Pain and PBs

Does the ability to tolerate pain make you a better runner? If you ask runners, the answer you get is usually “Yes.” But there’s very little actual evidence that people who can tolerate more pain run faster.

A new study in the Scandinavian Journal of Medicine and Science in Sports, from University of Kent researcher Alexis Mauger, offers a possible explanation for why previous studies have produced mixed results. Pain is important, Mauger argues; but the pain we experience during endurance exercise is different from the kinds of pain (like cold and pressure) that researchers usually study in laboratories.

The new study took 32 recreationally active volunteers and put them through a series of pain tests, as well as some physiological testing to measure VO2max, threshold, and other performance variables.

The pain tests included a cold pressor test (dip your hand in a bucket of ice water and hold it there for as long as possible) and a pain pressure threshold test (press a blunt probe into the subject’s thigh until they report the sensation transitions from pressure to pain). The former test measures pain tolerance (how much can you stand?), while the latter measures pain threshold (when does it start to hurt?).

The third pain test looked more specifically at exercise-induced pain. The subjects rode a cycling trial at a fixed level of effort, at 16 on a scale of 6 to 20 (which corresponds to somewhere between “hard” and “very hard”). They kept going until their power output dropped to 70 per cent of its initial value, while reporting their perceived pain on a scale of 1 to 10 every two minutes.

For the purposes of the experiment, “tolerance of exercise-induced pain” was defined as the pain score when the fixed-effort trial finished. On average, the subjects reported a pain score of 7.23 at that point. A crucial point here is that the subjects had to be able to differentiate between “effort” and “pain”—that’s somewhat tricky, but they were given specific instructions on which sensations were relevant to each measure.

The final part of the experiment was a 10-mile cycling time trial, and the key question was which of the baseline pain and/or physiological variables would be most successful at predicting 16 kilometre time.

When comparing the three different measures of pain, neither of the standard lab measures (cold and pressure) produced a statistically significant prediction 16 kilometre time. The exercise-induced pain score, on the other hand, did: Those who were willing to put up with more pain in the fixed-effort trial ultimately rode faster in the time trial.

For comparison, here are two of the graphs from the study, showing time trial performance as a function of the cold test results (top) and the exercise-induced pain results (bottom):

Pain and exercise graph.















The cold test gives pretty much a horizontal line: Those who lasted longest in the ice bucket weren’t necessarily faster (or slower) than those who lasted the shortest time. That doesn’t mean it’s totally irrelevant; it’s worth noting that those who lasted one minute or less do appear to have worse results than those who lasted seven minutes (which was the maximum permitted in the experiment). But there’s no significant trend—unlike in the exercise-induced pain graph.

Another way of looking at the results is to combine the pain data with the physiological variables, and see which factors matter most. Not surprisingly, aerobic fitness was the biggest predictor—specifically, the peak power attained at the end of the VO2max test, which represents a combination of aerobic fitness and economy.

But even after accounting for physiology (peak power output explained 74.7 per cent of the variance in the results), exercise-induced pain tolerance still explained a further 7.5 per cent of the variance. Among people who are notionally equal in physiology, in the other words, he or she who can suffer most still gains a marginal edge.

I have to admit that I’m a little unsure about the intricacies of the exercise-induced pain test, and what is actually being measured in it. How effectively are the subjects able to distinguish between pain and effort? What other factors might cause power output to decline at a fixed effort rating?

Still, the results do line up with our intuitive feelings about the importance of gutting it out, and it’s neat to see attempts to study this question systematically. It’ll be fun to see more research trying to get to the bottom of how and why pain matters.

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