Comparing the last training run with the first 10km of the marathon.
While looking at the data for my recent marathon it became clear quite quickly that something was wrong.
Here is the data for the last workout I did, one week before. This was a 10km run at marathon pace. So I averaged 4:05 min/km and my heart rate was low 160’s bpm.

Now looking at my marathon attempt. I adjusted my planned pace to aim for around 2 hours 55min finish. This equated to running at 4:10 pace. So running slower than the week before. Look at the heart rate, I was sitting at low 170’s, about 10bpm higher. It was clear I would not finish well right from the beginning.
