Alpynisto wrote:The whole concept of a lactate threshold is pretty outdated in sports science. A decade ago, it was all the rage but now they realize that lactate is not a limiter of performance and at best is a secondary measure of what is really going on. You don't need blood tests to understand and benefit from interval training. And a VO2max test really tells you nothing. If you want to be methodical, just get a good HRM that lets you download to the computer. Or just do fartleks and don't worry about all that stuff.
From my layman's understanding, what's outdated is the idea that lactic acid is the cause of fatigue, when in fact lactate is recycled for energy. However, there's still a threshold beyond which lactate production exceeds the body's ability to process it, and fatigue is associated with that threshold even though the precise cause has not been isolated from among the various things that go on at that point.
You should be able to get a rough idea of your lactate threshold just from subjective judgment of your effort level, it's been described as "comfortably hard" with fast but controlled breathing. See http://www.mcmillanrunning.com/training2.htm. It's specific to runners, but informative.