Gacon 45/15 Test
Designed by Georges Gacon, this test alternates 45 seconds of effort and 15 seconds of recovery over 150 metres, with intensity rising at each cycle, to measure your MAS precisely.
About the Gacon test
Often called the intermittent test or the 45/15 MAS test, this progressive, incremental test alternates effort and recovery sequences to measure Maximal Aerobic Speed precisely. Designed by Georges Gacon, a PE teacher and strength and conditioning coach, it has become a reference in the sports world.
Its distinctive feature: sequences of 45 seconds of intense effort followed by 15 seconds of recovery — an effective format that is easy to set up without complex equipment.
How the test works
The athlete runs at an increasing intensity for 45 seconds, followed by 15 seconds of walking or slow jogging. The intensity rises progressively after each complete cycle, making the test harder and harder until exhaustion. It assesses both general aerobic fitness and the ability to sustain effort under progressive fatigue.
Calculator
Calculate your MAS
Select the last level you completed to get your estimated MAS.
Doing the test yourself
You can run this test alone. The main requirement: access to a track or flat surface with an accurately measured 150 metres.
- A suitable venue: athletics track or flat, obstacle-free ground
- Floor markers defining the exact 150-metre distance
- A stopwatch or a watch with a timer (45 s / 15 s)
- Proper sports clothing, with suitable running shoes
Protocol
How the test unfolds
- Prepare your equipmentComfortable running shoes, a stopwatch or timing app, and something to hydrate with.
- Mark the distanceOn a track or flat path, set two markers 150 metres apart.
- Warm upA good warm-up (easy jogging, dynamic stretches) to avoid injury.
- Start the testRun the 150 metres in 45 seconds, then walk for 15 seconds. Increase the speed at each interval until exhaustion.
Reference chart
The full 35-level chart
| Level | Speed | Distance / 45 s | Time per 100 m |
|---|---|---|---|
| 1 | 8 km/h | 100.00 m | 45.00 s |
| 2 | 8.5 km/h | 106.25 m | 42.50 s |
| 3 | 9 km/h | 112.50 m | 40.00 s |
| 4 | 9.5 km/h | 118.75 m | 37.89 s |
| 5 | 10 km/h | 125.00 m | 36.00 s |
| 6 | 10.5 km/h | 131.25 m | 34.29 s |
| 7 | 11 km/h | 137.50 m | 32.73 s |
| 8 | 11.5 km/h | 143.75 m | 31.30 s |
| 9 | 12 km/h | 150.00 m | 30.00 s |
| 10 | 12.5 km/h | 156.25 m | 28.80 s |
| 11 | 13 km/h | 162.50 m | 27.69 s |
| 12 | 13.5 km/h | 168.75 m | 26.67 s |
| 13 | 14 km/h | 175.00 m | 25.71 s |
| 14 | 14.5 km/h | 181.25 m | 24.83 s |
| 15 | 15 km/h | 187.50 m | 24.00 s |
| 16 | 15.5 km/h | 193.75 m | 23.23 s |
| 17 | 16 km/h | 200.00 m | 22.50 s |
| 18 | 16.5 km/h | 206.25 m | 21.82 s |
| 19 | 17 km/h | 212.50 m | 21.18 s |
| 20 | 17.5 km/h | 218.75 m | 20.57 s |
| 21 | 18 km/h | 225.00 m | 20.00 s |
| 22 | 18.5 km/h | 231.25 m | 19.46 s |
| 23 | 19 km/h | 237.50 m | 18.95 s |
| 24 | 19.5 km/h | 243.75 m | 18.46 s |
| 25 | 20 km/h | 250.00 m | 18.00 s |
| 26 | 20.5 km/h | 256.25 m | 17.56 s |
| 27 | 21 km/h | 262.50 m | 17.14 s |
| 28 | 21.5 km/h | 268.75 m | 16.74 s |
| 29 | 22 km/h | 275.00 m | 16.36 s |
| 30 | 22.5 km/h | 281.25 m | 16.00 s |
| 31 | 23 km/h | 287.50 m | 15.65 s |
| 32 | 23.5 km/h | 293.75 m | 15.32 s |
| 33 | 24 km/h | 300.00 m | 15.00 s |
| 34 | 24.5 km/h | 306.25 m | 14.69 s |
| 35 | 25 km/h | 312.50 m | 14.40 s |
Calculating and interpreting your MAS
Note the last speed reached at the moment you were forced to abandon the required pace. Each level passed raises the difficulty, creating a direct relationship with MAS: reaching the highest levels indicates excellent aerobic fitness, while a lower ceiling can point to training adjustments.
Recommended gear
To run the test in good conditions
- Sports stopwatch View on Amazon →
- Set of training cones View on Amazon →
- Running shoes View on Amazon →
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Frequently asked questions
FAQ
Why 45 seconds of effort and 15 of recovery?
This intermittent format (45/15) alternates effort and short recovery to push the body progressively towards its MAS, while staying feasible without laboratory equipment.
What is the difference with the beep test?
The beep test is a continuous 20 m shuttle effort, whereas the Gacon test alternates cycles of 45 seconds of effort over 150 m and 15 seconds of walking recovery. This format is closer to interval training.
Do you need someone with you for this test?
No, it can be done alone with a stopwatch, but a partner or coach makes counting cycles and reading the time much easier.
What is the advantage of the intermittent format over a continuous effort?
Alternating effort and recovery lets you hold an intensity close to your MAS for longer than in a continuous test, which makes the test both more tolerable and closer to the real efforts found in team sports.