Cross-sectional and prospective associations of sleep duration and bedtimes with adiposity and obesity risk in 15 810 youth from 11 international cohorts

OBJECTIVES To investigate associations of bedtimes and sleep durations with adiposity levels in children and adolescents. METHODS Individual data were pooled for 12 247 children (5819 with follow-up adiposity at 2.3 ± 1.4 years post-baseline) and 3563 adolescents from 11 international studies. Associations between questionnaire-based sleep durations, bedtimes and four groups of combined bedtimes and sleep lengths (later-shorter [reference]/earlier-shorter/later-longer/earlier-longer) with measured adiposity (body mass index [BMI] and waist circumference z-scores) and weight status, were investigated. RESULTS In children, longer sleep durations were consistently associated with lower adiposity markers, and earlier bedtimes were related to lower BMI z-score. Compared to sleeping <10 h, longer baseline sleep duration favourably predicted Δwaist z-score in girls (≥10 and <11 h (β-coefficient (95% confidence interval [CI])): -0.06 (-0.12 to -0.01)) and boys (≥11 h: -0.10 [-0.18 to -0.01]). Combined groups that were defined by longer sleep (later-longer and earlier-longer sleep patterns) were associated with lower adiposity, and later-longer sleep favourably predicted Δwaist z-score in girls (-0.09 [-0.15 to -0.02]). In adolescents, longer sleep durations and earlier bedtimes were associated with lower BMI z-score in the whole sample, and also with lower waist z-score in boys. Combined groups that were characterized by earlier bedtimes were associated with the same outcomes. For example, earlier-shorter (-0.22 (-0.43 to -0.01) and earlier-longer (-0.16 (-0.25 to -0.06) sleep were both associated with lower BMI z-score. CONCLUSIONS If the associations are causal, longer sleep duration and earlier bedtimes should be targeted for obesity prevention, emphasizing longer sleep for children and earlier bedtimes for adolescents

Correction to: A closer look at the relationship among accelerometer-based physical activity metrics: ICAD pooled data.

Following publication of the original article [1], the author reported that the name of the collaborator group was missing from the author group

Age-related patterns of vigorous-intensity physical activity in youth:the International Children’s Accelerometry Database

Abstract Physical activity declines during youth but most evidence reports on combined moderate and vigorous-intensity physical activity. We investigated how vigorous-intensity activity varies with age. Cross-sectional data from 24,025 participants (5.0–18.0 y; from 20 studies in 10 countries obtained 2008–2010) providing ≥ 1 day accelerometer data (International Children's Accelerometry Database (ICAD)). Linear regression was used to investigate age-related patterns in vigorous-intensity activity; models included age (exposure), adjustments for monitor wear-time and study. Moderate-intensity activity was examined for comparison. Interactions were used to investigate whether the age/vigorous-activity association differed by sex, weight status, ethnicity, maternal education and region. A 6.9% (95% CI 6.2, 7.5) relative reduction in mean vigorous-intensity activity with every year of age was observed; for moderate activity the relative reduction was 6.0% (5.6%, 6.4%). The age-related decrease in vigorous-intensity activity remained after adjustment for moderate activity. A larger age-related decrease in vigorous activity was observed for girls (− 10.7%) versus boys (− 2.9%), non-white (− 12.9% to − 9.4%) versus white individuals (− 6.1%), lowest maternal education (high school (− 2.0%)) versus college/university (ns) and for overweight/obese (− 6.1%) versus healthy-weight participants (− 8.1%). In addition to larger annual decreases in vigorous-intensity activity, overweight/obese individuals, girls and North Americans had comparatively lower average vigorous-intensity activity at 5.0–5.9 y. Age-related declines in vigorous-intensity activity during youth appear relatively greater than those of moderate activity. However, due to a higher baseline, absolute moderate-intensity activity decreases more than vigorous. Overweight/obese individuals, girls, and North Americans appear especially in need of vigorous-intensity activity promotion due to low levels at 5.0–5.9 y and larger negative annual differences

Sitting time, fidgeting and all-cause mortality in the UK Women's Cohort Study

Introduction: Sedentary behaviours (including sitting) may increase risk of mortality independently of physical activity level. Little is known about how fidgeting behaviours might modify the association. Methods: Data were drawn from the UK Women’s Cohort Study. In 1999/2002, 12,778 women (age 37 to 78) provided data on average daily sitting time, overall fidgeting (irrespective of posture), and a range of relevant covariates including physical activity, diet, smoking status and alcohol consumption. Participants were followed for mortality over a mean of 12 years. Proportional hazards Cox regression models were used to estimate the relative risk of mortality in the high (vs. low) and medium (vs. low) sitting time groups. Results: Fidgeting modified the risk associated with sitting time (p value for interaction = 0.04), leading us to separate groups for analysis. Adjusting for a range of covariates, sitting for 7+ hours/day (vs. <5 hours/day) was associated with 30% increased risk of all-cause mortality (HR = 1.30, 95% CI 1.02, 1.66) only among women in the low fidgeting group. Among women in the high fidgeting group, sitting for 5/6 (vs. <5 hrs/day) was associated with decreased risk of mortality (HR = 0.63, 95% CI 0.43, 0.91), adjusting for a range of covariates. There was no increased risk of mortality from longer sitting time in the middle and high fidgeting groups. Conclusions: Fidgeting may reduce the risk of all-cause mortality associated with excessive sitting time. More detailed and better validated measures of fidgeting should be identified in other studies in order to replicate these findings and identity mechanisms, particularly measures that distinguish fidgeting in a seated from standing posture

Association of Resistance Exercise With the Incidence of Hypercholesterolemia in Men.

