One of the big debates in sports science over the last few years has been the question of 'too much recovery.' Is it possible that the techniques we use to recover from workouts - ice baths, antioxidant supplements, compression garments, etc - could in some cases be counterproductive? After all, the whole point of a workout is to impose physical stress on your body, so that it will adapt and get fitter and stronger. What if, by removing some of this stress with recovery aids, you're also removing the signals that tell your body to adapt?
While a few studies have investigated this question, the debate has mostly been theoretical so far. But now data is starting to roll in. An Australian team led by Llion Roberts of the University of Queensland and the Queensland Academy of Sport has just published the most comprehensive look yet at the link between ice baths and training adaptations in the Journal of Physiology - and the results are extremely interesting.
The study has two parts. First, they put 21 volunteers through a 12-week, twice-a-week strength training program and assessed changes in strength and muscle mass (measured with MRI). Half of the subjects took a 10-minute ice bath at 10°C after each workout, while the other half did 10 minutes of easy stationary biking. In pretty much every measure, the ice bath group did worse.
So what's happening? To find out, the researchers did a second, acute study with nine volunteers. In this case, they did two lower-body strength workouts, one followed by an ice bath and the other followed by active recovery. In both cases, they gave muscle biopsies before the workout, two hours after, 24 hours after and 48 hours after. (Ouch!) This allowed the researchers to explore the cellular signalling pathways involved in building bigger and stronger muscles. Sure enough, these pathways were attenuated after the ice bath.
What seems to be happening, then, is that whenever you hop in a post-workout ice bath, you slightly reduce the adaptation signals. This could be because ice baths reduce blood flow to the affected muscles, which reduces the supply of amino acids that trigger the synthesis of new muscle. It could also be the drop in muscle temperature itself that slows down the regeneration process. Either way, this decreased signalling after each workout adds up, over time, to smaller gains in muscle size and strength.
One important point to consider is that this study deals with strength training. Is the same true for endurance training adaptations? There are some good reasons to think the two responses are very different. An interesting study published last month actually suggested that cold-water immersion can boost the formation of new mitochondria, which is one of the key adaptations to endurance training. And a big Australian study last year had elite cyclists do three weeks of very intense (Grand Tour-style) training with or without ice baths, and found that ice baths didn't hurt and possibly helped.
For now, at least for endurance exercise, the question remains open; in fact, Roberts and his colleagues are currently looking more closely at mitochondrial responses to ice baths, and should have more to say soon. But it's important not to overgeneralise the current findings.
And one final nugget: The same research team also looked at markers of inflammation in the muscle biopsies they collected during this study. As you'd guess, there was plenty of inflammation triggered after the workout - but it was essentially the same whether the subjects had taken an ice bath or not. So the prevailing theory that ice baths decrease inflammation may need to be reexamined.
What should you do with this information? If you use ice baths on a regular basis, particularly after strength training, it's certainly worth thinking carefully about what you're expecting to get out of them.