Interrupting prolonged periods of sitting may improve postprandial insulin and glucose although it is unclear whether interruptions need to involve physical activity or simply a change in posture (from sitting to standing) to benefit adults without metabolic impairment. This study examined effects of interrupting sitting with intermittent walking, and intermittent standing on dynamic insulin and glucose responses in men without known metabolic impairment. A randomised three-arm, cross-over experimental study comprising three seven-hour days of sustained sitting. Twenty-five inactive men (aged 40.2±12.2 years) took part. The three interventions were; SIT-ONLY (uninterrupted sitting), SIT-STAND (sitting interrupted with 2min standing bouts every 20min) and SIT-WALK (sitting interrupted with 2min light-intensity walking bouts every 20min). An oral glucose tolerance test was administered at baseline and a standardised mixed test meal at hour three. Comparisons of Matsuda Index, and area under the curve (AUC) for insulin and glucose were made between interventions using generalised estimating equation models. Matsuda index was 16% higher (mean difference 1.2 [95%CI 0.1, 2.2] p=0.02), AUC for glucose 9% lower (-2.5mmol/L×7h [-3.7, -1.3mmol/L×7h] p<0.001) and AUC for insulin 21% lower (-546.5pmol/L×7h [-723.6, -369.3pmol/L×7h] p<0.001) in SIT-WALK compared to SIT-ONLY. There were no significant differences between SIT-STAND and SIT-ONLY in any main outcome measure. Interrupting sustained sitting with brief repeated bouts of light-intensity walking but not standing reduced insulin demand and improved glucose uptake during a simulated sedentary working day. The benefits of such minor behavioural changes could inform future workplace health interventions.

Background : Sitting behaviours have been linked with increased risk of all-cause mortality independent of moderate to vigorous physical activity (MVPA). Previous studies have tended to examine single indicators of sitting or all sitting behaviours combined. This study aims to enhance the evidence base by examining the type-specific prospective associations of four different sitting behaviours as well as total sitting with the risk of all-cause mortality. Methods : Participants (3720 men and 1412 women) from the Whitehall II cohort study who were free from cardiovascular disease provided information on weekly sitting time (at work, during leisure time, while watching TV, during leisure time excluding TV, and at work and during leisure time combined) and covariates in 1997–99. Cox proportional hazards models were used to investigate prospective associations between sitting time (h/week) and mortality risk. Follow-up was from date of measurement until (the earliest of) death, date of censor or July 31 2014. Results : Over 81 373 person-years of follow-up (mean follow-up time 15.7 ± 2.2 years) a total of 450 deaths were recorded. No associations were observed between any of the five sitting indicators and mortality risk, either in unadjusted models or models adjusted for covariates including MVPA. Conclusions : Sitting time was not associated with all-cause mortality risk. The results of this study suggest that policy makers and clinicians should be cautious about placing emphasis on sitting behaviour as a risk factor for mortality that is distinct from the effect of physical activity.

Objective: Health effects of different physical activity domains (ie, during leisure time, work and transport) are generally considered positive. UsingActive Worker consortiumdata, we assessed independent associations of occupational and leisure-time physical activity (OPA and LTPA) with all-cause mortality.Design: Two-stage individual participant data meta-analysis.Data source: Published and unpublished cohort study data.Eligibility criteria: Working participants aged 18–65 years.Methods: After data harmonisation, we assessed associations of OPA and LTPA with all-cause mortality. In stage 1, we analysed data from each study separately using Cox survival regression, and in stage 2, we pooled individual study findings with random-effects modelling.Results: In 22 studies with up to 590 497 participants from 11 countries, during a mean follow-up of 23.1 (SD: 6.8) years, 99 743 (16%) participants died. Adjusted for LTPA, body mass index, age, smoking and education level, summary (ie, stage 2) hazard ration (HRs) and 95% confidence interval (95% CI) for low, moderate and high OPA among men (n=2 96 134) were 1.01 (0.99 to 1.03), 1.05 (1.01 to 1.10) and 1.12 (1.03 to 1.23), respectively. For women (n=2 94 364), HRs (95% CI) were 0.98 (0.92 to 1.04), 0.96 (0.92 to 1.00) and 0.97 (0.86 to 1.10), respectively. In contrast, higher levels of LTPA were inversely associated with mortality for both genders. For example, for women HR for low, moderate and high compared with sedentary LTPA were 0.85 (0.81 to 0.89), 0.78 (0.74 to 0.81) and 0.75 (0.65 to 0.88), respectively. Effects were attenuated when adjusting for income (although data on income were available from only 9 and 6 studies, for men and women, respectively).Conclusion: Our findings indicate that OPA may not result in the same beneficial health effects as LTPA.

