A qualitative evaluation of remote training to develop a fitness surveillance system.

Objectives: In the USA, 18% of school-aged young people are classified as obese, and rural populations appear to be particularly at risk. Achieving high levels of fitness reduces the risk of obesity and underlying health conditions. To better understand youth obesity trends and fitness levels, annual fitness testing ([FT], that is, surveillance) in schools has been recommended. Although many K-12 schools conduct FT, surveillance programmes that compile unified standardised test results are rare. Design: Qualitative design. Setting: Physical education teachers from 11 schools (n = 13; n = 4 men) participated in remote training about conducting FitnessGram FT. Methods: Data included two semi-structured interviews per teacher on experiences with distance fitness training, implementing FitnessGram, and data entry for annual surveillance. Results: Inductive analysis using axial and open coding identified four themes: (1) barriers prior to study, (2) study training, (3) implementation challenges and suggestions and (4) teacher feedback. Teachers had an interest in FT but lacked the recommended training and equipment needed to implement it annually. Conclusion: Teachers believed the training they received (as part of this study) prepared them to collect reliable and valid data, and that FT had benefits for their students and programmes. Every teacher expressed interest in reporting annual surveillance data. Efforts to train teachers for FT through virtual professional development may be a viable means of establishing a unified surveillance system.

Energy intake and season interact to influence physiological stress load among midlife women.

Allostatic load (AL) is an index that measures physiologic stress associated with chronic disease risk. One factor that may influence overall physiologic stress load and AL is energy consumption, but whether this association differs across different seasons is unknown. We tested whether energy consumption interacted with the season to influence AL in 52 mid-life (40-60 years) women from the Life in All Seasons Study. Women completed an online 24-h recall every 10 days and had components of allostatic load measured seasonally. Women were from the greater Grand Forks, ND catchment area and were followed for one year between July 2012 and July 2014. We found a significant (p = 0.01) interaction between season and energy consumption on AL. Further inspection showed that, during the summer and winter seasons, the average allostatic load rose with relatively higher energy consumption. We also observed a linear and positive association between AL and energy intake in summer (ß = 0.0013 ± 0.0004; p = 0.001; r2 = 0.14) and winter (ß = 0.0011 ± 0.0004; p = 0.007; r2 = 0.10), but not in fall or spring. These results suggest that factors associated with distinct times of the year promote or prevent the effects of higher energy consumption on physiological stress load. Since allostatic load is linked to elevated disease risk, our results provide additional information that may help to explain seasonal differences in disease risk of some women.

Cross-sectional and longitudinal analysis of the active commuting behaviors of U.S. Department of the Interior employees.

BACKGROUND: Despite evolving evidence of the health and economic benefits of active transportation (AT) to work, few studies have examined the determinants of AT in large organizations with multiple worksites nor how trends in commuting change over time. METHODS: The data were obtained from the U.S. Department of the Interior Employee Commuting Census of 2010 (n = 23,230), and 2012-2016 (n = 21,725-25,974). The respondents were grouped into four commuting categories: non-active mode, walking, biking, and mixed-mode. Multinomial logistic regression analysis was utilized to examine the correlates of choosing AT to work for the 2010 data. Next, a repeated cross-sectional analysis was completed for all six years of data. RESULTS: In 2010, AT modes were only chosen by approximately 10% of respondents. Employees who lived farther from work and did not have a public transit station within 0.5 miles from home were generally less likely to choose AT. Respondents working in non-metro workplaces were less likely to bike or take mixed-modes to work, but more likely to walk. Men were more likely to choose AT modes, particularly biking. Respondents aged ≤30 yrs. were less likely to bike than those 31 to 40 yrs., but more likely than those ≥61 yrs. In 2010, the number of respondents that walked was higher, and biked and took mixed-modes was lower when compared to 2016, while the choice to take mixed-modes was higher in 2012 and 2013 when compared to 2016. Daily commuting distances in 2016 tended to be lower than 2010 and 2012, and higher than 2013. However, overall AT choice and commute distance remained reasonably stable over time. CONCLUSIONS: Respondents who lived close to their workplace and a public transportation station, worked in a metro location, were male and younger were more likely to choose AT modes to work. The results provide insight for the U.S. Department of the Interior and other large organizations to develop intervention strategies that support AT to work. Further research is warranted to understand the concurrent individual, social, and environmental barriers and facilitators for choosing AT to work.

