mantel-Haenszel χ2 tests were performed. Results. At baseline and follow-up, women who participated in vigorous PA were leaner than women who participated in moderate or light PA (p < .05). Longitudinal results indicated that a greater proportion of women who decreased PA intensity over the 20 months also increased BF% (66%), compared to participants who increased or maintained PA intensity (47%) (p < .05). Conclusions. PA intensity seems to play a role in long-term weight maintenance. Reducing PA intensity increases the risk of BF% gain in women. Efforts to help women maintain PA intensity along with other weight management strategies may prove beneficial in preventing unwanted body fat gain in middle-aged women.

Author contacts for retrieval of data for a meta-analysis on exercise and diet restriction.

OBJECTIVES The mode of contact and response levels of authors who had been asked to provide missing or incomplete data for a systematic review on diet and exercise interventions for weight loss was examined. METHODS We contacted authors by electronic mail, letter, or both. Survival analyses were performed with the Kaplan-Meier method to determine differences in the proportion of responders over time among the different modes of contact and to determine whether response rates differed between authors from the United States and those from other countries. Logistic regression was used to determine whether the number of items requested and publication date influenced the likelihood of response. RESULTS Two hundred forty-one (39.9 percent) studies had missing or incomplete data (e.g., sample size, age, caloric restriction, exercise amount, and so on). We were unable to locate ninety-five authors (39.4 percent). Of the remaining authors, forty-six authors (31.5 percent) responded to information requests. Time to respond differed by contact method (p < .05): e-mail (3 +/- 3 days), letter (27 +/- 30 days), and both (13 +/-12 days). Response rates from U.S. authors did not differ from those of other countries. CONCLUSIONS Our study suggests poor success in the acquisition of essential information. Given considerable time and resources, weight loss studies require improved reporting standards to minimize the relatively unsuccessful attempt to contact authors for important and necessary information.

Restricting night-time eating reduces daily energy intake in healthy young men: a short-term cross-over study

Few experimental data are available to support the notion that reducing night-time eating changes total daily energy intake (EI) or body weight in healthy adults. The present study primarily examined the short-term effect of night eating restriction (NER) on daily EI in healthy young men. It secondarily examined body weight and moods associated with NER. Using a cross-over design, twenty-nine men (20·9 (sd 2·5) years; 24·4 (sd 2·5) kg/m²) initiated a 2-week NER intervention (elimination of EI from 19.00 to 06.00 hours) and a 2-week control condition, counterbalanced and separated by a 1-week washout period. EI and macronutrient intake were assessed using computerised, multiple-pass 24 h food recalls, body weight via a digital scale and mood using the Profile of Mood States survey. Of the twenty-nine participants, twenty-seven (93 %) completed all aspects of the study. During the NER condition, the participants consumed less total energy per d than during the control condition (10 125 v. 11 146 kJ/d; F= 6·41; P= 0·018). During the NER condition, no energy was reported consumed between 19.00 and 06.00 hours; however, during the control condition, the energy intake of participants was 2920 (sd 1347) kJ/d between 19.00 and 06.00 hours. There was a significant difference in weight change between the NER (-0·4 (sd 1·1) kg) and control (+0·6 (sd 0·9) kg) conditions (F= 22·68; P< 0·001). Differences in total mood score or mood subscales between the NER and control conditions were not apparent (P>0·05). These findings provide support for NER decreasing short-term EI in healthy young men.

Dietary predictors of visceral adiposity in overweight young adults

The purpose of the present study was to determine the dietary predictors of visceral adipose tissue (VAT) area in overweight young adults. A total of 109 young adults (fifty males and fifty-nine females) ate ad libitum in a university cafeteria for 14 d. All food and beverages consumed in the cafeteria were measured using observer-recorded weighed plate waste. Food consumption outside the cafeteria (i.e. snacks) was assessed by multiple-pass 24 h recall procedures. VAT was determined using computed tomography. Stepwise regression demonstrated that the best predictor of visceral adiposity in women was total dietary fat (P <or= 0.05). In men, the model for predicting visceral adiposity included Ca and total dietary fat. We concluded that total dietary fat is the best predictor of VAT area in both men and women. While this relationship was independent in women, in men there was a synergistic relationship between dietary fat consumption and Ca consumption in predicting VAT.

Obesity increases risk of declining physical activity over time in women: a prospective cohort study

Research indicates that risk of obesity increases as physical activity (PA) decreases; however, the reciprocal effect has been rarely studied. The present investigation was conducted to determine the contribution of obesity on objectively measured PA over 20 months.

Test-Retest Reliability of the Bod Pod: The Effect of Multiple Assessments

The Bod Pod uses air-displacement plethysmography to estimate body fat percentage (BF%). This study was designed to assess the test-retest reliability of the Bod Pod. The study included 283 women (M age =41.0 yr., SD = 3.0). Each participant was tested at least twice in the Bod Pod. Results showed no significant mean difference between the test and the retest. The intraclass correlation coefficient (ICC) was .991. However, the absolute value of the initial trial differences (absolute mean difference) was .96 (SD = .90). A third assessment of BF% was taken when the initial trial difference was greater than 1 percentage point, and the two closest values were compared. This strategy resulted in a significant decrease in the absolute mean difference, from .96 to .55 percentage point, and ICC increased to .998. The Bod Pod appears to measure body fat percentage reliably; however, findings suggest that multiple trials may be necessary to detect small treatment effects.