You've probably been stopped in your tracks by a spasm the size of a golf ball in your calf, a charley horse, or a tremor that constricts your hamstrings. Like side stitches, muscle cramps are a reality for many runners, lifters, cyclists, and swimmers alike.
The main difference between side stitches and cramps is that the latter occurs in smooth involuntary muscle (more specifically, your diaphragm) while more common muscle cramps occur in large skeletal muscle that's under your voluntary control (i.e. your leg muscles). The cramps are sudden, painful, and can really throw off a workout (or your sleep). Of course, you know this if you're prone to muscle cramping. So, why do they happen in the first place?
"Cramps are not well understood, but there is research to show that cramps occur from changes in motor neuron excitability or random discharges of motor nerves that cause sudden—sometimes very painful—involuntary contraction of a muscle," says Marni Sumbal, MS, RD, CSSD, LD/N, endurance athlete and owner of Trimarni Coaching and Nutrition.
"Athletes who experience cramps may experience them during exercise (exercise-induced cramping) due to muscular fatigue or shortened muscle contraction (a.k.a. tight muscles and limited range of motion)," Sumbal says.
For expert-backed tips on preventing muscle cramps, alleviating pain when they strike, and keeping them from happening again, read on.