Jared M. Tucker

Physical Activity in U.S. Adults Compliance with the Physical Activity Guidelines for Americans

BACKGROUND To date, no study has objectively measured physical activity levels among U.S. adults according to the 2008 Physical Activity Guidelines for Americans (PAGA). PURPOSE The purpose of this study was to assess self-reported and objectively measured physical activity among U.S. adults according to the PAGA. METHODS Using data from the NHANES 2005-2006, the PAGA were assessed using three physical activity calculations: moderate plus vigorous physical activity ≥150 minutes/week (MVPA); moderate plus two instances of vigorous physical activity ≥150 minutes/week (M2VPA); and time spent above 3 METs ≥500 MET-minutes/week (METPA). Self-reported physical activity included leisure, transportation, and household activities. Objective activity was measured using Actigraph accelerometers that were worn for 7 consecutive days. Analyses were conducted in 2009-2010. RESULTS U.S. adults reported 324.5 ± 18.6 minutes/week (M ± SE) of moderate physical activity and 73.6 ± 3.9 minutes/week of vigorous physical activity, although accelerometry estimates were 45.1 ± 4.6 minutes/week of moderate physical activity and 18.6 ± 6.6 minutes/week of vigorous physical activity. The proportion of adults meeting the PAGA according to M2VPA was 62.0% for self-report and 9.6% for accelerometry. CONCLUSIONS According to the NHANES 2005-2006, fewer than 10% of U.S. adults met the PAGA according to accelerometry. However, physical activity estimates vary substantially depending on whether self-reported or measured via accelerometer.

Television viewing and obesity in 300 women: evaluation of the pathways of energy intake and physical activity.

We assessed the roles of energy intake and physical activity in the relationships among television (TV) viewing, body composition, and obesity using high‐quality measurement methods. Adult women (n = 300) reported TV viewing behavior, which was categorized into infrequent (≤1 h/day), moderate (2 h/day), and frequent (≥3 h/day) viewing. Body fat percentage (BF%) was assessed using plethysmography (Bod Pod) and BMI was calculated from height and body weight. Energy intake and physical activity, including time spent in sedentary, moderate, and vigorous physical activity (PA), were objectively measured using 7‐day weighed food records and 7‐day accelerometry, respectively. The mean BF% of frequent TV viewers (34.6 ± 6.9%) was significantly greater (F = 3.9, P = 0.0218) than those of moderate (31.5 ± 6.7%) and infrequent viewers (30.8 ± 7.0%); however, BMI did not differ across the TV viewing groups (F = 0.8, P = 0.4172). Controlling statistically for differences in age, education, time in sedentary activity, time in moderate activity, and energy intake, considered individually, had no influence on the relationships between TV viewing and BF%, nor TV and BMI. Moreover, the relationship between TV and BF% remained significant after adjusting for differences in BMI (F = 3.6, P = 0.0276). However, adjusting for total PA reduced the relationship between TV and BF% to nonsignificance (F = 2.5, P = 0.0810), as did time spent in vigorous PA (F = 2.2, P = 0.1307). These data suggest a strong relationship between TV viewing and BF%. This association appears to be due, in part, to differences in total PA, particularly vigorous PA, but not time spent in sedentary activity, moderate activity, or energy intake.

Significant and serious dehydration does not affect skeletal muscle cramp threshold frequency

Objective Many clinicians believe that exercise-associated muscle cramps (EAMC) occur because of dehydration. Experimental research supporting this theory is lacking. Mild hypohydration (3% body mass loss) does not alter threshold frequency (TF), a measure of cramp susceptibility, when fatigue and exercise intensity are controlled. No experimental research has examined TF following significant (3–5% body mass loss) or serious hypohydration (>5% body mass loss). Determine if significant or serious hypohydration, with moderate electrolyte losses, decreases TF. Design A prepost experimental design was used. Dominant limb flexor hallucis brevis cramp TF, cramp electromyography (EMG) amplitude and cramp intensity were measured in 10 euhydrated, unacclimated men (age=24±4 years, height=184.2±4.8 cm, mass=84.8±11.4 kg). Subjects alternated exercising with their non-dominant limb or upper body on a cycle ergometer every 15 min at a moderate intensity until 5% body mass loss or volitional exhaustion (3.8±0.8 h; 39.1±1.5°C; humidity 18.4±3%). Cramp variables were reassessed posthypohydration. Results Subjects were well hydrated at the studys onset (urine specific gravity=1.005±0.002). They lost 4.7±0.5% of their body mass (3.9±0.5 litres of fluid), 4.0±1.5 g of Na+ and 0.6±0.1 g K+ via exercise-induced sweating. Significant (n=5) or serious hypohydration (n=5) did not alter cramp TF (euhydrated=15±5 Hz, hypohydrated=13±6 Hz; F1,9=3.0, p=0.12), cramp intensity (euhydrated= 94.2±41%, hypohydrated=115.9±73%; F1,9=1.9, p=0.2) or cramp EMG amplitude (euhydrated=0.18±0.06 µV, hypohydrated= 0.18±0.09 µV; F1,9=0.1, p=0.79). Conclusions Significant and serious hypohydration with moderate electrolyte losses does not alter cramp susceptibility when fatigue and exercise intensity are controlled. Neuromuscular control may be more important in the onset of muscle cramps than dehydration or electrolyte losses.

