Hydrotherapy or cold water immersion has become common place in the professional sporting environment. Advocates include Paula Radcliff, the England Rugby team & NFL star Prince Kruah, to name but a few. The practice typically involves submerging your body in 12-15℃ water for five to ten minutes. The cold water temporarily constricts blood vessels reducing blood circulation.
It is the rewarming phase where blood circulation speeds increase, improving muscle regeneration. Cold water immersion is thought to aid the removal of waste products from the working muscles such as lactic acid. Other claims include; reduced swelling and tissue breakdown.
Another application of the same methodology is contrast water therapy (switching from hot water to cold water every minute). This is usually done in a shower for convenience. But does controlling the temperature that a muscle recovers at have an effect on its recuperation?
Research in this field is very contradictory. A paper in the International Journal of Sports Medicine studied the effect of cold water immersion, hot water immersion, contrast water therapy and passive recovery.
The experiments were conducted on twelve cyclists who performed five consecutive days of maximal effort training. Measurements of the athletes average power, core body temperature, heart rate and perceived exertion level were recorded during each session. Across the five days athletes in the cold immersion and contrast water therapy groups saw an increase in sprint speed (0.1 – 2.2 %) and trial time (0.0 – 1.7 %) (Vaile et al, 2008).
Considering that the athletes were performing max effort exercise on consecutive days you would expect their performance to tapper off fairly rapidly. So an increase – regardless of the percentage – in speed would suggest that cold water immersion and contrast water therapy are effective mechanisms for reducing muscle soreness.
However a paper in the British Journal of Sports Medicine had results inconsistent with this. It found no benefit to; isometric strength, hop distance, swelling or serum creatine kinase and found that cold water immersion caused an increase in PERCIEVED muscle soreness. It was a randomised & controlled, double blind study, comprising 40 participants. This should have made the results more consistent (Sellwood et al, 2007).
However the immersion periods were only 60 seconds, so it is very possible that the participants body temperature did not drop low enough to cause sufficient blood vessel constriction. Particularly as the conventional submersion time is between 5 & 10 minutes.
Given this contradiction I decided to search for a meta analysis of hydrotherapy. The “Effect of water immersion on recovery from fatigue” published in the European Journal of Human Movement in 2015 found that there was a “positive moderate effect of cold water immersion on the recovery process, but not with contrast immersion”. The study analysed 11 papers published between 1998 & 2013.
More research needs to be done in the field to prove just how effective cold water immersion is, but I am happy enough with these findings to say with confidence that CWI does reduce muscle soreness. I have been using cold water immersion as a recovery technique for a few years now but intermittently and not prioritising it as I perhaps should. Last weekend I changed that at the England Touch Rugby Nationals. I played 6 games in 3 days and ran my legs under cold water immediately after every game. I definitely felt fresher than usual. As such, I am now including cold water immersion into my recovery routine.