dude, ignoring the fact that what all of these people have said, there really is no steroid that does what u want. most steroids diminish endurance and speed. they make u stronger but endurance is always affected negatively for me. u produe more red blood cells with a lot of the comounds people use and that theoretically should make u have more endurance but it does the opposite in reality. more blood makes everything in ur body work harder and u get tired. I all it mud blood syndrome.
long story short, I can't think of a single comound that I'd say specifically boosts endurance and speed. possibly winny or var but not enough to speak of. u have to diet and exercise ur balls off. I broke my knee when I was 15 and was out for a year. came back the next year running a 4.54 40 yard and ran for 900 yards, and went undefeated in the regular season of wrestling. I did water aerobics, plyometrics and nothing but calisthetics. get at it dude