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  • Author: John J. Jakicic x
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Seth A. Creasy, Renee J. Rogers, Thomas D. Byard, Robert J. Kowalsky and John M. Jakicic

Background:

Identifying strategies to increase energy expenditure (EE) may help combat the harmful effects of sedentary behavior. This study examined EE during sitting, standing, and walking.

Methods:

Participants (N = 74) were randomized to 2 of the following activities: sitting using a laptop computer (SIT-C), sitting watching television (SIT-T), standing watching television (STAND), and walking at a self-selected pace ≤3.0 (mph) (WALK). Each activity lasted 15 minutes with a 3-minute transition period between activities. The experimental conditions were: SIT-C to STAND (N = 18), SIT-T to WALK (N = 18), STAND to SIT-C (N = 20), and WALK to SIT-T (N = 18). EE was measured using indirect calorimetry.

Results:

Based on the first activity performed, EE during WALK (55.92 ± 14.19 kcal) was significantly greater than SIT-C (19.63 ± 6.90 kcal), SIT-T (18.66 ± 4.01 kcal), and STAND (21.92 ± 5.08 kcal) (P < .001). Cumulative EE in SIT-T to WALK (74.50 ± 17.88 kcal) and WALK to SIT-T (82.72 ± 21.70 kcal) was significantly greater than EE in SIT-C to STAND (45.38 ± 14.78 kcal) and STAND to SIT-C (45.64 ± 9.69 kcal) (P < .001).

Conclusions:

Conclusion: Substituting periods of sitting or standing with walking significantly increases EE, but substituting periods of sitting with standing may not affect EE. Thus, the potential benefits of standing as opposed to sitting need further investigation beyond the role of EE.

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Robert J. Kowalsky, Sophy J. Perdomo, John M. Taormina, Christopher E. Kline, Andrea L. Hergenroeder, Jeffrey R. Balzer, John M. Jakicic and Bethany Barone Gibbs

Background: Limited research examines the influence of sit-stand desks on ratings of discomfort, sleepiness, and fatigue. This study evaluated the time course of these outcomes over 1 day. Methods: Adults (N = 25) completed a randomized cross-over study in a laboratory with two 8-hour workday conditions: (1) prolonged sitting (SIT) and (2) alternating sitting and standing every 30 minutes (SIT-STAND). Sleepiness was assessed hourly. Discomfort, physical fatigue, and mental fatigue were measured every other hour. Linear mixed models evaluated whether these measures differed across conditions and the workday. Effect sizes were calculated using Cohen’s d. Results: Participants were primarily white (84%) males (64%), with mean (SD) body mass index of 31.9 (5.0) kg/m2 and age 42 (12) years. SIT-STAND resulted in decreased odds of discomfort (OR = 0.37, P = .01) and lower overall discomfort (β = −0.19, P < .001, d = 0.42) versus SIT. Discomfort during SIT-STAND was lower in the lower and upper back, but higher in the legs (all Ps< .01, d = 0.26–0.42). Sleepiness (β = −0.09, P = .01, d = 0.15) and physical fatigue (β = −0.34, P = .002, d = 0.34) were significantly lower in SIT-STAND. Mental fatigue was similar across conditions. Conclusions: Sit-stand desks may reduce acute levels of sleepiness, physical fatigue, and both overall and back discomfort. However, levels of lower extremity discomfort may be increased with acute exposure.

