How to Run a Maximal Aerobic Speed (MAS) Test: A Field Protocol for Setting Real Interval Speeds

A coach plugs a runner's most recent 5K time into an online VO2max calculator, and out comes a tidy number. From that number comes a whole week of interval paces: 400m repeats at one speed, 1000m repeats at another. Two sessions later the 400s feel like a jog and the 1000s are turning into survival efforts by rep four. The formula didn't fail because the arithmetic was wrong. It failed because it was never measuring aerobic speed to begin with — it was extrapolating from a race performance that blends pacing strategy, weather, terrain, and how the runner happened to feel that particular Saturday. Maximal Aerobic Speed, usually shortened to MAS (or called vVO2max in some of the exercise physiology literature), is the slowest running speed at which oxygen uptake plateaus at its maximum. It's a physiological marker, and the only honest way to find it is to make someone run at genuinely rising speeds until they can't hold the pace anymore.

You don't need a treadmill, a mask, or a gas analyzer to do that. A track, a set of cones, and an audio pacing signal get you there. The protocol below covers setup, scoring, two studies behind the method and its limits, and — the part most field tests skip — exactly how to turn the resulting number into interval speeds that match what each rep is actually supposed to train.

Why a VO2max Formula Isn't the Same as a Real Pace

MAS is the point where running faster stops raising oxygen consumption and just accumulates fatigue faster. Billat and Koralsztein (1996), reviewing the concept in Sports Medicine, reported a detail that matters directly for how interval sessions get built around it: time to exhaustion at 100% of MAS averages roughly six minutes across the studies they surveyed, but individual values ranged from about two minutes to well over ten — even among athletes with near-identical MAS scores. Two runners can share an MAS of 16 km/h and have completely different tolerance for holding it: one folds at three minutes, the other grinds out eight. A race-time formula has no way to see that variability, because it never measures the runner's actual ceiling — it measures how fast they covered a different distance on a different day, then reverse-engineers a guess. A field MAS test measures the ceiling directly, which is the only way to know whether a prescribed interval speed sits at 85% of true capacity or 105% of it.

Equipment and Track Setup

The test needs an accurately measured loop, distance markers close enough together to catch pace drift early, and a way to signal the required pace without the athlete watching a stopwatch mid-run.

An unverified track is the single most common source of bad MAS data. A loop that's actually 385m instead of 400m makes every stage speed read roughly 4% fast, and that error compounds forward into every interval pace calculated from the result. Measure the loop before test day, not the morning of.

Step-by-Step MAS Field Test Protocol

1. Warm-up (10 minutes): Easy jog, dynamic mobility, two build-up strides, then one practice pass through a single marker interval so the athlete recognizes the audio cue before the clock starts.
2. Mark the loop: Place a cone or tape mark every 20m around the 400m loop — 20 markers per lap.
3. Pick a starting speed: 8 km/h for a detrained or general-fitness adult, 10 km/h for a regularly training runner, 12 km/h for a competitive endurance or team-sport athlete. Starting too high burns through stages and costs you resolution on the final number; starting too low just costs a few painless early minutes.
4. Set the pacing cue: Each 20m split should take 72 ÷ V seconds, where V is the stage speed in km/h. At a 12 km/h starting stage, that's 72 ÷ 12 = 6.0 seconds between beeps. At 15 km/h, it's 4.8 seconds.
5. Run 60-second stages: Speed increases by 0.5 km/h every 60 seconds. The athlete must be at or ahead of the cone each time the beep sounds.
6. End criteria: Stop the test when the athlete falls more than one marker behind the pacing signal on two consecutive markers, or reaches volitional exhaustion.
7. Cool-down: 5-10 minutes of easy jogging or walking.

Every stage is short and the increment is small — 0.5 km/h rather than a full km/h — on purpose. Coarser increments give a cleaner-looking test but a blunter number; a finer 0.5 km/h resolution matters once that MAS figure gets divided into training zones, since a 1 km/h rounding error at the top can shift a 100%-MAS interval pace by 15-20 seconds per kilometer.

Scoring: From Last Completed Stage to MAS

MAS is credited as the speed of the last fully completed 60-second stage. Some coaches stop there for simplicity. Others add a partial-stage credit: 0.5 km/h multiplied by the fraction of the next stage's required distance the athlete actually covered before dropping off pace.

