This is what my HRV looked like when I started to feel sick and resumed training too soon.
As I understand it, HRV - Heart Rate Variability allegedly measures the spacing in beats. More variability means your body is chillin' and relaxed; less variability means something is physically stressing you, like sickness, lack of sleep, etc.
At the end of Aug, I was starting to feel under the weather so I cut back on training and spent some time resting. Eager to not lose momentum, I headed out on a 40 mile bike ride as soon as my HRV was almost back to normal and pushed it right back down again.
Lesson learned: err on the side of giving yourself too much time to recover. Hope you found it interesting!
I used to always think that way until I realized that it's even better to be patient and not have to deal with prolonged recovery from starting back up too soon. I'll take better gains from properly waiting until I'm fully recovered every time