Phelps training at 8,000 feet and using a using hyperbaric chamber to aid recovery

See USA Today:

"...He says the chamber looks like a fish tank around his bed and the only downside is trying to watch TV through its walls."

[Link]

I wonder if this could be considered cheating? This is a medically sanctioned object that most athletes cannot afford?

UPDATE: This is what The World Anti Doping Agency (WADA) has to say about the chambers:

"... In 2006, the World Anti-Doping Agency’s ethics committee ruled that such chambers enhance performance and violate “the spirit of sport,” but the executive committee refrained from adding them to their list of prohibited substances and methods, instead asking for studies to look further into health implications. ..."

[Link]