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Brian Cook, Trisha M. Karr, Christie Zunker, James E. Mitchell, Ron Thompson, Roberta Sherman, Ross D. Crosby, Li Cao, Ann Erickson and Stephen A. Wonderlich

The purpose of our study was to examine exercise dependence (EXD) in a large community-based sample of runners. The secondary purpose of this study was to examine differences in EXD symptoms between primary and secondary EXD. Our sample included 2660 runners recruited from a local road race (M age = 38.78 years, SD = 10.80; 66.39% women; 91.62% Caucasian) who completed all study measures online within 3 weeks of the race. In this study, EXD prevalence was lower than most previously reported rates (gamma = .248, p < .001) and individuals in the at-risk for EXD category participated in longer distance races, F(8,1) = 14.13, p = .01, partial eta squared = .05. Group differences were found for gender, F(1,1921) 8.08, p = .01, partial eta squared = .004, and primary or secondary group status, F(1,1921) 159.53, p = .01, partial eta squared = .077. Implications of primary and secondary EXD differences and future research are discussed.

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Susan C. Duncan, Lisa A. Strycker, Terry E. Duncan and Nigel R. Chaumeton

It is important that studies on youth health behavior obtain sufficiently large representative samples so that power is adequate and results are generalizable. However, few researchers have documented procedures and methods for recruitment of a random stratified youth sample for studies on health-related behavior, specifically physical activity. This study describes the recruitment methods used to attain a stratified sample of 360 target youth (boys and girls from 10-, 12-, and 14-year-old cohorts), and a parent of each child, representing families in 58 neighborhoods. A peer of each target youth was also invited to participate. Recruitment was conducted primarily by telephone, using computer-assisted telephone interviewing (CATI) software. Approximately 38% of calls resulted in person contact, of which about 98% of families did not qualify. Of those qualified, about 68% agreed to participate. The telephone recruitment was supplemented by door-to-door recruitment in selected neighborhoods. The average cost of recruitment was approximately $99 per family by telephone and $64 door to door. Advantages and limitations of the recruitment method are discussed.

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Timothy K. Behrens and Mary K. Dinger

Background:

The purpose of this study was to compare steps·d-1 between an accelerometer and pedometer in 2 free-living samples.

Methods:

Data from 2 separate studies were used for this secondary analysis (Sample 1: N = 99, Male: n = 28, 20.9 ± 1.4 yrs, BMI = 27.2 ± 5.0 kg·m-2, Female: n = 71, 20.9 ± 1.7 yrs, BMI = 22.7 ± 3.0 kg·m-2; Sample 2: N = 74, Male: n = 27, 38.0 ± 9.5 yrs, BMI = 25.7 ± 4.5 kg·m-2, Female: n = 47, 38.7 ± 10.1 yrs, BMI = 24.6 ± 4.0 kg·m-2). Both studies used identical procedures and analytical strategies.

Results:

The mean difference in steps·d-1 for the week was 1643.4 steps·d-1 in Study 1 and 2199.4 steps·d-1 in Study 2. There were strong correlations between accelerometer- and pedometer-determined steps·d-1 in Study 1 (r = .85, P < .01) and Study 2 (r = 0.87, P < .01). Bland-Altman plots indicated agreement without bias between steps recorded from the devices in Study 1 (r = −0.14, P < .17) and Study 2 (r = −0.09, P < .40). Correlations examining the difference between accelerometer–pedometer steps·d-1 and MVPA resulted in small, inverse correlations (range: r = −0.03 to −0.28).

Conclusions:

These results indicate agreement between accelerometer- and pedometer-determined steps·d-1; however, measurement bias may still exist because of known sensitivity thresholds between devices.

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Simon Fryer, Tabitha Dickson, Stephen Hillier, Lee Stoner, Carl Scarrott and Nick Draper

Venipuncture is expensive, invasive, and impractical for many sport-science and clinical-based settings. Salivary free cortisol is often cited as a noninvasive practical alternative. However, when cortisol concentrations exceed the corticosteroid-binding globulin (CBG) point of 500 nmol/L, a lack of agreement between salivary and venous blood cortisol has been found. Alternatively, capillary blood may present a minimally invasive, cost-effective, and practical surrogate for determining cortisol concentration.

