When DH was about ten years old it snowed heavily and he went out sledging and playing in the snow for hours. The next day he woke up and couldn't stand or walk, when he tried to put weight on his legs they just gave way. He had to shuffle on his bottom for a couple of days before he recovered.
He saw a doctor at the time who said it was a cramp from playing in the snow. I've never heard of anything like this and wondered if something else was going on? He says it didn't feel like a cramp as such as he wasn't in pain, his legs just wouldn't bear his weight. Has anyone heard of anything like this happening?