Last year, I tracked my activity levels for a week, which proved a big surprise as I had thought I was continually active. On Mondays and Tuesdays I often spent ten hours sitting at my computer hardly moving, then slumped in front of the TV for another two hours. I couldn’t understand why I had sprouted a spare tyre but there was the reason. My preoccupation was squeezing into a favourite frock, but health experts now warn that sitting for hours poses serious health problems, regardless of how much exercise you do otherwise. According to NHS Choices, many adults in the UK spend more than seven hours a day sitting or lying, which typically increases with age to ten hours or more.

Recent studies link a sedentary lifestyle to an increased risk of heart disease, stroke, emphysema, type 2 diabetes, osteoporosis, backache, anxiety and depression, and also – perhaps more surprisingly – to various forms of cancer.

A huge long-term study published recently by the American Cancer Society found that ‘women who sit for six or more hours daily are at a ten per cent higher relative risk of any cancer’ than those who sit less than three hours a day, according to lead author Professor Alpa Patel. The risks of ovarian and bone marrow cancer were substantially higher at 43 and 65 per cent respectively. Another large-scale study found that people who sat down the longest compared with those who sat down the least had a 49 per cent increase in premature death from any cause.

The difficulty is teasing out precisely how continuous sitting causes these problems. According to a Cancer Research UK spokesperson, there is no clear evidence that ‘sitting in itself causes cancer unlike the direct risks posed by smoking, sun exposure, diet, obesity and alcohol’. However, there is evidence that physical activity protects against various forms of cancer, as well as many other chronic diseases.

Australian cancer epidemiologist Dr. Brigid Lynch believes that, while more research is needed, there are key mechanisms that may directly link sitting time with cancer and other health problems.

‘Human bodies are not suited to sitting for [many hours]. Our ancestors used to walk at least 20km daily to hunt and gather food, and pre-computers, few people sat all day. Sitting still may cause inflammation, [possibly because] it is part of the body’s repair process and until recent times people would only sit if they were sick or injured. Long periods of inflammation can lead to a range of chronic diseases including cancer.’

What’s more sitting involves minimal muscle activity: the body effectively shuts down. ‘When you are normally active, the large muscle groups play a key role in regulating your blood glucose and lipid levels – thus the links of sitting to diabetes and heart disease – and also produce anti-inflammatory proteins and peptides,’ explains Dr Lynch.

‘Long periods of sitting tend to slow the metabolism, the rate your body burns energy from food and drink, increasing body fat and leading to more circulating oestrogen in post-menopausal women. This would fit in with the higher risk of breast, ovarian and womb cancers,’ she adds.

WHAT YOU CAN DO

• Break up sitting time into small chunks and move around in between. ‘It engages your muscles and bones and gives all your bodily functions a boost,’ says Professor David Dunstan of the University of Melbourne.

• Sit on an ‘active sitting’ ball, eg, Technogym Wellness Ball, £230, www.technogym.co.uk.

• Do little things: be a fidget, have a chair that tips and tilts, walk to a colleague rather than email them, telephone standing up and moving around and take the stairs.

• Hold standing and ‘hiking’ meetings. They help people focus on the issue, partly because walking means people tend to put away their mobiles.

• Use a sit/stand desk, such as the Varidesk, from £325, www.varidesk.co.uk

• Take up active hobbies.

• For more ideas, see www.nhs.uk, search for: Why sitting too much is bad for your health.

 

IS SITTING THE NEW SMOKING?

Light smokers have a 500 per cent increased risk of developing cancer than people who have never smoked, whereas people who sit for long periods have an increased risk of about 60 per cent. But the risk is real. Only one in six people in the UK smokes but nearly everyone spends a large part of their day sitting down.