The habit of sitting still for long periods raises the risk of cancer and death, a study has found.
Cancer Risk Rises 9% for Each Additional Hour of Sitting Beyond 30 Minutes
According to a paper published Tuesday in the international journal PLOS Medicine by a research team led by Professor Frederick Ho of the University of Glasgow in the U.K., an analysis of data tracking 91,292 UK Biobank participants over about 12 years found that the risk of death from cancer increased 9% for each additional hour per day of prolonged uninterrupted sitting.
Using 30 minutes as a benchmark, the researchers classified sitting as "prolonged uninterrupted sitting" if it continued for more than 90% of that time, that is, more than 27 minutes. Conversely, if it lasted less than 30 minutes, or if the person got up and moved for more than 3 minutes within the 30-minute span, it was classified as "interrupted sitting time."
The analysis found that for each additional hour per day of prolonged uninterrupted sitting, the overall risk of cancer death rose 9% and the risk of developing cancer rose 3%. The risk of developing obesity-related cancer rose 5% and the risk of developing type 2 diabetes-related cancer rose 5%, the study found. Conversely, interrupted sitting time was linked to a tendency toward lower risk across all four categories.
Even sitting for the same eight hours produces different results. Those who got up and moved every hour differ from those who sat for four straight hours and then sat for another four straight hours. As with the latter case, the longer the uninterrupted stretch of sitting, the greater the risk.
Replacing Sitting with Light Activity Lowers Death Risk 12%
According to the research team, replacing just one hour of sitting time with light physical activity was estimated to lower the risk of cancer death by 12%.
If one hour is too long, raising the intensity and doing just 30 minutes of moderate activity was calculated to lower the risk by 8%. Just 5 minutes of high-intensity activity was found to be associated with a lower risk of overall cancer, obesity-related cancer, and type 2 diabetes-related cancer.
The researchers explained that these findings align with previous experiments showing that even brief movement during long periods of sitting improves metabolic response. For those who work sitting down for long periods, starting with low-burden light activity is interpreted as advantageous for putting this into practice.
However, this study did not separately analyze whether participants' sedentary behavior was due to work or leisure activity. The fact that participants' existing health conditions were not reflected in the study results was also pointed out as a limitation.
