I’m not sure the two are the same question, as i was wondering if hr drifted upwards at your threshold when improving fractional utilization.
I think real world data agrees with mader and heck’s model, in that the higher percent Cp is of vo2max, it brings lt1 along for the ride and as burnley suggests, becomes more compressed. Its basically a flatter pd curve.
Some have suggested either we all have the same gap between lt1 and Cp, or that they can move independently. There’s anecdotal evidence of improving lt1 without Cp, but only for individuals who don’t have a flat baseline so they really dont have a first threshold.