Question is simply, when overtrained and wanting to do light spins, should you be still using your training power zones or should you be training to heart rate instead?
The reason i ask is my zone 2 (power) heart rate is now about 15bpm higher (due to being overtrained), putting me in the tempo zone of heart rate. So should I cap my heart rate?
Hi
Here is a link worth watching
One thing to do if you are over trainedā¦ is take a small break and Rest more and fuel better. Oh! thats 3 things 
If really over-trained (as opposed to under-recovered), take time off, donāt worry about power or HR and the moment a session starts to feel even approaching any kind of effort, back it off (a lot).
A break now should allow you to pick up again when you feel able whereas continuning in a half arsed manner will drag it out.
Sounds like you are nonfunctional overreaching. A good read here:
I think if you are this far into overtraining there is no use in riding at all. You need to rest completely until you see normal hr values; forget about trying to maintain or hold on to fitness.
It really depends what zoning model your using for that info to be interpreted but either way, a ālight spinā should not be taxing the cardiovascular system at all. If you check out workouts filtered by Intensity set to Recovery, try one of these and by all means keep a note of how hard it feels and your HR - and take a break accordingly.
Thereās more tips and info here:
When I was feeling overtrained, I often felt that doing an easy 45-60minutes just delayed my recovery. Iād go a tiny bit too hard or instead of recoverying 100% Iād recover 50%. Iād do another easy ride the next day and would recover another 50% and still not be at 100%. Had I just taken a full day or two off I would have gotten to 100% much more quickly.
How do you know youāre overtrained?
Was about the write the same.
Increased heart rates can be observed for a variety of reasons. Mate of mine discovered that way that he has COVID. 
Increased heart rate over the past 6 weeks
Trouble sleeping
Fatigue / mentally tired all day
Depression
Not able to perform anywhere near what I was doing about 12 weeks ago
All followed a bout of intense stress whilst training high volume, working full time, 3 kids, losing job etc. Etc. I saw all this as impetus to train harder and let off more āsteamā but then led to gradual burn out after not getting enough sleep. RHR gone from 49 to mid-60s. Dropped from 4.2 W pkg to around 3.6. I took a week off when I noticed all this thinking it would do the trick but still the same. Iām noticing some improvements slowly but itās so frustrating not being able to train. Iām worried about going right back to where i was in the beginning.
I did think it was this at first but itās lasted 6 weeks now and Iāve not had any symptoms of COVID
Thanks I had no idea these workouts existed!
Should I expect HR values to return to normal? What I expect is that as I lose fitness, RHR baseline will also increase so I would not really be able to tell?
Thanks I listened to this. I found this quite scary but I note that this athlete went a lot further down the road than I did before stopping and reached what sounds like parasympathetic overtraining. I believe Iām in the sympathetic stage
Neither did he.
How did you determine that you are overtrained? For how long have you now cut out intensity and volume?
Long term reduction in performance ability not due to other obvious factors (e.g., illness).
IOW, feeling tired or unmotivated, or even performing poorly for a few days, is not overtraining.
Elevated resting heart rate, sleeplessness, irritability, etc., are also not overtraining, but may (or may not) accompany a reduction in performance.
