From the P&B.....may be a bucnh of scientifical BS but what I'm hearing from folks I know still involved in the silliness that is bike racing thsi stuff pans out..in....you know... like in the real world and stuff.
........ the current thinking is that lactate per se isn't actually the cause of muscular fatigue. It is a fuel and actually may buffer changes in muscular acidosis and prevent fatigue (this is probably why high intensity warmup that actually generate some lactate seem to improve performance in the actual event, the lactate ends up buffering changes in acid levels).
However, Billat's thing is getting mired in a lot of semantic crap in my opinion. The old idea of the lactate or anaerobic thresholds (as originally defined) are likely garbage. However, this doesn't negate the existence of a threshold speed or intensity above which fatigue occurs very very rapidly. That it occurs is more important practially than what you call it or what is causing it.
The simple fact is that a runner may be able to maintain (and these values are pulled out of my butt)
10mph for essentially forever
10.5 mph for an hour but it works the hell out of them
11 mph and they fatigue in a few minutes
again, values are for example only.
clearly there is a criticial threshold point above which fatigue occurs rapidly. from a practical standpoint, that's essentially what the old ideas of LT/AT/OBLA/etc. were describing.
you can graph velocity versus time to exhaustion and see that kind of pattern. below some level, the athlete can go until they get bored or run out of muscle glycogen, around some point they are working very hard but can maintain speed for extended periods (cyclists will test 20' although an hour maximum time trial isa better indicator), above that point and fatigue hits like a hammer after a few minutes.
It's actually looking like H+ production (rather than lactate per se) is the cause of this. It's also turning out (going to ccrow's point) that the aerobic engine is a much bigger determinant of this than previously thought. Mitochondria buffer acid levels and the bigger the aerobic engine, the less acid is produced.
A common trend in a lot of endurance sports is going back to volumes of low intensity aerobic work with just a bit of higher intensity stuff thrown on to top off the system (the system adapts quickly but stops adapting equally quickly, some of hte interval studies in cyclists show that 6 workouts across 3 weeks pretty uch maximizes the benefits)).
An example, there's a paper describing the training of the german track cycling team in the 1km (or was it 4k). An event last 4 minutes which most would argue is highly anaerobic. Most of their training was easy aerobic with some stage racing and a bit of specific track training thrown in at the end.
As I recall, a typical rowing race is roughly 6 minutes and even there they are going back to volumes of low intensity work to build the aerobic engine.
There's also an old idea (Maglioscho's book gets into this) that too much high intensity training can actually degrade the aerobic engine which *might* be what the US Rowing team was experiencing: if their caoches emphasized too much work around or at LT (or high intensity intervals) and lose aerobic engine size, that could actually be detrimental.
Translation of my long-winded crap: it may be better over extended periods of training to build this engine (again going to ccrow's comment) with lower intensity aerobic work. This can be topped off with higher intensity stuff as needed.
Maybe the boxer and martial artists who did extended road work weren't so wrong after all.