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

Abstract

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through a systematic review of six databases from database inception until October 2015 and two were additional unpublished studies where pertinent data were available.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.

Adding exercise or subtracting sitting time for glycaemic control: where do we stand?

“…Recent epidemiological evidence, including a harmonised meta-analysis of 16 prospective studies with over 1 million individuals (2-18 years follow-up) [1] probably confirm what the Diabetologia readership already suspected-too much sitting and too little physical activity are bad news. Indeed, these studies indicate that low levels of physical activity and large volumes of sedentary time (sitting) are jointly associated with increased cardiometabolic morbidity and mortality in a dose-dependent manner [1][2][3][4][5][6][7]. However, for many of those with type 2 diabetes, the more pertinent question continues to linger: what are the most effective countermeasures?…”

O comportamento sedentário é o novo tabagismo?

“…Especialmente, nessa área de pesquisa, temos pouco mais de 15 anos de evidências, algo recente quando comparado ao tempo, volume e qualidade de evidências que colocaram a atividade física na agenda da saúde pública 4 . Grande parte dos estudos que levantaram a hipótese do comportamento sedentário como um fator de risco, são provenientes de investigações conduzidas em países de renda alta e que investigaram o tempo de televisão como um marcador do comportamento sedentário [2][3]5 . Os estudos que investigaram as conse-quências para a saúde do comportamento sedentário e mediram o tempo de televisão como um indicador de comportamento sedentário, de uma forma geral, encontram medidas de efeito das associações de maior magnitude quando comparados aos estudos que mediram o tempo sentado.…”

“…Em um dos principais estudos até o momento dessa temática, Ekelund e colegas 5 analisaram a associação entre tempo sentado, tempo de televisão e risco de mortalidade por todas as causas em mais de um milhão de adultos. Os autores mostraram que, apesar do tempo sentado estar sozinho associado ao maio risco de mortalidade, quando a prática de atividade física foi considerada, houve uma atenuação considerável do risco de mortalidade entre os grupos mais ativos.…”

“…Especialmente, nessa área de pesquisa, temos pouco mais de 15 anos de evidências, algo recente quando comparado ao tempo, volume e qualidade de evidências que colocaram a atividade física na agenda da saúde pública 4 . Grande parte dos estudos que levantaram a hipótese do comportamento sedentário como um fator de risco, são provenientes de investigações conduzidas em países de renda alta e que investigaram o tempo de televisão como um marcador do comportamento sedentário [2][3]5 . Os estudos que investigaram as conse-…”

The impact of physical activity on cancer prevention and survivorship

“…A notable study showed that increased SB was associated with increased mortality rate, independent of PA [13]. Furthermore, a recent meta-analysis showed that SB was associated with a lower mortality rate in people with high levels of PA [hazard ratio ( [14], and interventions need to focus on reducing SB, not just increasing PA.…”