As you may remeber I published a post in July 2011 challenging the concept of CWI as a means of recovery in athletes http://georgenassis.blogspot.com/2011/07/some-thoughts-on-use-of-water-immersion.html. The idea was that CWI, which reduces exercise-induced inflammation, may result in attenuated adaptations to training. Let me remind you that exercise-induced inflammation is a "trigger" to adaptations and hence every method that reduces inflammation would affect adaptations to training in a negative way.
The study by Halson et al. (2014) published few days ago in Medicine & Science in Sports and Exercise tested the effect of repeated CWI sessions on performance of trained cyclists. Their results showed that, following 39 days of training, cyclists in the CWI condition did not show performance impairement compared with the control group. This data do not support the speculation that prolonged use of CWI may attenuate adaptations to training. I am sure you will build your own opinion by reading the paper, but there are 2 points I would like to raise; the first point is that CWI did not produce any performance benefit compared with the control condition in this study. So, what's the reason of using CWI besides the players/athletes satisfaction? The second point is that we still don't know what might happen with longer exposure to CWI.
In another study, volunteers had one limb in cold water post training while the other leg was not cooled (Fröhlich et al., 2014). The individuals performed strength training for both legs for a period of 5 weeks. The results of the study showed a tendency for greater strength gains in the control group.
Overall, these recent findings highlight the need for more studies on the effect of repeated CWI sessions on long-term performance. Given that it is difficult to have high performance athletes in these experiments, studies with competitive athletes would help a lot.
For more reading
Halson SL1, Bartram J, West N, Stephens J, Argus CK, Driller MW, Sargent C, Lastella M, Hopkins WG, Martin DT. Does Hydrotherapy Help or Hinder Adaptation to Training in Competitive Cyclists? Med Sci Sports Exerc. 2014 Feb 5. [Epub ahead of print]
Fröhlic M, Faude O, Klein M, Pieter A, Emrich E, Meyer T. Strength training adaptations after cold water immersion. J Strength Cond Res. 2014 Feb 18. [Epub ahead of print]