Originally Posted by DannoXYZ
The more effective test would be to measure blood-lactate at differnet RPMs with constant power-output. So at the same 250w, measure blood-lactate at 90-110rpms in 5-rpm increments. You'll find that lactate-levels will vary. There will be one rrpm in that range that yields lower lactate than the others, a valley of sorts if you graph it. This is where your muscular-efficiency is best.
While this might be an interesting test, it has nothing to do with lactate threshold. The data would show lactate concentration as a function of rpm for the performed protocol, but I don't know what would be learned beyond that. It's not at all clear that performance (e.g., time to exhaustion) will be correlated with lactate concentration. So while I might learn that I produce a lactate concentrattion of 3.0 mmol/l at 90 rpm and 250W and 3..3 mmol/l at 80 rpm and 250 W. There's no reason to believe, based on this test, that my performance (however that's measured) will improve in going from 80 to 90 rpm.