So as with all drugs, the results are dose dependent. Winstrol can certainly be used for endurance, however the doses employed are much lower than what one would use for bodybuilding. In the world of athletics, a little comes a long way. I’m talking like 5mg of winny/day, it also isn’t unheard of for marathon runners to use low doses of oxymetholone (anadrol), very harsh drug, in order to increase RBC count (anadrol has been documented to have roughly 5x the erythropoietic stimulus compared to test). And while being light in marathon running is a nessecary, some retention of muscle mass is def a benefit (however there’s a very narrow window of benefit in this case) as there’s a very thin line as to how much muscle mass is too much and how much is yeetdoopily.
Extreme endurance training causes chronically elevated cortisol and thus secondary hypogonadism in many, you being on TRT is already a slight advantage. You can add an extra 50mg or so to you’re trt regiment (a little bit will go a long way in the case of endurance exercise)
Don’t fuck with EPO, it’s expensive and very dangerous, having a HCT in the mid 60%'s will put you at risk for a stroke lol.