Does sedentary behaviour contribute to chronic disease or chronic disease risk in adults? A report prepared by the Scientific Committee of Agencies for Nutrition Action July 2009 Authors: Professor Grant Schofield, Professor of Public Health; Director, Centre for Physical Activity and Nutrition Research, AUT University Rob Quigley, NZ Registered Dietitian, Quigley and Watts Ltd Dr Rachel Brown, Lecturer, Department of Human Nutrition, University of Otago 1 Agencies for Nutrition Action are grateful to the Ministry of Health for the financial support to produce this review. Website: www.ana.org.nz Disclaimer: The views expressed in this report are the personal views of the authors and should not be taken to represent the views or policy of the Ministry of Health or the Government. 2 Contents Executive Summary .......................................................................................................... 6 Background ....................................................................................................................... 6 Aims .................................................................................................................................... 6 What is sedentary behaviour? ......................................................................................... 6 How much time do people spend in sedentary pursuits? .............................................. 7 Associations between sedentary behaviour and health ................................................. 7 Interventions to reduce sedentary behaviour ................................................................. 9 1. Background ............................................................................................................. 12 1.1 Introduction ....................................................................................................................... 12 1.2 Aim of the report .............................................................................................................. 13 1.3 Defining and conceptualising sedentary behaviour ....................................................... 14 1.3.1 What are metabolic equivalents? ................................................................................. 14 1.3.2 How was sedentary behaviour defined for this review? .............................................. 14 1.3.3 The difference between sedentary behaviours, sedentary lifestyle, NEAT and physical (in)activity .................................................................................................. 15 1.3.4 Why definitions are important ..................................................................................... 16 1.4 Sedentary behaviours and energy expenditure .............................................................. 18 1.4.1 Contribution of sedentary behaviours and light activities to energy burned ............... 18 1.4.2 Impact of labour-saving devices on daily energy expenditure .................................... 20 1.5 The prevalence of adult sedentary behaviour................................................................. 20 1.5.1 New Zealand evidence ................................................................................................. 20 1.5.2 International evidence .................................................................................................. 22 1.6 Perceptions of sedentary behaviour and physical inactivity ......................................... 23 1.6.1 Barriers, enjoyment and preference for sedentary behaviour – international data only ............................................................................................................................. 23 1.6.2 New Zealand data on barriers to physical activity ....................................................... 24 2. Review process ............................................................................................................ 25 2.1 Goal of the Scientific Committee ..................................................................................... 25 2.2 Topic identification ........................................................................................................... 25 2.3 Literature review process ................................................................................................. 25 3. Current reviews of sedentary behaviour .................................................................. 26 4. Measurement of Sedentary Behaviour...................................................................... 30 4.1 Measurement fundamentals and review ......................................................................... 30 4.2 Measurement tools for sedentary behaviour .................................................................. 31 4.2.1 Existing tools ............................................................................................................... 31 4.2.2 Self-report measures .................................................................................................... 31 4.2.3 Energy expenditure measures ...................................................................................... 32 4.2.4 Motion sensors ............................................................................................................. 32 5. Associations between sedentary behaviour and health ........................................... 51 5.1 Obesity................................................................................................................................ 52 5.2 Metabolic syndrome .......................................................................................................... 54 5.3 Diabetes .............................................................................................................................. 55 3 5.4 Cardiovascular disease and dyslipidaemia ..................................................................... 55 5.5 Cancer ................................................................................................................................ 56 5.6 Back pain, bone health, gallstones and mental health ................................................... 57 6. Interventions to decrease sedentary behaviour ........................................................ 58 7. Recommendations and future work .......................................................................... 66 7.1 Sedentary behaviours need to be addressed ................................................................... 66 7.2 Disseminating the message ............................................................................................... 66 7.3 Evidence gaps .................................................................................................................... 66 7.4 Intervening across settings ............................................................................................... 67 References ........................................................................................................................ 69 Appendix 1 ....................................................................................................................... 77 Literature identification ......................................................................................................... 77 Data handling process ............................................................................................................. 77 Assessment of papers .............................................................................................................. 