Today I got out in my new Newton shoes for a little over 5 miles of rolling hills coupled with a nice easy pace. I'm trying to build endurance, so I'm not out to break any records and my pace states that loud and clear. My average per mile was at about 8:00 minutes throughout the run give or take a few seconds during uphills and downhills.
So I've read how to build endurance and everyone seems to have the same frame of mind in thinking that to build endurance, you need to put in the miles. Those miles should not be at your threshold. The opposite holds true too. You shouldn't walk or jog too slow (depending on your current level of endurance) because the gains you get won't be as beneficial as picking up the pace for a consistent amount of time throughout your workout.
I guess the moral of the building endurance story is to get out of bed and figure out a way to push just hard enough to get your heart rate pumping in the zone that will give you the most endurance gains. You increase your lungs functional capacity as the size and number of your blood vessels actually increase. That is pretty cool. That brings up your respiratory rate, lung capacity, and the size and strength of your heart increases so you can go longer before hitting the wall. Okay, and last bit of fact: You keep metabolizing carbs and fats which is good too.
Distance: 5.11 miles
Time: 41:01 minutes
Pace: 8:02 per mile
Average Heart Rate: 139 BPM