MAS in Running: How to Understand, Test, and Improve Your Maximal Aerobic Speed

If you've spent any time looking into running performance, you've likely come across the term MAS (Maximal Aerobic Speed) — sometimes called VO2max pace or, if you've read French running literature, VMA (Vitesse Maximale Aerobie). Whatever name you use, it refers to the same thing: the fastest pace you can sustain while your body is still primarily fuelled by oxygen.

MAS is the single most useful benchmark for structuring your training. It determines your interval paces, predicts race times, and gives you a clear target to improve. Yet many runners either don't know their MAS or don't understand how to use it properly.

This guide breaks it all down — what MAS is, how to test it accurately, and the specific workouts that will push it higher.

1) What Exactly Is MAS?

Maximal Aerobic Speed is the running speed at which your oxygen consumption hits its ceiling — your VO2max. Beyond this speed, your body can't take in any more oxygen and starts relying heavily on anaerobic energy systems, which produce fatigue rapidly.

In practical terms, MAS is the pace you can hold for roughly 4 to 8 minutes at an all-out effort. It's not a sprint — it's a controlled, intense effort where you're right at the edge of what your aerobic system can deliver.

MAS vs. VO2max — What's the Difference?

• VO2max is a physiological measurement: the maximum volume of oxygen your body can use, expressed in ml/kg/min. It's typically measured in a lab with a gas exchange mask.
• MAS is the speed you run at when you reach that VO2max, expressed in km/h (or min/km pace). It's the field-friendly version of VO2max.

Here's the key insight: two runners can have the same VO2max but different MAS values. The runner with better running economy — a more efficient stride, less wasted energy — will run faster at the same oxygen consumption. That's why MAS matters more than VO2max for practical training purposes.

Typical MAS Values

2) Why MAS Matters for Every Runner

MAS is your aerobic engine. It directly determines all of your training and racing paces:

• 5K: raced at roughly 90–100% of MAS
• 10K: raced at 85–95% of MAS
• Half marathon: raced at 80–88% of MAS
• Marathon: raced at 75–85% of MAS
• Easy/base runs: run at 60–75% of MAS

The higher your MAS, the faster all your paces become at the same relative effort. A runner with an MAS of 18 km/h doing a marathon at 80% is running 14.4 km/h (4:10/km). A runner with an MAS of 14 km/h at the same 80% effort runs 11.2 km/h (5:21/km).

Improving your MAS raises the ceiling on everything.

3) How to Test Your MAS

There are several reliable protocols, ranging from simple to highly controlled. The most important thing is to pick one method and stick with it so you can track progress over time.

The Cooper Test (12 Minutes)

The most widely known field test:

• Run as far as you can in 12 minutes on flat terrain (a track is ideal).
• MAS ≈ distance (in metres) / 200

Example: 3,000 m in 12 min = MAS of approximately 15 km/h

Pros: Simple, no equipment needed. Cons: Pacing is critical — starting too fast will give you a lower result. Doesn't directly measure VO2max.

The 6-Minute Time Trial

A shorter variant:

• Run as far as you can in 6 minutes.
• MAS ≈ distance (in metres) / 100

Example: 1,600 m in 6 min = MAS of approximately 16 km/h

Shorter duration makes it easier to manage mentally, but demands a hard effort from the start.

The Vameval Test (Incremental Beep Test)

The gold-standard protocol used widely in France and increasingly around the world:

• Run on a track with markers every 20 metres.
• Follow audio beeps that get progressively faster (speed increases by 0.5 km/h every minute).
• Start at 8 km/h.
• Your MAS is the last complete stage you finish.

Pros: Progressive pacing removes the guesswork, very reliable, great for group testing. Cons: Requires audio recording and track markings.

The Leger-Boucher Shuttle Test (20m)

Similar to the Vameval but run as 20-metre shuttles (back and forth):

• Audio beeps that accelerate over time.
• Run between two cones, reaching each one before the beep.

Popular in schools and sports clubs. The direction changes make it slightly underestimate MAS for distance runners.

Estimating MAS from Race Results

If you have a recent 10K time, you can estimate your MAS:

Rule of thumb: MAS ≈ average 10K speed x 1.10 to 1.15

This is an approximation, but it's useful when you can't do a proper field test.

4) Training Zones Based on MAS

Once you know your MAS, you can dial in all your training paces:

The vast majority of your training should sit in Z1–Z2 (70 to 80% of total volume), with targeted sessions in Z4–Z5 to drive improvement.

5) Key Workouts to Improve Your MAS

Improving MAS requires interval training at intensities near or above 100% of MAS. The principle: push your aerobic system to its maximum, but with recovery periods that allow you to repeat the effort.

