Believe and You Will be Healed!

I have been meaning to finish my research into heat acclimation/acclimatisation and blog on that, but since we're so well and truly into summer here in Western Australia, with 10 days above 35 degrees in January, it seems a bit late!

Thus, it's more fitting to talk about ice baths! :-)

Or more appropriately, "cold water immersion" (CWI). I, myself, have had no less than three ice baths (CWI experiences) this week. Essential to me, as I've also just finished my highest mileage training week ever, hitting 165km + 4400m. Woohoo! Feeling good.

Canadian mountain rivers are NOT 14 degrees!

I've been aware of cold water recovery methods since I started running trails in 2006, watching my trail running buddies in Canada happily jumping into near-frozen streams in the mountains after long runs. A few years ago, I received a lovely phone call from a fellow who spent a lot of time helping Helen Stanger (AUS) train through her incredible ultra career. He asked, "Do you use ice baths for recovery?" and went on to state how important he felt they were for Helen. Last year, being "bathtub-less", I bought a large bin and started having some ice baths outside. I threw a thermometer into the water often, as I had it in my head that I should aim for 10-12 degrees.

But despite all the anecdotal reports from athletes raving about their love of ice baths, research has been quite contradictory. I decided to delve into it.

The main problem with the research is that it's all over the place. Immersion in water ranging from 0 degrees Celsius to 24 degrees Celsius. Full body immersion vs legs-only. Five minutes vs 20 minutes. Men vs women. Trained athletes vs novices. Winter swimmers vs rugby players. And test exercises that are commonly used as a way to measure "recovery" include eccentric muscle contractions with weight (e.g., using the quad). Hardly a practical application for most athletes. And these recovery "test" exercises are administered anywhere from 5 minutes after CWI to 24 hours after. No wonder we can't make sense of whether ice baths are good for us or not.

Pre-bathtub days, when I had to feed mossies, too

In one review (Beakley and Davison, 2009, Br J Sports Med, 44, 179-187), the authors report on what happens to our bodies when we immerse them in cold water. The stuff that's not so good - "cold shock." Increased heart rate, increased blood pressure, increased respiration, increased cortisol, decreased cerebral blood flow (a few people nearly passed out at 0 degrees), and oxidative stress. So why would we do it? Because the apparent benefits include vasoconstriction (constricting blood vessels), which should help remove metabolic waste from legs, decrease swelling/oedema and inflammation, and decrease muscle soreness. It reduces our core temperature, which gets us recovered and ready for exercise again sooner. Even the hydrostatic forces - the pressure of the water - pushes body fluid from the periphery to the core, which increases central blood volume. And cold water/ice has an analgesic effect. Who doesn't like a little numbing? :)

What I've taken from the research indicates this:

• Water temperature of approximately 12-14 degrees Celsius may be optimal. Colder, and anything approaching 0-5 degrees Celsius, induces too much stress. Just like most everything in life, moderation is key. Running is good, but too much running results in overtraining and injury. CWI is good, but too cold results in shock. One should not have a "shivering" response, as evidence indicates it's associated with free-radical production. 

• Immersion for 10-20 minutes appears optimal, at the temperature above.

• Training/racing should not be expected to be undertaken immediately afterwards, as cold muscles will have compromised contraction abilities and slow nerve conduction speeds (several studies had subjects "test" immediately after CWI). Core body temperature will naturally rise to baseline within 24 hours. It may be possible to speed this up with a warm shower (the idea of "contrast water therapy," which I won't go into).

Stream crossing mid-run. It really IS hard to move after this kind of CWI.

• Your belief in the power of CWI makes a difference. Cook and Beaven's (Br J Sports Med, 2013, 47, 705-709) novel study on CWI at 14 degrees for 15 minutes (vs other options) found that the rugby players who "liked" the ice bath had better sprint performance the next day than those who didn't. So, the ice bath helped, BUT believing in the ice bath appeared to help even more. Believe, and you will be healed! Use the placebo effect to your advantage, as it can also trigger your brain's "reward centre," which can then cause your body to dump some nice opioids into your system. Mmmmm, endogenous opioids....

• Immerse only over the hips. Do not immerse the "core" area including the major organs such as heart and lungs. There is no evidence of benefit to runners/athletes generally in doing this and it looks to bring more potential for harm/shock.

Finally, prepare adequate reading material, such as your favourite ultra running magazine, and ensure no small, impressionable children are nearby as you take that first step into the tub!