Alex Hutchinson draws on the latest research to answer your fitness and workout questions in this biweekly column on the science of sport.
Does cold really help recovery after a hard workout?
As appealing as the prospect of a soak in the hot tub after a workout may sound, the consensus among elite athletes is that you're better off doing the opposite.
Ice baths - one or more 10-minute stints in a tub of water kept at 12 to 15 C by adding ice - have become a ritualized response for athletes dealing with everything from the heavy impact of bone-jarring tackles to the repetitive stress of a marathoner's three-hour run.
Two-time Olympic miler Kevin Sullivan, for example, takes ice baths after every hard session. "And then if I'm feeling a little stiff or tired heading into a race," he says, "I'll try to use them in the days immediately leading up to the race."
The logic behind ice baths relates to the muscle damage that results from hard workouts. This damage is actually a good thing, because the "microtears" are what stimulate new muscle growth, says Greg Wells, an exercise physiologist at the Hospital for Sick Children in Toronto who advises several Canadian Olympic teams.
But the damage also produces muscle soreness, which peaks one or two days after the workout and can interfere with subsequent training. Ice baths cause blood vessels to constrict, forcing waste products out of the affected area. "It's almost like wringing out a sponge," Dr. Wells says. Then, when the area warms up again, new blood rushes in to help the healing process.
At least, that's the theory. But scientists putting ice baths to the test under laboratory conditions have produced mixed results.
Two Australian studies published last year illustrate the confusion. The first, from the British Journal of Sports Medicine, found no reduction in pain, swelling or muscle impairment in subjects who received three one-minute immersions in 5 C water after heavy leg-extension exercises.
The second, from the Journal of Strength and Conditioning Research, also had subjects perform leg presses, but used a longer ice bath and concluded that the technique was "associated with a smaller reduction, and faster restoration, of strength and power."
The question has yet to be answered to anyone's satisfaction, in part because it's not clear how to measure success, according to Peter Brukner of the University of Melbourne, a co-author of the first study.
"Even though our research [on ice baths] was unconvincing, I still encourage their use," he said in an e-mail.
For the pros who swear by ice baths, the simple definition of success is whether they feel good the next day - and that try-it-and-see approach is appropriate for recreational athletes, too, says sports physician Ian Cohen of the University of Toronto's MacIntosh Sports Medicine Clinic. (As for the other extreme, Dr. Cohen says it's probably best to save the hot compresses for loosening up chronically stiff joints or muscles before exercise.)
The only significant downside to an ice bath after working out, chattering teeth aside, is the possibility of tissue damage if you push the temperature too low - less than about 5 C.
So if a weekly basketball game leaves you sore the next day, try sitting in a bathtub of cold water right after the game. If it makes you feel better, stick with it.
Alex Hutchinson is a former member of Canada's long-distance running team and has a PhD in physics.
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