Spending large amounts of time sitting or lounging around during the day is linked to around 50,000 deaths per year in the United Kingdom and the National Health Scheme (NHS) spends in excess of £0.7 billion per year treating the health consequences, suggests research from Queen’s University Belfast and Ulster University published online in the Journal of Epidemiology & Community Health.
A Rael-Science post on the research says a large proportion of the UK population has sedentary jobs and leisure activities, and official physical activity recommendations regarding sedentary behaviour are vague.
Previous studies have shown that spending large parts of the day sitting down increases the risk of cardiovascular disease, type 2 diabetes, cancer and death and is a burden on health services. The effects on osteoporosis of prolonged periods of sitting – and the potential impact of less sedentary behaviour – are being explored in research led at the University of Strathclyde.
The academics were investigating whether extended periods of sitting, in a controlled laboratory setting, lead to increased bone loss, and whether breaking up sedentary behaviour has the opposite effect.
They expanded on their earlier research which demonstrated that prolonged sedentary behaviour could have an adverse effect on the hip bone mineral density of women.
The findings will have the potential to inform and shape future public health policy and physical activity guidelines aimed at improving bone health.
The study also involved colleagues at Glasgow Caledonian University, the University of Birmingham, the University of East Anglia and the Baker Heart and Diabetes Institute in Melbourne.
Dr. Alexandra Mavroeidi, a Senior Lecturer in Physical Activity for Health in Strathclyde’s School of Psychological Sciences & Health, is leading the study. She said: “Prolonged sedentary behaviour is a major and growing public health concern, but its role specifically in relation to bone loss and osteoporosis is not known.
“We know that in extreme environments, such as total bed rest, bone loss is very high. In everyday life, long periods of immobility such as this are rare; however, sedentary lifestyles are commonplace in modern society, through transport, work and leisure.
“Studies have shown that self-reported sedentary behaviour throughout the day is as much as six to eight hours and this increases to eight to 10 hours in older adults. We were the first to show that this type of behaviour might have an adverse effect on women’s hip bone mineral density.
“We are now aiming to test this further and see if extended periods of sitting in a controlled laboratory setting have an immediate acute effect on the bone metabolism of older adults. We also aim to examine the short-term effects, over five days, on healthy sedentary adults, of reducing sitting time through increased standing bouts.”
The study will use data and blood samples which have already been collected, but not analysed, in previous sedentary behaviour studies by the research group. If the proof of concept study identifies a significant effect of sedentary behaviour on bone metabolism, promoting frequent breaks from sitting could be a possible, and simple, preventative intervention for osteoporosis in later life.
The research is being funded by the Royal Osteoporosis Society, previously the National Osteoporosis Society.
Professor Jon Tobias, Professor of Rheumatology at the University of Bristol and Chair of the Society’s Research Grants Committee, said: “The Research Grants Committee had a difficult job in selecting a small proportion of successful projects among the large number of interesting and high quality applications that we received, but we were particularly impressed with Dr. Alexandra Mavroeidi’s research proposal.
“Her project will conduct pioneering research into the impact of extended periods of sitting on bone metabolism, and the benefits of breaking up sedentary behaviour through more frequent bouts of physical activity. This will help us to learn more about the mechanisms behind osteoporosis, and give us a better understanding of the relationship between lifestyle and bone health.
“Dr. Mavroeidi’s project has strong potential to make a significant difference, not only in the management of patients with osteoporosis, but also in the prevention of the disease for future generations.”
But no estimate of the financial impact that sedentary behaviour has on the NHS has been calculated, so the authors set out to do just that.
Figures calculated by other researchers on the impact sedentary behaviour has on the relative risks of five specific health conditions (type 2 diabetes, cardiovascular disease, colon cancer, endometrial cancer and lung cancer) and deaths from all causes were combined with figures on the percentage of adults who are sedentary on any given day of the week to estimate the overall impact sedentary behaviour has at a UK population level (population attributable fraction).
Figures on sedentary behaviour were taken from the Health Survey for England 2012, which reported that 30% of adults in England spent at least six hours/day sedentary on weekdays and that this increased to 37% of adults on weekends.
Meanwhile, actual overall NHS spending on each of the five conditions, uplifted for inflation, was used to estimate the financial impact sedentary behaviour had on the NHS for each of the conditions in the UK in 2016-17.
For all five conditions combined, this amounted to £0.8bn in 2016-17.
As a proportion of patients will have more than one of the five conditions, for example around 30% of people with type 2 diabetes will also have cardiovascular disease, the researchers revised their figures to adjust for double-counting caused by comorbidity. This reduced the overall cost of sedentary behaviour to the NHS for these five health conditions to £0.7bn in 2016-17.
Next they took the figure calculated for the fraction of deaths from all causes that could be attributed to a sedentary lifestyle and multiplied it with the actual numbers of deaths that occurred in the UK in 2016.
The researchers say their results suggest that 11.6% of all deaths were associated with sedentary behaviour and that 69,276 deaths might have been avoided in 2016 if sedentary behaviour was eliminated in the UK.
This is an observational study, and as such, can’t establish cause, and it also relied on estimates of people’s self-reported activity levels, which may not be accurate. The study was also limited by the evidence available for the link between sedentary behaviour and health outcomes.
The authors point out that these costs are probably a conservative estimate of the true burden of sedentary behaviour because sedentary behaviour is likely to be associated with several other cancers, musculoskeletal disorders, and mental health disorders, not included in their analysis.
Official physical activity recommendations regarding sedentary behaviour are vague, they say. Lead Investigator, Leonie Heron from the Centre of Public Health at Queen’s University Belfast, said: “Many individuals in the UK spend their leisure time in sedentary behaviour, and the workplace represents a significant proportion of unavoidable daily sitting time for many people.”
Measures should be taken to reduce sedentary behaviour with the aim of improving population health and reducing the financial burden to the health service, they conclude.
