Lee, I. (2016). Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women. The Lancet, 388, s. 1302Lancet, 388, s. -1310 Dette er siste tekst-versjon av artikkelen, og den kan inneholde små forskjeller fra forlagets pdf-versjon. Forlagets pdf-versjon finner du på www.sciencedirect.com: http://doi.org/10.1016/S0140-6736 (16) MethodsWe included data from 16 studies, of which 14 were identified through a systematic review of six databases from database inception until October 2015 and two were additional unpublished studies where pertinent data were available. All study data were analysed according to a harmonised protocol, which categorized reported daily sitting time and TV-viewing time into four standardised groups each, and physical activity into quartiles. We then combined data across all studies (N=1,005,791) to analyse the joint and stratified associations of daily sitting time and physical activity with all-cause mortality, and estimated summary hazard ratios using Cox regression. We repeated these analyses using TV-viewing time instead of daily sitting time. FindingsDaily sitting time was not associated with higher all-cause mortality rates among those in the most active quartile. Compared with the referent (<4 h of sitting per day and highest quartile of physical activity [>35.5 MET-hour/week]), there was no increased risk of dying during follow up in those who sat for more than 8h/day but who also reported >35.5 MET-hour/week of activity (HR=1.04; 95% CI, 0.99, 1.10). In contrast, those who sat the least (<4 h/day) and were in the lowest (<2.5 METhour/week) activity quartile had a significantly increased risk of dying during follow-up (HR=1.27, 95% CI, 1.22, 1.31). For TV viewing time, >3 hours/day was associated with higher mortality rates regardless of physical activity, except in the most active quartile, where mortality rates were significantly higher only in the >5 hours/day group. InterpretationHigh levels of moderate intensity physical activity (i.e. about 60 to 75 minutes per day) appear to eliminate the increased risk of death associated with high sitting time. However, this high activity level attenuates, but does not eliminate the increased risk associated with high TV viewing time.Funding None 3 INTRODUCTIONIn a seminal 1953 Lancet paper, Morris and colleagues demonstrated an increased risk of coronary heart disease (CHD) in London bus drivers compared with conductors.1 Since then, numerous observational studies have shown that lack of physical activity is a major risk factor for morbidity and premature mortality.2-4 Indeed, recent estimates indicate that not meeting physical activity recommendations is responsible for more than 5 million deaths globally each year.

These are the first population-representative findings on the deleterious associations of prolonged sedentary time with cardio-metabolic and inflammatory biomarkers. The findings suggest that clinical communications and preventive health messages on reducing and breaking up sedentary time may be beneficial for cardiovascular disease risk.

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OBJECTIVE -Total sedentary (absence of whole-body movement) time is associated with obesity, abnormal glucose metabolism, and the metabolic syndrome. In addition to the effects of total sedentary time, the manner in which it is accumulated may also be important. We examined the association of breaks in objectively measured sedentary time with biological markers of metabolic risk.RESEARCH DESIGN AND METHODS -Participants (n ϭ 168, mean age 53.4 years) for this cross-sectional study were recruited from the 2004 -2005 Australian Diabetes, Obesity and Lifestyle study. Sedentary time was measured by an accelerometer (counts/minute Ϫ1 Ͻ 100) worn during waking hours for seven consecutive days. Each interruption in sedentary time (counts/min Ն100) was considered a break. Fasting plasma glucose, 2-h plasma glucose, serum triglycerides, HDL cholesterol, weight, height, waist circumference, and resting blood pressure were measured. MatLab was used to derive the breaks variable; SPSS was used for the statistical analysis.RESULTS -Independent of total sedentary time and moderate-to-vigorous intensity activity time, increased breaks in sedentary time were beneficially associated with waist circumference (standardized ␤ ϭ Ϫ0.16, 95% CI Ϫ0.31 to Ϫ0.02, P ϭ 0.026), BMI (␤ ϭ Ϫ0.19, Ϫ0.35 to Ϫ0.02, P ϭ 0.026), triglycerides (␤ ϭ Ϫ0.18, Ϫ0.34 to Ϫ0.02, P ϭ 0.029), and 2-h plasma glucose (␤ ϭ Ϫ0.18, Ϫ0.34 to Ϫ0.02, P ϭ 0.025).CONCLUSIONS -This study provides evidence of the importance of avoiding prolonged uninterrupted periods of sedentary (primarily sitting) time. These findings suggest new public health recommendations regarding breaking up sedentary time that are complementary to those for physical activity.