The Relationships Between Depressive Symptoms, Functional Health Status, Physical Activity, and the Availability of Recreational Facilities: a Rural-Urban Comparison in Middle-Aged and Older Chinese Adults.

PURPOSE: This study drew upon the ecological system theory to demonstrate rural-urban differences in the relationships between the availability of recreational facilities, physical activity (PA), functional health status, and depressive symptoms in middle-aged and older Chinese adults. METHODS: Nationally representative data (n = 5949) from the Chinese Health and Retirement Longitudinal Study (CHARLS, 2011-2013) were examined using the multigroup structural equation modeling approach. RESULTS: The results suggest that higher availability of recreational facilities in the urban communities was associated with higher levels of leisure time physical activity (LTPA), better functional capacity, and less occurrence of depressive symptoms among urban participants. In contrast, LTPA engagement among rural participants was low and had negligible mitigating effects on functional decline and depressive symptoms. The findings also show that functional health status mediated the association between total PA and depressive symptoms in both rural and urban participants. However, high levels of total PA were directly associated with elevated depressive symptoms, suggesting that the context of PA and related socioeconomic factors might explain this association after the non-LTPA components were included. CONCLUSIONS: The findings highlight how complex patterns of intrapersonal, behavioral, and environmental correlates influence depressive symptoms in middle-aged and older Chinese adults. The context of PA should be considered when creating targeted strategies to prevent depressive symptoms. As an inactive lifestyle evolves with China's rapid urbanization, joint efforts from public health and urban planning should be made to promote LTPA and develop active living communities for achieving optimal health in later life.

The metabolizable energy of dietary resistant maltodextrin is variable and alters fecal microbiota composition in adult men.

Resistant maltodextrin (RM) is a novel soluble, nonviscous dietary fiber. Its metabolizable energy (ME) and net energy (NE) values derived from nutrient balance studies are unknown, as is the effect of RM on fecal microbiota. A randomized, placebo-controlled, double-blind crossover study was conducted (n = 14 men) to determine the ME and NE of RM and its influence on fecal excretion of macronutrients and microbiota. Participants were assigned to a sequence consisting of 3 treatment periods [24 d each: 0 g/d RM + 50 g/d maltodextrin and 2 amounts of dietary RM (25 g/d RM + 25 g of maltodextrin/d and 50 g/d RM + 0 g/d maltodextrin)] and were provided all the foods they were to consume to maintain their body weight. After an adaptation period, excreta were collected during a 7-d period. After the collection period, 24-h energy expenditure was measured. Fluorescence in situ hybridization, quantitative polymerase chain reaction, and 454 titanium technology-based 16S rRNA sequencing were used to analyze fecal microbiota composition. Fecal amounts of energy (544, 662, 737 kJ/d), nitrogen (1.5, 1.8, 2.1 g/d), RM (0.3, 0.6, 1.2 g/d), and total carbohydrate (11.1, 14.2, 16.2 g/d) increased with increasing dose (0, 25, 50 g) of RM (P < 0.0001). Fat excretion did not differ among treatments. The ME value of RM was 8.2 and 10.4 kJ/g, and the NE value of RM was -8.2 and 2.0 kJ/g for the 25 and 50 g/d RM doses, respectively. Both doses of RM increased fecal wet weight (118, 148, 161 g/d; P < 0.0001) and fecal dry weight (26.5, 32.0, 35.8 g/d; P < 0.0001) compared with the maltodextrin placebo. Total counts of fecal bacteria increased by 12% for the 25 g/d RM dose (P = 0.17) and 18% for the 50 g/d RM dose (P = 0.019). RM intake was associated with statistically significant increases (P < 0.001) in various operational taxonomic units matching closest to ruminococcus, eubacterium, lachnospiraceae, bacteroides, holdemania, and faecalibacterium, implicating RM in their growth in the gut. Our findings provide empirical data important for food labeling regulations related to the energy value of RM and suggest that RM increases fecal bulk by enhancing the excretion of nitrogen and carbohydrate and the growth of specific microbial populations.

Associations of objectively measured sedentary behavior, light activity, and markers of cardiometabolic health in young women.

