I'm not saying anyone should do this. This is more for endurance atheletes, not fat powerlifters.
Endurance atheletes, particularly high altitude ones, have taken a glucocorticoid called dexamethasone to increase endurance.
"'Our study indicates that for HAPE-susceptible climbers, taking dexamethasone improved exercise capacity, oxygen uptake kinetics and decreased the anaerobic threshold,' said lead researcher Manuel Fischler, MD, of the University Hospital in Zurich, Switzerland. 'Overall, this means that those climbers who took dex felt better, were able to do more, and probably experienced fewer altitude-related discomforts than both other groups.'"
There are other possible MOAs, such as, there might be a a vasodilation effect similar to clen. It also helps with altitude sickness. Altitude sickness is caused in part by increased CO2 concentrations changign kidney metabolism.
Here's where I got the quote: http://blog.talusoutdoor.com/?p=326 . It's a blog post that explains dexamethasone in depth.
Dexamethasone is a glucocorticoid, which is a drug that causes the effects of cortisone. Cortisone is to dexamethasone as testosterone is to trenbolone (or halotestin).
Glucocorticoids cause weight gain, insulin resistance, immune suppression - causing antiinflammatory effects. I think they also can activate mineralcorticoid receptors. Mineralcorticoids change sodium and potassium rentention.