No, its time to understand a few key points:
- heart rate zones are GUIDELINES and not fact
- Coggan and Friel and British Cycling are 3 popular HR zone systems and all 3 use LTHR to establish zones
- I’ve only used Coggan and Friel zones and they provide me with two different HR zones
- Friel and British Cycling have you do a 30-min all-out time trial to estimate lactate threshold heart rate (LTHR)
- a nice guy made a free tool (intervals-icu) and it claims to use Friel HR zones
- somebody above reports that intervals-icu incorrectly uses HRmax instead of LTHR for zones
Here is Coggan HR zones vs Friel HR zones for a ride earlier this week:
Same ride, different HR zone results from two different HR zone systems. They are both based on LTHR.