Worked example: an athlete completes every marker through the 14.5 km/h stage, then starts the 15.0 km/h stage. That stage requires covering 250m in 60 seconds (15 km/h × 1000m ÷ 3600s × 60s = 250m), but the athlete falls two markers behind at the 150m mark. Fraction completed is 150 ÷ 250 = 0.6. MAS = 14.5 + (0.5 × 0.6) = 14.8 km/h. Skipping the partial credit and simply recording 14.5 km/h is also defensible — what matters is picking one method and staying consistent, since switching scoring approaches between a baseline test and a retest manufactures an apparent change in fitness that's really just a change in arithmetic.

What the Research Actually Shows

Léger and Boucher (1980), publishing in the Canadian Journal of Applied Sport Sciences, built the original version of this style of test — the Université de Montréal Track Test — using continuous 2-minute stages that rose by 1 km/h, paced by an audio signal at markers around a track. Comparing the speed reached at exhaustion against directly measured treadmill VO2max in the same subjects, they reported a correlation of r = 0.96, tight enough that the field speed alone predicted lab-measured aerobic power about as well as a second lab visit would have. The limitation the authors flagged still applies: the endpoint is volitional, meaning the test ends when the athlete decides they can't hold the pace any longer, so motivation, pacing experience, and how much an athlete wants to impress the person holding the stopwatch all add variance a fixed-protocol treadmill test doesn't have to deal with.

Berthon and Fellmann (2002), reviewing maximal aerobic velocity testing methods in the Journal of Sports Medicine and Physical Fitness, found something anyone comparing results across different published protocols needs to reckon with: MAS isn't a fixed number independent of how it's measured. Testing protocols that varied stage duration (roughly one to three minutes) and increment size produced MAS values that shifted by close to a full km/h depending on which protocol generated them, with shorter stages and smaller increments generally yielding slightly higher figures than longer, coarser ones. Their proposed fix was a simplified, standardized protocol rather than a claim that one number is the single correct one — the practical takeaway is that a season-over-season MAS comparison only holds if the stage duration and increment stay identical from test to retest.

Typical MAS Ranges by Athlete Population

These bands are drawn from the range of values reported across field-testing literature and applied sport-science practice. Treat them as a rough starting classification, not a cutoff — protocol differences of the kind Berthon and Fellmann documented mean a value from one lab or program isn't perfectly interchangeable with a value from another.

Turning MAS Into Interval Training Speeds

This is the actual point of running the test: once MAS is known, every interval speed in a program can be set as a percentage of it instead of a guess. The table below uses an MAS of 16 km/h as a working example.

The 100-120% band is where the Billat and Koralsztein (1996) variability matters most in practice. Two athletes with the same 16 km/h MAS won't necessarily tolerate the same rep duration at 105% of it — one may hold six reps of 30 seconds cleanly while another falls apart by rep four. Use the percentage to set the speed, then adjust rep count and recovery individually based on how the session actually goes, rather than assuming a fixed prescription will land the same for every athlete who shares a test result.

Mistakes That Skew the Test

Retesting, Conditions, and Where the Field Test Falls Short

Retest every 6-8 weeks rather than weekly. A change of 0.5 km/h between two tests run three days apart is far more likely to be day-to-day noise — hydration, sleep, wind, how motivated the athlete felt that morning — than a real shift in aerobic capacity, and chasing that noise means adjusting a training program based on measurement error rather than actual adaptation.

The field test also has a real ceiling on precision that a lab test with gas-exchange analysis doesn't share. It can't distinguish a genuinely lower physiological capacity from an athlete who simply didn't push through the last stage, and a volitional endpoint means two testers running the same athlete on the same day can get slightly different numbers depending on how firmly they enforce the two-markers-behind cutoff. For most training purposes that trade-off is a reasonable one: what a coach actually needs is a real running speed to build a session around, not an oxygen-consumption figure that has to be converted back into a pace anyway. Used consistently, with the same loop, the same increment, and the same tester calling the same cutoff, the field MAS test gives that speed directly — and gives it without a treadmill, a mask, or a lab appointment.