just google what all the athletes (runners, cyclists) have been busted for... winny comes to mind and i believe anadrol also boost red blood cells
http://www.steroid.com/Anadrol-50.php - scroll down to bottom
http://www.steroid.com/Winstrol.php - ditto
and in my opinion - the benis of steroids and endurance is 3 - 5 %
i did anadrol and sust ... and built some good strength that year i broke the local time trial record 12 times... i also used a hypoxia training to elevate my red blood cells ability to carry oxygen (info for runners -
http://jap.physiology.org/cgi/conten...act/100/4/1238)
i can recomend a device if you would like... but here is a sight that will help explain how it works - i use a device that when i bought it was like 300 dollars and it totally works!!!
http://www.hypoxico.com/