You’ve held the same easy-run heart rate for three years. Your pace at that heart rate has barely moved. Maybe the number is the problem, not your training.
Phil Maffetone’s 180-minus-age formula, also called the MAF Method, has set the easy-pace ceiling for endurance athletes since the 1980s. Subtract your age from 180. Adjust for injury history. That’s your aerobic ceiling. It’s simple. It’s memorable. For athletes over 45 who’ve trained hard for years, it’s often too conservative.
Here’s what the research shows. The principle behind MAF has strong science behind it. Most training should happen at a genuinely easy heart rate. The formula itself is different. It’s never been validated against a real measured threshold in a controlled study. That gap widens exactly when it matters most: as you get older and fitter at the same time.
Where the 180-Minus-Age (MAF) Formula Actually Came From
Maffetone built the formula in the 1980s. Wearables didn’t exist yet. Lactate and gas-exchange testing lived only in a lab. Subtract your age from 180, then adjust for your training and health history.
Most articles paraphrase the adjustments loosely, something like “+5 if fit, -5 if not.” Maffetone’s actual published criteria are more specific.
| Adjustment | Who it applies to |
|---|---|
| Subtract 10 | Recovering from major illness, any operation/hospital stay, on regular medication, or Stage 3 (chronic) overtraining |
| Subtract 5 | Injury, regression or no improvement, more than 2 colds/flu per year, seasonal allergies or asthma, overfat, Stage 1-2 overtraining, or inconsistent/new to training |
| No change | Training consistently 4x/week for up to 2 years, with none of the above |
| Add 5 | 2+ years of consistent training, documented MAF Test progress, competitive improvement, and no injuries |
| Age 65+ | Formula “may need further individualizing”; up to 10 bpm may be added back |
| Under 16 | Formula doesn’t apply; fixed ceiling of 165 bpm used instead |
Source: Phil Maffetone, “The MAF 180 Formula,” philmaffetone.com
In short: most athletes land in “no change” or “-5.” Very few genuinely qualify for +5.
The Real Reason Age-Only Formulas Miss the Threshold
Here’s the finding that explains everything else. A treadmill study split 971 men and 301 women into three groups. The groups were low, medium, and high training status. Heart rate at VT1 climbed steadily with fitness. VT1 is the first ventilatory threshold. It’s the point where breathing shifts and steady effort gets harder to hold. In men, VT1 sat at 133 bpm at low fitness. It rose to 143 at medium fitness and 150 at high (Benitez-Munoz et al., 2024). Max heart rate itself? Statistically no different across the three groups.
Translation: getting fitter raises your aerobic ceiling a lot. It barely touches your max heart rate at all.
Think of it like a car. Max heart rate is the redline stamped on the tachometer. It doesn’t move no matter how you tune the engine. Threshold is your cruising speed. It’s the pace the engine can hold all day without straining. A tuned engine cruises faster without ever touching the redline. An age-only formula is built entirely off the redline. It has no way to see the cruising speed move.
That’s also why age-only formulas struggle individually. 220-minus-age, the formula behind 180-minus-age, was never derived from a controlled study (Robergs & Landwehr, 2002). It carries a standard error of 7 to 12 bpm. Tanaka’s version is 208 minus 0.7 times age. It’s more rigorous but still carries about 10 bpm of individual error (Tanaka et al., 2001). A field test of 180 marathon runners checked both formulas. Both missed real measured max heart rate by up to 4.9 bpm on average. Age alone explained only about a quarter of the difference between people (Nikolaidis et al., 2018).
Lactate threshold (LT1) and VT1 measure almost the same point. In 22 trained runners, the two showed 90% agreement (Cerezuela-Espejo et al., 2018). That’s why the same threshold shows up under different names, depending on which test you run.
Age explains a sliver of your ceiling.
Training status explains the rest.
180-Minus-Age at 25, 35, 45, 55, and 65: The Worked Comparison Table
Here’s the raw formula, Maffetone’s adjustments, and published threshold data, side by side.
| Age | 180-age raw ceiling | Adjusted range (-10 to +5) | Tanaka-predicted HRmax | Est. threshold, high fitness | Est. threshold, low fitness |
|---|---|---|---|---|---|
| 25 | 155 bpm | 145-160 bpm | 191 bpm | 154 bpm | 161 bpm |
| 35 | 145 bpm | 135-150 bpm | 184 bpm | 148 bpm | 155 bpm |
| 45 | 135 bpm | 125-140 bpm | 177 bpm | 142 bpm | 150 bpm |
| 55 | 125 bpm | 115-130 bpm | 170 bpm | 137 bpm | 144 bpm |
| 65 | 115 bpm | 105-120 bpm* | 163 bpm | 131 bpm | 138 bpm |
*Maffetone notes the formula may need individualizing past 65, with up to 10 bpm added back.
