A cramp seizes your calf at mile 4 and stops you cold. You grab the muscle, hop to the side of the path, and wait for it to pass. Runners know this moment well. Muscle cramps affect somewhere between 40% and 95% of athletes depending on the study, and 67% of triathletes report cramping during or after training or racing. The causes remain partially understood, but several practical methods reduce how often cramps happen and how badly they hurt when they do.

