Quadruple-Digit Post Count
Another vote for the New Alpinism, just keep it in context.The author clearly doesn't understand base endurance training at all.
@RichJ is correct, it takes a minimum of 30 minutes in the correct heart rate zone just to get the adaptation started, that's just to get it started, after that you are actually training your heart for base endurance and growing the needed mitochondria in the muscle fibers.
Push the heart rate too fast, as the author suggests and the left ventricle doesn't fill up with enough blood to get the stretching needed for it to adapt.
YES, walking is vastly underrated. People should be able to crank out four miles in one hour and not feel trashed at the end before they start even thinking of running/jogging.
There is a pretty big penalty for bigger people, but big guys can run, @aciampa is a perfect example, they just burn more calories doing it and efficiency/form becomes much more important. Al showed me this, I can walk for hours non stop, even with a 40 pound pack. But the instant I started running, boom heart rate went through the roof. Nothing I did changed it. Al gave one small suggestion and now I can run at a easy breathing pace no problem. Just in the last two weeks I've done two 90 minute runs and easily could of kept going.
If you do an hour run and feel wasted afterwards, you either pushed too hard, have bad form or your base endurance sucks or all of the above.
@Steve Freides is correct, race times are not relevant to training, in fact they are hugely detrimental. No racer runs at his or her training pace on race day. At least, they shouldn't be.
Don't focus on distance, don't focus on how fast you go, get your heart rate in the correct zone and stick to it. Walking, rucking or running, it doesn't matter. Training base endurance is the least specific of all. But if you want to be a better runner, you are going to have to practice it.
Training for the New Alpinism is excellent reading.
Moreover to your point about me, Ive had all the injury/pain nonsense related to running over the years and still no cartilage in my knees. Today, I run basically pain free at 235lbs.