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This Training Method Is Meant to Help You Slow Down on Easy Runs

Everything to know about the MAF method and letting heart rate guide your runs.

Runners often turn to time or distance, pace or feel to guide their workouts. But to get more precise about intensity, heart rate training offers an objective view of how hard you’re working and can help you get the most out of each step. 

One way to tune into heart rate: the Maffetone method, a.k.a. MAF method. It’s a strategy based on maintaining a low heart rate for most of your runs, with the goal of revving your fat-burning engine and help you avoid injury, illness, and overtraining.

“I’ve coached hundreds of runners through MAF, and for some, it’s been a complete game changer; for others it’s just been massively frustrating,” says Amanda Brooks, Denver-based running coach and founder of Run to the Finish. 

So what is the MAF method exactly, and is it for you? Let’s break it down.

The Idea Behind the MAF Method

This training strategy was created by Phil Maffetone, an applied kinesiologist, following decades of his clinical research about heart rate training. It can be called the Maffetone method or simply MAF—which is (obviously) short for his name but which also stands for maximum aerobic function. 

“The thesis behind the MAF method is that low heart rate training will allow runners to build endurance while reducing their injury risk and avoiding fatigue,” explains Laura Norris, owner and coach at Laura Norris Running in Boulder, Colorado. “This low heart rate zone is where the body oxidizes a higher ratio of fat than carbohydrates for energy production.” 

In other words, MAF keeps you in what’s considered the “fat-burning zone”—though it’s a misconception that running this way always equals fat loss, says Brooks. The benefit is more so that you train your body to run off of fat as fuel, which doesn’t burn as quickly as carbohydrates, so you can run longer.

To take advantage of the MAF method, you need a device to actually track your heart rate, whether that’s a smartwatch or chest strap (research suggests the latter is more accurate in some cases). 

How the MAF Method Works

The MAF method is based on a very straightforward formula: Take 180 (a number Maffetone came up with based on his research) and subtract your age. The resulting number is your max heart rate in beats per minute (bpm), which you should stay under for most runs. 

So, if you’re 40 years old, your heart rate shouldn’t go north of 140 bpm for nearly all your miles. In other words, it ensures that most of your running is easy running, which is the principle that most coaches recommend whether you’re following MAF or not.

But the plan does take a few other factors into account: 

If you’re recovering from a major illness or injury, subtract 10 beats

If you’re not improving in your training or are just coming back to training, or if you get a cold or the flu at least twice a year, subtract 5

If you’ve been training for at least two years without any injury, add 5

If you’re over 65, add up to 10 

If you’re under 16, use 165 bpm for your max

Does sticking under one number for your heart rate for most runs feel too strict though? For some people, it is, says Brooks. “Like most heart-rate running formulas, it doesn’t work for everyone,” she says.

On the other hand, the formula’s simplicity is what makes it so accessible for a wide audience. “It helps give people a guideline for figuring out what easy running should feel like,” Brooks adds. 

Contrary to popular belief, MAF doesn’t mean every single run should be done at a low heart rate. “Many people don’t realize that once you’ve been doing it for a while to build your base or return to running, you are absolutely supposed to start adding back in speed work,” says Brooks. “Then it really turns into a more traditional 80/20 program, but the easy days are defined by your MAF heart rate.”

Benefits of Using the MAF Method

“Where MAF can shine is for runners who have consistent issues with injuries or coming back from illness—it gives them a more specific way to guide training and often prevent running slightly too hard all the time,” says Brooks.

In research that Maffetone conducted, 76 percent of runners who used the method leading up to a 5K improved their race time and only 9.5 percent got an injury, compared with nearly 62 percent of runners who got injured when they maintained their normal training schedule instead of MAF. 

The MAF method is beneficial because of its emphasis on easy running, which should make up the bulk of any running routine. “Whether you call it low heart rate training, zone 2 training, or easy running, there are numerous benefits to runs below one’s aerobic threshold,” says Norris. 

For example, because running at a low heart rate spares glycogen (in favor of fat burning), you can often keep running longer at this intensity and with less fatigue afterward. “Plus, easy running places less stress on the musculoskeletal system, so you can run more mileage while controlling your injury risk,” Norris adds.

Drawbacks of Using the MAF Method

The formula for MAF is simple, which makes it very easy to use, but it can also be limiting. “Some individuals are outliers—they will have higher or lower heart rate zones than generic formulas predict,” says Norris. 

New runners and those over 40 often find it tricky to keep their heart rate low enough. Plus, adds Norris, factors other than age can affect heart rate. “Caffeine consumption, anxiety, hydration status, iron levels, and other variables will all alter your heart rate during exercise,” she says. “You may still be in an aerobic zone, but your heart rate may become decoupled from your oxygen consumption [your aerobic zone] due to caffeine ingestion or dehydration.”

Furthermore, using MAF does require wearing a heart rate monitor so you can keep an eye on your exact number throughout your runs. “Some runners get highly stressed out watching their heart rate,” says Brooks. 

Being that focused on specific numbers isn’t always necessary to achieve results. Runners who trained guided by rate of perceived exertion (RPE) showed similar improvements over six weeks of training, as those who ran guided by their heart rate in a study published in the Journal of Strength and Conditioning Research in 2017.

The Bottom Line on the MAF Method for Runners

MAF can be an approachable training technique to help ensure you’re not pushing too hard on what should be easy runs (that is, the majority of your mileage). But like any running plan, it takes some adjustments and isn’t ideal for everyone. 

“Whenever trying out a new training method, it’s important to assess whether you enjoy running any more or less with this approach,” says Norris. “If you don’t enjoy heart rate training, MAF is not for you.”

(10/05/2024) Views: 280 ⚡AMP
by Runner’s World