If you’ve been sidelined for a while with injury or illness, subtract another 5.
If you’ve been sidelined a long time (like recovering from a heart attack), subtract 10.
If you’ve been training at least four times a week for two years, add 0.
If you’ve trained hard for two years and are progressing in competition, add 5.
In my case, it works like this:
I’m fifty years old, so 180 – 50 = 130.
I run regularly and haven’t been injured, putting me in category C: no additional points.
So: My fat-burning threshold is 130 heartbeats per minute.
That means I can work out as long, as fast, and as strenuously as I please, but whenever my heart rate hits 130 and my wrist alarm starts beeping, I have to ease off until my pulse drops back below the threshold. Maffetone believes your body is content to burn fat as long as it’s not being pushed into oxygen debt. When you need more air, your heart begins to hammer; when your heart is pounding fast, it demands fast-burn fuel. So to wean yourself off sugar, you have to change both supply and demand: you cut the sugar from your diet and keep your pulse within your fat-burning zone.
Maffetone hit on the formula because of a happy accident. Heart rates “can be as low as 30 to 40 in those with great aerobic function to as high as 220 or higher in young athletes during all-out efforts,” Maffetone explained. Using those numbers as his range, he originally put clients through extensive physiological tests to determine precisely when their metabolism kicked over from fat to sugar. After a few years of playing with the numbers, he realized he could just subtract their age from 180 and get the same results as if he’d done the testing. Why the math works, Maffetone can’t say. It just does.
“One-eighty minus age itself is not a meaningful number,” he explained. “It is not associated with VO2 max, lactate threshold, or other traditional measurements.” It’s just a shortcut to the end number: your maximum aerobic heart rate. Maffetone was delighted, because the magic equation allowed him to stop being the middleman between the athletes and their bodies. Maffetone believes the more you understand your own internal signals and stop listening to other people—even to him—the healthier you’ll be. That was the beauty of the 180; it was so simple, anyone willing to invest fifty bucks in a heart-rate monitor could be their own sports-science lab.
Maffetone has tested it on hundreds of athletes, including triathlon legends like Mike Pigg and Mark Allen, and they’ve consistently come back with the same results: they recover faster from workouts, blow past their old records in competition, and leave chronic injuries behind. One reason they rarely get hurt is that they’re no longer gritting through fatigue. When you go into oxygen debt, your form crumbles. Your head drops, your feet thump, your knees go cockeyed. You get sloppy, and you pay for it. “It was obvious that training at various intensities affected both posture and gait,” Maffetone explained. “The more anaerobic, the more distortion of the body’s mechanics.”
“But if you’re always going slow,” I’d asked, “how do you ever get fast?”
“You work your way up a few heartbeats at a time.”
You adapt. The more workouts you do in the fat-burning zone, the easier they get; the easier they get, the faster you can go. Maffetone predicted my workouts would feel ridiculously slow for the first few weeks. If you’re used to running eight minutes a mile, he said, you might have to throttle back to ten and walk the hills to stop your heart-rate alarm from beeping. But you’ll become so good at running ten-minute miles, he promised, you’ll eventually be able to trot up any hill without breaking the 130-beat barrier. Before long, I should be able to run faster—and farther—than ever without hitting my heart-rate threshold or running low on fuel.
“Oh, and another thing,” Maffetone added. “Don’t be surprised if you feel a little bit, um … awful.” When your body is denied its sugar supply, it can get grouchy.
Ugh. I saw what he meant about four minutes into the first run. Fatigue kept washing in and out like waves; I’d be clipping along easily, then suddenly feel like I coming down with the flu. It would pass after a few minutes of woozy walking, only to come roaring back shortly after I started running again. It was the eeriest sensation, like being yanked back and forth by a tug-of-war inside my own digestive system.
WE NEED SUGAR!
Shut your pie-hole, we’re fine. Onward.
Maffetone had warned me to expect this, though, so I trudged on home and braced for a rough few days ahead.
Instead, I was greeted on the next morning’s run by a pleasant surprise: instead of head spins, I got beeping. My heart-rate monitor began to chirp while I was a few hundred yards up an easy climb, and it dawned on me that I hadn’t gotten dizzy yet. The storm had passed; it was as if my body had given up the fight and surrendered the secret fuel stash it was hoarding. Now my challenge was keeping the damn wrist alarm quiet. Every time I got into a groove and started to leg it out a little—beep beep beep. Hills were the worst. I tried taking long, deep belly-breaths in hopes of Zen-mastering my pulse down a few blips, but it didn’t help much. I spent that whole day—and the next, and the next—creaking along like a cyclist in granny gear.
At least Dutch skaters were going through the same thing. Back in the early ’90s, the Dutch national speed skating team also began experimenting with low heart-rate training. It was a valiant quest, because as much as the Dutch love their skating, they were still up against ever more daunting powerhouses like the United States, Norway, and Canada. But despite the stiffening competition, the Dutch eased back; they replaced hard workouts with easier ones. In the seventies, 80 percent of their workouts were high-intensity; that total dwindled to 50 percent in 1992 and just 30 percent by 2010. It wasn’t as if they were putting in more ice time, either. “We first hypothesized that the total amount of training hours would have been increased over the years. Our analyses showed that this was not the case,” a research team concluded in 2014, after analyzing thirty-eight years of Dutch training logs. “Surprisingly, there was no increase in net training hours,” the researchers added, “while performance increased considerably.”
Considerably. Now that’s a gentle way to put it. The Dutch destroyed. At the 2014 Winter Olympics, Dutch skaters crushed the field so relentlessly, on-air commentators complained it was bad for the sport. Together, Dutch men and women came home with twenty-three of thirty-six possible medals. Never in the history of the Games has one nation won so many gold medals in a single event. “The domination of their speed skating athletes has been total, with traditional rivals such as the USA, Canada and Norway utterly humiliated,” the British Guardian summed it up.
The Dutch secret was as old as the Games themselves. The key to going fast, the Greeks believed, was a long time going slow. They called it “fatigue work,” and until an ancient Greek athlete was twenty years old, he did little else. Fatigue work was raw, Rocky IV–style stuff: hiking mountains, carrying a heavy rock up and down a hill, climbing a rope slung over a tree branch, and the Ecplethrisma—running back and forth across the hundred-foot plethron, taking one step less every lap until you reached zero. The godfather of fatigue work, of course, was Milo of Croton; he came up with the idea of hoisting a newborn calf over his shoulders and carrying it around the stadium every day, gradually getting stronger as the heifer got bigger.
On the last day of my 2-Week Test, I tried a Milo of Croton experiment of my own. It was time to tally the results of my Maffetone immersion, which for me really boiled down to one question: was fat-as-fuel for real? Was it easy, sustainable, and effective? If by now I couldn’t do more on less food—and find that food easily and eat it on the fly—then Maffetone’s approach didn’t explain how Paddy and Xan and their Cretan brothers-in-arms got stronger as life got harder.