PURPOSE: To investigate the associations among objectively measured sedentary behavior, light physical activity, and markers of cardiometabolic health in young women. METHODS: Cardiovascular disease risk factors, homeostasis model assessment for insulin resistance (HOMA-IR), lipid accumulation product, and inflammatory markers were measured in 50 young, adult women. Accelerometers were worn over 7 days to assess sedentary time (<150 counts min(-1)), light physical activity (150-2,689 counts min(-1)), and moderate-to-vigorous physical activity (MVPA; ≥2,690 counts min(-1)). Multivariate regression examined independent associations of sedentary behavior and light physical activity with cardiometabolic health. Covariates included MVPA, cardiorespiratory fitness (VO2peak) and body mass, and body composition. RESULTS: Sedentary behavior was associated with triglycerides (p = 0.03) and lipid accumulation product (p = 0.02) independent of MVPA. These associations were attenuated by VO2peak and body mass or body composition (p ≥ 0.05). Light physical activity was independently associated with triglycerides and lipid accumulation product after adjustment for all covariates (p < 0.05). The association between light physical activity and HOMA-IR was independent of MVPA (p = 0.02) but was attenuated by VO2peak and body mass or body composition (p > 0.05). CONCLUSIONS: Sedentary behavior and light physical activity were independently associated with markers of cardiometabolic health in young, adult women. Our data suggest that VO2peak and body composition may be important mediators of these associations. Decreasing sedentary behavior and increasing light physical activity may be important for maintaining cardiometabolic health in young, adult women.

Development of a Fitness Surveillance System to Track and Evaluate Obesity in North Idaho.

BACKGROUND: Internationally 18% of youth are obese. Fitness testing can be used to establish fitness surveillance, which can inform policy and targeted interventions aimed at addressing obesity. The purpose of this study was to estimate the prevalence of overweight, obesity, and low fitness in Idaho school-aged youth through a pilot study. METHODS: A convenience sample of 13 teachers from 11 north Idaho rural schools collected FitnessGram fitness data: body composition (body mass index [BMI]), aerobic capacity (Progressive Aerobic Cardiovascular Endurance Run [PACER] test), muscular endurance (curl up), strength (pushup), and flexibility (sit and reach). RESULTS: A total of 761 students (aged 9-18 years) from grades 3&5, 7, and 9 to 12 participated in the study. Approximately 24% of 3&5 and 22% of 7th, and 12% of 9 to 12th-grade students were categorized as Needs Improvement/Health Risk by FitnessGram standards for BMI. Similarly, approximately 25% of 3&5, and 22% of 7 and 9 to 12th-grade students were considered Needs Improvement/Health Risk for PACER. IMPLICATIONS FOR SCHOOL HEALTH POLICY, PRACTICE, AND EQUITY: Results from fitness testing can provide school and public health representatives with a "needs assessment" of student health that can be used to help develop policies and practices to improve student health and wellbeing. CONCLUSIONS: This study provides a model for statewide annual fitness testing surveillance and reporting within K-12 public school physical education classrooms.

Association of Physical Educators' Socialization Experiences and Confidence with Respect to Comprehensive School Physical Activity Program Implementation.

Comprehensive school physical activity programs (CSPAPs) are recommended to support physical education (PE) and increase the amount of physical activity (PA) youth receive each day. However, adoption of CSPAPs in the United States is low. PE teachers are well positioned to lead the implementation of CSPAPs, but research is needed to better understand (a) PE teachers' confidence to assume the multiple roles involved with CSPAP implementation and (b) the factors that are associated with such confidence. This study examined PE teachers' role breadth self-efficacy (RBSE) as a measure of PE teachers' CSPAP-related confidence and its association with seminal life experiences as framed within teacher socialization theory. A survey was emailed to a stratified-random sample of 2976 PE teachers and distributed on social media, garnering a total of 259 responses. Exploratory structural equation modeling supported a three-factor solution for teacher socialization variables (acculturation, professional socialization and organizational socialization), in line with the theoretical framework, and a single factor solution for RBSE. Professional socialization and organizational socialization were significant predictors of RBSE, and qualitative data from open-ended survey questions supported these relationships. The results highlight the importance of preservice teacher education and current employment contexts in PE teachers' CSPAP-related confidence.

Whey protein but not soy protein supplementation alters body weight and composition in free-living overweight and obese adults.

