Prolonged Sitting Is Hazardous to Your Health, Even if You Exercise Regularly
Akshay Naik 18 January 2023
Results of a small cross-over study show that breaking up sedentary time behind a desk, by taking a five-minute stroll every half hour, was the optimal break to improve cardio metabolic and mental health.
The study was conducted by exercise physiologists from Columbia University and led by Dr Keith Diaz, associate professor of behavioural medicine at the university’s Vagelos College of Physicians and Surgeons. Results have been published online and reported in Medicine & Science in Sports & Exercise, the journal of the American College of Sports Medicine. 
Unlike other studies that test one or two activity options, Dr Diaz’s study tested five different exercise ‘snacks’—one minute of walking after every 30 minutes of sitting, one minute after 60 minutes;  five minutes every 30 minutes; five minutes after every 60 minutes; and no walking. 
“If we had not compared multiple options and varied the frequency and duration of the exercise, we would have only been to provide people with our best guesses of the optimal routine,” Dr Diaz explains. 
For the study, the researchers enrolled 11 adults in their 40s, 50s and 60s and compared health measures while sitting eight hours without breaks (control group) versus sitting eight hours and taking a one-minute or five-minute walking break every half hour, or every hour. Each of the 11 adults who participated came to Dr Diaz’s laboratory, where they sat in an ergonomic chair for eight hours, rising only for their prescribed exercise snack of treadmill walking or a bathroom break. Participants were allowed to work on a laptop, read and use their phones during the sessions and were provided standardised meals. 
Researchers kept an eye on each participant to ensure they did not over- or under-exercise and periodically measured the participants’ blood pressure and blood sugar—the key indicators of cardiovascular health. 
They found that the optimal amount of movement was five minutes of walking every half an hour. This was the only amount that significantly lowered blood sugar and blood pressure. Additionally, 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 an 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 lowered blood pressure by 4mmHg to 5mmHg compared with sitting all day. “This is a sizable decrease, comparable to the reduction you would expect from exercising daily for six months,” Dr Diaz says. 
Researchers also periodically measured participants’ level of mood, fatigue and cognitive performance during the testing. All walking regimens, except for one minute strolls every 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. People tend to repeat behaviours that make them feel good and that are enjoyable,” says Dr Diaz. 
“What we know now is that for optimal health, you need to move regularly at work, in addition to a daily exercise routine. While that may sound impractical, our findings show that even small amounts of walking spread throughout the work day can significantly lower your risk of heart disease and other chronic illnesses,” he concludes in the report.
The researchers are now testing 25 different doses of walking on health outcomes and also increasing the participants group to include a wider variety of people.
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