Woke up early this morning, my legs feel pretty good after yesterday evening's efforts which I'm pleased about. Thought you might be interested to see this morning's heart rate variability trace taken over a 10 minute period, the first 5 minutes recumbent and the second 5 minutes standing. The plot shows the R-R intervals of my heartbeat, or the gap between successive heart beats. The ideal position is for there to be a lot of R-R variation in both the standing and lying readings. You can see here that there is good variation whilst I am standing and much less variation when I am lying down, an indicator of fatigue or hard training, amongst many other things!
So, looking at this, today is a day for no really hard training or even a rest day but I plan a gentle potter around the lanes of Northumberland for a couple of hours. I'll try to repeat the measurements later on today to illustrate though how quickly these appearances can change, the whole thing seems to me to be very dynamic but does serve as a guide, amongst other markers of fatigue, to overreaching and possible overtraining.