The MAF method: the 180 formula, MAF tests and who it suits

The MAF method is the most stubborn idea in easy running: pick one heart rate, never go above it on your aerobic runs, and accept that you'll be overtaken by walkers for a while. Some runners swear by it. Others try it for a week, get humbled by a hill, and quit.

It's neither magic nor nonsense. The MAF method is a specific system created by Phil Maffetone, built around a single heart rate ceiling calculated with his "180 formula" and checked with a monthly MAF test. This post explains exactly how both work, using Maffetone's own published description, what the evidence does and doesn't show, and who MAF method running actually suits. If you lift as well as run, the same logic about keeping easy runs easy applies, and it's baked into an app for runners who don't want to quit the gym.

What is the MAF method?

MAF stands for maximum aerobic function. Maffetone and exercise scientist Paul Laursen describe it as a clinical approach Maffetone began developing in 1977, aimed at personalizing training around fat oxidation without needing lab tests (Maffetone and Laursen, 2020). Its best-known part is the MAF heart rate: a personal training heart rate meant to sit at a low-to-moderate intensity associated with maximal fat oxidation.

In practice, MAF method running means doing your aerobic training at or below that one heart rate, and tracking whether you get faster at it over time. It's a way of building an aerobic base with one number instead of five zones.

Two notes before the formula:

• ›MAF isn't based on a percentage of your max heart rate. The authors say plainly that 180 minus age isn't a meaningful number in itself, only a step toward the final MAF heart rate. If you want percentage-based zones instead, a heart rate zone calculator does that job.
• ›The full MAF program covers more than running. Maffetone's paper also discusses diet (with an emphasis on lower carbohydrate intake) and life stress. This post sticks to the training part.

The 180 formula, step by step

Here's the 180 formula as Maffetone and Laursen lay it out in their paper, paraphrased:

1. ›Start with 180 minus your age.
2. ›Adjust it by picking the one category that fits you best:
   • ›Subtract 10 if you have or are recovering from a major illness or operation, are in rehabilitation, take regular medication, or are chronically overtrained.
   • ›Subtract 5 if you're injured, have stopped improving in training or racing, get frequent colds or infections, have allergies or asthma, are acutely overtraining, or are new to exercise, returning to it, or training inconsistently.
   • ›No change if you've trained consistently (at least four times a week) for up to two years without any of the issues above.
   • ›Add 5 if you've trained for more than two years without those issues and have been improving in both MAF tests and competition.
3. ›That number is the top of your range. The bottom is 10 beats lower. You can train anywhere inside it.

The paper's own example: a 40-year-old in the "subtract 5" category gets a training range of 125–135 beats per minute.

If any of the medical categories apply to you, talk to a doctor before choosing a training heart rate. Medications in particular can change how your heart rate responds to exercise.

How the MAF heart rate compares with heart rate zones

Here's where it gets interesting. Because MAF isn't built on max heart rate, it doesn't map neatly onto percentage zones. A rough comparison, using the age-based max heart rate estimate of 208 − 0.7 × age from Tanaka, Monahan and Seals (2001) and the "no change" MAF category:

That's just arithmetic, and both numbers are estimates, so your own picture could differ by a lot. But it shows something useful: for people whose real max is close to the formula, the MAF ceiling often sits above a classic zone 2 and into the steady middle band. Train at the bottom of the MAF range and you're closer to zone 2; train at the ceiling and you may be in the territory covered by our guide to zone 3 training. The "subtract" categories pull it lower.

Age formulas cut both ways here. They're population averages, which is why running heart rate zones by age are a rough tool for any individual. MAF has the same weakness: two 40-year-olds with very different fitness and max heart rates get the same starting number.

The MAF test

The second half of the method is the MAF test, which Maffetone and Laursen describe as a monthly check of your pace (or power) at your MAF heart rate (Maffetone and Laursen, 2020).

How to run one, following their description:

1. ›Warm up easily.
2. ›Use the same place every time: the same track, flat route, or treadmill.
3. ›Run a fixed distance at your MAF heart rate and record your time. The paper's example is one runner's monthly results on a flat 5 km road course.
4. ›Repeat monthly and compare.

What you hope to see is faster splits at the same heart rate over months. The paper notes that altitude and temperature affect results, so test in similar conditions.

What the evidence says (and doesn't)

This is where honesty matters more than enthusiasm.

