Phil Maffetone

Phil Maffetone is nothing if not consistent. In 1995, I copyedited his book Training for Endurance, a pro bono task I was given by my boss at Multisport magazine, the late Bill Katovsky, who was a close friend of Phil’s. At that time, I was just beginning to ease back into running after a seven-year layoff, and the book inspired me to give heart rate training a try for the first time. The other thing I remember about the experience is Phil getting miffed at me because I misspelled his full first name on the cover page, inserting an extra “L” in Philip!

Anyway, my point is that Phil was then teaching the same phillosophy—sorry, philosophy—of endurance training he is today. Same maximal aerobic function (MAF) concept, same 180 – age formula, same emphasis on avoiding overstressing the body. What has changed is the context in which Phil teaches his method. I’m thinking of one change in particular, which is the popularization of the 80/20 endurance training method that is practiced by most elite endurance athletes and that I myself promote through this website and the books: 80/20 Running and 80/20 Triathlon.

The vast majority of nonelite endurance athletes spend way too much time training at moderate intensity. Both the Maffetone and 80/20 methods take direct aim at this error, requiring athletes who adopt them to slow down to one degree or another. An unfortunate consequence of this overlap is that the two methods have been lumped together in the public consciousness, regarded as all but interchangeable. I’ve even encountered athletes who mix and match the two, for example by using Phil’s zones with an 80/20 plan.

In fact, though, there are important differences between the Maffetone and 80/20 methods, beginning with their origins. The Maffetone Method, as its very name indicates, is the invention of one man. It did not exist, and was not practiced, anywhere on earth until Phil created it and began to teach it to athletes. Like many popular diets, this method was arrived at via a process of nonempirical inference grounded in mechanistic physiological reductionism. With diets, this process typically goes something like this: “Because carbohydrates have biochemical effect A on the body, and fats have biochemical effect B, and proteins have biochemical effect C, the optimal human diet must therefore comprise X percent carbohydrate, Y percent fat, and Z percent protein.” When applied to endurance training, the same approach looks like more this: “Because low-intensity exercise has biochemical effect A on the human body, and moderate-intensity exercise has biochemical effect B, and high-intensity exercise has biochemical effect C, the optimal endurance training program must therefore comprise X percent low intensity, Y percent moderate intensity, and Z percent high intensity.”

This is essentially the type of argument Phil Maffetone uses to persuade athletes that they should completely avoid what he calls anaerobic training until they have fully conditioned their aerobic system through low-intensity training and are almost ready to race. In an article appearing on his website, Phil cites three specific physiological mechanisms that support this argument:

  • Anaerobic activity can lower the number of aerobic muscle fibers, sometimes significantly.
  • Lactic acid, produced during anaerobic work, may inhibit aerobic muscle enzymes necessary for aerobic function.
  • Anaerobic training increases the respiratory quotient (a measure of fat- and sugar-burning) indicating the body is burning less fat.

What is lacking from this argument is any concrete evidence that training exclusively at low intensity for a long period of time before adding in a bit of work at higher intensities for a few weeks yields better competitive results than other training methods. It’s a classic example of a biological plausibility story standing in the place of complete science. This doesn’t mean the Maffetone Method isn’t effective; there’s plenty of anecdotal evidence that athletes who transition to it from the moderate-intensity rut yields good results. Personally, though, I need more than an intriguing hypothesis and a bunch of testimonials to entrust my own fitness to a training system, diet, or other method that promises to make me better.

The funny thing is, if you want to know which method of balancing of low, moderate, and high intensities is optimal for building endurance fitness, you don’t really need a physiologically grounded hypothesis. Heck, you don’t even need to know that lactic acid exists! All you have to do is look at what actually happens when athletes train with various intensity distributions.

Which brings us to the origin of the 80/20 method. Unlike the Maffetone Method, 80/20 wasn’t invented by anyone. Instead it evolved through a decades-long process of collective trial and error, in which elite endurance athletes tried different methods and retained those that proved more effective while discarding those that proved less effective. By the time exercise physiologist Stephen Seiler observed in the early 2000s that elite endurance athletes across disciplines and geographical boundaries adhered to an 80/20 intensity balance, these athletes had already been doing so for quite a while, and without having the foggiest idea why it worked. In fact, although controlled experiments have since demonstrated that an 80/20 intensity balance is optimal as well for mere mortals like you and me, we still lack a complete physiological explanation for its effectiveness. And that’s fine by me. I’d much rather know what works, but not why, than know why something might work but not whether it actually does.

Ironically, the original version of the 80/20 method, loosely speaking, was the training system developed by Arthur Lydiard in the 1950s. Like the Maffetone Method, Lydiard’s system entailed training exclusively at low intensity for an extended period of time before transitioning to phases featuring workouts at higher intensities. A big improvement on the interval-focused programs that had dominated the sport previously, it revolutionized endurance training, lifting elite performance standards to a whole new level. Over time, however, other coaches found ways to improve the method, most especially by allowing athletes to perform modest amounts of moderate- and high-intensity exercise throughout the entire training cycle—in other words, by further evolving the Lydiard/Maffetone approach into the 80/20 approach—and in so doing lifted elite performance standards higher still

The bottom line is that the Maffetone and 80/20 methods are similar but not the same. The table below summarizes the key differences.

