Jean-Philippe Chaput

Purpose : To determine the association between meeting 24-hour movement guidelines and markers of adiposity in children, including body mass index, waist circumference, waist-to-height ratio, and percentage body fat. Methods : The sample included 910 children aged 6–10 years from Northern Portugal. Meeting the 24-hour movement guidelines was defined as (1) moderate-to-vigorous physical activity (MVPA): ≥60 minutes per day, (2) sleep: 9 to 11 hours/night, and (3) screen time: ≤2 hours per day. Moderate-to-vigorous physical activity and sleep duration were assessed with wrist-worn accelerometry over 7 days, and screen time was assessed by parental report. Results : A total of 5.4% of the sample met none of the guidelines, whereas 23% met all 3 guidelines. Children who met individual guidelines (MVPA, screen time, and sleep) had significantly lower levels of body mass index z -scores and waist circumference, whereas those who met the MVPA and sleep guidelines had lower waist-to-height ratio. Those who met the MVPA guideline had lower percentage body fat than those who did not. There were significant linear trends (all P < .01) between the number of guidelines met (0, 1, 2, and 3) and lower levels of all markers of adiposity. Conclusions : We found significant associations between meeting 24-hour guidelines and lower levels of adiposity among Portuguese children.

Sleep, sedentary behavior (SB), standing, light-intensity physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) compose the 24-h day, and reallocating time between these behaviors is associated with premature mortality; however, whether these associations differ by sleep characteristics remains unclear. We examined associations between time reallocations across these device-measured behaviors and all-cause, cardiovascular disease (CVD) and physical activity-related cancer mortality, and potential effect modification by sleep duration and regularity. We conducted a population-based prospective cohort study among UK Biobank participants and applied compositional Cox regression. In 68 995 adults, 2668 deaths occurred over a mean follow-up of 8.0 years. Among participants meeting sleep duration guidelines, reallocating 30-min from sleep to standing, LPA, or MVPA was favorably associated with all-cause mortality, with HRs of 0.85 (95%CI 0.79, 0.92), 0.87 (0.81, 0.94), and 0.80 (0.74, 0.87), respectively. Among short sleepers, reallocating 30-min from sleep to SB, standing, or LPA was adversely associated with CVD mortality, with HRs of 1.18 (1.04, 1.34), 1.20 (1.04, 1.38), and 1.18 (1.03, 1.35), respectively. Beneficial associations of reallocating SB to sleep were evident among both regular sleepers and irregular sleepers. These observational findings suggest that associations between 24-h behavioral reallocations and mortality may vary according to sleep characteristics.

Introduction: Whether the timing of moderate-to-vigorous physical activity (MVPA) and sleep is independently and jointly associated with meeting physical activity guidelines in adults remains unclear. Methods: We cross-sectionally analyzed 2003–2006 National Health and Nutrition Examination Survey (NHANES) data. Non-pregnant adults aged ≥20 years with valid accelerometer data, ≥5 min/day of MVPA, and no mobility limitation were included (n=3,153). Participants were classified as: morning (06:00–09:59), midday (10:00–13:59), afternoon (14:00–17:59), evening (18:00–21:59), or overnight (22:00–05:59) MVPA groups if ≥50% of average daily MVPA occurred in that window; or as mixed if otherwise. Subsamples with valid sleep timing proxy data (n=2,370) were classified as: irregular sleepers if participants had a standard deviation of the sleep midpoint >1 h; otherwise, regular sleepers were further categorized by mean sleep midpoint as early (22:00–01:59), mid (02:00–03:59), or late (04:00–07:59). Survey-weighted modified Poisson models were used to estimate adjusted prevalence ratios (PRs) and 95% confidence intervals (CIs) for meeting PA guidelines (i.e., ≥150 min/week of moderate-equivalent activity), controlling for sociodemographic, behavioral, and health-related covariates. Results: Morning MVPA (PR = 1.48, 95% CI = 1.31–1.66) and early sleep (1.14, 1.01–1.28) were each associated with a higher prevalence of meeting PA guidelines compared to mixed MVPA and irregular sleep, respectively. Similar patterns were observed for joint groups of morning MVPA with early sleep (1.57, 1.14–2.16), morning MVPA with mid sleep (1.62, 1.34–1.96), and midday MVPA with mid sleep (1.44, 1.21–1.73) compared with mixed MVPA with irregular sleep. Conclusions: Accumulating MVPA predominantly in the morning and/or maintaining earlier sleep timing may inform timing-based strategies to support population-level adherence to PA guidelines.