Let me start by saying that I am not looking for ways to be more tired. I’m tired enough. However, a study suggesting that exercise punctuated by frequent breaks requires more energy than “steady-state” exertion has a certain counterintuitive attraction: I can exercise better by resting more.
The results of the study, published in Proceedings of the Royal Society B, are striking. Volunteers on treadmills and stair climbers used 20-60% more oxygen when walking in bursts of 10-30 seconds than they did covering the same distance without stopping. This apparently has something to do with the sheer inefficiency of stop-start activity. “We found that when starting 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 then walk for 10 or 30 seconds, so it proportionally weighs more for shorter rather than longer bouts.” Would 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, unbroken pace, but on the return journey I covered the same distance in bursts of 30 seconds, with rests in between. Or at least I tried to – even at a near jog, 30 seconds doesn’t take you very far. It’s about 75 steps, which won’t get you from corner to corner, or from one park bench to the next.
And it looks stupid: you’re never far enough from your previous rest spot to have a plausible reason for stopping again. You can halt mid-stride 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 overtook kept overtaking me, while I kept pausing as if I’d forgotten something, and then realising I hadn’t, all the way across 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 know which one I preferred.
I’ll tell you who really isn’t keen on 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. Thereafter it just strained at the end of the lead, trying to pull me into a standing position.
“We’re actually using more energy this way,” I said. The dog whined. There is a lot a dog doesn’t understand – for example, why it can’t take home a surgical glove it found in a hedge – but continual, unexplained halting is, from its point of view, a punishment, plain and simple.
If this study serves a rebuke to the sort 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 vote of confidence for anyone who counts leaping up from the sofa 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 a rope – you obviously get more exercise than someone who is good at it, but you don’t feel 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 unusually exhausted after our highly inefficient afternoon walk. Whether that was from the extra oxygen consumption or the sheer frustration, I’ll never know.
