I think it's pretty well established that most of the cyclists in the 90's and thousands of other endurance athletes were and probably still do use test along with HGH. But they use those compounds for recovery and to be able to train harder, for longer, and recover faster to be able to do it again sooner. so in that sense, test will increase your endurance, but only if you are willing push yourself and train like a Tour de France competitor. I would also be willing to bet that in the context of lance Armstrong's public statements about his drug use, "a little" is probably very subjective. My guess is that 300-500 mgs of test prop a week was probably pretty standard in those days.