A double-blind, randomized clinical trial was conducted to determine the effect of consumption of supplemental whey protein (WP), soy protein (SP), and an isoenergetic amount of carbohydrate (CHO) on body weight and composition in free-living overweight and obese but otherwise healthy participants. Ninety overweight and obese participants were randomly assigned to 1 of 3 treatment groups for 23 wk: 1) WP; 2) SP (each providing ~56 g/d of protein and 1670 kJ/d); or 3) an isoenergetic amount of CHO. Supplements were consumed as a beverage twice daily. Participants were provided no dietary advice and continued to consume their free-choice diets. Participants' body weight and composition data were obtained monthly. Dietary intake was determined by 24-h dietary recalls collected every 10 d. After 23 wk, body weight and composition did not differ between the groups consuming the SP and WP or between SP and CHO; however, body weight and fat mass of the group consuming the WP were lower by 1.8 kg (P < 0.006) and 2.3 kg (P < 0.005), respectively, than the group consuming CHO. Lean body mass did not differ among any of the groups. Waist circumference was smaller in the participants consuming WP than in the other groups (P < 0.05). Fasting ghrelin was lower in participants consuming WP compared with SP or CHO. Through yet-unknown mechanisms, different sources of dietary protein may differentially facilitate weight loss and affect body composition. Dietary recommendations, especially those that emphasize the role of dietary protein in facilitating weight change, should also address the demonstrated clinical potential of supplemental WP.

Estimates of adherence and error analysis of physical activity data collected via accelerometry in a large study of free-living adults.

BACKGROUND: Activity monitors (AM) are small, electronic devices used to quantify the amount and intensity of physical activity (PA). Unfortunately, it has been demonstrated that data loss that occurs when AMs are not worn by subjects (removals during sleeping and waking hours) tend to result in biased estimates of PA and total energy expenditure (TEE). No study has reported the degree of data loss in a large study of adults, and/or the degree to which the estimates of PA and TEE are affected. Also, no study in adults has proposed a methodology to minimize the effects of AM removals. METHODS: Adherence estimates were generated from a pool of 524 women and men that wore AMs for 13 - 15 consecutive days. To simulate the effect of data loss due to AM removal, a reference dataset was first compiled from a subset consisting of 35 highly adherent subjects (24 HR; minimum of 20 hrs/day for seven consecutive days). AM removals were then simulated during sleep and between one and ten waking hours using this 24 HR dataset. Differences in the mean values for PA and TEE between the 24 HR reference dataset and the different simulations were compared using paired t-tests and/or coefficients of variation. RESULTS: The estimated average adherence of the pool of 524 subjects was 15.8 +/- 3.4 hrs/day for approximately 11.7 +/- 2.0 days. Simulated data loss due to AM removals during sleeping hours in the 24 HR database (n = 35), resulted in biased estimates of PA (p < 0.05), but not TEE. Losing as little as one hour of data from the 24 HR dataset during waking hours results in significant biases (p < 0.0001) and variability (coefficients of variation between 7 and 21%) in the estimates of PA. Inserting a constant value for sleep and imputing estimates for missing data during waking hours significantly improved the estimates of PA. CONCLUSION: Although estimated adherence was good, measurements of PA can be improved by relatively simple imputation of missing AM data.

Understanding the Nature of Measurement Error When Estimating Energy Expenditure and Physical Activity via Physical Activity Recall.

BACKGROUND: The National Health and Nutrition Examination Survey physical activity questionnaire (PAQ) is used to estimate activity energy expenditure (AEE) and moderate to vigorous physical activity (MVPA). Bias and variance in estimates of AEE and MVPA from the PAQ have not been described, nor the impact of measurement error when utilizing the PAQ to predict biomarkers and categorize individuals. METHODS: The PAQ was administered to 385 adults to estimate AEE (AEE:PAQ) and MVPA (MVPA:PAQ), while simultaneously measuring AEE with doubly labeled water (DLW; AEE:DLW) and MVPA with an accelerometer (MVPA:A). RESULTS: Although AEE:PAQ [3.4 (2.2) MJ·d-1] was not significantly different from AEE:DLW [3.6 (1.6) MJ·d-1; P > .14], MVPA:PAQ [36.2 (24.4) min·d-1] was significantly higher than MVPA:A [8.0 (10.4) min·d-1; P < .0001]. AEE:PAQ regressed on AEE:DLW and MVPA:PAQ regressed on MVPA:A yielded not only significant positive relationships but also large residual variances. The relationships between AEE and MVPA, and 10 of the 12 biomarkers were underestimated by the PAQ. When compared with accelerometers, the PAQ overestimated the number of participants who met the Physical Activity Guidelines for Americans. CONCLUSIONS: Group-level bias in AEE:PAQ was small, but large for MVPA:PAQ. Poor within-participant estimates of AEE:PAQ and MVPA:PAQ lead to attenuated relationships with biomarkers and misclassifications of participants who met or who did not meet the Physical Activity Guidelines for Americans.

