Do you ever head out for a five-miler and find yourself running at exactly the same pace as you would for a 5km effort?
Well, a new study out of Queen’s University in Canada has found that it’s not only some of us who like to opt for a one-size-fits-all speed over multiple distances, but runners across the board – and offers some answers as to exactly why this might be.
The study, published in Current Biology, aimed to find out whether runners adapt their preferred speed for different distances and whether runners’ speeds are energy optimal – i.e they run at a pace which minimises the number of calories they burn over a specific distance.
To do so, researchers analysed data from 4,645 runners who wore a tracker called Lumo Run (now discontinued) to record their runs. The runners were 38% female and 62% male, ranged in age from 16 to 83 years, and had an average BMI of 24.4. They recorded a total of 37,201 runs over a 14-month period.
Researchers compared the average speed for runners who ran shorter distances of one, two and three miles, as well the average speed for runners who ran longer distances of five, six and seven miles.
They found no differences in speed across the shorter distances and only a very marginal reduction in speed for the longest distance runs (seven miles), where the average speed was just 0.028 metres per second slower than the average pace recorded for a five-mile run, which study authors estimate to be as little as a two percentile change in a runner’s race performance.
To determine if runners’ speeds were consistent with energy minimisation, authors compared the data with data from previous lab experiments, matching subjects across age, sex and BMI. They found speeds to be indistinguishable for ‘net cost of transport’ – so energy expenditure per unit distance travelled for each speed – which shows that runners prefer a particular running speed that is independent of distance but instead aims to minimise energy expenditure.
So, while some runners may run to burn calories, it would appear we naturally move at a speed to minimise how many we burn. The study authors say this method is ‘energetically rational when food is scarce and one must travel long distances to attain it’, but at the same time, ‘preferring a speed that minimises net cost per distance travelled is rational in the context of most modern lifestyles, where humans are no longer traveling long distances for food.’
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