When my kids were playing in a soccer tournament earlier this winter, they were due to play at least one game a day on 4 consecutive days, and sometimes two. Luckily for them there was a very-cold-unheated-outdoor-in-the-middle-of-a-Canberra-winter pool available for them to use!!
I wasn’t convinced of the value of this cold water immersion, compared to the stress placed on the immune system by running outside half naked in 5 degree temperature to get to the pool, then running back again dripping wet and still half naked. (Apparently it’s illegal to wear trackies and a warm top when you’re meeting your team mates pool side).
I did a little digging around on cold water immersion (CWI), more commonly known as “Ice Baths”, and found some interesting research. Here’s a quick summary.
What is an Ice Bath?
Ice baths come under the umbrella of cold water immersion. They are not actually baths chock full of only ice. That would definitely burn. They are a mix of water and ice, in any kind of vessel big enough to hold a human body, or part thereof. Generally the temperature is around 10 degrees C, although some research suggests that this is not cold enough, and favours a 6 degree submersion.
Why Would You Even Want to Jump Into an Ice Bath?
High intensity sport, or large volumes of low intensity sport, can cause fatigue which can reduce your performance. It can also reduce your ability to train well the next day. The more quickly you can recover from a bout of exercise, the better your next day performance will be, whether that’s in competition or in training.
It’s believed that immersing yourself in cold water post exercise bouts aids in recovery. That’s why you or I might think CWI is a good idea. Our kids…well, they tend to think it’s a good idea when their mates tell them it is.
Using Cold Water Immersion to Reduce Muscle Soreness.
Playing sport hard, long runs, high intensity interval training sessions, or sometimes even a reasonably moderate session of an exercise that is new to you, can leave you with what’s known as delayed onset muscle soreness (DOMS) aka “sore muscles”
Potentially, CWI can reduce this muscle soreness. The benefits include reduced pain at rest, reduced pain when stretching, and an increase in the active range of motion.
There are several mechanisms which might be at play here:
- Reduced nerve activity due to the cold temperature, which results in increased pain tolerance (1)
- A reduction in swelling due to the blood vessel constriction due to the low temperature (2)
- Reduced swelling due to the hydrostatic pressure of water (3)
One study has shown that it’s most likely not the actual immersion in water itself that has the benefit, rather the temperature of the water in which you immerse yourself. Immersion in 6 degree C water was more effective than 10 degrees, and more effective than contrast immersion alternating between 10 degree and 38 degrees C.(4).
Wouldn’t you just know the coldest option would be the most effective?
Does Cold Water Immersion Always Work?
Not necessarily. It appears the benefit of using cold water immersion in reducing muscle soreness only exists in trained athletes, so unless you’re well trained, you can keep the ice firmly in the freezer where it belongs.
CWI is also ineffective in recovering from a new training regime. So if you’re a well-trained runner who does 10k on the rowing machine in the gym, chances are an ice bath won’t help to stop the inevitable muscle soreness you’ll experience.
Will it Improve Your Performance?
There is not a huge amount of research on cold water immersion, despite its popularity as a recovery strategy. Whilst it might reduce muscle soreness, this may not necessarily translate to improved performance.
I took a quick look at eleven different studies which looked at the effect of CWI as a strategy to improve performance. Six of the eleven studies showed the CWI improved performance, but 5 showed either no improvement or reduced performance.
This was of course a small sample of studies, but there aren’t too many studies going around. And that’s the thing. There really isn’t enough research on the strategy to come down on one side or the other.
Patterns in the Research on Effectiveness of Ice Baths
- Studies which have looked at how well cold water immersion can prepare you for a second bout of exercise on the same day found either no effect or a negative effect on performance. This is probably due to a reduction in nerve velocity and the restriction of blood flow to the muscles.
- Studies testing the effect on performance 1 to 2 days after the cold water immersion had a tendency to find a more positive result.
Long Term Effects of Ice Baths
Research on the long term use of ice baths suggest that long term, chilling yourself in this manner too frequently could have a negative impact on the way you adapt to exercise.
CWI increases the release of the stress hormones cortisol and norepinephrine for up to 60 minutes after you jump out of the bath. These hormones act to break down the muscles, so this would reduce the body’s ability to adapt to training. And adapting to training is really the whole point of doing it. You stress your body repeatedly, it says “bloody hell, if she’s going to keep doing this to me I’d better get stronger”, and diligently goes about doing just that, getting stronger. But, if your cold water immersion bout is releasing hormones which break down muscle tissue, long term, you’re not going to be seeing the adaptation that you’re training for.
The release of stress hormones could also impair your ability to get a good night’s sleep, and sleep is THE most critical factor in recovering well.
The reduction in swelling which is brought about by ice baths could also have a long term detrimental effect on your fitness. Post-exercise swelling is part of the process that leads to muscle repair and strengthening.
It’s All in the Timing
Whilst there’s still a lot more research needed on cold water immersion and ice baths, a few things are apparent.
- CWI can reduce muscle soreness in trained athletes
- CWI might improve performance in subsequent exercise bouts which are 1 to 2 days post immersion
- CWI is likely to have no impact or could reduce performance on same day subsequent bouts of exercise
- Long term use of ice baths and cold water immersion as a recovery strategy is likely to have a detrimental effect on the body’s ability to adapt to training
- If you use cold water immersion as a recovery strategy, you should limit its use to times when you really need to recovery quickly for your next tough training session, or for an important event, but you should not use it as a matter of course.