http://www.ncbi.nlm.nih.gov/pubmed/22026588
I think its pretty experimental, with not much evidence at all showing that its going to make a difference. There are some risks with going into a hyperbaric chamber, depending on what exactly they're doing.
The above link was the closest thing I could find to any evidence of benefit from doing this.
I'm guessing, a professional athlete seeing multiple experts....someone suggested this MIGHT help and Steen decided to give it a try. Personally, I think this makes a lot more sense than seeing a chiropractor (like Crosby did).
Edit:
Just for clarity, the type of study linked above is a preliminary study you do when you want to see whether a treatment deserves to be studied formally. Its not meant to produce statistically relevant numbers....just more of a 'proof of concept' to obtain support for more meaningful studies.
This result looks somewhat promising, but the obvious glaring thing from first glance is that even though the guys showed some improvement....what improvement might they have had with doing nothing during that same interval? Maybe the chamber had nothing to do with it and it was just a matter of time. Also, at least one guy withdrew and they reported a few side effects that might not be trivial if you're the one experiencing them.
