The aim was to investigate (a) the effect of five different time sampling intervals (epoch settings) on different intensity levels when assessing physical activity with an accelerometer (CSA, WAM 7164), and (b) whether the placement of the monitor (on the hip and back) would affect the outcome. Sixteen children (aged 7 yrs) were monitored for four consecutive days. A significant main epoch effect was found for time spent at very high (p < .01) and high (p < .01) intensity activities. No significant difference between the two placements regarding total amount of physical activity (cnts • min−1) or different intensity levels was observed. In conclusion, different time sampling intervals, but not placement, should be carefully considered when assessing physical activity.
Andreas Nilsson, Ulf Ekelund, Agneta Yngve and Michael Söström
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.
Fuzhong Li and Peter Harmer
This study was designed to assess the factorial construct validity of the Group Environment Questionnaire (GEQ; Carron, Widmeyer, & Brawley, 1985) within a hypothesis-testing framework. Data were collected from 173 male and 148 female intercollegiate athletes. Based on Carron et al.’s (1985) conceptual model of group cohesion, the study examined (a) the extent to which the first-order four-factor model could be confirmed with an intercollegiate athlete sample and (b) the degree to which higher order factors could account for the covariation among the four first-order factors. The a priori models of GEQ, including both the first- and second-order factor models, were tested through confirmatory factor analysis (CFA). CFA results showed that the theoretically specified first- and second-order factor models fit significantly better than all alternative models. These results demonstrated that the GEQ possesses adequate factorial validity and reliability as a measure of the sport group cohesion construct for an intercollegiate athlete sample.
Timothy K. Behrens and Mary K. Dinger
The purpose of this study was to compare steps·d-1 between an accelerometer and pedometer in 2 free-living samples.
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.
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).
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.
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.
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.
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.
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.
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).
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.
Robert E. Davis and Paul D. Loprinzi
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).
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.
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.
In this national sample of U.S. children, adolescents and adults, we did not observe sufficient evidence of accelerometer reactivity.
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.
Alex Pinheiro Gordia, Teresa Maria Bianchini de Quadros, Jorge Mota and Luciana Rodrigues Silva
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.
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.
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%).
A universal step-count recommendation for young people may not be adequate and specific guidelines seem to be necessary for different countries or regions.
Maureen M. Bylina, Tzyy-Chyn Hu, Terrence J. Conway, Jane Perrin, Jennifer L. Eldridge Houser, Jennifer Hurst and Carolyn C. Cox
This study assessed perceptions about exercise among a convenience sample of low-income, urban, older adult patients at a publicly operated ambulatory primary-care clinic, and results were then compared with the findings of a national study. Although it was expected that the predominantly minority and economically disadvantaged participants in this study would trail significantly behind their White counterparts in their perceptions and behavior regarding exercise, findings demonstrated otherwise. Specifically, when physicians encourage moderate exercise, when patients believe that they can overcome barriers to exercise, and when the environment supports moderate exercise through the availability of community exercise classes, inequities in health behaviors can be reduced. Interventions designed to increase exercise for this population should be developed with an understanding of the many barriers that they will have to overcome, a focus on building confidence, and communicating the many benefits of this behavior.