# Zones of "Form %" in Fitness-Chart

**URL:** <https://forum.intervals.icu/t/zones-of-form-in-fitness-chart/3623>\
**Category:** Uncategorized\
**Created:** [12 April 2021 08:25 UTC](https://forum.intervals.icu/t/zones-of-form-in-fitness-chart/3623 "2021-04-12T08:25:30Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![David\_Plavcan](https://forum.intervals.icu/user_avatar/forum.intervals.icu/david_plavcan/32/4554_2.png) [@David\_Plavcan](https://forum.intervals.icu/u/David_Plavcan)\
**Post date:** [12 April 2021 08:25 UTC](https://forum.intervals.icu/t/zones-of-form-in-fitness-chart/3623/1 "2021-04-12T08:25:30Z")

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Hello!

i am wondering about Zone definitions (Transition, Fresh, Grey, Optimal, High Risk). In the fitness chart, they are based on the **relative** Form/TSB (Form %), while the linked reference defines them based on the absolut TSB: [Managing Training Using TSB | Joe Friel](https://joefrielsblog.com/managing-training-using-tsb/) (TSB = CLT - ALT)

For me (starting again training after long covid, so very low fitness arround 20), this makes now large difference for the “high risk” zone:

Taking Joe Friels Definition, it is ok to go up to -30 TSB. So for my fitness of 20, i could train now with an ATL up to 50 to avoid the high risk zone.

If i take the definition from the fitness chart, then the high risk zone is defined from -30% if relative Form/TSB. So my relative TSB should be no below -30%. This would mean that i should train now only with maximum ALT of 26 ? (20 + 0.3\*20 = 26).

Is there any scientific litereture for this “retlative definition” of these zones? Or where does this come from?

Thanks a lot!  
David

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**Author:** ![david](https://forum.intervals.icu/user_avatar/forum.intervals.icu/david/32/30189_2.png) [@david](https://forum.intervals.icu/u/david)\
**Post date:** [12 April 2021 17:04 UTC](https://forum.intervals.icu/t/zones-of-form-in-fitness-chart/3623/2 "2021-04-12T17:04:09Z")

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The zones come from Joe Friel and are for absolute TSB. I stuck with the same zones for % TSB because for myself doing approx 70 TSS/day they seem to work well whereas the absolute did not + I assumed the absolute zones were likely for someone doing 100 TSS/day so straight % seemed ok. You can switch to absolute form and see how that works.

I think TSB zones are more of a “rule of thumb” than science. I am 49 so I will take longer to recover from training that someone in their 20s and that isn’t factored in.

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**Author:** ![MedTechCD](https://forum.intervals.icu/user_avatar/forum.intervals.icu/medtechcd/32/40383_2.png) [@MedTechCD](https://forum.intervals.icu/u/MedTechCD)\
**Post date:** [14 April 2021 21:47 UTC](https://forum.intervals.icu/t/zones-of-form-in-fitness-chart/3623/3 "2021-04-14T21:47:48Z")

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If you know for sure that you take longer to recover, you should modify the “Fatigue Days”. That is the purpose of that number, but I haven’t found anything yet that explains what and how.