Seasonal temperature acclimatization in a semi-fossorial mammal and the role of burrows as thermal refuges.

Small mammals in habitats with strong seasonal variation in the thermal environment often exhibit physiological and behavioral adaptations for coping with thermal extremes and reducing thermoregulatory costs. Burrows are especially important for providing thermal refuge when above-ground temperatures require high regulatory costs (e.g., water or energy) or exceed the physiological tolerances of an organism. Our objective was to explore the role of burrows as thermal refuges for a small endotherm, the pygmy rabbit (Brachylagus idahoensis), during the summer and winter by quantifying energetic costs associated with resting above and below ground. We used indirect calorimetry to determine the relationship between energy expenditure and ambient temperature over a range of temperatures that pygmy rabbits experience in their natural habitat. We also measured the temperature of above- and below-ground rest sites used by pygmy rabbits in eastern Idaho, USA, during summer and winter and estimated the seasonal thermoregulatory costs of resting in the two microsites. Although pygmy rabbits demonstrated seasonal physiological acclimatization, the burrow was an important thermal refuge, especially in winter. Thermoregulatory costs were lower inside the burrow than in above-ground rest sites for more than 50% of the winter season. In contrast, thermal heterogeneity provided by above-ground rest sites during summer reduced the role of burrows as a thermal refuge during all but the hottest periods of the afternoon. Our findings contribute to an understanding of the ecology of small mammals in seasonal environments and demonstrate the importance of burrows as thermal refuge for pygmy rabbits.

A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults.

BACKGROUND: Although consumption of 3 meals/d is the most common pattern of eating in industrialized countries, a scientific rationale for this meal frequency with respect to optimal health is lacking. A diet with less meal frequency can improve the health and extend the lifespan of laboratory animals, but its effect on humans has never been tested. OBJECTIVE: A pilot study was conducted to establish the effects of a reduced-meal-frequency diet on health indicators in healthy, normal-weight adults. DESIGN: The study was a randomized crossover design with two 8-wk treatment periods. During the treatment periods, subjects consumed all of the calories needed for weight maintenance in either 3 meals/d or 1 meal/d. RESULTS: Subjects who completed the study maintained their body weight within 2 kg of their initial weight throughout the 6-mo period. There were no significant effects of meal frequency on heart rate, body temperature, or most of the blood variables measured. However, when consuming 1 meal/d, subjects had a significant increase in hunger; a significant modification of body composition, including reductions in fat mass; significant increases in blood pressure and in total, LDL-, and HDL-cholesterol concentrations; and a significant decrease in concentrations of cortisol. CONCLUSIONS: Normal-weight subjects are able to comply with a 1 meal/d diet. When meal frequency is decreased without a reduction in overall calorie intake, modest changes occur in body composition, some cardiovascular disease risk factors, and hematologic variables. Diurnal variations may affect outcomes.

Comparison of two different physical activity monitors.

BACKGROUND: Understanding the relationships between physical activity (PA) and disease has become a major area of research interest. Activity monitors, devices that quantify free-living PA for prolonged periods of time (days or weeks), are increasingly being used to estimate PA. A range of different activity monitors brands are available for investigators to use, but little is known about how they respond to different levels of PA in the field, nor if data conversion between brands is possible. METHODS: 56 women and men were fitted with two different activity monitors, the Actigraph (Actigraph LLC; AGR) and the Actical (Mini-Mitter Co.; MM) for 15 days. Both activity monitors were fixed to an elasticized belt worn over the hip, with the anterior and posterior position of the activity monitors randomized. Differences between activity monitors and the validity of brand inter-conversion were measured by t-tests, Pearson correlations, Bland-Altman plots, and coefficients of variation (CV). RESULTS: The AGR detected a significantly greater amount of daily PA (216.2 +/- 106.2 vs. 188.0 +/- 101.1 counts/min, P < 0.0001). The average difference between activity monitors expressed as a CV were 3.1 and 15.5% for log-transformed and raw data, respectively. When a conversion equation was applied to convert datasets from one brand to another, the differences were no longer significant, with CV's of 2.2 and 11.7%, log-transformed and raw data, respectively. CONCLUSION: Although activity monitors predict PA on the same scale (counts/min), the results between these two brands are not directly comparable. However, the data are comparable if a conversion equation is applied, with better results for log-transformed data.

