LLet me start by saying that I am not looking for ways to be more tired. I’m tired enough. However, a study suggests that exercise with frequent breaks requires more energy as “steady” exertion has a certain counterintuitive appeal: I can train better by resting more.
The results of the study, published in Proceedings of the Royal Society Bis striking. Volunteers on treadmills and stair climbers used 20-60% more oxygen when they walked in bursts of 10-30 seconds than when they covered the same distance without stopping. It seems to have something to do with the sheer inefficiency of stop-start activity. “We found that when you start from rest, a significant amount of oxygen is consumed to start walking,” said the study’s author, Francesco Luciano. “We incur this cost regardless of whether we run for 10 or 30 seconds, so it weighs proportionally more for shorter rather than longer bouts.” Will this strategy, I wondered, work for me?
I began my investigation with an everyday journey: a walk to the nearest post office, just over half a mile away. On the way there I walked at a brisk, uninterrupted pace, but on the return trip I covered the same distance in 30-second bursts, with rests in between. Or at least I tried – even at a near jog, 30 seconds doesn’t get you very far. It’s about 75 steps, which won’t take you from corner to corner, or from one park bench to the next.
And it seems silly: you’re never far enough from your previous resting place to have a plausible reason to stop again. You can stop in the middle to read an email, but not every 75 steps. You can pretend your shoe is untied, but not more than once or twice. On my walk home, the people I had overtaken continued to overtake me, as I kept pausing as if I had forgotten something, then realized I hadn’t, all over the park. You can’t help but arouse suspicion. The outbound journey took 12 minutes; the return, more than half an hour. I don’t know which came at a greater metabolic cost, but I do know which one I preferred.
I’ll tell you who really doesn’t like this approach to exercise: dogs. My afternoon study only had a sample of one animal, but the findings were clear: a dog simply will not tolerate a rest break every 30 seconds, much less every 10. As I sat on the first bench, the dog looked at me with a certain wary concern, as if I might be experiencing a cardiac event. After that it just strained at the end of the lead and tried to pull me into a standing position.
“We actually use more energy this way,” I said. The dog whined. There is much that a dog does not understand – for example, why he cannot take home a surgical glove that he found in a fence – but constant, inexplicable stopping is, from his point of view, a punishment, plain and simple.
If this study serves as a rebuke to the kind of people who jog in place while waiting at a level crossing – you’d be better off standing there with your arms folded, like the rest of us – it’s also a testament to confidence for all who count jumping up from the couch to answer the door as circuit training. There is clearly value in bursts of exercise of even the shortest duration, but enforced inefficiency is a little heartbreaking. It’s like being terrible at skipping 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, I can only say that both the dog and I were extremely exhausted after our highly inefficient afternoon walk. Whether it was from the extra oxygen consumption or the sheer frustration, I will never know.
