I can sympathize with TrojanHorse and the others that have missed time on the bike from injury.
After having been off the bike for almost 8 weeks my endurance and power is down while the required effort and heart rate is jacked up like a meth head that just scored.
I've done a couple rides which I used to be able to easily do in under two hours at an endurance HR now takes me 2hr 10, or more(!) at the high end of a tempo HR. and they are FLAT rides of 47'/mi gain. Sheeesh!
A 3.6 mile segment takes me 1 min 20 seconds longer to do with the same avg HR values.
The one mile long 2.8% hill repeat I used to do... add another 45 seconds to that effort with the same HR.
This truly sucks.