Originally Posted by
PeteHski
This is interesting. I guess that is the gold standard, but do you think it is really that critical for productive endurance training? I set my training zones relative to a 4 point FTP/MAP/AC/NM power curve and that appears to work fine. I'm curious what measuring my blood lactate would bring to the party at this point? I understand that my training zones would be refined (at least at the point of measurement), but are they likely to change significantly from what I train to anyway? I'm pretty sure I know my FTP/MAP power to within 10W.
I did it because I wanted an accurate estimate of LT1, which is the target for the low intensity part of polarized training and where the authorities tell us we should be doing 80% of our workouts. For a weak old hack like me, it's high Z1-low Z2, as defined by FTP in the 7-zone model, so it's not something you can just figure out with a power meter or HRM. Another benefit was determining FT2, which corresponds in most studies to FTP, and is another solid physiological datum, not an estimate of a theoretical quantity.
A good estimate of LT1 is important because above it the blood lactate rise inhibits lipolysis (fat breakdown) in adipose tissue, and fat utilization by muscle is one of the main things one is trying to improve by training in that zone. If you believe the experts, notably Iñigo San Millan, the adipose tissue response to lactate signaling is more of a non-linear off-switch than a graded response, so you want to get close to, but not exceed LT1.