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G. Gregory Haff, Alexander J. Koch, Jeffrey A. Potteiger, Karen E. Kuphal, Lawrence M. Magee, Samuel B. Green and John J. Jakicic

The effects of carbohydrate (CHO) supplementation on muscle glycogen and resistance exercise performance were examined with eight highly resistance trained males (mean ± SEM, age: 24.3 ± 1.1 years, height: 171.9±2.0 cm, body mass: 85.7 ± 3.5 kg; experience 9.9 ± 2.0 years). Subjects participated in a randomized, double blind protocol with testing sessions separated by 7 days. Testing consisted of an initial isokinetic leg exercise before and after an isotonic resistance exercise (IRT) session consisting of 3 leg exercises lasting ~39 min. Subjects consumed a CHO (1.0 g CHO ·kg body mass−1) or placebo treatment (PLC), prior to and every 10-min (0.5 g CHO ·kg body mass−1) during the IRT. Muscle tissue was obtained from the m vastus lateralis after a supine rest (REST) immediately after the initial isokinetic test (POST-ISO) and immediately after the IRT (POST-IRT). The CHO treatment elicited significantly less muscle glycogen degradation from the POST-ISO to POST-IRT (126.9 ± 6.5 to 109.7 ± 7.1 mmol·kg wet weight−1) compared to PLC (121.4±8.1 to 88.3±6.0 mmol·kg wet weight−1). There were no differences in isokinetic performance between the treatments. The results of this investigation indicate that the consumption of a CHO beverage can attenuate the decrease in muscle glycogen associated with isotonic resistance exercise but does not enhance the performance of isokinetic leg exercise.

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Robin P. Shook, Nicole C. Gribben, Gregory A. Hand, Amanda E. Paluch, Gregory J. Welk, John M. Jakicic, Brent Hutto, Stephanie Burgess and Steven N. Blair

Background:

Subjective measures of moderate and vigorous physical activity (MVPA) rely on relative intensity whereas objective measures capture absolute intensity; thus, fit individuals and unfit individuals may perceive the same activity differently.

Methods:

Adults (N = 211) wore the SenseWear Armband (SWA) for 10 consecutive days to objectively assess sedentary time and MVPA. On day 8, participants completed the International Physical Activity Questionnaire (IPAQ) to subjectively assess sitting time and MVPA. Fitness was assessed via a maximal treadmill test, and participants were classified as unfit if the result was in the bottom tertile of the study population by sex or fit if in the upper 2 tertiles.

Results:

Overall, estimates of MVPA between the IPAQ and SWA were not significantly different (IPAQ minus SWA, 67.4 ± 919.1 MVPA min/wk, P = .29). However, unfit participants overestimated MVPA using the IPAQ by 37.3% (P = .02), but fit participants did not (P = .99). This between-group difference was due to overestimation, using the IPAQ, of moderate activity by 93.8 min/wk among the unfit individuals, but underestimation of moderate activity among the fit participants by 149.4 min/wk.

Conclusion:

Subjective measures of MVPA using the IPAQ varied by fitness category; unfit participants overestimated their MVPA and fit participants accurately estimated their MVPA.

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Sally A. Sherman, Renee J. Rogers, Kelliann K. Davis, Ryan L. Minster, Seth A. Creasy, Nicole C. Mullarkey, Matthew O’Dell, Patrick Donahue and John M. Jakicic

Background:

Whether the energy cost of vinyasa yoga meets the criteria for moderate-to-vigorous physical activity has not been established.

Purpose:

To compare energy expenditure during acute bouts of vinyasa yoga and 2 walking protocols.

Methods:

Participants (20 males, 18 females) performed 60-minute sessions of vinyasa yoga (YOGA), treadmill walking at a self-selected brisk pace (SELF), and treadmill walking at a pace that matched the heart rate of the YOGA session (HR-Match). Energy expenditure was assessed via indirect calorimetry.

Results:

Energy expenditure was significantly lower in YOGA compared with HR-Match (difference = 79.5 ± 44.3 kcal; P < .001) and SELF (difference = 51.7 ± 62.6 kcal; P < .001), but not in SELF compared with HR-Match (difference = 27.8 ± 72.6 kcal; P = .054). A similar pattern was observed for metabolic equivalents (HR-Match = 4.7 ± 0.8, SELF = 4.4 ± 0.7, YOGA = 3.6 ± 0.6; P < .001). Analyses using only the initial 45 minutes from each of the sessions, which excluded the restorative component of YOGA, showed energy expenditure was significantly lower in YOGA compared with HR-Match (difference = 68.0 ± 40.1 kcal; P < .001) but not compared with SELF (difference = 15.1 ± 48.7 kcal; P = .189).

