Bathing in 55-degree water for 10 to 20 minutes is equally effective at promoting recovery whether you do it immediately post-workout or up to two hours later, according to a new study in The International Journal of Research in Exercise Physiology.
Intense workouts damage the muscle fibers, which in turn release inflammatory markers to try to repair themselves, explains Michael Ryan, Ph.D., associate professor of exercise science at Fairmont State University in West Virginia.
That leads to stiffness, swelling, and pain in the muscles, which can impact performance the next day. Ice baths mitigate those inflammatory responses by constricting blood vessels. Since they peak one to five hours post-workout, there’s no rush to cool off.
You'll likely benefit from taking an ice bath within several hours after a tough session—and maybe even one to two days later, says Lance Dalleck, Ph.D., the author of the study and an assistant professor of exercise and sport science at Western State Colorado University in Gunnison.
Ice baths are most beneficial after high-intensity exercise, endurance training, or workouts involving eccentric muscle contractions (like running downhill or doing squats, push-ups, or pull-ups).