Friday, October 14, 2011

Do runners get less efficient as they age?


We know that lots of things start to decline as you age — maximal heart rate, VO2max, muscle strength, power, flexibility, etc. But what about running economy? Do you become less efficient (in translating oxygen consumption into forward motion) as you get older, or do you keep the same efficiency while working with a smaller total capacity? Researchers at the University of New Hampshire looked at this question by studying 51 sub-elite runners in three groups: young (18-39), master (40-59) and old (60+), and published the results in the Journal of Strength & Conditioning Research. Here’s what they found:measurements of how much oxygen they used (in ml per kg of bodyweight per minute) at different submaximal speeds. What’s of interest is the slope of those lines, which tells you how much oxygen they use per metre. And as it happens, there was no significant difference in the slopes between the three groups, contradicting the researchers’ hypothesis that running economy would decline with age.

This is a surprising result, and one we should look at with considerable suspicion. It’s a fairly small study, and the paces involved were relatively slow in order to make sure that the oldest runners could maintain them comfortably and remain below lactate threshold (which causes the slope to deviate from linear). Still, it does suggest that age-related decline in running economy, even if it does turn out to exist, is a relatively small factor. Instead, other factors like declining aerobic capacity and muscular strength are probably the main reasons we slow down as we age. And that’s kind of good news, because we already know how to fight those particular types of decline: keep training.

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