LLet me start by saying that I’m not looking for ways to become more tired. I’m tired enough. However, a study suggesting that exercise punctuated by frequent breaks requires more energy than steady-state exercise has a certain counterintuitive appeal: I can exercise better by resting more.
The results of the study, published in Proceedings of the Royal Society Bare striking. Volunteers on treadmills and stair climbers used 20-60% more oxygen when walking in 10-30 second bursts than when covering the same distance without stopping. This apparently has something to do with the sheer inefficiency of stop-start operations. “We found that starting from rest consumes a significant amount of oxygen to initiate walking,” said study author Francesco Luciano. “We incur these costs regardless of whether we then run for 10 or 30 seconds, so it weighs proportionally more for shorter than for longer periods.” Would this strategy, I wondered, work for me?
I started my research with a daily journey: a walk to the nearest post office, just over half a kilometer away. On the way out I ran at a brisk, uninterrupted pace, but on the return trip I covered the same distance in 30-second bursts, with rest breaks in between. Or at least I tried – even if you’re almost jogging, 30 seconds won’t get you very far. There are about 75 steps, so you don’t get from corner to corner or from one park bench to another.
And it looks stupid: you’re never far enough from your previous resting spot to have a plausible reason to stop again. You can stop halfway through to read an email, but not after every 75 steps. You can pretend your shoe is loose, but not more than once or twice. On my walk home, the people I was passing kept passing me, while I kept pausing as if I had forgotten something, and then realized that I had not, all the way across the park. You can’t help but arouse suspicion. The outward journey took 12 minutes; the return, more than half an hour. I don’t know which one had the higher metabolic cost, but I do know which one I preferred.
I’ll tell you who really isn’t excited about this approach to exercise: dogs. My afternoon study only had a sample of one animal, but the findings were clear: A dog simply won’t tolerate a rest every 30 seconds, let alone every 10. As I sat on the first couch, the dog looked at me with a some wary concern, as if I might be experiencing a cardiac event. Then he just strained at the end of the lead, trying to pull me into a standing position.
“We actually use more energy this way,” I said. The dog whined. There’s a lot a dog doesn’t understand – like why he can’t take home a surgical glove he found in a hedge – but constant, inexplicable halting is, from his point of view, a punishment, plain and simple.
If this study is a rebuke to the kind of people who jog in place while waiting at a level crossing – you’re better off standing there with your arms folded like the rest of us – it’s also a vote of confidence for everyone who jumping up from the couch to open the door counts as circuit training. There’s clearly value in bursts of exercise, even of the shortest duration, but enforced inefficiency is a bit heartbreaking. It’s like being terrible at jumping rope: you obviously get more exercise than someone who’s good at it, but you don’t feel any better about yourself when you’re done.
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For my part, all I can say is that both the dog and I were unusually exhausted after our very inefficient afternoon walk. Whether that was due to the extra oxygen consumption or sheer frustration, I will never know.