Conclusions:

YOGA meets the criteria for moderate-intensity physical activity. Thus, YOGA may be a viable form of physical activity to achieve public health guidelines and to elicit health benefits.

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John M. Jakicic, Wendy C. King, Bethany Barone Gibbs, Renee J. Rogers, Amy D. Rickman, Kelliann K. Davis, Abdus Wahed and Steven H. Belle

Background:

To compare moderate-to-vigorous intensity physical activity (MVPA) assessed via questionnaires to an objective measure of MVPA in overweight or obese young adults.

Methods:

MVPA was assessed in 448 [median BMI = 31.2 (Interquartile Range: 28.5–34.3) kg/m2] young adults [median age: 30.9 (Interquartile Range: 27.8–33.7) years]. Measures included the SenseWear Armband (MVPAOBJ), the Paffenbarger Questionnaire (MVPAPAFF), and the Global Physical Activity Questionnaire (GPAQ). The GPAQ was used to compute total MVPA (MVPAGPAQ-TOTAL) and MVPA from transportation and recreation (MVPAGPAQ-REC).

Results:

The association between MVPAOBJ and MVPAPAFF was r s = 0.40 (P < .0001). Associations between MVPAOBJ and MVPAGPAQ-TOTAL and MVPAGPAQ-REC were r s = 0.19 and r s = 0.32, respectively (P < .0001). MVPAGPAQ-TOTAL was significantly greater than MVPAOBJ (P < .0001). Median differences in MET-min/week between MVPAOBJ and MVPAPAFF or MVPAGPAQ-REC were not significantly different from zero. There was proportional bias between each self-reported measure of MVPA and MVPAOBJ. There were significant associations between all measures of MVPA and fitness. MVPAOBJ was significantly associated with BMI and percent body fat.

Conclusions:

Objective and self-reported measures of MVPA are weakly to moderately correlated, with substantial differences between measures. MVPAOBJ provided predictive validity with fitness, BMI, and percent body fat. Thus, an objective measure of MVPA may be preferred to self-report in young adults.

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Bethany Barone Gibbs, Wendy C. King, Kelliann K. Davis, Amy D. Rickman, Renee J. Rogers, Abdus Wahed, Steven H. Belle and John Jakicic

Background:

Sedentary behavior (SED) has been measured almost exclusively by self-reported total SED or television time in longitudinal studies. This manuscript aimed to compare self-reported vs. objectively measured SED.

Methods:

Among overweight and obese young adults enrolled in a weight loss trial, baseline SED was assessed by 3 methods: 1) a questionnaire assessing 8 common SEDs (SEDQ), 2) 1 question assessing SED from the Global Physical Activity Questionnaire (SEDGPAQ), and 3) a monitor worn on the arm (SEDOBJ). In addition, television time (SEDTV) was isolated from the SEDQ. SED measures were compared using Spearman’s correlations, signed-rank tests, and Bland-Altman plots.

Results:

In 448 participants, SEDQ and SEDGPAQ were only weakly associated with SEDOBJ (rs = 0.21; P < .001, rs = 0.32; P < .001, respectively). Compared with SEDOBJ, SEDQ more often overestimated SEDOBJ (median difference: 1.1 hours/day; P < .001), while SEDGPAQ more often underestimated SEDOBJ (median difference: –0.7 hours/day; P < .001). The correlation between SEDTV and SEDOBJ was not significantly different from 0 (rs = 0.08; P = .08).

Conclusions:

SEDQ and SEDGPAQ were weakly correlated with, and significantly different from, SEDOBJ in overweight and obese young adults. SEDTV was not related to SEDOBJ. The poor associations of self-reported and objectively measured SED could affect interpretation and comparison across studies relating SED to adverse health outcomes.