Reducing sedentarism

Wendy Brown, Lars Bo Andersen, Anderssen Sigmund

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Reducing Sedentarism
Brown, WJ*1; Brown, WJ*1; Andersen, LB*2; Anderssen, SA*3
1The University of Queensland, Australia; 2University of Southern Denmark, Denmark; 3Norwegian School of Sports
Medicine, Norway
Western lifestyles have changed remarkably over the last century, with decreasing levels of physical activity and
increased sitting in most populations. While the health impacts of low physical activity have been extensively
researched in the last 50 years, the epidemiology of sitting has only recently emerged as a scientific area of
enquiry. Recent estimates suggest that working adults spend between 7 and 10 hours each day sitting, with about
half this time spent sitting at work. This paper will examine the hypothesis that too much sitting is a risk factor for
poor health, even in those who meet the current physical activity guidelines. First, the biological plausibility of too
much sitting being a health risk will be briefly considered. Second, a review of the evidence on the health effects of
sitting will be presented. This will include results from observational cohort studies on the relationships between
sitting and diabetes, cardiovascular diseases, cancers, depression, obesity and all-cause mortality, as well as from
experimental studies on the relationships between sitting and metabolic risk factors. Although some findings
indicate clear dose-response relationships between sitting and health outcomes, it is difficult to define a
deleterious 'dose' of sitting as few studies have considered sitting in all domains (eg work, leisure, transport).
There is however increasing evidence to suggest that sitting for >8 hours a day is associated with increased risk of
many health outcomes.
Wendy J Brown
Numerous epidemiological studies have found an association between amount of sitting, TV-viewing or other
sedentary behaviours and different health outcomes. A meta-analysis recently showed that TV-viewing was
associated with type 2 diabetes, cardiovascular disease and all-cause mortality. However, measures of sedentary
behaviour may be surrogate measures for lack of physical activity, and interventions aiming to reduce sedentary
activities may fail to increase physical activity and health. There are very few well designed studies where the
amount of physical activity is controlled for when the detrimental effect of sedentary behaviour is analyzed, and
only one randomized trial has manipulated sedentary behaviour with small breaks to improve health without
changing physical activity substantially. Many studies have adjusted the analysis between sedentary behaviour and
health for physical activity level, but is the information on physical activity level sufficiently good to avoid too much
residual confounding? This presentation will look at problems related to showing that sedentary behaviour is
decreasing health independent of physical activity level. The problem is important because future preventive
strategies may change substantially if it turns out that reducing sedentary behaviour may be as effective as
increasing physical activity. Some countries have already changed physical activity guidelines and included special
recommendations related to sedentary time, but it is questionable if these changes are based on solid evidence.
Lars B Andersen
Sedentary behaviors include sitting during leisure time, at work, and during commuting. Sedentary behaviors such
as TV viewing, using a computer or driving a car typically demands low levels of energy expenditure. Youth and
adults spend most of their waking time sitting or doing light activities, and most of them do little of moderate to
vigorous intensity activity. This combination leads to an overall low energy expenditure which has a detrimental
effect on many health outcomes. Dealing with this combination – giving low levels of energy expenditure - would
reduce the risks of various diseases such as cardiovascular diseases, type 2 diabetes, musculoskeletal diseases, and
psychological disorders. In addition, low level of energy expenditure is one of the key determinants of the current
epidemic of overweight and obesity in Europe. In order to both reduce sitting time and to increase the level of
physical activity there are several potential solutions. Among them is promotion of physical activity at school, to
focus on active transport, to focus on the build environment, to do structural changes at the workplace, and to
increase the neighborhood walkability. Programs will be more effective in communities where physical activity is
made easy.
Sigmund A Anderssen
Antal sider2
StatusUdgivet - 2012
BegivenhedInternational Convention on Science, Education & Medicine in Sport - Glasgow, Storbritannien
Varighed: 19. jul. 201224. jul. 2012


KonferenceInternational Convention on Science, Education & Medicine in Sport