cramps (like your calf would) or becomes irritated. What Causes It? There are a few leading theories, but the answer most likely lies in a combination of them. One is that as a runner starts getting tired, his or her breathing is likely to get shorter and more shallow. Because your diaphragm is only fully relaxed when you've fully exhaled, those shallow breaths mean that the diaphragm is in a state of constant tension. Like any muscle, when it's hyper-exerted, it can cramp. This seems like the most likely theory to us. A final popular theory is that it's caused by eating too much or too close to exercise. There isn't much in the way of hard science to back this up, the idea is that when your stomach is more expanded with food, it puts increased pressure on the organs and tissues around it. Combine with the aforementioned jiggle-factor and whammo, cramp. What Cures It? There's all manner of myth and sorcery and miracle cures here, including something about running with clumps of grass or pebbles in each of your hands. Silliness. That said, different methods work for different people. Here is what we have found to work best, both in our own experience and in our research. 1. As soon as you feel the cramp coming on, slow down a bit. This will allow you to take bigger, deeper, slower breaths. Inhale fully, and even more importantly, exhale fully. This will allow your diaphragm to relax more. Focus