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Background: The joint associations of total and intensity-specific physical activity with obesity in relation to all-cause mortality risk are unclear.Methods: We included 34 492 adults (72% women, median age 62.1 years, 2034 deaths during follow-up) in a harmonised meta-analysis of eight population-based prospective cohort studies with mean follow-up ranging from 6.0 to 14.5 years. Standard body mass index categories were cross-classified with sample tertiles of device-measured total, light-to-vigorous and moderate-to-vigorous physical activity and sedentary time. In five cohorts with waist circumference available, high and low waist circumference was combined with tertiles of moderate-to-vigorous physical activity.Results: There was an inverse dose-response relationship between higher levels of total and intensity-specific physical activity and mortality risk in those who were normal weight and overweight. In individuals with obesity, the inverse dose-response relationship was only observed for total physical activity. Similarly, lower levels of sedentary time were associated with lower mortality risk in normal weight and overweight individuals but there was no association between sedentary time and risk of mortality in those who were obese. Compared with the obese-low total physical activity reference, the HRs were 0.59 (95% CI 0.44 to 0.79) for normal weight-high total activity and 0.67 (95% CI 0.48 to 0.94) for obese-high total activity. In contrast, normal weight-low total physical activity was associated with a higher risk of mortality compared with the obese-low total physical activity reference (1.28; 95% CI 0.99 to 1.67).Conclusions: Higher levels of physical activity were associated with lower risk of mortality irrespective of weight status. Compared with obesity-low physical activity, there was no survival benefit of being normal weight if physical activity levels were low. [ABSTRACT FROM AUTHOR]

Objective: Observational studies have linked occupational standing or walking to musculoskeletal pain. These prior studies, however, are flawed as few accounted for physical exertion; a potential confounder that accompanies many standing-based occupations. The purpose of this study was to examine the individual and joint associations of occupational standing/walking and exertion with musculoskeletal symptoms.Methods: Data for this analysis come from the 2015 National Health Interview Survey, a US nationally representative survey. Occupational standing/walking and exertion were assessed by self-report on a 5-point Likert scale. The presence of musculoskeletal symptoms (pain, aching and stiffness) for upper extremities (neck, shoulders, elbows, wrists and fingers), lower extremities (hips, knees, ankles and toes) and lower back was also assessed.Results: Occupational standing/walking was associated with a greater likelihood of upper extremity, lower extremity and lower back musculoskeletal symptoms; however, associations were attenuated and no longer significant with adjustment for exertion. When stratified by levels of occupational exertion, occupational standing/walking was associated with musculoskeletal symptoms only among the group with high exertion (eg, OR=1.69 (95% CI: 1.48 to 1.94) for lower back symptoms comparing high/high for standing or walking/exertion vs low/low). Among groups with low exertion, occupational standing/walking was not associated with musculoskeletal symptoms (eg, OR=1.00 (95% CI: 0.85 to 1.16) for lower back symptoms comparing high/low for standing or walking/exertion vs low/low).Conclusion: Results from this US representative survey suggest that the association between occupational standing/walking and musculoskeletal symptoms is largely driven by the co-occurrence of occupational exertion and does not provide evidence that standing or walking incurs adverse musculoskeletal symptoms. [ABSTRACT FROM AUTHOR]

Wearable physical activity monitors (PAMs) have potential to positively influence physical activity. However, high rates of disengagement have been reported, which dampens enthusiasm, as these devices are unlikely to impact habitual physical activity if they are not worn for a sustained period of time. The purpose of this study was to identify demographic and device-use characteristics (e.g. data sharing) associated with sustained device engagement. Current PAM users (n = 418; mean age: 35.0 ± 12.5; 78% female) from across the USA were recruited online and completed a baseline web-based survey in 2015–2016 comprising questions about demographics and device use. Participants were followed-up again in 2017, at which time they reported whether or not they still used a PAM. Sustained PAM engagement was defined as those who continued use at follow-up. The median follow-up time was 15.5 (±3.7) months. In fully adjusted models, the following were significantly associated with long-term engagement: age (odds ratio [OR]: 1.03; 95% confidence interval [CI]: 1.01–1.05, p =.014), Hispanic ethnicity (OR: 3.67; 95% CI: 1.20–11.26, p =.023), running as a preferred exercise (OR: 1.82; 95% CI: 1.02–3.24, p =.043), wanting to monitor health variables as a reason for choosing to use a PAM (OR: 1.73; 95% CI: 1.02–2.92, p =.042), and sharing data from the PAM publicly on social media (e.g. Facebook and Twitter; OR: 5.11; 95% CI: 1.64–15.93, p =.005). A number of sociodemographic and use characteristics were associated with sustained device use over a median follow-up of 1.3 years. One modifiable factor that may lead to longer device engagement is encouraging users to share data publicly. [ABSTRACT FROM AUTHOR]

Objectives: To examine the joint associations of accelerometer-measured physical activity and sedentary time with all-cause mortality.Methods: We conducted a harmonised meta-analysis including nine prospective cohort studies from four countries. 44 370 men and women were followed for 4.0 to 14.5 years during which 3451 participants died (7.8% mortality rate). Associations between different combinations of moderate-to-vigorous intensity physical activity (MVPA) and sedentary time were analysed at study level using Cox proportional hazards regression analysis and summarised using random effects meta-analysis.Results: Across cohorts, the average time spent sedentary ranged from 8.5 hours/day to 10.5 hours/day and 8 min/day to 35 min/day for MVPA. Compared with the referent group (highest physical activity/lowest sedentary time), the risk of death increased with lower levels of MVPA and greater amounts of sedentary time. Among those in the highest third of MVPA, the risk of death was not statistically different from the referent for those in the middle (16%; 95% CI 0.87% to 1.54%) and highest (40%; 95% CI 0.87% to 2.26%) thirds of sedentary time. Those in the lowest third of MVPA had a greater risk of death in all combinations with sedentary time; 65% (95% CI 1.25% to 2.19%), 65% (95% CI 1.24% to 2.21%) and 263% (95% CI 1.93% to 3.57%), respectively.Conclusion: Higher sedentary time is associated with higher mortality in less active individuals when measured by accelerometry. About 30-40 min of MVPA per day attenuate the association between sedentary time and risk of death, which is lower than previous estimates from self-reported data. [ABSTRACT FROM AUTHOR]