Prolonged Sitting Leads to Glucose and Insulin Spikes

Over the last few years, a big pile of evidence has emerged suggesting that prolonged sitting is very bad for your health. No matter how much or how hard you exercise, if you spend the rest of the day motionless at a desk or on the couch, metabolic changes take place in your muscles that increase your risk of nasty outcomes like heart disease and death. But researchers are still trying to puzzle out exactly what's going on in the muscles, in order to answer some key questions -- like how much sitting is too much, how often you need to take a break, and how much you need to move around to shake your muscles out of sedentary mode.

Travis Saunders, a researcher who is working on these very questions, has an interesting post on his blog, Obesity Panacea, describing an Australian study that offers some new insights into these questions. The gist: volunteers sat around for five consecutive hours, and partway through (after two hours) they drank a test drink with some sugar and fat in it to see how well their body responded. Some of the volunteers sat for the whole time, while others took two-minute walk breaks (at either "light" or "moderate" intensity) every 20 minutes. The results:

As you can see, the blood sugar levels spiked higher pretty much right away in the group that hadn't taken any walking breaks. Then, eventually, the insulin response caught up and brought the blood sugar levels crashing back down. The result: total levels of both insulin and glucose during the experiment were more than 20% higher in the uninterrupted sitting group.

The other interesting nugget: the "light" and "moderate" intensity walk breaks had identical effects. This suggests that you don't need to leap up and hammer burpees and jumping jacks to get the effect of a break -- a mild stroll to the water cooler should suffice. Do you really have to do it every 20 minutes? We'll have to wait for another study to answer that question. Personally, I'm hoping every hour will turn out to be good enough! Anyway, Travis's post has more details and context on the study -- well worth a read.