Purpose:

The aim of this study was to determine whether cortisol concentrations sampled from capillary blood and saliva accurately reflect those found in venous blood across a large range of concentrations after intense exercise.

Methods:

Eleven healthy aerobically trained male subjects were recruited. Capillary, salivary, and venous blood samples were collected before and after (immediately and 5, 10, 15, and 20 min after) a treadmill VO2 max test.

Results:

Capillary and venous concentrations increased at a similar rate after exercise (Cohen d.14–.33), increasing up to 15 min postexercise before a decline was seen. Salivary cortisol values increased at a slower rate than venous and capillary cortisol but continued to increase 15 min postexercise (Cohen d .19–.47 and .09–.72, respectively).

Conclusions:

Capillary cortisol accurately reflects concentrations assayed from venous blood across a range of values below and above the CBG binding point. Capillary sampling provides a minimally invasive, cost-effective, practical surrogate for assessment of hypothalamic-pituitary-gland function.

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Alex Pinheiro Gordia, Teresa Maria Bianchini de Quadros, Jorge Mota and Luciana Rodrigues Silva

Purpose:

Weight status-referenced pedometer step-count guidelines for young people have been developed for populations from high-income countries and may not be applicable to middle- and low-income countries. The objectives of this study were 1) to develop cut-off points for pedometer-determined step count in young Brazilians using waist circumference (WC) as a reference criterion, and 2) to analyze the capacity of previous recommendations to discriminate abdominal obesity in the sample studied.

Methods:

A cross-sectional study was conducted on 1,044 schoolchildren (456 boys) aged 6–17 years from Northeastern Brazil. WC was measured and daily step counts were determined with a pedometer.

Results:

The area under the curve (AUC) of step count was significant for boys (AUC = 0.55; 95%CI: 0.50–0.59) and girls (AUC = 0.57; 95%CI: 0.53–0.61). Our cut-off points (14,414 and 11,355 steps for boys and girls, respectively) were more balanced in terms of sensitivity and specificity compared with previous recommendations. The use of previous guidelines to classify step count in the sample provided very low sensitivity or specificity and wide variation in the prevalence of insufficient physical activity (39.3–77.0%).

Conclusions:

A universal step-count recommendation for young people may not be adequate and specific guidelines seem to be necessary for different countries or regions.

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Deborah Leachman Slawson, Barbara S. McClanahan, Linda H. Clemens, Kenneth D. Ward, Robert C. Klesges, Christopher M. Vukadinovich and Edwin D. Cantler

Adequate calcium intake is integral to bone health as well as for optimal athletic performance. This study was conducted to investigate: (a) food sources of calcium in a sample of collegiate athletes, (b) gender and/or ethnic differences in food sources of calcium, and (c) whether athletes that derive less of their calcium intake from dairy sources increase their calcium intake from supplements or other food sources. Participants were African-American and Euro-American NCAA Division 1-A athletes. Eighty-five men and 59 women participated. Calcium intake for the previous 7-day period was assessed with a brief calcium screen.

Men consumed significantly more calcium than women (1,354 vs. 898 mg/day), with female cross-country runners exhibiting the lowest average intake (605 mg/day). Both men and women obtained the majority of their calcium from dairy products and mixed dishes, while men consumed significantly more calcium-fortified foods. Several gender and ethnic interactions for calcium intake from food groups were found. Mean total dairy calcium intake was found to vary according to total calcium intake in men, and supplemental calcium was not used to augment low dairy intakes of calcium in any group.

While African-Americans and Euro-Americans athletes were consuming similar levels of calcium, the female athletes in the sample did not get adequate amounts.

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Robert E. Davis and Paul D. Loprinzi

Objectives:

To examine whether accelerometer-measured physical activity–based reactivity was present in a nationally representative sample of U.S. children (6–11 yrs), adolescents (12–17 yrs), and adults (≥20 yrs).

