How to use this tool
A complete walkthrough of the calculator, the underlying methodology, and how to interpret results. For the full theoretical background, see the accompanying paper. This guide covers the practical application.
1. What this tool does
This calculator prescribes individualised running distances for high-intensity interval training (HIIT) performed as shuttle runs (back-and-forth between two cones). It addresses a problem that simple straight-line speed prescription cannot solve: in a shuttle, the athlete loses time decelerating into the turn and re-accelerating out of it. That lost time means a player running at the same target speed will cover less total distance in a shuttle than on a straight track during the same work period.
The tool starts from the player's aerobic and speed profile, calculates a target running speed, then corrects the prescribed distance to account for the acceleration and deceleration time around each direction change. The output is a personalised distance each player should aim to cover during the work bout, plus the number of shuttle legs and a practical group bucket.
2. Two prescription pathways
The tool supports two ways to derive the target running speed, depending on which test results you have for each player.
Pathway A — MAS + MSS via %ASR
If you have measured both MAS (Maximal Aerobic Speed, from a graded running test or a 1 to 2 km time trial) and MSS (Maximal Sprinting Speed, from a 30 to 40 m sprint test), the tool computes the target running speed using the Anaerobic Speed Reserve (ASR) framework:
v_target = MAS + (%ASR × (MSS − MAS))
The %ASR setting controls how far above MAS the player runs. Typical values for high-intensity intermittent work sit between 20 and 35 percent, depending on session duration, work-to-rest ratio, and the desired physiological response.
Pathway B — vIFT via %vIFT
If you only have a vIFT (the final velocity reached on the 30-15 Intermittent Fitness Test), the tool uses the simpler vIFT-based prescription:
v_target = %vIFT × vIFT
Typical values sit between 85 and 105 percent of vIFT for short HIIT runs. Pathway B already integrates aerobic, neuromuscular, and COD qualities into a single composite speed (because the 30-15 IFT itself includes shuttle running and direction changes), which is why the recommended percentages differ from %ASR.
3. About the 30-15 Intermittent Fitness Test
For team sports staff who can run only one fitness test per testing block, the 30-15 IFT is often the most efficient choice: it gives you vIFT directly, usable here in Pathway B. The relationship MAS ≈ vIFT ÷ 1.25 can be used to estimate MAS for player profiling purposes (e.g. classifying endurance/hybrid/speed types via the MSS-to-MAS ratio), but MAS should not be derived from vIFT for programming. Doing so means going one step backward: vIFT is already the more integrated measure for shuttle prescription, so converting it back to MAS only to feed Pathway A loses information. For more detail on this, see Buchheit (2025), Metabolic Conditioning for Team Sports, HIIT Science Masterclass.
4. Player profile interpretation
When both MAS and MSS are entered, the tool labels each player as Endurance, Hybrid, or Speed based on the MSS-to-MAS ratio (Sandford, 2021):
| Endurance | MSS / MAS < 1.7 — relatively low sprint speed compared with aerobic capacity. These players tend to handle longer continuous bouts well. |
| Hybrid | MSS / MAS between 1.7 and 1.9 — balanced profile. The most common category in team sports. |
| Speed | MSS / MAS > 1.9 — high sprint capacity relative to aerobic. These players can hit very high speeds in short bouts but may need more recovery. |
When only vIFT is provided, the tool estimates MAS from vIFT and labels the profile with an asterisk (Endurance*, Hybrid*, Speed*) to flag that the classification is approximate.
5. Reading the results
Each calculation returns the following outputs:
| Target speed | The speed the player should run at during the work bout, in km/h or m/s. |
| SL Dist | Straight-line distance: what the player would cover on a non-shuttle track at the target speed for the full work duration. Reference value only. |
| COD Dist | The COD-corrected distance: what the player should actually cover when running back and forth. This is the prescription. |
| Group | The COD distance rounded to the nearest practical bucket (default 5 m), so multiple players with similar prescriptions can be grouped into a single coaching wave. |
| Legs · CODs | Number of full or partial shuttle legs the player runs, and the number of direction changes between them. Legs = CODs + 1. |
| Last leg | The length of the final leg, measured from the last cone the player crossed. May be shorter than a full shuttle. |
| Reduction | Percentage reduction of the COD-corrected distance compared with the straight-line distance. Quantifies how much COD penalty the prescription absorbed. |
| Flag | Optional warning. See section 6. |
6. Practical considerations
Acceleration and deceleration inputs
Each player has a MaxAcc and MaxDec input in m/s². These should reflect realistic in-game capacities for sub-maximal directional changes, not theoretical maxima from a sprint test. Typical values for adult team-sport athletes sit between 4 and 8 m/s². When in doubt, 7.5 m/s² is a reasonable default for both.
Utilization ratios
If you prefer to enter the player's raw maximal accel and decel (e.g. from sprint testing) and let the tool scale them down to a realistic in-shuttle value, use the Decel and Accel utilization ratios in the settings panel. A value of 1 means use the raw value as-is. A value of 0.6 means apply 60 percent of the raw value. The default of 1 assumes the values you entered are already realistic. See Table 1 of the companion paper (SPSR #294) for typical utilization ratio values across player categories.
Group bucket
The Group bucket setting (default 5 m) controls how prescriptions are rounded for practical squad coaching. Larger buckets (e.g. 10 m) reduce the number of groups but increase individual error. Smaller buckets (e.g. 2 or 3 m) give tighter prescription but may produce too many groups to coach efficiently.
Flag warnings
| Terminal rule applied | The last leg extends beyond the shuttle length to preserve total work. The player crosses the start line and continues a short distance further. Documented behaviour, not an error. |
| Shuttle longer than required distance, no COD needed | The straight-line distance the player would cover during the work bout is shorter than the shuttle length. The player runs in a straight line and never reaches the turn cone. No direction change happens. The COD-corrected distance equals the straight-line distance. Consider shortening the shuttle to introduce direction changes. |
| d_turn ≈ 80% L | The distance lost per direction change approaches 80 percent of the shuttle length. The shuttle may be too short for this player at this target speed; consider lengthening the shuttle. |
| d_turn ≥ L | The COD distance penalty exceeds the entire shuttle length. The prescription is not realistic in the current shuttle. Increase shuttle length, lower the target speed, or both. |
7. About this tool and citation
This calculator is a companion to the 2026 paper by Buchheit and colleagues on COD shuttle prescription in HIIT (SPSR #294). All calculations are open and match the accompanying spreadsheet exactly. The web tool runs entirely in your browser; no player data is sent to a server or stored anywhere.
Developed in collaboration with HIIT Science and Athletica. The spreadsheet version, the full article, and additional resources are available on the accompanying website post.
How to cite the paper
Buchheit, M., Lopez Sagarra, A., Ogden, A., & Houben, C. (2026). From Rule of Thumb to Mechanistic Formula: An AI-Assisted Model for Shuttle Run Distance Correction in HIIT. Sport Performance & Science Reports, #294.
How to cite the tool
Buchheit, M. (2026). COD Shuttle Prescription Tool [Web application]. Retrieved from martin-buchheit.net. Companion to Buchheit et al. (2026), SPSR #294.