Yogi Berra, who famously claimed never to have said most of the things he said, supposedly figured that baseball was 90 percent mental, and the other half physical. That’s the kind of math you get into when you start trying to apportion the credit for sports victories and the blame for defeats. It’s an unanswerable question.
But we enjoy asking it anyway, as I discovered after writing a book arguing that endurance, a seemingly simple physical parameter, is influenced by the brain. Pretty much every interview I did after it was published included some version of that question: OK, so the brain matters… but how much, exactly? I became an expert at dodging the question and hedging my answers. (“Well, it really depends on the context… which reminds me of a great but unrelated anecdote.”)
But no longer. Thanks to a new study in the European Journal of Sport Science, from a research team at the Swiss Federal Institute of Sport led by Phillip Röthlin, I can finally provide some numbers. The study involved 25 members (17 boys, 8 girls) of the Swiss under-17 national cycling team. They did a series of physiological and psychological tests, then raced a time-trial up a mountain. Stick the results into a stats program, and you’ve got an answer for the relative importance of various traits and parameters in athletic performance.
The physiological side was represented by a VO2 max test, which is the gold-standard measure of aerobic fitness and quantifies how quickly your heart and lungs can deliver oxygen to be used by your muscles. As befits elite teen cyclists, the values were impressive, averaging 63 ml/kg/min for the women and 71 ml/kg/min for men—not quite “world class,” but certainly “highly trained” and perhaps in some cases “elite.”
Previous studies have found that VO2 max is a good predictor of performance: one 2010 study, for example, found that it explained 81.3 percent of the variation in ten-mile race times among well-trained runners. There are two caveats, though.
One is that this number depends on who the population is. Grab random volunteers off the street, and you’ll find VO2 max is an amazing predictor of race performance. Sample the finalists in an Olympic race, on the other hand, and you’ll find that it’s not very good at predicting finishing order. Everyone in the Olympic field had to have a stratospherically high VO2 max just to make it to the start line, so other factors play a bigger role in differentiating them.
The other caveat is that it depends which parameters you include in your model. The 2010 study compared VO2 max to other physiological parameters like running economy and lactate threshold, and outperformed them. (An even better predictor, it turned out, was the runners’ speed at the end of the VO2 max test, which is a hybrid measure of VO2 max and running economy.) But no psychological parameters were included, so the claim that VO2 max explains 81.3 percent of race performance is based on the assumption that the brain doesn’t matter at all.
The Swiss study’s main aim was to run this kind of study while including both mental and physical characteristics. They measured five different psychological factors in the athletes:
- Mental techniques: the use of self-talk, imagery, goal-setting, activation (i.e. getting psyched up), and relaxation
- Self-compassion: handling mistakes and personal weaknesses without harsh self-criticism
- Mental toughness: perseverance, rebounding after failure, performing well even when conditions are difficult
- Achievement motivation: a need for success and striving for excellence
- Action and state orientation: whether you quickly refocus after errors or failure (action orientation), or tend to dwell on them (state orientation)
Each of these parameters was assessed with psychological questionnaires, and quantified on one-to-five or one-to-seven scales.
The time trial was a relatively short 1,320-meter climb (a little more than three-quarters of a mile), rising 410 feet. The uphill race was chosen to eliminate the effects of air resistance and drafting. The distance is another important caveat to keep in mind, since the relative contributions of mind and muscle probably differ depending on the duration. My best guess is that mental factors become increasingly important as the distance gets longer, but I don’t have any data to support it!
The results are expressed in terms of “standardized regression coefficients,” which essentially tell you the relative size of the effect. The biggest predictor, not surprisingly, was VO2 max, which had a coefficient of 0.48. In mathematical terms, if you improve your VO2 max by 1 standard deviation, you expect your race time to improve by 0.48 standard deviations.
That may seem a little abstract, but it’s a little clearer when you compare different factors. The biggest psychological predictor was perseverance, a characteristic that falls under the umbrella of achievement motivation. For example, people who agreed with the statement “I find it difficult to maintain my efforts in sports over a long period of time” would be rated as having low perseverance. Perseverance had a coefficient of 0.11, meaning that its influence was roughly a quarter (i.e. 0.11/0.48) as strong as VO2 max—still a strongly significant finding.
On the other hand, people who reported using mental relaxation techniques actually performed worse in the time trial. The effect was very small, with a coefficient of 0.03 indication that VO2 max was 16 times better at predicting performance. And more to the point, this is where the drawbacks of looking at correlation rather than causation (which would require a trial in which participants were randomly assigned to either use or not use mental relaxation techniques) become apparent. It seems likely that this finding is either a statistical fluke or that weaker or more anxious athletes are the ones telling themselves to calm down before the start.
And that’s it. Other than sex (males were, on average, faster than females), none of the other predictors were statistically significant. So the final tally is that the physiological factor, VO2 max, has 3.4 times more explanatory power than the two psychological ones, which you could take to mean that short uphill cycling races among near-elite teens are 77 percent physical and 23 percent mental.
I hope you don’t take that literally, of course. Not only is it totally specific to the context, but it also depends on which variables you include or exclude. Maybe there are other physical parameters, like leg strength or cycling economy, that matter a lot in short uphill cycle races. And I can also guarantee that we don’t yet know how to properly quantify the various mental parameters that might affect the results. But consider this a proof of principle: if you want to know who’s going to win a race, a simple pencil-and-paper psychological test will give you insights that you can’t get in the lab—just like Yogi said, more or less.
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