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Yuri Feito, David R. Bassett, Dixie L. Thompson and Brian M. Tyo

Background:

Activity monitors are widely used in research, and are currently being used to study physical activity (PA) trends in the US and Canada. The purpose of this study was to determine if body mass index (BMI) affects the step count accuracy of commonly used accelerometer-based activity monitors during treadmill walking.

Methods:

Participants were classified into BMI categories and instructed to walk on a treadmill at 3 different speeds (40, 67, and 94 m·min−1) while wearing 4 accelerometer-based activity monitors (ActiGraph GT1M, ActiCal, NL-2000, and StepWatch).

Results:

There was no significant main effect of BMI on pedometer accuracy. At the slowest speed, all waist-mounted devices significantly underestimated actual steps (P < .001), with the NL-2000 recording the greatest percentage (72%). At the intermediate speed, the ActiGraph was the least accurate, recording only 80% of actual steps. At the fastest speed, all of the activity monitors demonstrated a high level of accuracy.

Conclusion:

Our data suggest that BMI does not greatly affect the step-counting accuracy of accelerometer-based activity monitors. However, the accuracy of the ActiGraph, ActiCal, and NL-2000 decreases at slower speeds. The ankle-mounted StepWatch was the most accurate device across a wide range of walking speeds.

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Ellen Yard and Dawn Comstock

Background:

There are over 7 million US high school athletes and one-third are overweight or obese. Our objective was to examine injury patterns by body mass index (BMI) in high school athletes.

Methods:

Certified athletic trainers (ATCs) at 100 nationally representative US high schools submitted exposure and injury information during the 2005 to 08 school years via High School RIO (Reporting Information Online). We retrospectively categorized injured athletes as underweight (≤15th percentile), normal weight (15th−85th percentile), overweight (85th−95th percentile), or obese (≥95th percentile).

Results:

ATCs reported 13,881 injuries during 5,627,921 athlete-exposures (2.47 injuries per 1000 athlete-exposures). Nearly two-thirds (61.4%) of injured high school athletes were normal weight. The prevalence of overweight and obesity was highest among injured football athletes (54.4%). Compared with normal weight athletes, obese athletes sustained a larger proportion of knee injuries (Injury Proportion Ratio [IPR] = 1.27, 95% CI: 1.14 to 1.42) and their injuries were more likely to have resulted from contact with another person (IPR = 1.31, 95% CI: 1.26 to 1.37). Compared with normal weight athletes, underweight athletes sustained a larger proportion of fractures (IPR = 1.45, 95% CI: 1.10 to 1.92) and a larger proportion of injuries resulting from illegal activity (IPR = 1.59, 95% CI: 1.03 to 2.46).

Conclusions:

Injury patterns differ by BMI. BMI-targeted preventive interventions should be developed to help decrease sports injury rates.

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Reid Reale, Gregory R. Cox, Gary Slater and Louise M. Burke

We examined the relationship between the regain of body mass (BM) after weigh-in and success in real-life judo competition. Eighty-six (36 females, 50 males) senior judoka volunteered for this observational study of an international judo competition. Subjects were weighed at the official weigh-in and one hour before their first competition fight (15–20 hr later). Regain in BM after weigh-in was compared between medal winners and nonmedalists, winners and losers of each fight, males and females and across weight divisions. Heavyweights were excluded from analysis. Prefight BM was greater than BM at official weigh-in for both males and females, with % BM gains of 2.3 ± 2.0 (p ≤ .0001; ES= 1.59; CI95% [1.63, 2.98]) and 3.1 ± 2.2 (p ≤ .0001; ES = 2.03; CI95% [2.30, 3.89]), respectively. No significant differences were found between weight divisions for post weigh-in BM regain. Differences in post weigh-in BM regain were significantly higher in medal winners than nonmedalists for males and females combined (1.4 ± 0.4% BM; p = .0026; ES= 0.69; CI95% [0.05, 2.34]) and for males alone (1.5 ± 0.6% BM; p = .017; ES= 0.74; CI95% [0.02, 2.64]), but not for females (1.2 ± 0.7% BM; p = .096; ES = 0.58; CI95% [-0.02, 2.31]). Differences in BM regain after weigh-in between winners and losers were significant across all fights (0.9 ± 0.3% BM; p = .0021; ES= 0.43; CI95% [0.31, 1.41]) but not for first round fights (0.8 ± 0.5% BM; p = .1386, ES = 0.38; CI95% [-0.26, 1.86]). Winners showed a greater regain in BM post weigh-in than losers. This may reflect the greater magnitude of the BM loss needed to achieve weigh-in targets which also relates to the experience level of successful athletes.

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Katie J. Thralls, Jeanne F. Nichols, Michelle T. Barrack, Mark Kern and Mitchell J. Rauh

Early detection of the female athlete triad is essential for the long-term health of adolescent female athletes. The purpose of this study was to assess relationships between common anthropometric markers (ideal body weight [IBW] via the Hamwi formula, youth-percentile body mass index [BMI], adult BMI categories, and body fat percentage [BF%]) and triad components, (low energy availability [EA], measured by dietary restraint [DR], menstrual dysfunction [MD], low bone mineral density [BMD]). In the sample (n = 320) of adolescent female athletes (age 15.9± 1.2 y), Spearman’s rho correlations and multiple logistic regression analyses evaluated associations between anthropometric clinical cutoffs and triad components. All underweight categories for the anthropometric measures predicted greater likelihood of MD and low BMD. Athletes with an IBW ≤85% were nearly 4 times more likely to report MD (OR = 3.7, 95% CI [1.8, 7.9]) and had low BMD (OR = 4.1, 95% CI [1.2, 14.2]). Those in <5th percentile for their age-specific BMI were 9 times more likely to report MD (OR 9.1, 95% CI [1.8, 46.9]) and had low BMD than those in the 50th to 85th percentile. Athletes with a high BF% were almost 3 times more likely to report DR (OR = 2.8, 95% CI [1.4, 6.1]). Our study indicates that low age-adjusted BMI and low IBW may serve as evidence-based clinical indicators that may be practically evaluated in the field, predicting MD and low BMD in adolescents. These measures should be tested for their ability as tools to minimize the risk for the triad.

