Can Physiology Identify Champions?

It’s easy (as a high-school coach of mine used to say) to tell the difference between a cart-horse and a thoroughbred. But if you line up a bunch of thoroughbreds, can you predict which one will win the race?

That’s a much harder proposition, and one that exercise scientists have been struggling with for decades. It has become axiomatic that measures like VO2 max can distinguish between couch potatoes and athletes, but it can’t pick the winner from among a group of athletes of roughly similar ability.

Still, it’s an obvious fact that some athletes consistently beat other athletes—so what gives them their edge? Is it physical or mental? Is there something we can measure?

Norwegian researchers recently published a neat study of 12 female cross-country skiers in the journal Medicine & Science in Sports & Exercise. Six of them were the best of the best of the best: they were, in fact, ranked No. 1 to 6 in the overall World Cup standings in 2015 and included four Olympics champions and five world champions.

The other six were labeled “national class,” though you have to be pretty darn good to be a national class cross-country skier in Norway. Two had finished in the top 15 of a World Cup race, and all were well-trained elite athletes among the top 15 Norwegians.

The skiers were tested while roller-skiing on a treadmill, both at fixed pace (to measure efficiency) and in all-out three-minute time trials using two different skiing techniques (double-poling on near-flat terrain and diagonal uphill). Lots of parameters were measured.

The biggest difference? Well, the champions skied farther (by 6 to 7 percent) and faster during the time trials, of course. In terms of physiological variables, the main differentiator was VO2 max (as measured during the three-minute trials, rather than the usual incremental test). The champions averaged ~70 and ~65 mL/min/kg in diagonal and double-poling, while the national-class group was 10 and 7 percent lower, respectively.

One of the surprises is that there were no differences in efficiency. When both groups were skiing at the same speed, they were burning the same amount of energy. There was also no difference in oxygen debt incurred during the time trial, which is a measure of how much anaerobic power you can produce—a crucial differentiator in mass-start ski races and sprint finishes.

So why is it that the champions have bigger aerobic engines? Genetics is one possible (and likely) contribution. But the six-month training diaries filled out by the subjects also offer some interesting insights.

Here’s the total training volume for the two groups; WC is world-class and NC is national-class, HIT is high-intensity endurance training, MIT is medium-intensity, and LIT is low-intensity:

Training patterns of elite skiers.

The world-class athletes consistently accumulated more training, particularly low-intensity training during the early preseason months. The unanswered question is whether they train more because they’re the top athletes, able to focus full-time on sport, or whether they’re the top athletes because they train more. There’s undoubtedly a mix of chicken and egg there; the question is how much of each.

Anyway, it’s interesting to see that VO2 max, which is often dismissed these days as a useless measurement, seems to be the biggest difference between good and great among these particular athletes. It would be interesting to see similar data in other sports like running.

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