noun
leg cramp; charley horse
Refers specifically to a sudden, painful muscle cramp in the calf. Common in everyday conversation.
夜中にこむら返りが起きて、飛び起きた。
I woke up with a start when I got a leg cramp in the middle of the night.
運動中にこむら返りを起こさない
Make sure to drink plenty of fluids so you don't get a leg cramp during exercise.