Methods:

Data from the 2003–2006 National Health and Nutrition Examination Survey (N = 674, 6–85 yrs) were used. Physical activity (PA) was assessed using the ActiGraph 7164 accelerometer, with PA assessed over 7 days of monitoring. Two PA metrics were assessed, including activity counts per day (CPD) and time spent in moderate-to-vigorous PA. Evidence of reactivity was defined as a statistically significantly change in either of these 2 PA metrics from day 1 of monitoring to days 2 or 3, with day 1 of monitoring being a Monday.

Results:

Suggestion of reactivity was observed only for the adult population where CPD from days 2 and 3 (297,140.6 ± 7920.3 and 295,812.9 ± 8364.9), respectively, differed significantly from day 1 (309,611.5 ± 9134.9) over the monitoring period (4.0% to 4.5% change). The analysis was conducted 2 additional times with differing start days (Tuesday and Wednesday), and this approach failed to demonstrated a reactive presence.

Conclusion:

In this national sample of U.S. children, adolescents and adults, we did not observe sufficient evidence of accelerometer reactivity.

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Renee Beach Sample, Kurt Jackson, Allison L. Kinney, Wiebke S. Diestelkamp, Senia Smoot Reinert and Kimberly Edginton Bigelow

Falls occur in 33% of older adults each year, some leading to moderate to severe injuries. To reduce falls and fall-related injuries, it is important to identify individuals with subtle risk factors elevating their likelihood of falling. The objective of this study was to determine how postural sway measures differed between fallers and nonfallers under standard and dual-task conditions. Quietstanding posturography measures were collected from 150 older adults during standard, cognitive, manual, and cognitive+manual tasks, and analyzed through traditional and nonlinear analyses. Of the traditional measures, M/L sway range and 95% confidence ellipse sway area showed statistically significant differences in all 4 test conditions between fallers and nonfallers. Although the manual dual task showed the most stable balance, effect sizes demonstrated larger differences between fallers and nonfallers. Nonlinear analysis revealed M/L sample entropy and M/L α-scaling exponent differentiating between fallers and nonfallers, with the cognitive task demonstrating larger differences. Based on the results, it is recommended to: (1) apply M/L sway range and 95% confidence ellipse area, (2) use the manual task to differentiate between fallers and nonfallers when using traditional analyses, and (3) use the cognitive task and M/L alpha and M/L sample entropy when using nonlinear analyses.

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Constantinos A. Loucaides, Sue M. Chedzoy, Neville Bennett and Karen Walshe

This study examined the association between self-reported physical activity and a number of potential correlates in a sample of 256 Grade-6 children. Physical activity was assessed in both summer and winter, and children and parents completed questionnaires assessing potential correlates of physical activity. Analyses revealed that gender, time spent playing outside, self-efficacy in overcoming barriers, and number of items of exercise equipment at home were variables associated with physical activity in both seasons. School location was a variable associated with physical activity only in the summer, whereas private-lesson attendance, sports-club attendance, and best friend’s physical activity were variables associated with physical activity only in winter. Variance explained in physical activity were 42% and 51% in winter and summer, respectively.

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Sam Zizzi, Dave Goodrich, Ying Wu, Lindsey Parker, Sheila Rye, Vivek Pawar, Carol Mangone and Irene Tessaro

Although much has been learned about the global determinants of physical activity in adults, there has been a lack of specific focus on gender, age, and urban/rural differences. In this church-based community sample of Appalachian adults (N = 1,239), the primary correlates of physical activity included age, gender, obesity, and self-efficacy. Overall, 42% of all participants and 31% of adults age 65 years or older met recommended guidelines for physical activity, which suggests that most participants do not engage in adequate levels of physical activity. Of participants who met physical activity guidelines, the most common modes of moderate and vigorous activity were walking briskly or uphill, heavy housework or gardening, light strength training, and biking. These particular activities that focus on building self-efficacy might be viable targets for intervention among older adults in rural communities.