For background: I am 55. Have been using Trainerroad for 2 years. Road Cycling for 12 years. So far 80k km. Last year 10k km. My FTP raised from 230 to 251 using trainerroad over the last year.
After long or very stressing events (> 200km or > 4000 altitude) when I try to ride the bike the next day I feel short of breath and my heartrate which usually easily rises to 140-150 stays in the low 110-120 even though it feels hard.
Is this a usual sign of training fatigue or something severe I should look into. I do not think that I encountered this in my younger years when training. Maybe some sign of age?