Maximal Aerobic Speed (MAS) is the benchmark metric for programming High-Intensity Interval Training (HIIT) because it allows coaches to calculate exact running distances in meters for every repetition.
The mathematical prescription formula is: Distance (meters) = [MAS (km/h) × % Intensity × Duration (seconds)] / 3.6. For example, an athlete with a 16.0 km/h MAS running 15-second intervals at 110% MAS covers exactly 73.3 meters per rep. Generate your custom interval distances automatically with our free online MAS interval calculator.
In endurance running, soccer, rugby, and track & field, athletes often perform intervals with vague instructions like "run hard" or "80% effort." The result is almost always the same: athletes sprint the first two repetitions, build up extreme lactic acidosis, and stagger through the remainder of the session at sub-optimal velocities. By calibrating workouts against Maximal Aerobic Speed (MAS), you eliminate guesswork and keep cardiovascular stimulus at peak physiological efficiency.
1. The Physiology: Why Intermittent HIIT Trumps Continuous Running
Groundbreaking research led by Dr. Véronique Billat and Dr. Martin Buchheit demonstrated that the primary stimulus for expanding an athlete's aerobic ceiling is the total time spent at or near 100% of VO₂max ($T@\text{VO}_2\max$).
Continuous Running Bottleneck
If an athlete runs continuously at 100% MAS, exhaustion occurs in 4 to 8 minutes ($T_{\lim}$). The athlete must stop due to muscular fatigue, limiting their high-intensity training volume to under 8 minutes.
The Intermittent Advantage
By alternating short bouts (e.g. 15s run / 15s rest), oxygen uptake ($\text{VO}_2$) remains elevated during recovery while myoglobin oxygen stores and phosphocreatine (PCr) rapidly reload. Athletes easily accumulate 15 to 25 minutes near VO₂max.
If you have not yet evaluated your baseline speed, first complete our validated 6-Minute MAS Running Test or convert your shuttle score with the Beep Test to MAS Conversion Guide.
2. The 3 Core Categories of MAS Workouts
Coaches divide MAS interval training into three distinct physiological zones:
Long Intervals: Aerobic Capacity & Threshold (90% – 95% MAS)
Bout duration: 2 to 4 minutes. Rest: 1:1 to 2:1 ratio. Example: $5 \times 800\text{m} \text{ @ } 92\% \text{ MAS}$ with 2 minutes slow jogging recovery. Builds mitochondrial density, lactate clearance, and 5K/10K race stamina.
Short Intermittent Intervals: Classic Aerobic Power (100% – 110% MAS)
Bout duration: 15s to 30s. Rest: 1:1 ratio (15s/15s or 30s/30s). Example: $2 \text{ sets of } [8 \times (15\text{s @ } 105\% \text{ MAS} / 15\text{s slow jog})]$ with 3 minutes between sets. Maximizes stroke volume and running economy.
Supramaximal Intervals: Neuromuscular & Anaerobic Power (115% – 125% MAS)
Bout duration: 10s to 15s. Rest: 1:2 to 1:3 ratio (passive standing rest). Example: $8 \times (10\text{s @ } 120\% \text{ MAS} / 20\text{s rest})$. Develops high-speed turnover and repeated sprint ability without heavy lactic burnout.
⏱️ Generate Your Custom Interval Split Distances Instantly
Enter your MAS or test result into our free interactive tool to receive exact meter markers for 15s/15s, 30s/30s, 200m, and 400m repetition targets.
🧮 Open Free MAS Pace Calculator3. The Prescription Formula: How to Calculate Exact Rep Distances
To set up an interval session on an athletic track, turf pitch, or open field, you must convert speed into meters:
📐 The Mathematical Distance Formula
$$\text{Distance (meters)} = \frac{\text{MAS (km/h)} \times (\% \text{Intensity} / 100) \times \text{Work Duration (seconds)}}{3.6}$$
Worked Example 1 (15s / 15s Workout):
- Athlete MAS = 15.0 km/h
- Target intensity = 105% MAS ($15.0 \times 1.05 = 15.75\text{ km/h}$)
- Work duration = 15 seconds
- $\text{Distance} = (15.75 \times 15) / 3.6 = \mathbf{65.6\text{ meters}}$ (round to 66 meters).
Worked Example 2 (30s / 30s Workout):
- Athlete MAS = 14.0 km/h @ 100% MAS for 30 seconds
- $\text{Distance} = (14.0 \times 30) / 3.6 = \mathbf{116.7\text{ meters}}$ (round to 117 meters).
