significance of being limited by legs or by heart/lungs
These days it often seems when I'm on a fast 30 mile ride that the limiting factor to my performance is heart/llung capacity - there's just a limit to the amount of air I can breathe over a sustained period. When I'm feeling on top form (and do my fastest rides) that often seems to be the case, but if I'm feeling tired for whatever reason it's usually the way the legs feel that is limiting. Also the fitter I get the more it seems the lungs are limiting rather than the legs. What's the take-home lesson from this in terms of training - e.g. do heavy legs mean you need a couple of days off?