I'm interested in CPET too. It's obviously entirely inappropriate for those at the sicker end of the scale, but many housebound patients would probably endure a relapse to get data that could be used to further research, or support disability claims. I have never heard of someone using two-day CPET results to claim disability in the UK, but I do wonder if it's possible. Just imagine how much we'd know today if the money that went into PACE had gone into a huge exercise physiology study of fatigued patients - we might even have some subsets. But perhaps Dr Enlander's Sinai exercise study will do a bit of that for us.