Energy availability describes the amount of dietary energy remaining for physiological functionality after the energy cost of exercise is deducted. The physiological and hormonal consequences of low energy availability (LEA) are well established, but the impact of LEA on physical activity behavior outside of exercise and, specifically, nonexercise activity thermogenesis (NEAT) has not been systematically examined. The authors conducted a secondary analysis of a repeated-measures crossover study in which recreationally trained young men (n = 6, 25 ± 1.0 years) underwent two 4-day conditions of LEA (15 kcal·kg fat-free mass−1 ·day−1) with and without endurance exercise (LEA + EX and LEA EX) and two energy-balanced control conditions (CON + EX and CON EX). The duration and intensity of physical activity outside of prescribed exercise were assessed using the SenseWear Pro3 armband. LEA did not alter NEAT (p = .41), nor time spent in moderate to vigorous (p = .20) and low-intensity physical activity (p = .17). However, time spent in low-intensity physical activity was lower in LEA + EX than LEA − EX (13.7 ± 0.3 vs. 15.2 ± 0.3 hr/day; p = .002). Short-term LEA does not seem to impact NEAT per se, but the way it is attained may impact physical activity behavior outside of exercise. As the participants expended similar amounts of energy during NEAT (900–1,300 kcal/day = 12.5–18.0 kcal·kg fat-free mass−1·day−1) and prescribed exercise bouts (15.0 kcal·kg fat-free mass−1·day−1), excluding it as a component of energy expenditure may skew the true energy available for physiological functionality in active populations.
Alexandra Martin, Hande Hofmann, Clemens Drenowatz, Birgit Wallmann-Sperlich, Billy Sperlich, and Karsten Koehler
Clemens Drenowatz, Olivia Wartha, Jochen Klenk, Susanne Brandstetter, Martin Wabitsch, and Jürgen Steinacker
This study examined the association between biological maturity, CVD risk, fitness and health behavior in 709 (359 male, 350 female) 8-year-old children (range: 6.3–8.9 years). Sports participation and sedentary behavior was assessed via parent questionnaire. Height and weight was measured and maturity status was predicted based on % of adult-height reached. Fitness was assessed via a test battery and CVD risk was determined using mean arterial pressure, cholesterol and intra-abdominal fat. BMIpercentiles (BMIPCT) differed significantly among early, average and late maturing children. Early maturing children displayed a higher CVD risk profile (0.5 vs. -0.2), lower fitness scores (-0.4 vs. 0.2), and spent more time watching TV (51 vs. 43 min/day) compared with their peers. After controlling for BMIPCT differences remained only for fitness in boys and TV time in girls.
Jessica L. Chandler, Keith Brazendale, Clemens Drenowatz, Justin B. Moore, Xuemei Sui, Robert G. Weaver, and Michael W. Beets
Background: The primary purpose of this study was to determine which physical activity (PA) opportunity elicits the most moderate to vigorous PA (MVPA) in after-school programs. This study used a 3-group cross-over design in which participants were exposed to 3 variations of activity structures: free play, organized, or a mixture. Methods: PA was measured using ActiGraph GT3X+ accelerometers. All data were transformed into percentage of time spent sedentary or in MVPA. Repeated-measures mixed-effects models were used to examine differences in MVPA and sedentary among the 3 activity sessions. Participants included 197 unique children, aged 5–12 years, and were 53% male and 55% white. Results: Statistically significant differences were observed in the percentage of time boys spent in MVPA during free play and mixed compared with organized only sessions (35.8% and 34.8% vs 29.4%). No significant difference was observed in the percentage of time girls spent in MVPA during free play compared with organized or mixed (27.2% and 26.1% vs 26.1%). Both boys and girls experienced ∼10% less time sedentary during free play compared with the others. Conclusion: Offering free play during PA opportunities can help children attain as much if not more MVPA compared with only offering organized, adult-led games.
Gregory A. Hand, Robin P. Shook, Daniel P. O’Connor, Madison M. Kindred, Sarah Schumacher, Clemens Drenowatz, Amanda E. Paluch, Stephanie Burgess, John E. Blundell, and Steven N. Blair
Background: The present study examined, among weight-stable overweight or obese adults, the effect of increasing doses of exercise energy expenditure (EEex) on changes in total daily energy expenditure (TDEE), total body energy stores, and body composition. Methods: Healthy, sedentary overweight/obese young adults were randomized to one of 3 groups for a period of 26 weeks: moderate-exercise (EEex goal of 17.5 kcal/kg/wk), high-exercise (EEex goal of 35 kcal/kg/wk), or observation group. Individuals maintained body weight within 3% of baseline. Pre/postphysical activity between-group measurements included body composition, calculated energy intake, TDEE, energy stores, and resting metabolic rate. Results: Sixty weight-stable individuals completed the protocols. Exercise groups increased EEex in a stepwise manner compared with the observation group (P < .001). There was no group effect on changes in TDEE, energy intake, fat-free mass, or resting metabolic rate. Fat mass and energy stores decreased among the females in the high-exercise group (P = .007). Conclusions: The increase in EEex did not result in an equivalent increase in TDEE. There was a sex difference in the relationship among energy balance components. These results suggest a weight-independent compensatory response to exercise training with potentially a sex-specific adjustment in body composition.
Amanda E. Paluch, Robin P. Shook, Gregory A. Hand, Daniel P. O’Connor, Sara Wilcox, Clemens Drenowatz, Meghan Baruth, Stephanie Burgess, and Steven N. Blair
Background: This study examined how life event occurrences and stressfulness influence objectively measured light through vigorous physical activity (PA) among young adults. Methods: Every 3 months over a 12-month period, 404 healthy young adults completed questionnaires on the occurrence and stress of 16 life events and wore an accelerometer for 10 days. Results: A modest positive relationship was seen between cumulative life event occurrences [between effect: β = 22.2 (9.7) min/d, P = .02] and cumulative stress [between effect: β = 7.6 (2.9) min/d, P = .01] with light through vigorous PA among men. When considering events individually, job change, starting a first job, beginning a mortgage, and changes in a relationship influenced men’s PA. For women, mortgage, starting a first job, job change, and engagement had significant associations. Life event stressfulness influenced PA in women more than in men. For men, stress from changes in a relationship or job positively influenced PA. Stress of a mortgage, quitting a job, changing jobs or a first job influenced women’s PA. Conclusion: Considering each life event individually was more informative than the summation of life events or summation of stress. Specific life events substantially altered PA, and this change varied by gender, direction of association, and PA intensity and duration.