Triathletes participate in a grueling endurance sport - in the Olympic version, it means swimming about 1 mile, bicycling 40 miles and then running 6.2 miles. Those in the Ironman version get even more extreme, a 2.4 mile swim, 112 mile bike race and then running a full marathon, 26.2 miles.

Clearly, in both training and competition, they regularly push their bodies beyond the limits most of us can endure. There is no doubt that triathletes are tougher than most people, the mystery is why.

19 triathletes and 17 non-athletes participated in a recent study. The triathletes were people who trained for and competed in at least two triathlons per year — including in some cases the notoriously challenging Ironman. The non-athletes were people who did non-competitive exercises, like jogging, swimming, or aerobics classes. 

All the participants were put through a battery of psychophysical pain tests, involving the application of a heating device to one arm and the submersion of the other arm in a cold-water bath. They also filled out questionnaires about their attitudes toward pain.

Is it mind over matter?

In the tests, the triathletes identified pain just as well as non-athletes, but they perceived it as less intense and were able to withstand it longer. The researchers explain that detecting pain is a relatively straightforward sensory experience, whereas evaluating pain and being willing and able to endure it involves attitude, motivation, and life experience. The triathletes reported fearing and worrying less about pain, which may help explain their higher tolerance, the researchers say.

The triathletes also showed a better ability to inhibit pain than non-athletes, as measured by conditioned pain modulation – the degree to which the body eases one pain in response to another. The researchers say psychology may be a factor here too. The triathletes with less fear of pain tended to exhibit better pain regulation. Previous studies have similarly found that psychological manipulation can affect pain perception. Triathletes exhibited higher pain tolerance (P<.0001), lower pain ratings (P<.001), and lower fear of pain values (P<.05) than controls. The magnitude of CPM was significantly greater in triathletes (P<.05), and negatively correlated with fear of pain (P<.05) and with perceived mental stress during training and competition (P<.05).

"In our study, triathletes rated pain lower in intensity, tolerated it longer, and inhibited it better than individuals in a control group," says
Prof. Ruth Defrin
of Tel Aviv University. "We think both physiological and psychological factors underlie these differences and help explain how triathletes are able to perform at such a high level."

The chicken or the egg?

Another explanation for triathletes' lower pain ratings, higher pain tolerance, and better pain regulation is that they have taught their bodies to respond powerfully to painful stimuli through their intense training. The TAU researchers say their study – along with existing literature – suggests that psychology and physiology together enable triathletes to do what they do.

"It is very difficult to separate physiology and psychology," says Defrin. "But in general, experience is the sum of these factors."

The researchers plan to do further research to determine whether triathletes participate in their sport because they feel less pain or feel less pain because they participate in their sport. If it turns out that intense training in fact helps reduce and regulate pain, it could be used to treat people with chronic pain. Like triathletes, chronic pain patients suffer daily, but their pain is out of their control and has the opposite effect, weakening rather than strengthening pain inhibition.

Citation: Geva N, Defrin R., Enhanced pain modulation among triathletes: A possible explanation for their exceptional capabilities, Pain August 2013 doi:10.1016/j.pain.2013.06.031