Originally Posted by
hansen01
What would you recommend for threshold intervals?
2x20 minutes at or just under FTP or 3-4 x 10 at 105% with 5 minutes rest between intervals.
So targeted training should be performed at a level which can be sustained for the entire ride?
For the periods of interest, without the rest of the ride taking too much out of you that isn't possible.
The problem is that impact is non-linear. Past threshold lactic acid accumulation is proportional to power raised to the fourth power. Ride 20% too hard past threshold trying to keep up and your lactic acid will accumulate twice as fast putting a premature end to the effort. Simplistically fatigue varies with the square of power, although you also have a finite number of "matches" to burn past which hard efforts don't work.
On the bottom end loafing along in the pace line you don't stress things (and aren't taking 20 minute pulls up front which would help your FTP).