The Impact of Low Accelerometer Wear Time on the Estimates and Application of Sedentary Behavior and Physical Activity Data in Adults.

BACKGROUND: This investigation sought to determine how accelerometer wear (1) biased estimates of sedentary behavior (SB) and physical activity (PA), (2) affected misclassifications for meeting the Physical Activity Guidelines for Americans, and (3) impacted the results of regression models examining the association between moderate to vigorous physical activity (MVPA) and a clinically relevant health outcome. METHODS: A total of 100 participants [age: 20.6 (7.9) y] wore an ActiGraph GT3X+ accelerometer for 15.9 (1.6) hours per day (reference dataset) on the hip. The BOD POD was used to determine body fat percentage. A data removal technique was applied to the reference dataset to create individual datasets with wear time ranging from 15 to 10 hours per day for SB and each intensity of PA. RESULTS: Underestimations of SB and each intensity of PA increased as accelerometer wear time decreased by up to 167.2 minutes per day. These underestimations resulted in Physical Activity Guidelines for Americans misclassification rates of up to 42.9%. The regression models for the association between MVPA and body fat percentage demonstrated changes in the estimates for each wear-time adherence level when compared to the model using the reference MVPA data. CONCLUSIONS: Increasing accelerometer wear improves daily estimates of SB and PA, thereby also improving the precision of statistical inferences that are made from accelerometer data.

Preprandial ghrelin is not affected by macronutrient intake, energy intake or energy expenditure.

BACKGROUND: Ghrelin, a peptide secreted by endocrine cells in the gastrointestinal tract, is a hormone purported to have a significant effect on food intake and energy balance in humans. The influence of factors related to energy balance on ghrelin, such as daily energy expenditure, energy intake, and macronutrient intake, have not been reported. Secondly, the effect of ghrelin on food intake has not been quantified under free-living conditions over a prolonged period of time. To investigate these effects, 12 men were provided with an ad libitum cafeteria-style diet for 16 weeks. The macronutrient composition of the diets were covertly modified with drinks containing 2.1 MJ of predominantly carbohydrate (Hi-CHO), protein (Hi-PRO), or fat (Hi-FAT). Total energy expenditure was measured for seven days on two separate occasions (doubly labeled water and physical activity logs). RESULTS: Preprandial ghrelin concentrations were not affected by macronutrient intake, energy expenditure or energy intake (all P > 0.05). In turn, daily energy intake was significantly influenced by energy expenditure, but not ghrelin. CONCLUSION: Preprandial ghrelin does not appear to be influenced by macronutrient composition, energy intake, or energy expenditure. Similarly, ghrelin does not appear to affect acute or chronic energy intake under free-living conditions.

Determinants of Variance in the Habitual Physical Activity of Overweight Adults.

BACKGROUND: The number of days of data and number of subjects necessary to estimate total physical activity (TPA) and moderate-to-vigorous physical activity (MVPA) requires an understanding of within- and between-subject variances, and the influence of sex, body composition, and age. METHODS: Seventy-one adults wore accelerometers for 7-day intervals over 6 consecutive months. RESULTS: Body fat and sex influenced TPA and MVPA. The sources of subject-related variation for TPA and MVPA were within-subject (48.4% and 54.3%), between-subject (34.3% and 31.8%), and calendar effects (17.3% and 13.9%). Based on within-subject variances, the error associated with estimating TPA and MVPA by collecting 1 to 7 days of data ranged from 28.2% to 13.3% for TPA and 62.0% to 28.6% for MVPA. Based on between-subject variances, detecting a 10% difference between 2 groups at a power of 90% requires approximately 200 and 725 subjects per group for TPA and MVPA, respectively. CONCLUSIONS: Estimates of MVPA are more variable than TPA in overweight adults, therefore more days of data are required to estimate MVPA and larger sample sizes to detect treatment differences for MVPA. Log-transforming data reduces the need for additional days of data collection, thereby improving chances of detecting treatment effects.

