How sitting down for too long can increase the risk of cancer
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, lying down or lying awake for hours a day, has long been associated with poorer health outcomes, including obesity, type 2 diabetes, some types of cancer and premature death.
However, most sedentary behavior guidelines focus on total time spent sedentary, rather than whether this time is accumulated in many short intervals or fewer long intervals.
“The health effects of sedentary behavior may depend not only on total sedentary time, but also on whether this time is accumulated in long-term bouts or is interrupted by activity,” researchers at the University of Glasgow wrote.
“Experimental studies have shown that interrupting long periods of sitting with short periods of activity can improve metabolic responses compared to uninterrupted sitting.”
For the study published in the journal PLOS MedicineResearchers analyzed data from 91,292 UK Biobank participants who wore activity monitors for seven days and were followed for approximately 12 years.
Activity levels were categorized as “prolonged sedentary behavior,” meaning that a person is inactive 90 percent of the time within a 30-minute period, “intermittent sedentary behavior,” meaning a 30-minute period is broken up by more than 10 percent sedentary activity, and “varying degrees of physical activity.”
Long-term sedentary behavior was associated with a 9 percent higher risk of cancer death as well as a higher incidence of cancer overall, obesity-related cancers (esophageal, liver, kidney, pancreatic, colorectal, breast, ovarian and thyroid cancers) and type 2 diabetes-related cancers.
However, those who interrupted lying and sitting movements with short movements had a lower risk of cancer and type 2 diabetes.
Replacing just one hour a day of prolonged sitting with light physical activity, such as walking, was associated with a 12 percent reduced risk of death from cancer.
According to the NHS, adults should do some form of physical activity every day to stay healthy, as well as exercise twice a week. This could be strength training, running, walking, swimming, or even pushing the lawnmower.
The NHS also suggests that people should reduce the time they spend sitting or lying down and break up long periods of inactivity with some activity.
“Current health guidelines focus predominantly on moderate or vigorous exercise, but our findings suggest that gentle movements should not be ignored,” the researchers said. “Going forward, clinical studies will help us go beyond general recommendations and develop personalized strategies for breaking up sitting time.”
