What exactly is wrong with those people who run, bike and swim crazy distances in any weather, then do it again a few weeks later? One answer comes from researchers at Tel Aviv University, who measured the perception and response to pain of a group of triathletes and in another group of people who were never inclined to swim 2.4-miles, bike 112 miles, and run 26.2 miles. ScienceDaily reports that the lucky 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. The researchers found that 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 triathletes also reported fearing and worrying less about pain, and they 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. Next question: which came first, the chicken or the egg? Did the triathletes learn to deal with pain, or did their ability to deal with pain encourage them to become triathletes? Read more in ScienceDaily.