I have done two runs over the past few days - both at the same pace of 8 mins per Klm. The first was 10Klms done using run/walk 30/30 and second was non-stop 5Klms parkrun. It is interesting for me to note that my average heart rate for the longer 10K using run/walk was only 117BPM -- BUT the 5K non-stop parkrun done at the same pace as the 10k was at an average HR of 134.
My understanding is when doing a steady state run, HR should increase to a certain level - and then level out. It can and does rise above the level with increased distance . However, my HR seems to constantly rise to maximum regardless of what pace I do????