4. Master MAS Interval Distance Lookup Table
Use this reference table to find target running distances (in meters) for standard 15-second and 30-second interval repetitions across various MAS levels:
| MAS (km/h) | 15s @ 100% | 15s @ 105% | 15s @ 110% | 15s @ 115% | 30s @ 95% | 30s @ 100% | 30s @ 105% |
|---|---|---|---|---|---|---|---|
| 12.0 km/h | 50.0 m | 52.5 m | 55.0 m | 57.5 m | 95.0 m | 100.0 m | 105.0 m |
| 13.0 km/h | 54.2 m | 56.9 m | 59.6 m | 62.3 m | 102.9 m | 108.3 m | 113.8 m |
| 14.0 km/h | 58.3 m | 61.3 m | 64.2 m | 67.1 m | 110.8 m | 116.7 m | 122.5 m |
| 15.0 km/h | 62.5 m | 65.6 m | 68.8 m | 71.9 m | 118.8 m | 125.0 m | 131.3 m |
| 16.0 km/h | 66.7 m | 70.0 m | 73.3 m | 76.7 m | 126.7 m | 133.3 m | 140.0 m |
| 17.0 km/h | 70.8 m | 74.4 m | 77.9 m | 81.5 m | 134.6 m | 141.7 m | 148.8 m |
| 18.0 km/h | 75.0 m | 78.8 m | 82.5 m | 86.3 m | 142.5 m | 150.0 m | 157.5 m |
| 19.0 km/h | 79.2 m | 83.1 m | 87.1 m | 91.0 m | 150.4 m | 158.3 m | 166.3 m |
| 20.0 km/h | 83.3 m | 87.5 m | 91.7 m | 95.8 m | 158.3 m | 166.7 m | 175.0 m |
5. The Team Sport "Eurofit" Grid Method
In team sports (soccer, rugby, lacrosse), running an entire squad together at one uniform pace means the fastest players undertrain while slower players drop out. Top strength and conditioning coaches solve this using the Eurofit MAS Grid:
🏉 How to Set Up an MAS Conditioning Grid
- Group your athletes into 3 or 4 speed bands (e.g., Band 1: 14.0 km/h, Band 2: 15.0 km/h, Band 3: 16.0 km/h, Band 4: 17.0 km/h).
- Mark out concentric rectangular grids on a pitch. Each grid's perimeter corresponds to each group's target 15-second distance (e.g. 64m, 68m, 73m, 78m).
- All athletes run simultaneously for 15 seconds, reaching the opposite sideline on the whistle, rest for 15 seconds, and run back.
- Every player experiences the exact same physiological intensity (110% of their individual MAS) with zero administrative chaos.
6. Common Mistakes to Avoid in Interval Programming
❌ Running the Rest Periods Too Fast
During active recovery (e.g. the 15s rest in 15s/15s), the speed must drop to 40%–50% MAS (a very slow shuffle). Jogging at 70% MAS prevents phosphocreatine replenishment.
❌ Too Many Sessions per Week
High-intensity aerobic intervals place significant eccentric stress on hamstrings and calves. Cap true MAS interval sessions at 2 per week for endurance runners and 1 per week for in-season team athletes.
⚠️ Ignoring Environmental Heat & Wind
On hot, humid days (>28°C / 82°F), cardiac drift causes heart rate to max out prematurely. Reduce target intensity by 3% to 5% or add 5 seconds to recovery bouts.
⚠️ Skipping Progressive Overload
Do not increase speed every week. Progressive overload is achieved first by adding repetitions (e.g. 10 reps to 12 reps), then adding a second set, and only then bumping speed by 2%.
Frequently Asked Questions (FAQ)
A classic session is $5 \times 1,000\text{m} \text{ @ } 92\%–95\% \text{ MAS}$ with 2 minutes jog recovery, or $2 \times [10 \times (30\text{s @ } 105\% \text{ MAS} / 30\text{s jog})]$ with 3 minutes rest between sets.
Use active recovery (slow jogging at 45%–50% MAS) for workouts at 95% to 105% MAS to promote continuous aerobic metabolism. Use passive recovery (standing or walking) for supramaximal sprint workouts (>115% MAS) to allow maximal phosphocreatine resynthesis.
Yes for long intervals (2 to 4 minutes). However, short intervals (15s/15s) are impractical on consumer treadmills due to motor acceleration lag. For short HIIT, an athletic track, open pitch, or manual non-motorized curved treadmill is superior.
Running at velocities above your normal race pace stimulates high-threshold motor unit recruitment, enhances tendon stiffness, and trains neuromuscular coordination, allowing you to consume less oxygen at submaximal marathon and half-marathon paces.