Hi. I am circa 6-7 weeks into an 80/20 IM plan prepared by Matt for me for my A Race in July, with a B Race Half Marathon in early April.
Last week I had a 2+ hour run scheduled being 1km in Z1 and the balance in Z2. For whatever reason, in the first hour my HR would not come down from Z3 and so I walked. A lot. It just wouldn’t budge until over 60 minutes done and even then it was a struggle keeping it in Z2. In the early weeks of training this was kind of the norm but it generally has settled down well to enable me to run in Z2 most of the time.
I realise this recent glitch could have been due to numerous factors but my question is – what do I do? Do I just ignore it and run based on effort? Do I continue to be strict and risk a less than productive session?
Every once in awhile my watch will show something way off. Like it’ll read Z1 as I’m huffing and puffing up a hill or it’ll show Z4 while I’m just bebopping along a flat road easily breathing through my nose. For those instances, I go by RPE or glance at my pace and see how that pace aligns with my zones. Sure, my TP and my Strava data will be off for this session, but I’m willing to risk that in order to have a productive session.
On the other hand, if my HR is reading higher than normal and I feel crappy or sluggish, then it might actually be an accurate reading and I’ll dial back the pace/effort to stay in zone.
This is one example why Pace is a better measure of intensity than HR. I think the real solution is to switch from HR to Pace. You can, and should, still monitor HR, but HR is so easily influenced by other factors that it can sabotage your training if you use only HR.