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.

Patterns of habitual physical activity in youth with and without Prader-Willi Syndrome.

Children classified as overweight or obese and those with disabilities are at a greater risk of not meeting the minimum recommendation of 60 min a day of moderate to vigorous physical activity (PA). Youth with Prader-Willi Syndrome (PWS) appear to participate in less PA compared to nonsyndromal children, likely due to syndrome-related factors. However, description of PA patterns in youth with PWS is lacking. The purpose of this study was to characterize PA in youth with PWS and to compare it to PA in children with nonsyndromal obesity. Twenty-four youth with PWS (ages 8-16 years) and 40 obese children without PWS (OB) (ages 8-11 years) wore accelerometers for eight consecutive days. Data were screened for compliance and classified into PA intensities: sedentary behavior (SED), light (LPA), moderate (MPA), vigorous (VPA) and moderate plus vigorous (MVPA). Youth with PWS spent 19.4% less time in weekly LPA (p=0.007) and 29.8% less time in weekly VPA compared to OB controls (p=0.036). All other intensities were similar between groups. In addition, PWS participated in less LPA and VPA during the weekends compared to OB, and less LPA on weekdays when compared to OB. There was also a trend towards PWS participating in less MVPA during the weekends and less VPA during the weekends than OB controls. There was a trend towards PWS participating in less VPA on weekends compared to weekdays, while OB participated similarly in VPA on weekdays and weekend days. On average, neither PWS nor OB children met minimum MVPA recommendations. The results suggest there is a need to design exercise programs for PWS youth that focus on integrating vigorous intensity activities, especially during the weekends when structured PA may not be available.

Dietary Patterns as Predictors of Body Fat and BMI in Women: A Factor Analytic Study

Purpose. To identify independent patterns of diet using factor analysis to determine the extent to which dietary patterns account for differences in body fat percentage (BF%) and body mass index (BMI). Also, to ascertain the extent to which the associations are influenced by age, education, menopause, energy intake, and physical activity. Design. Study design was cross-sectional. Setting. Study setting was approximately 20 cities in the Mountain West. Subjects. The study included 281 apparently healthy female nonsmokers. Measures. Diet was assessed using 7-day weighed food records, and foods were categorized using the American Diabetes and American Dietetic Associations Exchange Lists and expressed as servings per 1000 kcal. BF% was measured using the Bod Pod, and physical activity was estimated using accelerometers worn for 1 week. Analysis. We used factor analysis, general linear models, and partial correlations. Results. Three dietary patterns were identified: (1) Prudent Pattern, (2) Low-fat Milk, and (3) Meat. Higher consumption of the Prudent Pattern corresponded with significantly lower BF% (F = 8.5, p = .0038) and BMI (F = 4.4, p = .0363). The Low-fat Milk pattern was inversely related to BF% (F= 5.4, p = .0207) and BMI (F= 9.5, p = .0023). Higher intake of the Meat pattern was related to higher levels of BF% (F= 4.5, p= .0346) and BMI (F= 4.2, p = .0418). Conclusion. These findings support an association between dietary patterns and body composition. Dietary patterns reflect the complex interrelationships inherent in day-to-day eating and are strongly related to differences in BF% and BMI in women.

A 4-Year Prospective Study of Soft Drink Consumption and Weight Gain: The Role of Calorie Intake and Physical Activity

Purpose. Examine the association between soft drink consumption and risk of weight gain over 4 years. Also, determine if the relationship between soft drink intake and weight gain is a result of differences in calorie intake or physical activity (PA), or other potential mediating factors. Design. Four-year prospective cohort. Setting. Approximately 20 cities in Utah and Wyoming. Subjects. One hundred seventy nonsmoking, apparently healthy women. Measures. At baseline, soft drink consumption and menopause status were measured using a questionnaire; calorie intake was estimated using 7-day, weighed food records; and PA was assessed using 7-day accelerometer data. Weight was assessed using an electronic scale at baseline and follow-up. Analysis. Multiple regression and partial correlation. Results. Four-year weight gain in participants who, at baseline, consumed sugar-sweetened soft drinks (2.7 ± 5.1 kg) was greater than in participants who consumed artificially sweetened soft drinks (–.1 ± 4.4 kg) or no soft drinks (.5 ± 5.1 kg) (F = 5.4, p = .022). Adjusting for objectively measured PA had no effect on risk of weight gain. However, controlling statistically for differences in calorie intake significantly weakened the relationship between soft drink consumption and weight gain by 28%. Conclusion. Consuming artificially sweetened soft drinks or no soft drinks instead of sugar-sweetened soft drinks may help to reduce risk of weight gain in women. The relationship appears to be partly a function of differences in calorie intake, but not differences in PA.

