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David A. White, Youngha Oh and Erik A. Willis

Background: Research suggests that accumulating moderate to vigorous physical activity (MVPA) in longer continuous bouts may have beneficial effects on metabolic syndrome risk factors. The objective of this study was to examine the independent associations of MVPA bout patterns on metabolic syndrome risk factors among a nationally representative sample of youth. Methods: Results are based on 3165 children and adolescents (6–18 y old) from the 2003–2006 National Health and Nutrition Examination Survey. Accelerometers measured MVPA accumulated in bouts of: <5, 5 to 10, and ≥10 minutes over 7 days. Participants were categorized into quartiles based on percentage of each bout duration. Sensitivity analysis was conducted using 3 versions of MVPA cut points for youth. A series of general linear models were used to compare metabolic syndrome risk factors between groups. Results: Youth participating in longer continuous bouts of MVPA had lower body mass index percentile (P < .02), waist circumference (WC) (P < .01), WC percentile (P < .02), and waist to height ratio (P < .01) than youth participating in shorter bouts of MVPA. When analyzed for interactions between MVPA and bout pattern quartile, only 1 cut point showed a significant interaction for WC and WC percentile. Conclusion: Longer continuous bouts of MVPA had beneficial effects on body anthropometrics and weight status, although these effects may be moderated by total MVPA.

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Jeffery J. Honas, Erik A. Willis, Stephen D. Herrmann, Jerry L. Greene, Richard A. Washburn and Joseph E. Donnelly


There is limited data regarding objectively measured energy cost and intensity of classroom instruction. Therefore, the purpose of current study was to objectively measure energy cost and subsequently calculate MET values using a portable indirect calorimeter (IC) for both normal classroom instruction (NCI) and active classroom instruction (ACI).


We assessed energy expenditure (EE) and intensity levels (METs) in elementary school children (17 boys and 15 girls) using an IC (COSMED K4b2). Independent t-tests were used to evaluate potential sex and grade level differences for age, BMI, VO2, EE, and METs.


The average EE for NCI and ACI were 1.8 ± 0.4 and 3.9 ± 1.0, respectively. The average intensity level for NCI and ACI were 1.9 ± 0.4 and 4.2 ± 0.9 METs, respectively.


PA delivered through ACI can elicit EE at a moderate intensity level. These results provide evidence for ACI as a convenient/feasible avenue for increasing PA in youth without decreasing instruction time.

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Erik A. Willis, Amanda N. Szabo-Reed, Lauren T. Ptomey, Jeffery J. Honas, Felicia L. Steger, Richard A. Washburn and Joseph E. Donnelly

Background: High-intensity functional training (HIFT) may offer an attractive, time-efficient alternative to traditional aerobic exercise. However, limited information is available in the literature regarding HIFT meeting exercise guidelines for energy expenditure (improve health outcomes: ≥1000 kcal/wk; weight management: ≥2000 kcal/wk) and level of intensity (moderate: 3–6 metabolic equivalents [METs], vigorous: ≥6 METs) elicited by this approach. Thus, the primary aim was to objectively measure energy expenditure and intensity of HIFT sessions. Methods: Energy expenditure was assessed in 20 adults (18–50 y, 50% females). The HIFT session format included the following segments: warm-up (∼5 min), exercise (∼35 min), and cooldown (∼5 min). Participant oxygen consumption (COSMED, L/min and mL/kg/min), heart rate (Polar RS400), and physical activity (ActiGraph GT3X+) were collected in 15-second intervals. Average kcal per minute, METs, total kcal per session, and percent maximum heart rate (HRmax) were calculated. Results: METs ranged from 5.5 to 11.6 for the complete session (including warm-up and cooldown). Participant’s HRmax was ∼80% (range: 69%–100%). Average energy expenditure was ∼485 kcal per session (∼1400 kcal/wk). The vigorous-intensity exercise portion (∼35 min) contributed to 80% of total energy expenditure. Conclusions: HIFT has the potential to meet the recommendations for exercise to improve health outcomes.

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David A. White, Erik A. Willis, Chaitanya Panchangam, Kelli M. Teson, Jessica S. Watson, Brian F. Birnbaum, Girish Shirali and Anitha Parthiban

Purpose: To quantify the differences in daily physical activity (PA) patterns, intensity-specific volumes, and PA bouts in youth with and without heart disease (HD). Methods: Seven-day PA was measured on children/adolescents with HD (n = 34; median age 12.4 y; 61.8% male; 70.6% single ventricle, 17.7% heart failure, and 11.8% pulmonary hypertension) and controls without HD (n = 22; median age 12.3 y; 59.1% male). Mean counts per minute were classified as sedentary, light, and moderate to vigorous PA (MVPA), and bouts of MVPA were calculated. PA was calculated separately for each hour of wear time from 8:00 to 22:00. Multilevel linear mixed modeling compared the outcomes, stratifying by group, time of day, and day part (presented as median percentage of valid wear time [interquartile range]). Results: Compared with the controls, the HD group had more light PA (33.9% [15%] vs 29.6% [9.5%]), less MVPA (1.7% [2.5%] vs 3.2% [3.3%]), and more sporadic bouts (97.4% [5.7%] vs 89.9% [9.2%]), but fewer short (2.0% [3.9%] vs 7.1% [5.7%]) and medium-to-long bouts (0.0% [1.9%] vs 1.6% [4.6%]) of MVPA. The HD group was less active in the late afternoon, between 15:00 and 17:00 (P < .03). There were no differences between groups in sedentary time. Conclusion: Children/adolescents with HD exhibit differences in intensity-specific volumes, PA bouts, and daily PA patterns compared with controls.