This week I came across an article in PLOS ONE looking at the difference between “getting exercise” and “getting up”: Minimal Intensity Physical Activity (Standing and Walking) of Longer Duration Improves Insulin Action and Plasma Lipids More than Shorter Periods of Moderate to Vigorous Exercise (Cycling) in Sedentary Subjects When Energy Expenditure Is Comparable by Bernard M. F. M. Duvivier et al. Here’s the question: which is better for your health — doing some high-intensity exercise an hour a day, but basically sitting the rest of the time, or skipping high intensity exercise entirely while spending several hours a day up and on your feet?
Researchers randomly assigned participants to one of three exercise regimens:
- SITTING: 8 hours/day sleeping or otherwise lying down; 1 hour/day walking; 1 hour/day standing; and the rest (14 hours) sitting.
- INTENSE EXERCISE: 8 hours/day sleeping or otherwise lying down; 1 hour/day walking; 1 hour/day standing; 1 hour/day working hard on a stationary bike; and the rest (13 hours) sitting
- MINIMAL INTENSITY: 8 hours/day sleeping or otherwise lying down; 5 hours/day walking; 3 hours/day standing; and the rest (8 hours) sitting.
Notice that the “intense exercise” option is close to what many folks hope to be able to do. It’s spending a full hour at some heavy-duty aerobics, with the rest of the time working at a desk, watching TV, and puttering around. It’s hard to picture how one could structure one’s life to match the minimal intensity scheme. This may be why all twenty of the study participants were between 19-23 years old: it seems like something a college student might be able to handle for a few days at a time.
The participants were assigned to these different exercise plans in random order, for four days at a time, with ten days “washout” in between for which they were asked to go back to their usual levels of activity. Researchers measured their activity by strapping monitors to their legs; they kept track of their calorie intake by keeping food diaries.
After each four-day segment, participants had their cholesterol and triglycerides measured. Each participant was also given a glucose tolerance test: after drinking a liquid with 75 grams of glucose, blood sugar and insulin levels were measured over the next two hours.
So which group had the better cholesterol numbers? Which group needed less insulin to process the same amount of sugar — that is, had less insulin resistance? You see this coming, don’t you. The “minimal intensity” regimen was associated with blood test markers for better heart health and lower risk of diabetes.
Of course, this is just a preliminary study. Studying four days of altered activity won’t tell us what a lifetime of different habits might do for health, and lower blood sugar on a test today doesn’t necessarily mean a lower chance of developing diabetes 5-10 years from now. I’d love to see a study that had less walking and more standing: I’m a lot more likely to get a standing desk than I am to get a job walking all the dogs in my neighborhood. Still, it’s one more piece of data suggesting that a few hours a week at the gym can’t correct the damage of a week sitting at a computer and watching TV.
(Image credit: “Bethesda Fountain” by Ed Yourdon, under a Creative Commons attribution & share alike license.)