I’m sure you know the obvious answers…there is a thread here
One take (assuming heat and hydration is dialed) is that muscular fatigue leads to more muscular recruitment leads to more oxygen demand leads to cardiac drift.
Another take from here (https://www.peakendurancesport.com/endurance-training/training-structure-and-planning/discontinuous-training-master-stroke-endurance-athletes/) is:
“Another explanation is that CV-Drift occurs as a result of the release of a hormone called catecholamine, which is released as part of the body’s ‘fight or flight’ responses to physical stress”
(Appl. Physiol. 1999;86:799–805)
Not sure how much of this is tapping into the unknown.
Would be interested on your take.
How would you solve this for me?