78 Writing the report ................................................................................................................... 79 Research questions .................................................................................................................. 79 Example search strategy ......................................................................................................... 80 Appendix 2: Prevalence of sedentary behaviour tables............................................... 82 Appendix 3: Table of studies investigating the association between sedentary behaviours, chronic disease and chronic disease risk ........................ 89 4 List of Tables Table 1: Behaviours included or not included in this review ........................................................................15 Table 2: Abstracts of review articles relating to sedentary behaviour ...........................................................26 Table 3: Measuring sedentary behaviour .......................................................................................................35 Table 4: Summary of obesity studies and sedentary behaviour .....................................................................53 Table 5: Summary of metabolic syndrome studies and sedentary behaviour ................................................54 Table 6: Summary of diabetes studies and sedentary behaviour ...................................................................55 Table 7: Summary of cardiovascular disease/dyslipidaemia studies and sedentary behaviour .....................56 Table 8: Summary of cancer studies and sedentary behaviour ......................................................................56 Table 9: Summary of miscellaneous studies and sedentary behaviour ..........................................................57 Table 10: Interventions to decrease sedentary behaviour ..............................................................................59 List of Figures Figure 1: Model of determinants of sedentary behaviour and outcomes of interest 13 Figure 2. Comparison of two people's time spent in activities ......................................................................19 Figure 3: Energy expended from different activities .....................................................................................19 Figure 4: Average hours per day spent watching TV or video, by priority of activity and age .....................21 Figure 5: Typical placement of an inclinometer such as the activpal, which is able to differentiate standing and sitting time ..............................................................................................................................................33 5 Executive Summary Background Sedentary behaviours include sitting time at work, reading, sitting while travelling, computer time and television viewing. Increased sedentary time may substantially increase risk of chronic disease (Hamilton et al 2007). This increased risk may be independent of habitual physical activity levels. That is, the potential negative effects from so many hours of sedentary activity every day may not be negated by bouts of moderate to vigorous physical activity a few times a week. In contrast to the large amount of epidemiological, basic scientific (both cellular and physiological) and intervention data about exercise, little is known about the cellular signals, physiological responses and disease outcomes of prolonged sitting and other sedentary behaviours. Aims The aim of the report was to answer the following questions: 1. What is the context for sedentary behaviour in the adult population? For example:  What is sedentary behaviour and how has it been defined/conceptualised?  Is sedentariness prevalent among adults?  How is sedentary behaviour measured? 2. What are the associations between adult sedentary behaviours and chronic disease and chronic disease risk (and other social factors/behaviours such as productivity, cognition and food intake1)? 3. What interventions/environments are effective in reducing adult sedentary behaviours? 4. What are the recommendations for sedentary time for the adult population? Methods Databases of scientific publications and relevant websites were searched for papers published from January 1996 to 21 November 2008, a time span chosen to make the analyses manageable. The search terms and an example strategy are provided at the end of the methods section. Additional searches on key author surnames were also undertaken. What is sedentary behaviour? Sedentary behaviour should be viewed as a discrete behaviour separate from physical activity. For this review, activities with a metabolic equivalent (MET, where 1 MET is 1 No papers about sedentary behaviour relationship with cognition or worker productivity were found. 6 amount of energy used when completely at rest) of less than 1.5 are classified as sedentary behaviour (Pate et al 2008). Also for the purpose of this review, at least one indicator of sedentary behaviour had to be measured in some way; for example, time spent watching television (TV), time spent using a computer or gaming, time spent sitting at work, and/or time spent reading. How much time do people spend in sedentary pursuits? There is a marked lack of measurement of sedentary behaviour in New Zealand‘s large nationwide surveys. One measure of sedentary behaviour comes from the New Zealand Time Use Survey, where participants were asked to record time spent watching TV or videos. Nine out of ten (88%) respondents watched TV, making this the most popular leisure time activity of New Zealanders. On average, people watched just under two hours (1 hour 59 minutes) of TV or videos per day as a primary activity (Statistics NZ 2009). The only population-based prevalence sample that used an objective measure of sedentary behaviour is the National Health and Nutrition Examination Survey (NHANES) 2003/04, which sampled 6329 participants in the USA. Results showed that children and adults in the USA spent 54.9% of their waking time, or 7 hours 42 minutes per day, in sedentary behaviours (Matthews, et al 2008). How is sedentary behaviour measured? Valid and reliable measurement of sedentary behaviour is important. Like physical activity measurement, sedentary behaviour measurement has used self-report, energy expenditure and motion sensors to try to understand the degree to which people move, or do not move. Motion sensors probably provide the best option across a range of research questions for measuring sedentary behaviours. They are less costly and more portable than energy expenditure methods, and are not prone to recall problems experienced in self-report. They are also likely to be suitable across a range of ages, from young children to older adults, making comparisons using the same units feasible. Associations between sedentary behaviour and health The literature review shows there is some evidence that sedentary behaviour may adversely affect health and health risk. The studies are mainly cross-sectional, with a few prospective studies emerging recently. The first prospective study2 to use a sample that is representative of a general population is the 14-year follow-up of nearly 20,000 Canadians in the Canadian Fitness Survey (Katzmarzyk et al 2009). In this study, increasing sitting time was associated with higher all-cause death and cardiovascular disease death, but not cancer death. These effects persisted independently of physical activity measures. 2 A study that follows people over time to see if ill health results from earlier behaviours. 