I love your interest in learning some of the research surrounding contrast baths. I will try and keep this relatively short because it could spiral out of control fairly quick (as with any research).

Please just keep in mind that this is only a portion of the bigger picture, and I encourage you to do some of your own research. Just be warned that there will be a lot of conflicting information if (and when) you embark on your journey.

In the early 1990’s it was thought that the alternating temperatures simply changed the internal temperature of the muscles, resulting in quicker recovery times. This was believed because you could then essentially make it whatever your desired temperature was to promote better tissue health.

In 1994 and 1997, a group of researchers from Bringham Young University in Utah investigated these claims using the calves of some individuals and a regimen of 20 minutes with four minute cycles each. In 1994 two whirlpool baths were used, whereas in 1997 study bags of ice and heating pads were used instead (but the same stipulations were kept).

The intramuscular temperature was taken using needle mounted thermometers placed 1cm deep in to the calf, as well as just under the skin to compare. The researchers found no significant changes to the internal temperature of the muscles, but did notice surface temperature changes with the skin.

To veer away from the 90’s and come up to the last 10-15 years: one of the reasons that active recovery is infinitely more beneficial than passive recovery is because you are giving your body a middle ground to return to its own resting state, as opposed to having these huge shifts from nothing to activity and back again. This is why warming up prior to a workout or event is so effective as well.

Dr. Darryl Cochrane at Massey University’s School of Sport, Exercise and Nutrition in New Zealand, suggests that contrast hydrotherapy perhaps works from a “muscle pumping action.” The thought being that the alternating temperatures result in blood vessel constriction and dilation. He notes that this mimics muscle pumping that occurs during light aerobic activity.

This is also why cooling-down after a workout or athletic event is so beneficial as well (in a nut shell). The contraction and extension of your muscles results in a “muscle pumping action” for your blood vessels. This helps in many ways, as outlined in the post on contrast bathing that you just came from.

Contrast bathing may be a more appealing alternative to going for a 10 minute swim right after doing a huge relay race, or going on a brisk 15 minute walk right after running a marathon. Because if you think about it, if you could get the same benefit from just submerging a specific area in to alternating temperatures of water (which seems to replicate some of the factors that result in the same type of recovery from an active cool-down) you can see why this would be a popular option. With the reduced motion, the chance of injury that is present anytime that you move is virtually alleviated as well. Which may be why this is so effective with overuse types of injuries.

Ian Wilcock, a former masters student at Auckland’s University of Technology wrote his Health Science’s thesis on the effects of recovery after explosive activities and workouts contrasting each of: water immersion, active recovery, and passive recovery. Ian states that most research studies that deal with recovery more focus on the physiological response of what the soft tissues and organs are doing, and simply extrapolate out that these should cause X, Y, and Z changes throughout the body. Leading him to argue that the research should not be allowed to definitively say that they aid in any form of recovery – especially with athletes. I think this to be quite a poor and pessimistic assessment of the situation.

I bring this up to give you a bit of another perspective. Ian also points out, however, that many of these physiological changes from immersion therapy (and hydrotherapy in general) may come from hydrostatic pressure changes, rather than the temperature(s) of the water immersion itself. I think it is important to add this piece to the puzzle; especially when we just mentioned that the contrasting temperatures of the water will grow and shrink blood vessels, causing that same kind of pumping effect.

Adding in the fact that hydrostatic pressure changes enhance this pumping effect even more – in my mind – gives what we are trying to do a lot of additional credibility. If you would like to read his full thesis online, you may do so by clicking here (you will be taken to an online-pdf).

To finish this, I would like you to keep in mind that everyone is different. Whether you are thinking about athletes compared to other athletes, or athletes compared to everyday individuals. I mean to say that everyone is going to experience everything in their own unique way. Try a contrast bath – especially if you have an overuse injury or general aches and pain. You may find this cheap, simple, and often enjoyable method of recovery more beneficial than you ever thought possible.