Every extra hour spent sitting or lying down could increase the risk of cancer and cancer-related death, a study has suggested.
A sedentary lifestyle, such as sitting, reclining or lying down while awake for hours of the day, has long been associated with poorer health outcomes, including obesity, type 2 diabetes, some types of cancer and early death.
But most sedentary behaviour guidelines focus on total time spent still, rather than whether that time is accumulated in many short intervals or fewer prolonged intervals.
“The health effects of sedentary behaviour may depend not only on total sedentary time, but also on whether that time is accumulated in prolonged bouts or interrupted by activity,” researchers at the University of Glasgow wrote.
“Experimental studies have shown that interrupting prolonged sitting with short bouts of activity can improve metabolic responses compared with uninterrupted sitting.”
For the study, published in the journal PLOS Medicine, researchers analysed data from 91,292 UK Biobank participants who had worn activity monitors for seven days and were followed for about 12 years.
Activity levels were categorised as either “prolonged sedentary”, meaning in a bout of 30 minutes the person was sedentary 90 per cent of the time, “interrupted sedentary behaviour”, where a bout of 30 minutes is broken up with more than 10 per cent non-sedentary activity, and “varying degrees of physical activity”.
Prolonged sedentary behaviour was associated with a 9 per cent higher risk of cancer mortality, as well as overall cancer incidence, obesity-related cancers (such as oesophageal, liver, kidney, pancreatic, colorectal, breast, ovarian, and thyroid cancers), and type 2 diabetes-related cancers.
But those who interrupted their lying and sitting down with short bursts of movement had a lower risk of cancers and type 2 diabetes.
Replacing just one hour a day of prolonged sitting with light physical activity, such as a walk, was associated with a 12 per cent lower risk of cancer death.
Adults should do some type of physical activity every day to stay healthy, as well as exercising twice a week, according to the NHS. This could be strength training, running, walking, swimming or even pushing a lawn mower.
The NHS also suggests people should reduce the time they spend sitting or lying down and break up long periods of not moving with some activity.
“Current health guidelines focus heavily on moderate or vigorous exercise, but our findings show that light movement shouldn’t be ignored,” the researchers concluded. “Moving forward, clinical trials will help us move beyond blanket advice and develop personalised strategies for breaking up sitting time.”
