Don’t sit for too long at a time — get up and move every now and then

It costs nothing; getting up a few times doesn’t take much time at all. The hard part is that once you sit down, you tend to lose track of time, so you’ll need a reminder.

A U.S. observational study used accelerometers to measure activity levels without grouping participants. It divided people into four groups based on total daily sitting time; those in the group with the most sitting had a 2.63 times higher mortality risk than the group with the least (HR 2.63). When grouped by duration of each continuous sitting session, the group with the longest sessions had a 1.96 times higher risk than the group with the shortest sessions (HR 1.96). This shows that both total daily sitting time and duration of each session are independently linked to risk. Another meta-analysis of millions of participants also found that people who sat for over 8 hours daily and did little to no exercise had a 1.59 times higher mortality risk compared to those who sat for under 4 hours and were most active (HR 1.59). Even among the most active group, those who sat over 8 hours daily still had an HR of only 1.04, showing no statistically significant difference.

Diaz KM 等 (2017). Patterns of Sedentary Behavior and Mortality in U.S. Middle-Aged and Older Adults: A National Cohort Study. Annals of Internal Medicine. https://doi.org/10.7326/M17-0212；Ekelund U 等 (2016). Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women. Lancet. https://doi.org/10.1016/S0140-6736(16)30370-1

The key takeaway is that how much you move matters more than how long you sit; sufficient physical activity essentially eliminates the extra risk from prolonged sitting. Keep in mind that these studies are purely observational, so many of the people who sat the most were already unwell — the “2.63 times higher risk” partly reflects this pre-existing health condition. Additionally, the same meta-analysis found that watching TV for over 3 hours daily increased risk across all activity levels; for the most active group, this threshold rose to 5 hours.