Phil Maffetone was an endurance sports coach who made his name by developing a training philosophy that was characterized by an extreme overemphasis on the importance of fat metabolism. He taught his athletes to do virtually all of their training at a very low intensity to maximize fat metabolism and stimulate physiological adaptations that increased the body's capacity for fat oxidation in subsequent workouts. Over time, Maffetone believed, the athlete would be able to swim, bike or run faster and faster at the same, low, fat-burning intensity. (I'm using the past tense not because Maffetone has passed on, but rather because he seems to have reinvented himself as a musician.)
There are a numerous problems with the Maffetone Method. The fact that the body's ability to increase its fat burning capacity is far more limited than Maffetone believed is the smallest of them. A much greater problem is that it's impossible to maximize performance in standard endurance sports events such as half-marathons and Olympic-distance triathlons without doing a fair amount of training at high intensities. Threshold workouts, VO2max intervals and even all-out sprints produce valuable fitness benefits that complement those resulting from slow and steady workouts, which simply cannot replicate these complementary benefits on their own.
Having said this much, I have very recently come to a place where I appreciate the value of exercising at a very low intensity
specifically, of running at a very slow pacemore than I did before. I did not come to this place voluntarily. My body seems to have been seriously disrupted by my recent relocation and return to outside-the-home work for the first time in seven years. I've been running very poorly ever since my return to San Diego. For a while I tried to get through it with the right mixture or patience and pushing, but recently I decided to try another tactic. I cut out all of the threshold runs, interval workouts, and even moderate-intensity base runs that were causing me such misery and replaced them with what I generally consider to be recovery runs, in which I run as slow as necessary to feel comfortable, even if my pace is utterly embarrasing to my ego.
I have found that, by essentially embracing necessity in this way, I am indeed able to "feel good" once again when running, and one should feel good when running most of the time, even when training very hard. I'm also able to spend just as much time running as before, and I've even begun to take advantage of the gentleness of my training by going longer than I had been planning to do before I took evasive action. Yesterday I did my first two-hour run in a while.
My rationale for taking this approach has little to do with fat metabolism and everything to do with the nervous and immune systems. I saw my poor running as a symptom that my body was under stress. I changed my training in a way that heeded my body's message to me yet without sacrificing my desire to maintain (or regain) a high level of fitness. I certainly have not yet reaped benefits that will allow me to once again run faster and comfortably, but I think I'm on my way. In any case, I'm now planning to continue running very slowly longer than is strictly necessary, as a little experiment to see how far the Maffetone Method can take me.