The term "charley horse" has been around since the 1880s, when players on the Chicago White Stockings went to the racetrack and everyone bet on a horse named Charley - except for one player named Joe Quest. When the horse the others bet on came up lame after the last turn, Quest is alleged to have told his teammates, "Look at your old Charley horse now!" "Charley horse" became the accepted name for leg cramps.
What causes these painful spasms? Orthopedic docs at the University of Toledo Medical Center say they're due to involuntary, repetitive firing of dysfunctioning nerves, and they don't start in the muscle tissue. That's why athletes who are well-hydrated get cramps (although dehydration can cause them too), why you get them in bed at night and why loading up on potassium and salt doesn't necessarily prevent them.
The nerve dysfunction is aggravated if you don't stretch regularly; don't get regular physical activity (but don't overdo it!); sit for long periods of time; are overweight or pregnant; take diuretics and/or develop electrolyte disturbances.
To prevent them, start by walking as much as possible, with a goal of 10,000 steps a day. Wear supportive, comfortable shoes. Hydrate well. Avoid intensely exercising the same muscles day after day.
To treat them when they happen? A swig of dill pickle juice can quiet down the contraction! The theory is that it overloads nerve receptors in the mouth and esophagus to calm the nervous system's excessive misfiring. Restoring your electrolyte balance with Pedialyte or Gatorade Zero also works.
(c)2020 Michael Roizen, M.D. and Mehmet Oz, M.D.