There have been a number of questions/requests for additional functionality when setting up zone systems. But there are at this moment some limitations in Intervals that can’t be solved without a lot of (re)-coding work. My goal here is to sum up those limitations and inform people who are struggling to set up their preferred zone system. This list is valid at this date. Please let me know if something is missing.
- The lowest zone, Z1, must start at zero. That’s because Intervals needs to be able to assign every single data point to a zone. And setting the lowest zone start value at 0 is the only way to achieve that.
- The highest zone has HRmax as upper border
- The maximum number of zones is 7. There have been requests for 9 zones as per TP/WKO, but it can’t be done now.
- You can reduce the number of zones to three by deleting zones from a preset, which might look the way to go when using Seiler/Polarized, but doing this will invalidate the Training Classification on the Totals page and screw up the S1/S2/S3 totals on the weekly overview. That’s because for those 2 functionalities, Intervals is grouping Z1 & Z2 as S1, Z3 & Z4 as S2 and anything higher as S3. As long as you have 2 zones below the first ventilation point and 2 zones in between VT1 and VT2, you’re OK. Those 2 breakpoints will probably be used in any modern zone system as these are clear physiological borders. How you pinpoint them is another thing. Lab test, Lactate, % HRmax, %LTHR, FTP test, etc…
- Basically your best bet is to use 5-7 zones for both Power/HR and eventually also for Pace with those anchor points at the top of Z2 and Z4. This will keep the Classification and Seiler functionality intact.
- When setting up a zone system, check if you can adapt it with the above known limitations. In many cases, you can do that with a little creativity. If for example you want to use a zone system where there’s only one zone in between VT1 and VT2, split it up and use the sum of the splits in charts. While you can give each zone a descriptive name, you will however see the hardcoded sequential zone number prominently. That can create confusion when your coach gives you a workout in what he calls Z4 because in the above example it will be Z5 in Intervals as a consequence of the splitted Z3.
Hope this helps for those struggling to configure things as requested by the chosen zone system.