To quantify the association between daily total sitting and all-cause mortality risk and to examine dose-response relationships with and without adjustment for moderate-to-vigorous physical activity. Studies published from 1989 to January 2013 were identified via searches of multiple databases, reference lists of systematic reviews on sitting and health, and from authors’ personal literature databases. We included prospective cohort studies that had total daily sitting time as a quantitative exposure variable, all-cause mortality as the outcome and reported estimates of relative risk, or odds ratios or hazard ratios with 95% confidence intervals. Two authors independently extracted the data and summary estimates of associations were computed using random effects models. Six studies were included, involving data from 595,086 adults and 29,162 deaths over 3,565,569 person-years of follow-up. Study participants were mainly female, middle-aged or older adults from high-income countries; mean study quality score was 12/15 points. Associations between daily total sitting time and all-cause mortality were not linear. With physical activity adjustment, the spline model of best fit had dose-response HRs of 1.00 (95% CI: 0.98-1.03), 1.02 (95% CI: 0.99-1.05) and 1.05 (95% CI: 1.02-1.08) for every 1-hour increase in sitting time in intervals between 0-3, >3-7 and >7 h/day total sitting, respectively. This model estimated a 34% higher mortality risk for adults sitting 10 h/day, after taking physical activity into account. The overall weighted population attributable fraction for all-cause mortality for total daily sitting time was 5.9%, after adjusting for physical activity. Higher amounts of daily total sitting time are associated with greater risk of all-cause mortality and moderate-to-vigorous physical activity appears to attenuate the hazardous association. These findings provide a starting point for identifying a threshold on which to base clinical and public health recommendations for overall sitting time, in addition to physical activity guidelines.

Objectives Simultaneously define diet, physical activity, television (TV) viewing, and sleep duration across cardiometabolic disease groups, and investigate clustering of non-diet lifestyle behaviours. Design Cross-sectional observational study. Setting 22 UK Biobank assessment centres across the UK. Participants 502 664 adults aged 37–63 years old, 54% women. 4 groups were defined based on disease status; ‘No disease’ (n=103 993), ‘cardiovascular disease’ (CVD n=113 469), ‘Type 2 diabetes without CVD’ (n=4074) and ‘Type 2 diabetes + CVD’ (n=11 574). Main outcomes Diet, physical activity, TV viewing and sleep duration. Results People with ‘CVD’ report low levels of physical activity (3 h/day; 1.42 (1.39 to 1.45)), and poor sleep duration (8 h/night; 1.37 (1.34 to 1.39)) relative to people without disease. People with ‘Type 2 diabetes + CVD’ were more likely to report low physical activity (1.71 (1.64 to 1.78)), high levels of TV viewing (1.92 (1.85 to 1.99)) and poor sleep duration (1.52 (1.46 to1.58)) relative to people without disease. Non-diet behaviours were clustered, with people with ‘CVD’ or ‘Type 2 diabetes + CVD’ more likely to report simultaneous low physical activity, high TV viewing and poor sleep duration than those without disease (2.15 (2.03 to 2.28) and 3.29 (3.02 to 3.58), respectively). By contrast, 3 in 4 adults with ‘Type 2 diabetes’, and 2 in 4 adults with ‘CVD’ have changed their diet in the past 5 years, compared with only 1 in 4 in the ‘No disease’ group. Models were adjusted for gender, age, body mass index, Townsend Deprivation Index, ethnicity, alcohol intake, smoking and meeting fruit/vegetable guidelines. Conclusions Low physical activity, high TV and poor sleep duration are prominent unaddressed high-risk characteristics of both CVD and type 2 diabetes, and are likely to be clustered together.

Mental health disorders are major contributors to the global burden of disease and their inverse relationship with physical activity is widely accepted. However, research on the association between physical activity and positive mental health outcomes is limited. Happiness is an example of a positive construct of mental health that may be promoted by physical activity and could increase resilience to emotional perturbations. The aim of this study is to use a large multi-country dataset to assess the association of happiness with physical activity volume and its specificity to intensity and/or activity domain. We analysed Eurobarometer 2002 data from 15 countries (n = 11,637). This comprised one question assessing self-reported happiness on a six point scale (dichotomised: happy/unhappy) and physical activity data collected using the IPAQ-short (i.e. walking, moderate, vigorous) and four domain specific items (i.e. domestic, leisure, transport, vocation). Logistic regression was used to examine the association between happiness and physical activity volume adjusted for sex, age, country, general health, relationship status, employment and education. Analyses of intensity and domain specificity were assessed by logistic regression adjusted for the same covariates and physical activity volume. When compared to inactive people, there was a positive dose–response association between physical activity volume and happiness (highly active: OR = 1.52 [1.28-1.80]; sufficiently active: OR = 1.29 [1.11-1.49]; insufficiently active: OR = 1.20 [1.03-1.39]). There were small positive associations with happiness for walking (OR = 1.02 [1.00-1.03]) and vigorous-intensity physical activity (OR = 1.03 [1.01-1.05). Moderate-intensity physical activity was not associated with happiness (OR = 1.01 [0.99-1.03]). The strongest domain specific associations with happiness were found for “a lot” of domestic (OR = 1.42 [1.20-1.68]) and “some” vocational (OR = 1.33 [1.08-1.64]) physical activity. Happiness was also associated with “a lot” of leisure physical activity (OR = 1.15 [1.02-1.30]), but there were no significant associations for the transport domain. Increasing physical activity volume was associated with higher levels of happiness. Although the influence of physical activity intensity appeared minimal, the association with happiness was domain specific and was strongest for “a lot” of domestic and/or “some” vocational physical activity. Future studies to establish causation are indicated and may prompt changes in how physical activity for improving mental health is promoted.