Alison
Very helpful and I suspected that was the answer. Do you have a view on a limit on the time above Zone 2 in a run before it impacts the capacity building meaningfully? I can always do easier trail runs but the reality is at times HR goes up (as it does down). Less that 20%? Or perhaps it is just a 1:1 match with time above Zone 2 (e.g., 20% of time in Z3+ = 20% less capacity building impact). Thanks
Caperton