OBJECTIVE: To examine the associations of resistance exercise, independent of and combined with aerobic exercise, with the risk of development of hypercholesterolemia in men. PATIENTS AND METHODS: This study used data from the Aerobics Center Longitudinal Study, which is a cohort examining the associations of clinical and lifestyle factors with the development of chronic diseases and mortality. Participants received extensive preventive medical examinations at the Cooper Clinic in Dallas, Texas, between January 1, 1987, and December 31, 2006. A total of 7317 men aged 18 to 83 years (mean age, 46 years) without hypercholesterolemia at baseline were included. Frequency (times per week) and total amount (min/wk) of resistance and aerobic exercise were determined by self-report. Hypercholesterolemia was defined as a total cholesterol level of 240 mg/dL or higher or physician diagnosis. RESULTS: During a median (interquartile range) follow-up of 4 (2 to 7) years, hypercholesterolemia developed in 1430 of the 7317 men (20%). Individuals meeting the resistance exercise guidelines (≥2 d/wk) had a 13% lower risk of development of hypercholesterolemia (hazard ratio [HR], 0.87; 95% CI, 0.76-0.99; P=.04) after adjustment for general characteristics, lifestyle factors, and aerobic exercise. In addition, less than 1 h/wk and 2 sessions per week of resistance exercise were associated with 32% and 31% lower risks of hypercholesterolemia (HR, 0.68; 95% CI, 0.54-0.86; P=.001; and HR, 0.69; 95% CI, 0.54-0.88; P=.003), respectively, compared with no resistance exercise. Higher levels of resistance exercise did not provide benefits. Meeting both resistance and aerobic exercise guidelines (≥500 metabolic equivalent task min/wk) lowered the risk of development of hypercholesterolemia by 21% (HR, 0.79; 95% CI, 0.68-0.91; P=.002). compared with meeting none of the guidelines. CONCLUSION: Compared with no resistance exercise, less than 1 h/wk of resistance exercise, independent of aerobic exercise, is associated with a significantly lower risk of development of hypercholesterolemia in men (P=.001). However, the lowest risk of hypercholesterolemia was found at 58 min/wk of resistance exercise. This finding suggests that resistance exercise should be encouraged to prevent hypercholesterolemia in men. However, future studies with a more rigorous analysis including major potential confounders (eg, diet, medications) are warranted

Associations of vigorous-intensity physical activity with biomarkers in youth

Introduction: Physical activity (PA) conveys known cardiometabolic benefits to youth, but the contribution of vigorous-intensity PA (VPA) to these benefits is unknown. Therefore, we sought to determine, a) the associations between VPA and cardiometabolic biomarkers independent of moderate-intensity PA (MPA) and time sedentary, and b) the accelerometer cutpoint that best represents the threshold for health-promoting VPA in youth.Methods: Data from the International Children's Accelerometry Database (ICAD) were analyzed in 2015. The relationship between cardiometabolic biomarkers and 4 categories of VPA estimated via 3 sets of cutpoints were examined using isotemporal substitution quantile regression modeling at the 10th, 25th, 50th, 75th, and 90th percentile of the distribution of each biomarker, separately. Age, sex, accelerometer wear time, sedentary time, and MPA were controlled for while allowing substitution for light-intensity PA. Data from 11,588 youth (4-18yrs) from 11 ICAD studies (collected 1998-2009) were analyzed.Results: Only 32 of 360 significant associations were observed. Significant, negative relationships were observed for VPA with waist circumference and insulin. Replacing light intensity PA with VPA (corresponding to at the 25th to 90th percentiles of VPA) was associated with a .67 (-1.33, -0.01; P = .048) to 7.30cm (-11.01, -3.58; P < .001) lower waist circumference using Evenson and ICAD cutpoints (i.e., higher CPM). VPA levels were associated with 12.60 (-21.28, -3.92; P = .004) to 27.03 pmol/l (-45.03, -9.03; P = .003) lower insulin levels at the 75th to 90th percentiles using Evenson and ICAD cutpoints when substituted for light PA.Conclusions: Substituting light PA with VPA was inversely associated with waist circumference and insulin. However, VPA was inconsistently related to the remaining biomarkers after controlling for time sedentary and MPA

Cross-sectional and prospective associations of sleep duration and bedtimes with adiposity and obesity risk in 15 810 youth from 11 international cohorts.

