Well, I don't know if my experience will apply to your situation. The problem I have is that my legs burn and feel fatigued before I think they should. It feels like what used to be referred to as a build up of lactic acid in the muscle tissue, though I think current thinking on what is actually happening has changed a bit. Because of it, I had to back off on a climb or ease up from a harder pace because that burning sensation forced me to give up before I felt I'd given it all I could, before I felt my legs should really be tired. What has helped me is Sportlegs capsules. They aren't a miracle drug-they don't make me feel strong if I'm not in shape, but they help hold off the lactic acid burn sensation that I've felt was holding me back these past couple years.