I had a race this last weekend that I really haven't had time to train for like I needed to, but I gave it my best anyway. Looking back I think I was probably pushing too hard early on, but I'm curious to get other thoughts on this. I spent just under 5 hours in HR Z2, just over 5 hours in HR Z3, and just under an hour in HR Z4. All of the Z4 work was climbing, with my gearing I couldn't keep my HR any lower than that. My pace really dropped off dramatically the last couple of hours, and I was cramping pretty badly as well. My thoughts were that I just spend too much time in Z3. Others?