BACKGROUND: Few middle-aged and older adults engage in regular leisure-time exercise. Incidental physical activity (IPA) encompasses activities of daily living outside the leisure-time domain. No dose-response study is available to guide IPA-focused interventions and guidelines. We examined the associations of device-assessed IPA intensities (vigorous [VIPA], moderate [MIPA], light [LIPA]) with major adverse cardiovascular events (MACE) and mortality, and we estimated the “health equivalence” of LIPA and MIPA against 1 minute of VIPA. METHODS: A total of 24 139 nonexercisers from the 2013 to 2015 UK Biobank accelerometry substudy (56.2% women) with a mean±SD age of 61.9±7.6 years were analyzed using a prospective cohort design. IPA energy expenditure and daily durations of VIPA, MIPA, and LIPA were calculated with a validated machine learning-based intensity classifier. MACE included incident stroke, myocardial infarction, and heart failure; CVD death; CVD mortality; and all-cause mortality. RESULTS: Analyses included 22 107 (MACE), 22 174 (CVD mortality), and 24 139 (all-cause mortality) participants, corresponding to 908/223/1071 events over 7.9 years of follow-up. IPA volume exhibited an L-shaped association with a nadir at ≈35 to 38 kJ·kg ⁻¹ ·d ⁻¹ , corresponding to hazard ratios of 0.49 (95% CI, 0.39–0.61) for MACE, 0.33 (95% CI, 0.22–0.52) for CVD mortality, and 0.31 (95% CI, 0.25–0.38) for all-cause mortality. Any amounts of VIPA or MIPA were associated with lower risk, with a plateau of ≈14 minutes per day (VIPA) and 34 to 50 minutes per day (MIPA). The median VIPA (4.6 min/d) and MIPA (23.8 min/d) durations were associated with CVD mortality hazard ratio of 0.62 (95% CI, 0.46–0.83) and 0.50 (95% CI, 0.31–0.80), respectively. LIPA showed a subtle inverse gradient which was statistically significant only for CVD mortality at levels >130 minutes per day. One minute of VIPA was equivalent to 2.8 (MACE) to 3.4 (CVD mortality) minutes of MIPA and 34.7 (CVD mortality) to 48.5 (MACE) minutes of LIPA. CONCLUSIONS: Any daily IPA amount of vigorous or moderate intensity was associated with lower CVD risk in a dose-response manner. LIPA had weak associations with all outcomes. One minute of vigorous or ≈3.0 to 3.5 minutes of moderate IPA was associated with a similar degree of lower CVD risk. Our findings highlight the potential cardiovascular health value of incidental physical activity, especially for people who struggle to do structured exercise.

BACKGROUND: Blood pressure (BP)–lowering effects of structured exercise are well-established. Effects of 24-hour movement behaviors captured in free-living settings have received less attention. This cross-sectional study investigated associations between a 24-hour behavior composition comprising 6 parts (sleeping, sedentary behavior, standing, slow walking, fast walking, and combined exercise-like activity [eg, running and cycling]) and systolic BP (SBP) and diastolic BP (DBP). METHODS: Data from thigh-worn accelerometers and BP measurements were collected from 6 cohorts in the Prospective Physical Activity, Sitting and Sleep consortium (ProPASS) (n=14 761; mean±SD, 54.2±9.6 years). Individual participant analysis using compositional data analysis was conducted with adjustments for relevant harmonized covariates. Based on the average sample composition, reallocation plots examined estimated BP reductions through behavioral replacement; the theoretical benefits of optimal (ie, clinically meaningful improvement in SBP [2 mm Hg] or DBP [1 mm Hg]) and minimal (ie, 5-minute reallocation) behavioral replacements were identified. RESULTS: The average 24-hour composition consisted of sleeping (7.13±1.19 hours), sedentary behavior (10.7±1.9 hours), standing (3.2±1.1 hours), slow walking (1.6±0.6 hours), fast walking (1.1±0.5 hours), and exercise-like activity (16.0±16.3 minutes). More time spent exercising or sleeping, relative to other behaviors, was associated with lower BP. An additional 5 minutes of exercise-like activity was associated with estimated reductions of –0.68 mm Hg (95% CI, –0.15, –1.21) SBP and –0.54 mm Hg (95% CI, –0.19, 0.89) DBP. Clinically meaningful improvements in SBP and DBP were estimated after 20 to 27 minutes and 10 to 15 minutes of reallocation of time in other behaviors into additional exercise. Although more time spent being sedentary was adversely associated with SBP and DBP, there was minimal impact of standing or walking. CONCLUSIONS: Study findings reiterate the importance of exercise for BP control, suggesting that small additional amounts of exercise are associated with lower BP in a free-living setting.

BACKGROUND: Sleep and physical activity (PA) are important lifestyle-related behaviors that impact cardiometabolic health. This study investigated the joint associations of daily step count and sleep patterns (regularity and duration) with cardiometabolic biomarkers in adults. METHODS: We conducted a cross-sectional study using pooled data from the Prospective PA, Sitting, and Sleep Consortium, comprising 6 cohorts across Europe and Australia with thigh-worn accelerometry data collected between 2011 and 2021. The sleep regularity index, a metric that quantifies day-to-day sleep consistency, sleep duration (h/d), and steps (per day), was derived from the accelerometer data and categorized based on tertiles and sleep duration guidelines. We used multivariate generalized linear models to examine joint associations of sleep patterns and total daily step count with individual cardiometabolic biomarkers, including body mass index, waist circumference, total cholesterol, HDL (high-density lipoprotein) cholesterol, triglycerides, HbA1c (glycated hemoglobin), and a composite cardiometabolic health score (mean of the 6 standardized biomarker Z scores). RESULTS: The sample included 11 903 adults with a mean±SD age of 54.7±9.5 years, 54.9% female, a sleep regularity index of 78.7±10.4, and 10 206.4±3442.2 daily steps. Lower PA (<8475 steps/d) combined with either lower sleep regularity (sleep regularity index <75.9) or short sleep duration (84.5 or 7–8 h/d) and high step count (>11 553 steps/d). The combination of low sleep regularity and low daily steps was associated with higher body mass index (2.92 [2.61–3.24] kg/m ² ), waist circumference (8.58 [7.78–9.38] cm), total cholesterol (0.15 [0.07–0.23] mmol/L), and lower HDL levels (0.17 [0.14–0.2] mmol/L), regardless of sleep duration. The combination of short sleep and low step count had the strongest unfavorable associations for body mass index (2.31 [1.98–2.65] kg/m ² ) and waist circumference (7.01 [6.15–7.87] cm). CONCLUSIONS: Our findings suggest that the potential deleterious associations of irregular or insufficient sleep with cardiometabolic health outcomes may be exaggerated by lower daily PA. Investigation of the prospective joint association of sleep patterns and PA with cardiometabolic health may be warranted.