Let’s start with what we know about research on sitting, then explain why it can be misleading as it relates to work. A number of studies have found a significant association between prolonged sitting time over a 24-hour period and increased risk for cardiovascular disease. A 2015 study, for instance, followed more than 150,000 older adults — all of whom were healthy at the start of the study — for almost seven years on average. Researchers found that those who sat at least 12 hours a day had significantly higher mortality than those who sat for less than five hours per day.

A 2012 study in JAMA Internal Medicine followed more than 220,000 people for 2.8 years on average and found similar results. Prolonged sitting over the course of a day was associated with increased all-cause mortality across sexes, ages and body mass index. So did a smaller but longer (8.6 years on average) study published in 2015 in the Journal of Physical Activity & Health.

Another study from 2015, which followed more than 50,000 adults for more than three years, also found this relationship. But it found that context mattered. Prolonged sitting in certain situations — including when people were at work — did not have this same effect.

Why might that be? Sitting itself may not be the problem; it may be a marker for other risk factors that would be associated with higher mortality. Unemployed or poorer people, who would also be more likely to have higher mortality, may be more likely to spend large amounts of time sitting at home. For some, sedentary time is a marker, not the cause, of bad outcomes.

Studies looking specifically at work don’t find a causal pattern. One 2015 paper focused on workers age 50 to 74 in Japan, for more than 10 years on average per participant. It found that — among salaried workers, professionals and those in home businesses — there was no association between sitting at work and cardiovascular risk. A 2016 study examining Danish workers also failed to find a link.