If I sprained my knee how long do I ice it ann when do I put heat on it?

If pain is relieved. Classic teaching is ice first and heat later. Fact is, both increase blood flow. That's why your face turns red equally when you go outside in heat or freezing. So, apply if it feels good and don't if it feels bad. Neither make it heal better of faster per any valid study. Avoid freezing or burning skin. Don't keep ice on if it hurts.