I've been trying to pay closer attention to my HR data lately, and notice that after a good long 40 or 50 miles, at a solid effort (not lazy, not all out, very steady) my HR data is kinda all over the place. Granted, I'm riding over some pretty hilly terrain with lots of up and down's, but...wouldn't the most effective way to ride be to lock onto an ideal HR and try to keep it there?
....Or is it more effective to 'push' up a hill and recover after it? (vs taking the hill easy, and working the downhill at the same effort)
I've noticed that when I ride shorter/harder, the data is obviously more uniform and my HR does not deviate from 170's during such time periods. I can post some screenshots if what I'm takling about isn't clear.