Issues with HR on PDR
I'm now on week 8 of the intermediate program, on the last day of week 7 and the first day of week 8 I wasn't able to get my heart rate up to 100% which would have been 197bpm, I was only able to get it up to 193. However, last week I was able to get it up the first two sessions, any idea why I wasn't able to reach it? My legs were feeling pretty sore after the second last session, maybe I'm not getting enough recovery or enough sleep? It just seemed like I didn't have the energy reserve to push to 197, I was running outside in a flat field and wasn't able to do it. I ran outside the last times when I reached it.
Any ideas or suggestions would be greatly appreciated.