Originally Posted by asgelle
Lactate threshold is properly defined as an exercise intensity usually interms of power or VO2. It is never a force. For example, my legs can exert a force of 90 lbs virtually indefinitly, yet I reach my functional threshold (higher than LT) at 250W and a force of about 35 lbs.
Well, it's really a measurement of blood-lactate levels. LT is defined as the "knee point" on the molality graph where blood-lactate it takes a sharp turn upwards and can't be cleared fast enough to maintain equilibrium.
In your example, if you were producing 250w @ 90rpms, you can exert the same force at 5% higher RPMs (on gear lower on straight-block) and probably get 5% more power. Your HR will increase, however, if it was below VO2-max, then you won't be overdriving the lungs.
Although in your case, your legs might be stronger than your cardio system, so you might actually have higher power-output at lower-RPMs.
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.