Sedentary behaviour in older adults: investigating a new therapeutic paradigm

Older age is associated with an increased risk of many diseases, poor physical function and frailty, cognitive decline and other forms of disability. Also, some groups such as South Asians have higher rate of disease. Research has shown that many of these factors are improved by higher levels of physical activity. However, little is known about the role of sedentary behaviour i.e., sitting time in older adults. Some research has started to show that reducing the time that you spend sitting can reduce the risk of many diseases and improve functional health. This research suggests that improvements in health may be gained by simply helping people to swop time spent sitting with time spent standing or in light-intensity walking. Older adults spend around 70% of their day sitting but little is currently known about whether reducing sitting time promotes health and wellbeing in older adults. This may be particularly relevant to older adults where fear of falls, joint pain, decreased physical function and other contraindications may limit motivation and ability to engage in much purposeful exercise. This grant is therefore going to focus on investigating the impact of sitting in older adults. The results of this research will inform larger studies and public health initiatives aimed at reducing sitting time in the future.

Our research plan includes three work packages. In work package one, we will develop a method of estimating time spent sitting and in physical activity which hasn't been done before in older adults. This will be done in a laboratory where participants will complete a set of activities and we will measure the intensity of these activities. Another part of this work package is to use existing data that has been collected as part of the Health Survey for England. We will re-analyse this data to investigate how much sitting and physical activity older adults do, when and how often they do these behaviours (e.g., morning ,afternoon, evening, numbers of times in the day and how long for each time), and compare this to other age groups. We will also look at the relationship between sitting and physical activity with health and wellbeing in older adults. This data will be supplemented with data that we have collected within our department in a large population of older multi-ethnic adults. Work package two will develop a novel way of measuring sitting time which allows researchers to capture the location of where older adults spend the their time around the home/car environment and more accurately measure sitting time. This will involve a wrist worn device along with very small tags that can be attached to objects (such as chairs, tables, computers etc). We can then combine the information from both devices to measure time spent sitting but also the type of sitting behaviour and the location around the home (e.g., sofa in living room, computer in office, dining table etc). This will help researchers to develop ways to help people to reduce their sitting time. This novel method will be tested in a laboratory and also a small number of people will be asked to test it in their daily lives. Once they have done this we will ask them for feedback on perceptions of sedentary behaviour and these novel method of measuring sitting. Work package three will be a laboratory study to investigate the impact of sitting down all day (condition one), reducing sitting by standing every 30 minutes for a few minutes (condition two) and reducing sitting by slowly walking every 30 minutes for a few minutes (condition three). Participants will come into the laboratory and perform each of these conditions over a day (8am-5pm). During these conditions blood sugar, insulin, fats in the blood, mood and cognitive function will be measured. This work package will investigate how harmful sitting is for health and whether health can be improved by reducing sitting time either by standing or light walking or both.

Recent evidence has shown that many of deleterious factors associated with older age are ameliorated by higher levels of moderate-to-vigorous intensity physical activity (MVPA). In contrast, little is known about the role of sedentary behaviour (sitting) in older adults. Observational and intervention level data in the general population suggests that reducing sedentary time has significant impacts on metabolic health, cardiovascular disease and mortality, independent of MVPA. This suggests that potential improvements in health may be gained by simply helping individuals substitute time spent sitting with time spent standing or in light-intensity ambulation. However, little is known about whether reducing sedentary behaviour promotes health and well-being in older adults. This grant is therefore primarily focused on investigating the impact of sedentary behaviour in older adults. This will provide the foundations with which to inform larger efficacy trials and public health initiatives aimed at reducing sedentary behaviour in the future.

We propose three distinct, but complementary, work packages that will enable a step change in knowledge around the impact of sedentary behaviour in older adults. 1) Utilising existing datasets, which have both objective and subjective measures of sedentary behaviour and MVPA, work package one will focus on establishing the prevalence and strength and nature of the association between sedentary behaviour, MVPA and health in older adults. 2) Work package two will refine the measurement of sedentary behaviour by combining accelerometry with radio frequency identification (RFID) technology to provide a more accurate and detailed assessment of sedentary behaviour. 3) Work package three, in a laboratory setting, investigates the acute effect of sedentary time, reduced sedentary time and increased light-intensity physical activity on metabolic and psychological health in a sample of 116 multi-ethnic older adults.

This grant will lead to multiple beneficiaries, but fundamentally it is hoped it will lead to an increased focus on novel therapeutic lifestyle strategies for maintaining health and wellbeing in older age across ethnic groups. Given the aging population, this has a high clinical and societal priority. In particular, it is essential that therapeutic approaches beyond the traditional 30 minutes of moderate-to-vigorous physical activity are explored.

Work Package 1 is aimed at accurately measuring the prevalence of sedentary behaviour and physical activity in older adults and the independent impacts of these factors on indicators of health and wellbeing. This will help inform public health guidance and prioritise resource allocation. For example, such information will be important for future NICE public health guidance, including accurate prevalence estimates which are essential in undertaking cost-effectiveness modelling. In addition, determining the strength of association between sedentary behaviour and health/wellbeing and how these vary compared to younger groups will help clarify the importance of this behaviour to clinical audiences.

Work Package 2 is focused on developing a novel measurement tool that will allow a wealth of new data to be gathered around where older adults spend the majority of their sedentary/active behaviour around the home/car/other and how this varies through the day; this will be enhanced by gathering qualitative data to gain insights into perceptions of sedentary behaviour. This will therefore provide both the academic and the commercial communities with a high-quality platform with which to develop interventions aimed at the reduction of sedentary behaviour in the future. For example, start-up companies are starting to emerge that are developing devices and tools to help individuals reduce their sedentary behaviour. However, these have been focused on younger, working-age, populations. We will provide the information needed to help re-prioritise this work towards older cohorts.

Work Package 3 will build on the other phases by helping confirm the causal nature of the relationship between reduced sedentary behaviour and metabolic health. In addition, it will provide novel evidence investigating whether reduced sedentary behaviour improves positive affect and cognitive function in older adults. This will provide the final piece of evidence needed to confirm the importance of sedentary behaviour in older adults and enable downstream research to be initiated looking at behaviour change techniques in older adults and how prolonged periods of sedentary behaviour can be engineered out of daily life.

Further information around impact and dissemination of the research is listed in the "Pathways to Impact" document that accompanies this application.