A study tracking more than 90,000 people over a decade found that sitting for longer than half an hour at a time each day raises the risk of dying from cancer. The risk increases by 10% for every additional hour of continuous inactivity, according to researchers from the University of Glasgow.
Study Details and Key Findings
The findings, published in Plos Medicine, analyzed data from wearable devices worn by over 91,000 UK Biobank participants followed for an average of 12 years. Prolonged inactivity lasting more than 30 minutes was associated with higher cancer risks. However, breaking up sedentary behaviour with physical activity reduced the risk.
Dr Frederick Ho, lead author at the University of Glasgow, said: “What our data shows is that sitting for more than 30 minutes at a time is particularly linked to a higher risk of cancer. The good news is that breaking up your sitting time with something as simple as a short walk could be protective.”
Impact of Replacing Sedentary Time with Activity
Replacing one hour of sedentary behaviour daily with light physical activity, such as ironing or washing up, was associated with a 12% lower risk of cancer death. Replacing 30 minutes of inactivity with moderate physical activity, like walking at an average pace, led to an 8% lower risk. The risk was 22% lower when five minutes of inactivity was replaced with five minutes of vigorous physical activity each day.
Dr Ho added: “Current health guidelines focus heavily on moderate or vigorous exercise, but our findings show that light movement should not be ignored. Moving forward, clinical trials will help us move beyond blanket advice and develop personalised strategies for breaking up sitting time.”
Limitations and Expert Commentary
The researchers noted limitations, as the study was observational and could not prove causation. Prof Kevin McConway, emeritus professor of applied statistics at the Open University, who was not involved in the research, said the findings were interesting but further research would be needed.
Beneficial activities included slow walking and housework, suggesting even light movement can reduce cancer risks associated with prolonged sitting.