Short MAS Intervals (200–400 m)

High-intensity intervals with short recovery:

• 30/30s: 30 seconds at 100–105% MAS / 30 seconds easy jog recovery. 2–3 sets of 8–12 reps.
• 200 m repeats: 200 m at 100–105% MAS / 200 m jog recovery. 10–15 reps.
• 300 m repeats: 300 m at 100% MAS / 100 m walk/jog recovery. 8–12 reps.

When: Year-round. Excellent for building VO2max without excessive fatigue or injury risk.

Long MAS Intervals (800–1,200 m)

Longer, more demanding efforts that maximise time spent at VO2max:

• 1,000 m repeats: 1,000 m at 95–100% MAS / 2–3 min jog recovery. 4–6 reps.
• 800 m repeats: 800 m at 100% MAS / 90 sec–2 min recovery. 5–8 reps.
• 1,200 m repeats: 1,200 m at 95% MAS / 3 min recovery. 3–5 reps.

When: During specific preparation phases, once or twice a week maximum.

Fartlek-Style MAS Work

For those who prefer to leave the track:

• Pick visual landmarks (lamp posts, trees, junctions).
• Alternate 1–3 min at MAS effort with 1–2 min easy jog recovery.
• 20–30 min of fartlek total.

Fartlek adds variety and also trains your ability to handle irregular pace changes — a useful skill for racing.

Hill Repeats

Hills are a powerful tool for MAS development with reduced impact stress:

• Find a hill of 100–200 m at 5–8% gradient.
• Run up at MAS effort (your speed will be slower, but the cardiac demand is the same).
• Jog/walk back down for recovery.
• 8–12 reps.

Strength training is an excellent complement to hill work, building the muscular power that supports high-intensity running.

6) Sample 6-Week MAS Development Programme

Here's an example plan for a regular runner (MAS ~15 km/h, 4 sessions/week):

Every interval session starts with a 15–20 min easy run warm-up and ends with a 10 min cool-down.

Key Principles

1. No more than 2 MAS sessions per week — the rest should be easy running
2. Build gradually: increase reps first, then interval duration
3. Listen to your body: if you can't hold pace on the final reps, reduce the volume
4. Be consistent: 6–8 weeks of regular work to see measurable gains

7) MAS-Based Race Time Predictions

Your MAS gives you a solid estimate of potential race times:

These estimates assume appropriate distance-specific training. MAS alone isn't enough — endurance, fatigue resistance, and running economy all play a major role, especially over the half marathon and marathon.

8) Common Mistakes

Running Intervals Too Fast

The classic trap: blasting the first few reps at 110–120% MAS, then falling apart. The result? You spend less total time at VO2max, and the session is actually less effective than running at a steady, correct pace.

Neglecting Easy Running

MAS improves in part thanks to volume at easy pace. Your mitochondria — the powerhouses of your muscle cells — develop primarily during Z2 runs. A runner who only does interval work will plateau quickly.

Testing Too Often

An MAS test is a maximal effort that requires proper recovery. Test yourself 2–3 times per year at most — at the start of a training cycle and after a block of specific work.

Ignoring Accumulated Fatigue

If you stack intense weeks without a recovery week, chronic fatigue will mask your real progress. Schedule a recovery week (volume reduced by 30–40%) every 3–4 weeks.

9) FAQ

How fit do I need to be to start MAS training?

As soon as you're running consistently (3+ times per week) for at least 2–3 months. Beginners can start with gentle 30/30 sessions — even at 10–12 km/h, interval work delivers real benefits.

Does MAS decline with age?

Yes, VO2max drops by roughly 5–10% per decade after age 30–35. But regular interval training significantly slows this decline. Runners in their 50s and 60s who train consistently often maintain a higher MAS than sedentary people in their 30s. For more on this, read our guide to running after 50.

Can I do MAS intervals on a treadmill?

Absolutely. The advantage is that the pace is set for you — no guesswork. The downside: the belt moves under your feet, so there's less propulsion demand. Set 1% incline to simulate outdoor air resistance. And watch your hydration — treadmill running generates more heat.

What's the difference between MAS and threshold pace?

Threshold pace (lactate threshold / VT2) sits at roughly 80–88% of MAS. It's the pace you can hold for 40–60 minutes. MAS is above that — sustainable for 4–8 minutes maximum. Both should be trained as complementary elements.

Conclusion

MAS is the most practical performance benchmark in distance running. Knowing yours lets you set precise training paces across every session. Improving it — through well-dosed interval work built on a solid foundation of easy running — is the most direct path to getting faster at every distance.

Three principles to remember: test it regularly, train it with structure (no more than 2 hard sessions per week), and never neglect the aerobic base that supports it.

Further Reading

• Fundamental Endurance: The Complete Guide
• Understanding Mitochondria: Your Running Powerhouses
• Strength Training Basics for Runners
• Running After 50: How to Adapt Your Training