Joe Henderson wrote a treatise in 1969 promoting the promise of running long and slow and for long distances. Go slow to get fast was the idea. That's Joe, above, from his website where you can find his treatise--complete with a revised Introduction--all in one place.
Wikipedia summarizes the theory thusly:
Long slow distance (LSD) is a form of aerobic endurance training in running and cycling. Physiological adaptations to LSD training include improved cardiovascular function, improved thermoregulatory function, improved mitochondrial energy production, increased oxidative capacity of skeletal muscle, and increased utilization of fat for fuel. Ernst van Aaken (1910–1984), a German physician, is generally recognized as the founder of the long slow distance method of endurance training.
The theory certainly has its detractors, but I like the notion of fewer injuries and focusing on the enjoyment of one's sport rather than the pain-for-gain approaches. I'm not saying it's for everyone and certainly not claiming any proficiency about training, but I do assert it is an attractive approach.
One of the runners that Joe writes about is Tom Osler, about whom I posted here a while back. As with Tom, I was turned onto to Joe Henderson by Ian Jackson, but again, that is a story for another day.
Given that I'm of a certain age, I also enjoy the context of Joe's writing. It was a time of change, rethinking, and shatterings of the status quo. It's refreshing to me to capture that sense of all thing's possible again. Not that Joe gets into that, more that if you went through any of that time you can catch a whiff of it. Those times were certainly a counterpoint to today's days of retraction.
Joe, like Tom, writes about endurance running, but all is applicable to endurance cycling, at least I think that's true.
I'm also just now getting into this book that came out in 2007 titled Base Building for Cyclists: A New Foundation for Endurance and Performance by Thomas Chapple. He also argues that if you build your anaerobic system up by going hard all the time, you do so at the expense of your aerobic system. This is too bad, he says, because you can build and build and build your aerobic capacity over years. And once you do that, you train your body to burn fat, so that when you really need to burn carbs for anaerobic performance you've got some available to burn.
Or at least that's how I'm getting it. My response is to go even slower instead of striving harder. At least for now as I work to build that base. Again, remember I am a neophyte when it comes to all this training stuff, so use your own judgment.
Keep it challenging, but slow, man, slow,