Question: Should I soak in hot or cold water for the best post-run recovery?
Answer: I'll admit it -- I've dreamed about soaking in a hot tub during some of my long runs. Although it seems relaxing and therapeutic, a post-run hot tub or heating pad is definitely NOT recommended. The reason? After a long run or any tough workout, your joints and muscles are inflamed. If you put heat on them, the blood flow to those areas will increase, which can make them even more inflamed. In addition, you may already be slightly dehydrated post-run, and the heat from the hot tub may dehydrate you even more.
So what's the best post-run recovery technique? An ice bath will help reduce inflammation of tissues and joints, relieve soreness, and speed up your recovery. Just fill your bath tub with cold water and get in, so your body can adjust to the temperature. Then dump in one or two 5-pound bags of ice (as tolerated). Stay in the tub for 10 minutes.
If you really don't like the cold, it's fine to go in the tub wearing running tights and a sweatshirt -- you'll still get the same benefits. Or, if the polar bear thing just isn't for you, a cold shower will also help reduce inflammation or soreness. And, if you really can't tolerate the cold, at the very least, try putting bags of ice or frozen vegetables on sore or inflamed parts (your knees are probably the body parts that could use it most) for 10 to 15 minutes post-run. Or sit in a tub or pool of cool water.
Also see: How to Deal With Post-Run Muscle Soreness