doug in co wrote:
If your RPE and self-evaluation is reliable, you don't need HRV. But most of us can't reliably evaluate our stress levels and ability to absorb training. I started with HRV after getting old and becoming unable to do that anymore, found myself repeatedly overreaching and needing weeks to recover. My secret is I'm tired all the time ;-) and the HRV helps me not to overload.
I agree with the above.
Just these past 8 days, I belatedly found I had a very low-grade virus. Felt really low-energy for 2-3 days despite it being a pullback week, and for the 1st 2 days I was thinking "WTF?" as I know I typically feel really good on pullback weeks after 2 days. I did have a brief cough for a morning, but I didn't even consider it to be significant at the time.
But my HRV continued to not improve during those 2-3 days, and even went down a little on the 2nd day despite me doing very low exercise. On the 3rd day, I decided to just pull the plug and rest, and by then it was very clear that I was under a bug since there was no possible other explanation for my dragginess (good sleep hrs, low to no training).
Started feeling better very quickly, and in the ensuing days, HRV has gone back up to almost-normal. It may not be a perfect metric, but it's something I'm definitely paying attention to now as an additional data point - I'll start to really consider life stressors, illness, or other things, and if my general feeling of malaise and HRV are suggesting I take it easy - I'm not going to gut out the workouts like I've typically done in the past. (Prolonging illness when you do that.)