I set out intending to run for 90 minutes while keeping my heart rate in the range of 160-170 bpm for my weekly ‘long run’, but as the first hour felt so easy, I ploughed on to half marathon distance.
The map below shows the route together with that pacing required to maintain my heart rate in the desired range:
[slower] Blue-Green-Yellow-Orange-Red [faster].
For the first three-quarters of the run it was difficult to hold back and run ‘slowly’ to prevent my heart rate rising…particularly on uphill stretches; and for the last quarter it was hard to keep my heart rate up since my legs were stiffening up and didn’t want to move any more.
My time for my unplanned steady pace first half marathon distance (21.0975km) run was 2h 2m 45s.
My aerobic decoupling was 1.1% which means I was able to continue outputting the same power (i.e. running at the same pace) through the run without my heart rate increasing, so apparently my heart is strong but my legs are weak.
The chart below shows my average pace for each 1km of the run in blue, and my elevation as the grey shaded area. Apart from a couple of steep uphill sections when I had to back off to keep my heart rate below 160 bpm, my pace was in the range 5:40/km to 5:57/km throughout.