Maffetone 80/20
Is there a place for moderate- and high-intensity training? Only in the last few weeks before competition. Yes! Up to 20% of training is done at these intensities throughout the training cycle
How is low intensity defined? Through a one-size-fits-all heart rate formula of 180 – age Through validated field or lab tests aimed at pinpointing an individual athlete’s current ventilatory threshold
How is training intensity monitored? Heart rate Take your pick: Heart rate, pace, power, perceived effort




A few years ago, New York Times writer Gretchen Reynolds penned an interesting article titled “Running as the Thinking Person’s Sport.” It focused on a then-recent study by neuroscientists at the University of Arizona in which it was shown that high-level distance runners had significantly higher levels of connectivity in certain parts of the brain compared to nonrunners.

In interpreting these findings, Reynolds wrote that “running seems to be a kind of mobile math puzzle,” an idea that the study’s lead author, Gene Alexander, expanded upon, saying, “It requires complex navigational skills plus an ability to plan, monitor and respond to the environment, juggle memories of past runs and current conditions, and also continue with all of the sequential motor activities of running, which are, themselves, very complicated.”

If it’s true that, as this study indicates, running makes people smarter, then it must also be true that smarter people make better runners. There is no consensus definition of “intelligence” among scientists, but I like the one proposed by David Krakauer, an evolutionary biologist and president of the Santa Fe Institute, who has said, “Intelligence is making hard problems easy.” The reason this way of looking at the phenomenon appeals to me is that it’s inclusive and pragmatic. It recognizes that intelligence is not some global aptitude that one either has or doesn’t have but is rather a diverse collection of mental skills, which different people have in different degrees. No person is capable of making all types of hard problems easy, and very few people are incapable of making at least one type of hard problem easy.

Top athletes are among those who count as highly intelligent by Krakauer’s definition. As he explained in a 2015 interview for Nautilus, “Something that we’d find tremendously difficult—skiing downhill at a very high velocity or getting a small ball into a basket or getting a ball over a net at over 70 miles an hour, things that we struggle with . . . they make look effortless. And that’s not really that different from a mathematician effortlessly solving a theorem, or a musician remembering a symphony. The difference [exists in] the part of the brain that stores the relevant information, and for some reason when we’re talking about the motor system, it’s not intelligence. I think part of the reason for that is because it’s not exclusively human, because marine mammals make swimming look effortless. Birds make flying look effortless—we can’t do that. And surely that can’t be intelligence because we can’t do it.”

Krakauer continues, “If you reduce the theory to intelligence to, on the one hand, this notion of efficient solutions to hard problems, and simultaneously think about it in terms of the energy and resources that neurons require to solve the problem, then in fact, the motor system is arguably more intelligent than the frontal cortex.”

Long before I met David Krakauer at the 2015 Goldlab Symposium and learned about his take on intelligence, I had already become convinced that certain types of intelligence are vital to success in endurance sports. Pacing is arguably the defining mental skill in endurance racing. It is not easy to get from the start line to the finish line of a 10K or a marathon in the least time possible. While physical fitness determines the highest velocity you can sustain over a given distance on a given course on a given day, this number is fundamentally unknowable. Discovering it as you go is the job of your brain, and it is a job that most athletes suck at. Effective pacing requires intentional practice, but it’s also a matter of natural aptitude, as is the case with all mental skills. My advice to athletes is that you exploit the advantage of natural pacing ability if you have it and that you take pacing skill development more seriously than most athletes do regardless of your innate aptitude.

Pacing is one form of self-regulation. Another form of self-regulation that impacts endurance performance is restraint. All athletes understand the value of hard work, and a majority of serious racers are willing to work hard, but in my experience, relatively few of those who are willing to work hard have the restraint to consistently resist working hard when doing so is unwise. Forcing it in workouts where the target splits are out of reach, sticking to the training plan instead of dialing back in the face of excessive fatigue, grinding out the last mile of a 20-miler despite red-flag pain in your knee—such behaviors are the norm among competitive runners, not the exception.

As the saying goes, “It’s easy to train hard, but hard to train smart.” Hard trainers are a dime a dozen, but where smart training is concerned, the bar is low. This state of affairs represents a golden opportunity to gain an advantage over other athletes by taking pride in exercising restraint throughout the training process. It can be hard at first, but if you persist in the effort it can become your special thing. Instead of rushing to reclaim a Strava segment from a local rival who makes a point of taking it from you, laugh privately and take your revenge in the next race.

A third form of intelligence that aids the athlete is the ability to learn and adapt through trial and error. Athletes who are smart in this way pay attention to cause and effect in their training, figure out what works for them and what doesn’t, and adjust accordingly. I can think of a number of noteworthy examples of athletes whose training evolved over the course of their careers and who performed better because of the changes they made. One example is the legendary triathlete Mark Allen, who overcame a propensity toward injury early in his career by swapping his favored low-volume, high-intensity training approach for a high-volume, low-intensity approach under the guidance of coach Phil Maffetone.


In summary, if you’re smart, take full advantage of this gift in your training and racing. And if you’re not so smart (and let’s face it, most of us aren’t so smart), emulate those who are and you’ll at least have an advantage over other not-so-smart runners who make no effort to get smarter.

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