This is a synthesis of published formulas and study-reported percentages. It’s not a lab measurement of any real person. Individual scatter runs 7 to 12 bpm even in validated formulas. Treat any single number here as a starting estimate, not a diagnosis.
The story it tells is clear. At 25, the raw formula sits within about 1 bpm of a trained runner’s real threshold. That’s a genuine match. By 45, the gap opens to about 7 bpm. By 55, it’s roughly 12. By 65, it’s about 16 bpm.
The formula doesn’t get less accurate randomly. It gets less accurate in one direction: low. And it gets there fastest for the athletes who trained hardest.
Untrained athletes land differently. A 65-year-old who hasn’t trained sits closer to 138 bpm, the low-fitness column. The -5 or -10 adjustment most beginners qualify for pulls the formula toward a safe start, not a permanent limit.
What the MAF Method Gets Right
None of this means MAF is a bad idea. The principle underneath it has strong research behind it. Spend most of your training at a heart rate you could hold a conversation at. That’s true even where the exact bpm number isn’t.
Stephen Seiler studied elite cyclists, rowers, runners, and cross-country skiers. He found they converge on roughly 80% low-intensity and 20% high-intensity training. That held regardless of sport or coach (Seiler & Kjerland, 2006). A later controlled trial tested this directly. Athletes who trained in that low-intensity-heavy, polarized pattern gained more fitness. They beat athletes training mostly at threshold or mostly at high volume with no intensity spread (Stoggl & Sperlich, 2014). More on that split in polarized vs. pyramidal training.
Run easy on your easy days. MAF was right about that before it became mainstream sports science. The same logic underpins Zone 2 training today, covered in depth here.
Where MAF and Zone 2 part ways is precision. Zone 2 is defined by a measured or estimated threshold that moves with your fitness. MAF is defined by a formula that doesn’t move once you’ve picked your adjustment.
The MAF Test Has Never Been Peer-Reviewed
Here’s the honest gap. Search for a controlled, peer-reviewed study of the MAF Test itself. That’s the practice of retesting your pace at a fixed heart rate every few weeks. You won’t find one. None exists.
Maffetone and Laursen published a 2020 paper framing MAF as clinically useful (Maffetone & Laursen, 2020). It’s the closest thing to a peer-reviewed citation MAF supporters have. But it’s a narrative paper, not a validation study. No sample size, no bpm error data, no lactate comparison against the formula’s predictions.
That doesn’t mean the MAF Test is useless. Pace-at-fixed-heart-rate is a legitimate way to track aerobic fitness. But the specific claims are different. The claim that a +5 bpm ceiling captures your real progress comes from Maffetone’s own case series. It’s not independent research. One coaching site puts the formula’s population-level hit rate at 85 to 90 percent. It also admits no individual can know if they’re a hit or a miss.
Take a runner I’ll call Dave, 52, training for a fall marathon. He’d held 128 bpm, 180 minus 52 with no adjustment, for two years. His easy pace hadn’t moved. A field test put his real aerobic threshold near 141 bpm. That’s in line with the high-fitness estimate for his age. He’d been training 13 beats below his real ceiling. He was walking hills to stay under a number that never measured him specifically. Six weeks at the corrected ceiling changed that. His easy pace picked up 20 seconds per mile at the same effort.
How to Find Your Real Aerobic Ceiling
180-minus-age is a fine place to start with zero test data. The same logic applies to 220-minus-age as a starting max heart rate estimate. That’s before you’ve run a real max-effort test. It’s a poor place to stay once you have years of consistent training behind you. That’s especially true past 45. The gap between the formula and your real threshold only grows from there.
The better path is to measure it. A field test, a lab test, or enough training history all beat a fixed subtraction. If you’re not sure your “easy” days are actually easy, that grey-zone drift is worth checking before you trust any ceiling.
AthleteOS sets your Zone 2 ceiling from your measured or estimated LT1. It doesn’t use a fixed age subtraction. Open your training plan. You’ll see, in bpm, exactly how far your 180-minus-age number sits from your real aerobic threshold. Watch that ceiling move as your training status changes. It won’t drift further off as you get older.
Heart rate doesn’t lie about effort.
It just needs the right ceiling to measure against.