A note on using HRV apps - I probably should have done this already.
There are a number of good sites on the web that explain what HRV is and how to use it for training. If you are interested in the technical details, they are pretty easy to find. Be careful though. If you're a gearhead like me, you can fall in. Alan Couzens, James Heathers, and some other have some pretty good technical information out there but the websites for the apps will get you started. The general idea behind the apps is that HRV (heart rate variability) can be used as an indicator of how ready you are to train. By measuring the distance between heartbeats (the variability), you can tell if your body is rested or not. Be extension, you can determine whether or not you are ready for hard training or need a rest day. This is the idea: https://www.alancouzens.com/blog/overtraining_HRV.html Generally speaking higher HRVs over time are better indications of aerobic fitness than lower HRVs. But everyone has a range, which among other things, is also related to age. As