Funder: Bristol UniversityFunder: Loughborough University; Id: http://dx.doi.org/10.13039/501100000857Funder: Norges Idrettsh‐gskoleOBJECTIVES: To investigate associations of bedtimes and sleep durations with adiposity levels in children and adolescents. METHODS: Individual data were pooled for 12 247 children (5819 with follow-up adiposity at 2.3 ± 1.4 years post-baseline) and 3563 adolescents from 11 international studies. Associations between questionnaire-based sleep durations, bedtimes and four groups of combined bedtimes and sleep lengths (later-shorter [reference]/earlier-shorter/later-longer/earlier-longer) with measured adiposity (body mass index [BMI] and waist circumference z-scores) and weight status, were investigated. RESULTS: In children, longer sleep durations were consistently associated with lower adiposity markers, and earlier bedtimes were related to lower BMI z-score. Compared to sleeping <10 h, longer baseline sleep duration favourably predicted Δwaist z-score in girls (≥10 and <11 h (β-coefficient (95% confidence interval [CI])): -0.06 (-0.12 to -0.01)) and boys (≥11 h: -0.10 [-0.18 to -0.01]). Combined groups that were defined by longer sleep (later-longer and earlier-longer sleep patterns) were associated with lower adiposity, and later-longer sleep favourably predicted Δwaist z-score in girls (-0.09 [-0.15 to -0.02]). In adolescents, longer sleep durations and earlier bedtimes were associated with lower BMI z-score in the whole sample, and also with lower waist z-score in boys. Combined groups that were characterized by earlier bedtimes were associated with the same outcomes. For example, earlier-shorter (-0.22 (-0.43 to -0.01) and earlier-longer (-0.16 (-0.25 to -0.06) sleep were both associated with lower BMI z-score. CONCLUSIONS: If the associations are causal, longer sleep duration and earlier bedtimes should be targeted for obesity prevention, emphasizing longer sleep for children and earlier bedtimes for adolescents.This work was supported by a British Heart Foundation Immediate Postdoctoral Basic Science Research Fellowship awarded to PJC (grant number: FS/17/37/32937), who is also a member of The White Rose Child & Adolescent Sleep Research Network which is funded by a White Rose Collaboration Grant. This work was further supported by the National Prevention Research Initiative (grant number: G0701877) (http://www.mrc.ac.uk/research/initiatives/national-prevention-research-initiative-npri/). The funding partners relevant to this award are: British Heart Foundation; Cancer Research UK; Department of Health; Diabetes UK; Economic and Social Research Council; Medical Research Council; Research and Development Office for the Northern Ireland Health and Social Services; Chief Scientist Office; Scottish Executive Health Department; The Stroke Association; Welsh Assembly Government and World Cancer Research Fund. This work was additionally supported by the Medical Research Council (grant numbers: MC_UU_12015/3 & MC_UU_12015/7), the Research Council of Norway (grant number: 249932/F20), an Australian Research Council (ARC) Discovery Grant (grant number: DP0664206), the National Health & Medication Research Council (grant numbers: APP274309 & APP1176885), Bristol University, Loughborough University, and the Norwegian School of Sport Sciences. The funders were not involved in the design of the study, the collection, analysis, or interpretation of the data, report writing, or the decision to submit the final report for publication

Accelerometer-measured sedentary and physical activity time and their correlates in European older adults: The SITLESS study

Background: Sedentary behavior (SB) and physical activity (PA) are important determinants of health in older adults. This study aimed to describe the composition of accelerometer-measured SB and PA in older adults, to explore self-reported context-specific SB, and to assess socio-demographic and functional correlates of engaging in higher levels of SB in participants of a multi-center study including four European countries. Methods: 1360 community-dwelling older adults from the SITLESS study (61.8% women; 75.3±6.3 years) completed a self-reported SB questionnaire and wore an ActiGraph accelerometer for seven days. Accelerometer-determined compositional descriptive statistics were calculated. A fixed effects regression analysis was conducted to assess the socio-demographic (country, age, sex, civil status, education and medications) and functional (BMI and gait speed) correlates. Results: Older adults spent 78.8% of waking time in SB, 18.6% in light-intensity PA (LPA), and 2.6% in moderate to vigorous PA (MVPA). Accelerometry showed that women engaged in more LPA and walking and men engaged in higher amounts of MVPA. Watching television and reading accounted for 47.2% of waking time. Older age, being a man, single, taking more medications, being obese and overweight, and having a slower gait speed were statistically significant correlates of more sedentary time. Conclusions: The high amount of SB of our participants justifies the need to develop and evaluate interventions to reduce sitting time. A clinically relevant change in gait speed can decrease almost 0.45 percentage points of sedentary time. The distribution of context-specific sedentary activities by country and sex showed minor differences, albeit worth noting

Correction to: Physical activity intensity, bout-duration, and cardiometabolic risk markers in children and adolescents.

An amendment to this paper has been published and can be accessed via a link at the top of the paper