7 Obesity Out of 51 studies, 38 (29 cross-sectional and nine prospective) reported significant positive associations between sedentary behaviour and obesity, 12 reported no association (10 cross-sectional and two prospective). No studies showed a negative association. Taken together, there is considerable evidence that sedentary time is associated with increased risk of obesity per se and weight gain in lean people. At this stage more robust measurement and consistency of measurement across studies is required. We conclude there is sufficient evidence, both in terms of plausible mechanisms and epidemiological evidence, that sedentary time is associated with increased risk of obesity per se and weight gain in lean people, and to alert the public to the risks of high TV time, occupational sitting and high sedentariness in general. Metabolic syndrome Out of 19 cross-sectional studies, 14 reported significant positive associations between sedentary behaviour and metabolic syndrome and five reported no association. No studies showed a negative association. Taken together we have only a limited amount of epidemiological evidence, confined to cross-sectional studies, for an association so it is premature to discuss the magnitude of these effects. Diabetes All three reviewed studies (one cross-sectional and two prospective) reported significant positive associations between sedentary behaviour and diabetes. No studies reported no association and no studies showed a negative association. More work needs to be carried out, but we can conclude that there is some evidence for this link. Cardiovascular disease and dyslipidaemia All four reviewed studies (two cross-sectional and two prospective) reported significant positive associations between sedentary behaviour and cardiovascular disease and dyslipidaemia. No studies reported no association, and no studies showed a negative association. Although there are only a few studies, there is some evidence that sedentary behaviour is an independent risk factor for cardiovascular disease. Cancer On balance the evidence for sedentariness causing cancer is limited. There are few studies with equivocal results. More evidence is needed before drawing conclusions or making public health recommendations for reducing cancer risk. Certainly there is a plausible link, with some prospective evidence for some cancers at this stage. Back pain, bone health, gallstones and mental health There has been limited investigation into other outcomes such as back pain, bone health, gallstones and mental health. All of the associations reported are in cross-sectional studies. More research needs to be carried out to draw conclusions about an effect for these outcomes. 8 Interventions to reduce sedentary behaviour Few studies have examined interventions to reduce sedentary behaviour. Some studies have been undertaken within the workplace such as standing work stations, and interventions incorporating a low-speed treadmill (Levine et al 2008). Workplace sitting is highly prevalent in most office environments and therefore appears to be a great place to start intervention. Levine and colleagues substituted a traditional sit-down desk for a desk that incorporates a low-speed treadmill into its design. Instead of sitting it is possible to walk at 1 to 2 km/h while working on office-based tasks such as talking on the telephone and undertaking computer work. Within a community setting programmes that encourage or support increased light or moderate activity such as walking and/or use of pedometers (De Cocker et al 2008) may reduce sedentary behaviour. The 10,000 Steps approach in Belgium saw a 30-minute differential in sitting time at follow-up in the intervention community compared to the control communities (i.e. the intervention community reduced sitting time). Recommendations and future work Sedentary behaviours need to be addressed Although this field is still very much in the development stage, there is sufficient evidence to suggest that sedentary behaviour is a distinct risk for multiple health outcomes and that this risk appears to be independent of time spent doing moderate and/or vigorous physical activity. Because of the lack of measurement of sedentary behaviour, there is insufficient evidence to explain the nature of the relationship between sedentary behaviour and multiple health outcomes, and how much sedentary time is acceptable. Therefore, more research is required. It is important to acknowledge the role that light activity and habitual movement (e.g. slow walking, walking around the house/office) may play in health, and especially in energy expenditure. We recommend: 1. Research: investigating doses and levels of sedentary behaviour and the resulting disease risk to inform policy decisions and help develop recommendations and guidelines. Evidence gaps are detailed in the section below. 2. Policies and Guidelines: Government agencies such as the Ministry of Health, SPARC and Department of Labour consider the role of sedentary behaviour when developing policies and guidelines. Disseminating the message The simple message is to ―move more, sit less‖. Dissemination of this message can occur in a variety of different settings including workplaces, primary care settings, sport and recreation, and public health, as well as the wider community. 9 Evidence gaps At present there are several gaps in the research literature; filling these will provide important evidence for policy and action in this area. Research priorities include:  Epidemiology: measuring how sedentary New Zealanders are, trends, and which population groups have the highest levels of sedentariness.  Epidemiology: further detailed epidemiological work, especially prospective studies that incorporate objective measures to understand the health outcomes associated with high levels of sedentary behaviour.  Physiology: further physiological work investigating the effect of sedentary behaviour on biomedical outcomes related to glucose metabolism and blood lipids. This will build on research already underway and well reviewed by Hamilton et al (2007).  Environmental influences: investigating the macro and micro (e.g. settings-based) environmental factors that promote sedentariness.  Interventions: researching the efficacy of environmental re-engineering to promote standing and ambulatory pursuits, which should be both in the broader urban environment and specific to settings such as workplaces, schools and social settings. Intervening across settings Approaches that involve changing sedentary behaviour in specific settings are likely to be effective. We suggest workplace and family/whānau settings are appropriate places to make improvements. In the workplace many adults spend long periods of time sitting. We suggest organisations could adopt the following approaches:  Acknowledge sedentary behaviour is a workplace health and productivity issue and address sedentary behaviour in a systematic way.  Provide vertical (or height-adjustable) work stations for employees that allow workers to stand for part of the day while continuing to work at computers and other office/factory equipment. Treadmill-based work stations could be considered by workplaces in the future.  Encourage staff to ―walk and talk‖ where practical, by moving about the workplace when communicating with each other rather than using email, phones and seated meetings.  Encourage staff with largely sedentary tasks to take breaks that involve movement of some kind. Home environments are often characterised by long periods of sitting, especially watching electronic media. At the individual and family/whānau levels we suggest the following interventions may be effective in reducing sedentariness: 10