• ›The method comes from clinical practice, not trials. The 2020 paper describes decades of Maffetone's clinical work and reports uncontrolled observations, such as runners improving race times after months of training at their MAF heart rate. Those are observations without a comparison group.
• ›The authors say it still needs testing. Their own abstract states that the relationship between training at this heart rate and lab measures of fat oxidation, health outcomes and athletic performance must be verified scientifically (Maffetone and Laursen, 2020). They also write that neither the 180 nor the 220 formula replaces lab testing.
• ›We couldn't find a controlled trial of the 180 formula itself in Europe PMC. That doesn't mean the method doesn't work; it means the evidence is practice-based.
• ›The fat-oxidation idea is plausible but individual. Fat oxidation does peak at moderate intensities: in one lab study of trained cyclists, it peaked at about 74% of max heart rate on average (Achten, Gleeson and Jeukendrup, 2002). But the MAF paper itself notes that the intensity of peak fat oxidation varies enormously between people. And burning more fat during a run isn't the same as losing body fat; that's the whole debate behind is zone 2 fat burning.

What is well supported is the broader principle MAF enforces: most of an endurance athlete's training should be easy. Well-trained endurance athletes do about 80% of their sessions at low intensity (Seiler, 2010). MAF is one blunt, practical way of making yourself do that.

MAF method running: how to actually do it

• ›Expect to slow down. A lot, at first. Hills may mean walking. That's the method working, not failing. It's the same experience people have with zone 2 running, and the same advice applies: slow down, walk the climbs, give it months.
• ›Use a chest strap if you can. Wrist sensors can be jumpy, and a single ceiling is unforgiving of bad readings.
• ›Cross-check with effort. If you're at your MAF heart rate and gasping, something is off: the formula, the sensor, or the conditions. Effort-based training is a good second opinion; easy aerobic running should feel like RPE 3–4 and allow full sentences.
• ›Respect heat and drift. On hot days, the same heart rate means a slower pace. Long runs drift upward too, which is why any fixed number for marathon runners heart rate is only a rough guide.
• ›Decide what to do with hard sessions. Maffetone's published example is a runner who trained aerobic-only for a full year. Most mainstream plans keep one or two harder sessions a week alongside slow aerobic miles. Choose one approach on purpose rather than mixing them by accident.

Who the MAF method suits

Good fit:

• ›Runners who turn every run into a medium-hard run and need a hard ceiling to break the habit.
• ›Beginners and returning runners who want a simple rule.
• ›Base-building phases, especially before a long race.
• ›People who like data and enjoy watching one number improve month to month.

Less ideal:

• ›Runners whose real max heart rate is far from average, in either direction. A one-size formula will be off.
• ›People training for short, fast races who need regular high-intensity work.
• ›Anyone taking medication that affects heart rate, or with a heart condition. Get advice from a professional first.
• ›Hybrid athletes who measure easy days by feel anyway; RPE may do the same job with less fuss.

How exrsz approaches easy running

exrsz builds a periodized plan from your goal, schedule, level and equipment, with clearly easy aerobic runs as the base and harder sessions placed where they won't collide with your lifting. It balances running and lifting in one plan, adapts each week to how you actually trained, and reshuffles missed sessions so easy days stay easy.

FAQ

What is the MAF method?

The MAF method is Phil Maffetone's training approach built around a personal aerobic heart rate ceiling, calculated with his 180 formula and checked with a monthly MAF test (Maffetone and Laursen, 2020). Aerobic training is done at or below that heart rate.

How do I calculate my MAF heart rate?

Subtract your age from 180, then subtract 10, subtract 5, leave it, or add 5 depending on your health and training history. The result is the top of your range; the bottom is 10 beats lower.

What is a MAF test?

A MAF test is a regular time trial, usually monthly, where you run a set distance on the same course at your MAF heart rate and record your pace. Improving pace at the same heart rate is the sign of progress.

Is the MAF method backed by research?

Partly. Its creators describe it as clinically developed and say its links to fat oxidation, health and performance still need to be verified scientifically (Maffetone and Laursen, 2020). The underlying principle of doing most training easy is well supported (Seiler, 2010).

Is MAF heart rate the same as zone 2?

Not exactly. MAF isn't based on max heart rate, and for many people its ceiling lands above a percent-of-max zone 2, around zone 3. The bottom of the MAF range is often closer to zone 2.