Is MAS the same as VO₂max?

No. VO₂max is a volume of oxygen per minute per kilo of body weight. MAS is the running speed at which you reach it. Two runners with the same VO₂max can have different MAS, because one of them uses less oxygen to run at a given speed.

Is MAS the same as VMA?

Yes. VMA is the French abbreviation of vitesse maximale aérobie, the same quantity as MAS. Some sources also write vVO₂max or velocity at VO₂max.

Why does my MAS change from one test to another?

Each test is an estimate of the same number, and each has its own error. A beep test reads MAS in half-km/h steps and includes turns, a VAMEVAL is run on a track without turns, and a Cooper run depends on pacing. Compare results from the same test only.

How often should I retest my MAS?

Every six to eight weeks during a training block, in the same conditions. Training paces set from an old MAS drift too slow or too fast once fitness changes.

What is MAS (maximal aerobic speed)?

The definition

Run faster and your body takes in more oxygen. At some speed it stops taking in more. That plateau is VO₂max, and the lowest speed that gets you there is your MAS.

So MAS is a speed, not a volume. A runner with a MAS of 15 km/h is running at 4 min per kilometre when they reach their aerobic ceiling.

How you measure it

A lab finds MAS with a gas analyser on a treadmill. On a field, you run a graded test and read the speed of the last stage you completed.

Test	Start	Increase	What you read
Beep test	8.0 km/h	about 0.5 km/h per level	speed of your last level
VAMEVAL	8 km/h	0.5 km/h per minute	speed of your last stage

For the beep test, level 5 is 10.5 km/h, level 8 is 12.0, level 10 is 13.0 and level 12 is 14.0. The beep test calculator does the conversion for any level and shuttle. The VAMEVAL calculator does the same for the track test.

Both tests give an estimate. A different test gives a slightly different MAS for the same runner, so keep to one.

What it is used for

Setting paces. Most running programmes prescribe sessions as a share of MAS. A runner with a MAS of 14 km/h who is told to run at 90 % runs 12.6 km/h, which is 4 min 46 s per kilometre. At 80 % it is 11.2 km/h, or 5 min 21 s. The pace calculator works these out for any MAS.

Following progress. A MAS that goes up by 0.5 km/h across a block is a clear sign the work is paying off, provided the test conditions were the same.

Comparing athletes. In a squad, MAS puts runners of different sizes on one scale of speed.

What MAS does not tell you

A race time. Running economy and the fraction of MAS you can hold for the distance both matter. Two runners with the same MAS can finish a 10 km minutes apart.
Sprint ability or repeated-effort ability. For team sports that run short intervals, a test with recovery periods such as the 30-15 IFT gives a speed that fits short intervals better. The difference is covered in VIFT vs MAS.
VO₂max itself. You can estimate VO₂max from a beep test level with a published equation, see the formula and table, but the estimate carries the usual error of an estimate.

A worked example

A player stops at level 10 of the beep test. Their MAS is 13.0 km/h, which is 4 min 37 s per kilometre. Their training paces:

Share of MAS	Speed	Pace per km
100 %	13.0 km/h	4 min 37 s
90 %	11.7 km/h	5 min 08 s
80 %	10.4 km/h	5 min 46 s

Four weeks later they reach level 11, 13.5 km/h. The same 90 % now means 12.15 km/h. The paces move with the test, which is why a retest is part of the plan.

Common mistakes

Reading the first missed level as MAS. MAS is the speed of the last level completed, not the one you failed.
Applying percentages of a VIFT to a MAS. They are different scales. Keep each with its own test.
Using a MAS from an old test. After six to eight weeks of training it is out of date.
Mixing tests. A beep test MAS and a VAMEVAL MAS are not interchangeable to a tenth of a km/h.