BackgroundPrevious studies have been unable to characterise the association between physical activity and obesity, possibly because most relied on inaccurate measures of physical activity and obesity.Methods and FindingsWe carried out a cross sectional analysis on 5,500 12-year-old children enrolled in the Avon Longitudinal Study of Parents and Children. Total physical activity and minutes of moderate and vigorous physical activity (MVPA) were measured using the Actigraph accelerometer. Fat mass and obesity (defined as the top decile of fat mass) were measured using the Lunar Prodigy dual x-ray emission absorptiometry scanner. We found strong negative associations between MVPA and fat mass that were unaltered after adjustment for total physical activity. We found a strong negative dose-response association between MVPA and obesity. The odds ratio for obesity in adjusted models between top and the bottom quintiles of minutes of MVPA was 0.03 (95% confidence interval [CI] 0.01–0.13, p-value for trend <0.0001) in boys and 0.36 (95% CI 0.17–0.74, p-value for trend = 0.006) in girls.ConclusionsWe demonstrated a strong graded inverse association between physical activity and obesity that was stronger in boys. Our data suggest that higher intensity physical activity may be more important than total activity.

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms 1 Sex differences in overall and cause-specific mortality among HIV-infected adults on Methods:The ART Cohort Collaboration (ART-CC) combines 19 cohorts of individuals started on cART in Europe and North America (NA). We analyzed patients infected via injecting drug use (IDU) or heterosexual sex using Cox proportional hazards models.Results: 32,443 European (45.9% women), 1,162 (32.5% women) Canadian and 2,721 (15.5% women) US patients were included. In Europe and NA, women were younger, more likely to have acquired HIV heterosexually, be AIDS-free and have higher CD4 counts and lower HIV-1 RNA at baseline. European women had lower rates of all-cause (adjusted Hazard Ratio:0.76; 95%CI: 0.68-0.84) and non-AIDS mortality (0.67; 0.57-0.78) than men, but AIDS-mortality rates were similar (0.90; 0.75-1.09). Women had lower mortality due to non-AIDS infections (0.6 versus 1.3 per 1000 person-years), liver diseases (0.4 versus 1.7), non-AIDS malignancies (0.6 versus 2.0) and cardiovascular diseases (0.6 versus 1.0). Between-sex differences in all-cause mortality were larger in heterosexuals (0.70; (interaction p-value=0.043). No sex differences in all-cause mortality were found in Canada (HR women 1.13; 0.82-1.56) or US (HR women 1.12; 0.79-1.58). Conclusions:The increasing importance of non-AIDS mortality is leading to emergent sex differences among HIV-positive patients in Europe, as in the general population. In spite of the better clinical characteristics at cART initiation, women in NA had similar mortality to men. 3 INTRODUCTIONHigher life expectancy in women compared with men has been well documented since the early and mid 20 th century in the general population of industrialised countries [1][2][3], and since 2006 in developing countries [4]. The reasons are not fully understood, but important reductions in between-sex mortality differences have occurred in countries with high female smoking rates and high levels of female participation in the work-force, supporting a strong contribution of lifestyle factors and gender roles [1][2][3][4].Among HIV-positive people, the introduction of combination antiretroviral therapy (cART) has led to dramatic reductions in mortality rates [5][6], with an increasing proportion of deaths in treated HIV-positive people being due to causes not conventionally considered HIV-related [7]. Such changes may lead to emergent differences between mortality rates in treated HIV positive men and women but, unfortunately, sex-stratified analyses are not commonly reported given the low proportion of women among the Western HIV epidemics.Studies reported to date have produced contradictory results. Reports from the United States, largely based on seroprevalent cohorts, continue to report worse outcomes in HIV-infected women than men [8][9][10]. In Canada, no se...