I use heart rate variability as a recovery/overload indicator.
I have used it for a few years with great success. It gives a window into my nervous system and tells me if I am recovered enough or indeed if I went hard enough in a session. For instance when I am doing blocks of SS training I measure my HRV the next morning, if it drops significantly after day 1 I went too hard and it wasn’t SS. Normally it remains stable for 2-3 days then drops on the 4th, indicating the block should end.
Anyway, in the past I have seen a low number, and feeling fine thought, ah I’ll train anyway, this has come back to bite me almost every time.
It can give me signs that I have an infection brewing (steadily increasing sympathetic drive) 2-3 days before systems so can stop me over-doing it.
This is a case when the body is telling me something (albeit via a measuring system) but my mind sometimes overides it to tell me I’m fine.
Incidentally HRV is far more sensitive than resting heart rate etc. and in my opinion is of far more use and every athlete should be measuring it if they can (easy with a garmin ant stick).
There is also interesting evidence that when VO2max interval workload is prescribed based on HRV that the results were improved despite a lower training load.How are you processing your results? I spent a few months recording data, extracting the HRV with Kubios, graphing the results. I struggled to see any correlation between work/rest and the Kubios results. If anything it highlighted to me that morning RHR seemed to most accurately reflect previous effort.