Just come across this. Say to train in zone 1 wor
This guy is a sport scientist/coach. I subscribed to his channel too. He had some good videos on how to analyze HR and pace data .
Back to your query. When this youtuber mentioned zone 1, he was quoting Dr Seiler. Dr Seiler is the father of Polarized Training, which over time was also called 80/20 training. In his Polarized training, he used his training intensity zone which is only has Three zones. The intensity are divided into three zone by two lactate lines LT1 (2 mmol/L) and LT2 (4 mmol/L).
SO in our usual 5 zones model, we use LTHR or Max HR into percentage and HOPE to get the border of Zone 4 and 5 as close to LT2, while the border of zone 2/3 as close to LT1. Ideally to fall exactly there.
That is why when you guy are ready for a 5km all out, I advise to do LTHR and zone it, at least this method gets your border of 4/5 very close to LT2. And when you guys are able to hold steady state HR at steady state pace over more than one hour, best is 1.5hr , I mentioned before in my post it's time to narrow that steady state HR and pace as close to LT1 as possible. Beside lab test or Lactate field test kit, these two methods are as close you will get to the LT1 and LT2 points. Better that zoning via MAx HR via percentage.
So when the youtuber quoted Dr Seiler's below zone 1 for 80% of your training, it actually mean below LT1, and in the 5 zones model that we are used to, it is below the border of zone 2/3. Nothing has changed.