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Tina Smith, Sue Reeves, Lewis G. Halsey, Jörg Huber and Jin Luo

decrease in physical activity has been shown to have an inverse relationship with body mass. 3 , 4 Furthermore, obese people who undertake more physical activity have been shown to be metabolically healthier than their less active counterparts. 5 , 6 It is still unclear as to the effects of being

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Danielle Symons Downs, Krista S. Leonard, Jessica S. Beiler and Ian M. Paul

 higher risk), race/ethnicity (minorities at greater risk), and parity. 17 , 22 Specific to parity, primiparous women (first-time mothers) are at greater risk for high GWG than multiparous women (mothers with 1 child or more already), and this risk is observed across women of all body mass index (BMI

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Arny A. Ferrando and Nancy R. Green

The effect of boron supplementation was investigated in 19 male bodybuilders, ages 20–27 years. Ten were given a 2.5-mg boron supplement while 9 were given a placebo every day for 7 weeks. Plasma total and free testosterone, plasma boron, lean body mass, and strength measurements were determined on Days 1 and 49 of the study. Plasma boron values were significantly (p<0.05) different as the experimental group increased from (±SD) 20.1 ±7.7 ppb pretest to 32.6 ±27.6 ppb posttest, while the control group mean decreased from 15.1 ±14.4 ppb pretest to 6.3 ±5.5 ppb posttest. Analysis of variance indicated no significant effect of boron supplementation on any of the dependent variables. Both groups demonstrated significant increases in total testosterone, lean body mass, 1-RM squat, and 1-RM bench press. The findings suggest that 7 weeks of bodybuilding can increase total testosterone, lean body mass, and strength in lesser trained bodybuilders, and that boron supplementation had no effect on these measures.

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Molly Burger and Dennis Dolny

The purpose of this study was to examine the relationships among body mass index (BMI), body image perception, physical activity habits, and exercise stage of change in college-aged females. Volunteers (N = 134) completed a survey of demographics, Stage of Exercise Scale (SOES; Cardinal, 1995a; Cardinal, 1995b), Physical Activity History questionnaire (PAH; Jacobs, Hahn, Haskell, Pirie, & Sidney, 1989), and Body Shape Questionnaire (BSQ; Cooper, Taylor, Cooper, & Fairburn, 1987). Participants were categorized into five exercise stages of change: precontemplation, contemplation, preparation, action, and maintenance. Relationships between the variables were analyzed with Pearson r correlations. Kruskal-Wallis independence tests were also used for analyses. Approximately 60% of the participants reported current physical inactivity or irregular exercise. BMI and body image score were significantly linearly related, with higher body mass indicating more negative body image (r = 30, p <.017). Significant differences existed between exercise stages for physical activity score, X2 (3, N = 134) = 19.98, p <.05. Based upon follow-up tests participants in the maintenance stage had significantly higher physical activity scores than all other stages. No significant differences were found for BMI or body image between exercise stages. Regular exercisers had the highest frequency of disordered eating and weight-preoccupied attitudes and behaviors. The majority of these women were not currently regularly physically active, professed dissatisfaction with their current level of activity, and expressed a fear of being fat. Further study directed at specific factors related to body image and exercise behaviors, as well as the impact of stage-specific interventions are suggested.

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Ai-Wen Hwang, Chiao-Nan Chen, I-Chin Wu, Hsin-Yi Kathy Cheng and Chia-Ling Chen

This cross-sectional study investigated the correlates of body mass index (BMI) and risk factors for overweight among 91 children with motor delay (MD) aged 9–73 months. Anthropometric measurements and questionnaires regarding multiple risk factors were obtained. Simple correlations between BMI percentile classifications and potential predictors were examined using Spearman’s rank/Pearson’s correlations and χ2 analysis. Multiple predictors of overweight were analyzed using logistic regression. BMI was correlated positively with higher caloric intake (rs = .21, p < .05) and negatively with passive activity (rs = -.21, p < .05). When multiple predictors were considered, more severe dysphagia (odds ratio [OR], 2.81, p = .027, 95% confidence interval [CI], 1.13–7.04) and antiepileptic drug use (OR, 19.12, p = .008, 95% CI, 2.14–170.81) had significant partial effects on overweight status. Agencies supporting early development should consider caregiver education regarding the potential implication of feeding style and medication on BMI.

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Barbara Coiro Spessato, Carl Gabbard and Nadia C. Valentini

Our goal was to investigate the role of body mass index (BMI) and motor competence (MC) in children’s physical activity (PA) levels during physical education (PE) classes. We assessed PA levels of 5-to-10-year old children (n = 264) with pedometers in four PE classes. MC was assessed using the TGMD-2 and BMI values were classified according to CDC guidelines. We found small-to-moderate positive correlations between MC and PA; BMI was not significantly correlated with MC and PA. The linear regression model indicated that overall MC was a better predictor of PA than BMI. Our results suggest that children with higher MC find a way to be more active even in a structured setting such as a PE class. Our findings draw attention to the importance of promoting MC, especially for children with high BMI.