MAS Plateau: Why You're Stuck and How to Get Faster Again

You do your interval sessions every week, you follow the plan to the letter, but your latest test shows the same MAS as six months ago. Worse: you sometimes feel less sharp than last year on your 30/30s. Welcome to the MAS plateau — an almost universal phase for any runner who has already digested those first years of rapid progression.

The good news is that stagnation is almost never a genetic ceiling. In 9 cases out of 10, the plateau comes from an imbalance in training, not a physiological limit. Here are the 7 most common causes — and the concrete levers to get moving upward again.

1) You always do the same MAS session

That's trap number one. You found a session that "works" (10×400 m for example), you pull it out every week, and after 8 to 12 weeks your body is no longer stimulated. The aerobic system progresses through adaptation to a new constraint — when the constraint becomes routine, the adaptation stops.

How to break out

• Vary the interval duration over a 4 to 6 week cycle: alternate short MAS (200–400 m), medium MAS (500–800 m) and long MAS (1000–1500 m).
• Vary the format: pyramids (200-400-600-800-600-400-200), progressive-pace sessions, 3–5 min blocks.
• Vary the environment: track, flat road, fartlek on trail, short hill repeats.

The principle: your body needs to constantly wonder "what's being done to me here?". It's that controlled disorientation that forces adaptation.

2) You run your intervals too fast (or too slow)

Many plateaued runners make one of these two mistakes:

• Too fast: they start at 105–110% of MAS on the first reps, collapse afterwards, and end up spending little total time in the useful zone.
• Too slow: they stay at 90–95% out of comfort, without really stressing VO2max.

The effective window is narrow: 95 to 102% of MAS for the bulk of the volume.

How to break out

• Calibrate with your watch: if your MAS is 16 km/h, your 100% MAS pace is 3:45/km. Over 400 m, that's 1:30. Not 1:25 (too fast), not 1:35 (too slow).
• First rep = exact target pace, not faster.
• If you can't hold the pace on the last 2 reps, you started too fast.

Also read the complete MAS guide to fully understand pace zones.

3) You neglect your aerobic base

This is the most underrated lever for plateaued runners. VO2max — and therefore MAS — depends largely on two peripheral factors:

• Mitochondrial density in your muscle fibres.
• Capillarisation (the number of small vessels feeding the muscle).

Both adaptations develop primarily during long easy runs — not during intervals. That's why a runner doing 4 quality sessions a week without easy volume eventually hits the ceiling: they no longer have the cellular infrastructure to absorb and use the oxygen they're pumping at MAS.

How to break out

• Aim for 70 to 80% of your weekly volume at easy aerobic pace (60–75% of MAS, comfortable conversation).
• Add one long slow run per week, 1h15 to 2h depending on your goal.
• To better understand the cellular mechanics behind this work, read understanding mitochondria.

4) You stack weeks with no recovery

The myth of linear progression does a lot of damage. You tell yourself: "if I push one more all-out week, I'll progress faster". Wrong. Progression happens during recovery, not during effort. If you never let your body supercompensate, you accumulate chronic fatigue — which mimics a MAS plateau, or even regression.

How to break out

• Apply a 3+1 structure: 3 weeks of increasing load, 1 deload week (-30 to -40% volume, -50% intensity).
• If you've strung together 6+ weeks without an easy week, take 10 days in "reserve" mode before launching a new block.
• Watch the overload signals: degraded sleep, high resting HR, dropping motivation, interval paces falling apart.

Many runners "unlock" 1 km/h of MAS after a simple forced recovery week — the MAS was there all along, masked by fatigue.

5) You neglect strength work

MAS isn't just a matter of heart and lungs. At MAS pace, each stride applies 2 to 3 times your body weight to the ground. If your muscles can't return that energy efficiently, you lose speed at the same VO2max — this is what we call running economy.

And running economy is a major factor in plateauing once you reach a certain level. You can gain 3–5% of speed at the same MAS just by improving your strength and muscular stiffness.

How to break out

• 2 strength training sessions per week, focused on legs and posterior chain (squats, lunges, calves, core).
• 1 short hill session (8–12 × 30 s uphill at 6–8% gradient) every 1–2 weeks: it's MAS + strength in a single session.
• Light plyometrics (bounding, skipping, jumps) as an add-on to your warm-up drills.

6) You test your MAS in poor conditions

If you do your MAS test coming out of an intense block, at 25°C in full sun, or on terrain you don't know — you're measuring your form on the day, not your real MAS. Many "plateaus" are actually repeated measurement errors.

How to break out

• Test in stable, favourable conditions: same track, same time of day, same weather if possible, same protocol.
• Not after a heavy intensity block: take 4 to 7 days of deload before a test.
• 2 to 3 tests per year maximum — otherwise the test becomes just another session and loses its reference value.
• Cross-check several indicators: field test + recent 10K time + sensations on your usual sessions.

7) You don't sleep / you don't eat enough

Sleep and nutrition aren't "bonus" parameters. They're the material conditions of adaptation. A runner who sleeps 6 hours a night with a slight calorie deficit recovers much worse than the same runner at 8 hours and balanced calories — for exactly the same training.

How to break out

• 7h30 to 9 hours of sleep per night, consistently. Short nights during a quality block kill adaptation.
• Enough carbohydrates around quality sessions. No fasted MAS sessions — you'll mess it up and get tired for nothing.
• Protein at 1.4–1.8 g/kg/day during quality blocks, to support muscle rebuilding.

Re-launch plan: a 6-week cycle to break the plateau

Here's a template plan to restart after 2–3 months of stagnation.

Easy = aerobic base (65–75% of MAS). Each quality session starts with a 15–20 min warm-up and ends with a 10 min cool-down.

The 3 golden rules of the re-launch cycle

1. No more than 2 quality sessions per week — the 3rd is always one too many when coming out of a plateau.
2. Total volume increases by 5 to 10% per week maximum over weeks 2–5, then reload before the test.
3. Evaluate by feel, not just by stopwatch. A session that subjectively becomes easier at the same pace = real progression, even if the final test hasn't budged.

What if it still doesn't work?

If after 8 to 12 well-conducted weeks you're still not progressing, examine these first:

• Are you coming out of a break (injury, COVID, overtraining)? Count 3–6 months before getting back to your best level.
• You're getting older: VO2max declines by roughly 5–10% per decade after age 35 — it's manageable but real. See our article on running after 50.
• You're plateauing at an already high level: above 18–20 km/h MAS, gains come in tenths, and the focus shifts toward running economy and fatigue resistance rather than raw VO2max.

In any case, remember that a stable MAS but a 10K speed that keeps improving is just as (or more) beneficial than a rising MAS — it's the sign that your running economy and threshold are improving. MAS is just one indicator among many.

Conclusion

A MAS plateau is almost never a physiological wall: it's a signal that your training, your recovery or your testing conditions need to evolve. Identify which of the 7 causes applies to you — often it's a combination — then apply a 6-week re-launch cycle with variety, recovery and strength work.

And if in doubt: reduce before adding. A runner who does less but better progresses more than a runner who piles on sessions in fatigue.

Further Reading

• MAS in Running: Understanding, Testing and Improving
• Fundamental Endurance: The Complete Guide
• Understanding Mitochondria: Your Running Powerhouses
• Strength Training Basics for Runners
• Running After 50: How to Adapt Your Training