It comes out of nowhere - while you're playing tennis, gardening, sitting on the couch or even when you're fast asleep.
Suddenly a muscle gets locked in spasm, it's hard as a rock, and the pain borders on unbearable.
Muscle cramps usually target your legs and can last for a few seconds to 15 minutes or more.
Yet as common as cramps can be, experts don't know exactly what causes most cases.
And there's no solid science on how to best treat them. Here's what we do know:
They're common in summer
That's because when you exert yourself in …