Originally Posted by
banerjek
A lot of people plan their effort so they use up their stuff in the time available. There's no need to lollygag just because you're out for awhile, nor are you prohibited from sprinting -- even if I'm out all day, max HR will top 170. Besides, if you're spending the vast majority of the time climbing mountains on a bicycle or skis, it's not like you're going to be taking it that easy.
Fine, but if you use up all your 'stuff' in a 5 hr ride you'll be drained not wired. And if you use a power meter you can pick any metric (NP, IF) that measures intensity and it will be significantly lower for a 5 hr ride vs a shorter high intensity ride. I equate vigorous with high intensity and that's not possible for 5 hrs.