Is the time right for quantitative public health guidelines on sitting? A narrative review of sedentary behaviour research paradigms and findings

Abstract

Sedentary behaviour (SB) has been proposed as an 'independent' risk factor for chronic disease risk, attracting much research and media attention. Many countries have included generic, non-quantitative reductions in SB in their public health guidelines and calls for quantitative SB targets are increasing. The aim of this narrative review is to critically evaluate key evidence areas relating to the development of guidance on sitting for adults. We carried out a non-systematic narrative evidence synthesis across seven key areas: (1) definition of SB, (2) independence of sitting from physical activity, (3) use of television viewing as a proxy of sitting, (4) interpretation of SB evidence, (5) evidence on 'sedentary breaks', (6) evidence on objectively measured sedentary SB and mortality and (7) dose response of sitting and mortality/cardiovascular disease. Despite research progress, we still know little about the independent detrimental health effects of sitting, and the possibility that sitting is mostly the inverse of physical activity remains. Unresolved issues include an unclear definition, inconsistencies between mechanistic and epidemiological studies, over-reliance on surrogate outcomes, a very weak epidemiological evidence base to support the inclusion of 'sedentary breaks' in guidelines, reliance on self-reported sitting measures, and misinterpretation of data whereby methodologically inconsistent associations are claimed to be strong evidence. In conclusion, public health guidance requires a consistent evidence base but this is lacking for SB. The development of quantitative SB guidance, using an underdeveloped evidence base, is premature; any further recommendations for sedentary behaviour require development of the evidence base and refinement of the research paradigms used in the field.

Detecting prolonged sitting bouts with the ActiGraph GT3X

“…Nowadays, studies investigating SB use small and lightweight body‐worn sensors capable to record free‐living behavior over several days . However, the device‐based SB measure is not consistent with its definition, and research is far away to stipulate evidence‐based health recommendations …”

“…7 However, the device-based SB measure is not consistent with its definition, 8,9 and research is far away to stipulate evidence-based health recommendations. 10 Probably the most frequently used sensor to measure SB is the ActiGraph (ActiGraph LCC, Pensacola, USA). The ActiGraph with its proprietary counts per minute (cpm) was originally developed to measure physical activity.…”

Device-Measured Sedentary Behavior, Physical Activity and Aerobic Fitness Are Independent Correlates of Cognitive Performance in Healthy Middle-Aged Adults—Results from the SCAPIS Pilot Study

“…However, subjective assessments of sedentary behavior in one domain may not be a valid measure of the total amount of daytime SED [43]. SED has been shown to be a risk factor for metabolic health, that is partly independent of aerobic fitness and MVPA [32] (but see also [44,45]). It would therefore be expected that higher %SED would be associated with worse rather than better cognitive functions, especially among low fit individuals.…”

Associations Between Television Time and activPAL-Measured Duration and Pattern of Sedentary Time Among Pregnant Women at Risk of Gestational Diabetes in the UK

“…Within epidemiological studies, the associations 46 between television time and cardiometabolic health outcomes are generally interpreted to be 47 effects of sitting. However, the association between TV time and poor health outcomes is 48 stronger than the association between total sitting time 1-3 or time spent sitting in other 49 confounding effects by socioeconomic position 5 , or factors such as snacking 1 , have been put 52 forward as potential explanations, the type of sitting associated with TV time may play an 53 important role. For example, based on experimental evidence showing that breaking up 54 sitting is associated with lower glucose and insulin levels compared to uninterrupted bouts of 55 sitting 6 , it has been suggested that watching TV might be associated with prolonged ST, and 56 be detrimental for that reason 1,2,7 .…”