If you’re sitting down, you might want to stand up while reading this.
Building on a growing body of evidence about the dangers of the modern sedentary workplace and lifestyle, a team of researchers has found that long periods of uninterrupted sitting can lead to earlier death — regardless of how much a person exercises and even when accounting for age, gender and other factors. The survey, considered one of the largest of its kind, was published Monday in a scholarly medical journal.
Dr. Keith Diaz, the lead author of the study and the director of the Exercise Testing Laboratory at Columbia University, said the most surprising findings were that it wasn’t just the total number of hours of sitting accumulated over the day, but that uninterrupted sitting over long periods such as 60 to 90 minutes, increased the risk for early death.
“This finding I think will help shift our understanding about the risks of sitting by showing that to reduce the harmful consequences of sitting one needs to both decrease the overall time they spend sitting and take frequent movement breaks when they do sit,” Dr. Diaz told The Washington Times in an email.
The study was published in the Annals of Internal Medicine and followed a national representative population of 8,000 individuals older than 45 for an average of four years.
The researchers employed the use of hip-mounted accelerometers to monitor how long people sat and their movement. Previous studies evaluating sedentary time and health had participants self-report their sitting and movement periods.
The researchers recorded 340 deaths over the course of the four-year follow-up. When adjusting for multiple variables — such as age, race and sex — the researchers found that total number of sitting hours over the day and the accumulation of most of one’s sitting time in long, uninterrupted periods were associated with early death.
Even when participants incorporated exercise into their routine, “all-cause mortality” was higher if participants frequently sat for more than 60 to 90 consecutive minutes at a time.
“We think this gives a clear message that besides exercising, you also should be mindful of moving (and not being sedentary) throughout the day,” Dr. Diaz said.
The participants recorded an average 12.3 hours of sedentary time in a 16-hour waking day. To combat adverse effects, the researchers recommend taking movement breaks every 30 minutes throughout the day and said interventions should target this goal.
“Both the total volume of sedentary time and its accrual in prolonged, uninterrupted bouts are associated with all-cause mortality, suggestive that physical activity guidelines should target reducing and interrupting sedentary time to reduce risk for death,” the authors wrote in their conclusion.
The science is mixed on intervention techniques. Dr. Diaz pointed out that a study led by Johns Hopkins researchers that was published last month found that occupational standing — jobs such as retail sales, restaurant cooks, restaurant servers and factory machine operators — was associated with higher risks of heart disease and overall lower cardiovascular health.
Conversely, while jobs that involved combinations of sitting, standing and walking resulted in lower cardiovascular risk for men, there were elevated risks among women, the Johns Hopkins researchers concluded.
Dr. Diaz suggests that employers encourage breaks every 30 or 60 minutes to stand up or walk around, but he acknowledges that it could be a difficult sell.
“Naturally, employers probably would be apprehensive to do so over concerns of work productivity. So in the end, it may come down to employee wellness versus work productivity for employers — although there certainly could be some middle ground,” he said.
Uses of treadmill desks, cycling desks, and exercise balls instead of chairs are intervention techniques that haven’t been thoroughly evaluated for effectiveness. A 2014 study published in the journal Sports Medicine concluded that active workstations could contribute to overall health, but the effects on work productivity were unknown.
The prices of treadmill desks range from a few hundred dollars to almost $1,500. Stability balls, which range in price from $7 to $20, are believed to engage different muscles so the worker is active even while sitting at a desk. Other stand-up desks can have pedals or position a high chair to allow the user to perch, taking some pressure off legs.
Dr. Diaz said the study didn’t evaluate the optimal length of a break but added that it had to be longer than one minute. The best results were also associated with longer or more vigorous breaks.
“In our study, we found that the longer the movement break, the better. … We also found that the more intense your movement break, the better,” Dr. Diaz said. “In our study, breaks had to be at least one minute in length. Although this could suggest a one-minute break is enough, we need intervention studies to really determine this.”