There is growing evidence that prolonged sitting – a requirement of many office workers, computer experts, journalists and other employees – is hazardous to one’s health, even if such people exercise regularly. Based on these findings, doctors advise all adults to sit less and move more. But how often do we need to get up from our chairs and for how long?
Few studies have compared multiple options to come up with the answer most office workers want to know – what is the least amount of activity needed to counteract the health impact of a workday filled with sitting?
Now, a study by exercise physiologists at Columbia University in New York has an answer – just five minutes of walking every 30 minutes during periods of prolonged sitting can offset some of the most harmful effects.
The study, led by behavioral medicine Prof. Keith Diaz at the university’s College of Physicians and Surgeons, has just been published online in Medicine and Science in Sports and Exercise, the journal of the American College of Sports Medicine, entitled “Breaking Up Prolonged Sitting to Improve Cardiometabolic Risk: Dose-Response Analysis of a Randomized Cross-Over Trial.”
Difference between latest study and previous studies
“If we hadn’t compared multiple options and varied the frequency and duration of the exercise, we would have only been able to provide people with our best guesses of the optimal routine.”
Keith Diaz, College of Physicians and Surgeons, Columbia University
Unlike other studies that test one or two activity options, Diaz’s study tested five different exercise options: one minute of walking after every 30 minutes of sitting; one minute after 60 minutes; five minutes every 30; five minutes every 60; and no walking.
“If we hadn’t compared multiple options and varied the frequency and duration of the exercise, we would have only been able to provide people with our best guesses of the optimal routine,” Diaz noted.
Each of the 11 adults who participated in the study came to Diaz’s lab where participants sat in an ergonomic chair for eight hours, rising only for their prescribed exercise snack of treadmill walking or a bathroom break. Researchers kept an eye on each participant to ensure they did not over- or under-exercise and periodically measured their blood pressure and blood sugar (key indicators of cardiovascular health). Participants were allowed to work on a laptop, read and use their phones during the sessions and were provided standardized meals.
The optimal amount of movement, the researchers found, was five minutes of walking every 30 minutes. This was the only amount that significantly lowered both blood sugar and blood pressure. In addition, this walking regimen had a dramatic effect on how the participants responded to large meals, reducing blood sugar spikes by 58% compared with sitting all day.
Taking a walking break every half hour for one minute also provided modest benefits for blood sugar levels throughout the day, while walking every 60 minutes (either for one minute or five minutes) provided no benefit.
All amounts of walking significantly reduced blood pressure by four to five mmHg compared with sitting all day. “This is a sizeable decrease, comparable to the reduction you would expect from exercising daily for six months,” added Diaz.
The researchers also periodically measured participants’ levels of mood, fatigue and cognitive performance. All walking regimens, except one minute per hour, led to significant decreases in fatigue and significant improvements in mood. None of the walking regimens influenced cognition.
“The effects on mood and fatigue are important,” Diaz said. “People tend to repeat behaviors that make them feel good and that are enjoyable.” The Columbia researchers are currently testing 25 different regiments of walking on health outcomes and testing a wider variety of people: Participants in the current study were in their 40s, 50s and 60s, and most did not have diabetes or high blood pressure.
“What we know now is that for optimal health, you need to move regularly at work, in addition to a daily exercise routine,” he concluded. “While that may sound impractical, our findings show that even small amounts of walking spread through the workday can significantly lower your risk of heart disease and other chronic illnesses.”