Ice Baths: Body and Mind
A new study finds mental and physical effects of a post-workout chill.
By Alex Hutchinson Published January 07, 2013
Do ice baths work? There have been plenty of studies, with conflicting and confusing results — perhaps because they use different temperatures, different durations, different exercise protocols, and different definitions of success. These days, I tend to ignore most of them, because they just add to the confusion. But I found this one, just published online in the British Journal of Sports Medicine by a pair of researchers in Britain and Sweden, very interesting.
The basic structure of the study was pretty standard. A dozen high-level rugby players took part in three separate high-intensity workouts in three different weeks; after each one, they had a different recovery protocol (15 min soaking in cold 14 C water, 15 min soaking in warm 30 C water, or a control with no soaking). One day later, they did an intermittent sprint test (5 x 40 m), to see how well they could maintain their maximum speed over the five sprints.
Here’s a measurement of their core body temperature, which shows the unsurprising result that ice baths cool you down:
So what about performance in the sprint test? Here’s what they found overall:
Sure enough, the cold-water group was able to maintain performance best. And strangely, the warm-water group also did better than the control group. Is this a sign that water itself has healing properties — or that doing ANY sort of specific recovery activity helps to convince you that you’ll do better next time, which turns into a self-fulfilling prophecy?
Here’s the really interesting part of the analysis. You can look at the results from a purely physiological perspective: how strong is the correlation between the percentage drop in body temperature during the recovery protocol and the subsequent sprint performance? The correlation coefficient is 0.6948 (perfect correlation would be 1). You can also look at it from a purely psychological perspective: the correlation between the volunteers’ subjective rating of the recovery intervention (their response when asked, immediately after the recovery bath, to rate it on a scale of 1-5) and subsequent sprint performance was quite similar: 0.5886. In other words, asking athletes how they felt about the ice bath is almost as effective as measuring the change in their body temperature for predicting how much the ice bath will help them.
But the best correlation of all comes when you combine both the physiological and psychological measures, producing a 0.7743 correlation. The implication: athletes who are effectively cooled by an ice bath and believe that the ice bath will help them are most likely to benefit. Ultimately, this isn’t just about ice baths: almost everything that athletes do for recovery (and perhaps for training too) likely combines physiological and psychological elements.
This has some pretty important implications. For example, the authors mention a previous study that appeared to find that ice baths actually hindered recovery — in that study, not coincidentally, the negative effects were linked to negative subjective beliefs about the effectiveness of ice baths. Similarly, a study of compression garments a few years ago found that they helped the runners who believed they’d help before the study started, and hurt the ones who believed they wouldn’t help. I expect more studies will start to do like this one and track subjective impressions in order to check when they’re interfering with or perhaps obscuring physiological effects.
And the most important message of all, I guess, is that whatever you’re doing in training, you should embrace it and suppress any doubts!