Adherence to the 2010 Dietary Guidelines for Americans and the relationship to adiposity in young women.

OBJECTIVE To determine the relationship between adherence to the 2010 Dietary Guidelines for Americans and adiposity in young women with and without statistical adjustment for physical activity (PA). METHODS Participants included 324 young women (aged 17-25 years). The researchers measured dietary intake using the Dietary History Questionnaire and determined diet quality using the 2010 Healthy Eating Index (HEI-2010). BOD POD (Cosmed, Rome, Italy, 2006) and accelerometry were used to assess body fat and PA, respectively. RESULTS Women in the top quartile of HEI-2010 had significantly lower percent body fat than women in the lowest 3 quartiles (F = 3.36; P = .03). Controlling for objectively measured PA weakened this relationship by 20%. These young women (top quartile of HEI-2010) also had 0.37 odds (95% confidence interval, 0.16-0.85) of having body fat > 32%. CONCLUSIONS AND IMPLICATIONS Young women whose diets most closely meet the 2010 Dietary Guidelines for Americans have lower adiposity.

Characteristics of Youth Presenting for Weight Management: Retrospective National Data from the POWER Study Group.

BACKGROUND There are no existing multisite national data on obese youth presenting for pediatric weight management. The primary aim was to describe BMI status and comorbidities among youth with obesity presenting for pediatric weight management (PWM) at programs within the Pediatric Obesity Weight Evaluation Registry (POWER). METHODS Data were collected from 2009-2010 among 6737 obese patients ages 2-17. Patients were classified in three groups by BMI (kg/m(2)) cutoffs and percent of the 95th percentile for BMI: (1) obesity; (2) severe obesity class 2; and (3) severe obesity class 3. Weighted percentages are presented for baseline laboratory tests, blood pressure, and demographics. Generalized logistic regression with clustering was used to examine the relationships between BMI status and comorbidities. RESULTS Study youth were 11.6 ± 3.4 years of age, 56% female, 31% black, 17% Hispanic, and 53% publicly insured. Twenty-five percent of patients had obesity (n = 1674), 34% (2337) had severe obesity class 2, and 41% (2726) had severe obesity class 3. Logistic regression revealed that males (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.5-2.0), blacks (OR, 1.7; 95% CI, 1.5-2.0), age <6 years (OR, 2.0; 95% CI, 1.5-2.6), and public insurance (OR, 1.8; 95% CI, 1.5-2.0) had a higher odds of severe obesity class 3. Severe obesity class 3 was associated with higher odds of laboratory abnormalities for hemoglobin A1c (OR, 1.7; 95% CI, 1.3-2.2), alanine aminotransferase ≥40 U/L (OR, 1.9; 95% CI, 1.3-2.6), and elevated systolic blood pressure (OR, 2.5; 95% CI, 2.0-3.0). CONCLUSIONS Youth with obesity need earlier access to PWM given that they are presenting when they have severe obesity with significant comorbidities.

Meat Intake Increases Risk of Weight Gain in Women: A Prospective Cohort Investigation

Purpose. Examine the extent to which meat consumption influences risk of weight gain in women during a 20-month period. Additionally, to determine the extent to which demographic, lifestyle, and dietary factors influence the meat-weight gain association. Design. Prospective cohort. Setting. Two metropolitan areas of the Mountain West. Subjects. Two hundred thirty-seven middle-aged women. Measures. Diet was assessed by using 7-day weighed food records, and physical activity was measured by using accelerometers. Other potential confounders included age; initial body weight; energy intake; percentage of energy from fat, protein, and carbohydrate; dietary fiber intake per 1000 kcal; and time in the investigation. Two meat variables were studied: very lean meat (VLM) and other meat (Meat). Analysis. Multiple regression, partial correlation, and relative risk. Results. Each additional serving (1 ounce) of Meat consumed at baseline per 1000 kcal was associated with a 1.19-kg gain in weight over time (F = 7.3, p = .0073). Controlling for physical activity, fiber, and macronutrient intake, individually, strengthened the relationship. Servings of VLM per 1000 kcal were not predictive of weight change (F= .00, p = .9576). With all potential confounders controlled, the relative risk of gaining weight (>5 pounds) for women with Low Meat intake was .36 (95% confidence interval = .17–.76) compared to women with High Meat intake. Conclusion. Consuming meats other than those in the VLM category is associated with increased risk of weight gain over time.