How to Pace the IM Marathon?
Hey everyone,
I’m a few weeks out from my first full IM and I’m still unsure how I should pace the marathon. Do most people run it mainly in Z2 or Z3?
Some background:
36M, 60 kg, 170 cm (if that matters).
Ran my first standalone marathon beginning of 2024 in 3:13 off 4 runs/week (2 quality sessions, 1 long run, 1 recovery run), peaked at ~58 km/week, the rest of the week I was doing cross-training (swimming, cycling, gym).
In 2024 and 2025 I also did a couple of sprints, ODs, and three 70.3 races.
My last 70.3 was 4:22 overall, with a 1:25 HM. I finished with absolutely nothing left in the tank.
This full training block has included a lot of high Z3 work.
Saturday I had the long bike session and Sunday I did 32 km total (2 km warm-up, 3 x 8 km @ Z3 with 2 km easy between).
I finished it, but definitely felt like I could not sustain that pace for the entire marathon.
If all goes to plan, I’ll peak at around 75 km/week.
Right now, I feel faster than in 2024, but I don’t know if I could hold Z3 for the entire marathon, especially after swimming and cycling, the training plan seems to point toward that pace though.
For those with more IM experience, how do you pace the run?
Should marathon pace in training feel “barely manageable” like this?
Does tapering usually make that pace feel much more sustainable on race day?
Or should I hold back I run mid Z2/high Z2?
I know I have to adapt on race day depending on weather, how my body feels and so on, but if all goes well, the race should be better than the training block, right?