Side cramp or ''stitch": This cramp strikes you in the side, as the name implies, or even in the lower abdominal area. It's mainly the result of shallow breathing, not breathing deeply from the lower lung, says Jeff Galloway, a 1972 Olympian and veteran runner who has trained more than 200,000 runners and walkers and runs a marathon training program. ''The side pain is a little alarm" alerting you that you're breathing too shallowly, Galloway says. An imbalance of blood electrolytes (such as calcium, potassium, and sodium) in your body may also contribute, says Pete McCall, an exercise physiologist and spokesman for the American Council on Exercise.
To avoid side cramps, Galloway suggests deep lung breathing. His advice: Put your hand on your stomach and breathe deeply. If you're breathing from your lower lungs, your stomach should rise and fall.
Side cramps affect beginners more than long-timers, Galloway notes. "Veteran runners shift [naturally] to lower lung breathing," he says.
To avoid side pain, don't start your run jackrabbit fast. Many side stitches are simply a result of starting too fast. "It's always better during the first 10 minutes to be more gentle," Galloway says.
Nervousness can play a role, too. When nerves hit, "you have a tendency to breathe more rapidly, or some do," Galloway says. "When that happens, a lot of people revert to shallow breathing," which can bring on a side cramp.