Winded, in my legs?

[Eden]

hmmm all very interesting, but that heavy feeling may still be related to lactic acid, but of course in conjuction with other things too. Hydration, nutrition and fitness all are factors in how fast you will tire.

"the accumulation of lactic acid during exercise can interfere with muscle contraction, nerve conduction and energy production, leading to acute fatigue. That’s one reason you tire during a training session. Yet lactic acid isn’t just a useless byproduct of energy metabolism — it is an important energy source."
from http://tkdtutor.com/11Training/LacticAcid.htm

It does seem to be universally agreed on that soreness after training is not caused by lactic acid, but by micro tears in your muscles.

more interesting information on lactic acid http://www.lagrange.org/articles/Y05...ticacid-rf.htm