Last week a fascinating study was published by SBRN member David Dunstan and colleagues in Australia, which examined the acute (e.g. short-term) impact of uninterrupted sitting on metabolic health. In this new study, individuals with overweight or obesity were asked to perform 3 separate conditions in random order.
- Uninterrupted sitting – participants sat for 5 consecutive hours
- Sitting plus light intensity breaks – similar to the uninterrupted sitting condition, except that participants had a 2 minute walk break at a light intensity every 20 minutes throughout the day
- Sitting plus moderate intensity breaks – similar to the light intensity breaks condition, except that the breaks were at a moderate intensity
The figure below nicely demonstrates the basic protocol for the three conditions.
In all three conditions participants were given a standardized 760 calorie test drink at baseline (for reference, that’s about the same as a medium McDonald’s triple-thick milkshake), and had blood taken every hour to determine the glucose and insulin response. This is pretty similar to an oral glucose tolerance test, except that the test drink included both sugar and fat, while an oral glucose tolerance test involves only sugar. This sort of drink will produce a spike in insulin and glucose levels in the blood, but a healthier person will have a lower spike than an unhealthy person. A big spike in glucose or insulin levels suggests that your body has to work harder to get sugar into your muscles, which is a sign of insulin resistance and a risk factor for diabetes.