Effects of the interaction of sex and food intake on the relation between energy expenditure and body composition.

BACKGROUND: The relation between physical activity energy expenditure (PAEE) and percentage body fat (%BF) is not very strong in the general population. It is possible that variables such as sex, food intake, or both may in part explain this poor coupling. OBJECTIVE: This study was designed to show the relation between PAEE and %BF and to determine whether sex, food intake, or both influence the strength of the relation. DESIGN: We used doubly labeled water or energy intake balance, indirect calorimetry, dietary interview, and dual-energy X-ray absorptiometry to measure total energy expenditure (TEE), resting energy expenditure (REE), food intake, and %BF, respectively, in 91 healthy persons (women: aged 48 y, 38.6%BF, n = 47; men: aged 47 y, 24.1%BF, n = 44). RESULTS: TEE, PAEE, and REE were significantly lower in women than in men. TEE was related to %BF in women (r = 0.53, P < 0.0001) but not in men (r = -0.22, P > 0.05). The relation between PAEE and %BF was significant in men (r = -0.34, P < 0.03) but not in women. PAL was also significantly related to %BF in men (r = -0.36, P < 0.02) but not in women. Macronutrient intake (% of total energy) did not differ significantly between the sexes, but carbohydrate (r = -0.44, P < 0.003) and fat (r = 0.31, P < 0.04) intakes were significantly related to %BF in women. CONCLUSIONS: These results suggest that the relation between PAEE and %BF is stronger in men than in women. Macronutrient composition seems have a stronger influence on %BF in women than in men.

Developing a statewide childhood body mass index surveillance program.

BACKGROUND: Several states have implemented childhood obesity surveillance programs supported by legislation. Representatives from Idaho wished to develop a model for childhood obesity surveillance without the support of state legislation, and subsequently report predictors of overweight and obesity in the state. METHODS: A coalition comprised of the Idaho State Department of Education and 4 universities identified a randomized cluster sample of schools. After obtaining school administrator consent, measurement teams traveled to each school to measure height and weight of students. Sex and race/ethnicity data were also collected. RESULTS: The collaboration between the universities resulted in a sample of 6735 students from 48 schools and 36 communities. Overall, 29.2% of the youth in the sample were classified as overweight or obese, ranging from 24.0% for grade 1 to 33.8% for grade 5. The prevalence of overweight and obesity across schools was highly variable (31.2 ± 7.58%). Hierarchical logistic regression indicated that sex, age, race/ethnicity, socioeconomic status, and region were all significant predictors of overweight and obesity, whereas school was not. CONCLUSIONS: This coalition enabled the state of Idaho to successfully estimate the prevalence of overweight and obesity on a representative sample of children from all regions of the state, and subsequently identify populations at greatest risk.

The US Department of Agriculture Automated Multiple-Pass Method reduces bias in the collection of energy intakes.

BACKGROUND: The US Department of Agriculture Automated Multiple-Pass Method (AMPM) is used for collecting 24-h dietary recalls in What We Eat In America, the dietary interview component of the National Health and Nutrition Examination Survey. Because the data have important program and policy applications, it is essential that the validity of the method be tested. OBJECTIVE: The accuracy of the AMPM was evaluated by comparing reported energy intake (EI) with total energy expenditure (TEE) by using the doubly labeled water (DLW) technique. DESIGN: The 524 volunteers, aged 30-69 y, included an equal number of men and women recruited from the Washington, DC, area. Each subject was dosed with DLW on the first day of the 2-wk study period; three 24-h recalls were collected during the 2-wk period by using the AMPM. The first recall was conducted in person, and subsequent recalls were over the telephone. RESULTS: Overall, the subjects underreported EI by 11% compared with TEE. Normal-weight subjects [body mass index (in kg/m(2)) < 25] underreported EI by <3%. By using a linear mixed model, 95% CIs were determined for the ratio of EI to TEE. Approximately 78% of men and 74% of women were classified as acceptable energy reporters (within 95% CI of EI:TEE). Both the percentage by which energy was underreported and the percentage of subjects classified as low energy reporters (<95% CI of EI:TEE) were highest for subjects classified as obese (body mass index > 30). CONCLUSIONS: Although the AMPM accurately reported EIs in normal-weight subjects, research is warranted to enhance its accuracy in overweight and obese persons.