RAST Anaerobic Sprint Test Calculator
Enter body mass and all six 35-meter sprint times to estimate RAST anaerobic power, fatigue index, percentage decrement, and per-sprint power loss.
Peak power735
- Minimum power
- 483.27
- Average power
- 599.79
- Relative peak power
- 9.8
- Relative average power
- 8
- RAST fatigue index
- 7.81
- Peak-to-minimum power loss
- 34.25%
- Sprint percentage decrement
- 7.5%
Six-sprint breakdown
| Sprint | Time (s) | Speed (m/s) | Power (W) | W/kg | Below peak |
|---|---|---|---|---|---|
| 1 | 5 | 7 | 735 | 9.8 | 0% |
| 2 | 5.15 | 6.8 | 672.63 | 8.97 | 8.49% |
| 3 | 5.3 | 6.6 | 617.12 | 8.23 | 16.04% |
| 4 | 5.45 | 6.42 | 567.55 | 7.57 | 22.78% |
| 5 | 5.6 | 6.25 | 523.16 | 6.98 | 28.82% |
| 6 | 5.75 | 6.09 | 483.27 | 6.44 | 34.25% |
Assumes the standard RAST distance of 35 meters, six maximal sprints, and 10-second recoveries between sprints.
Compare repeated tests only when timing method, surface, footwear, recovery interval, weather, and starting technique are kept consistent.
How to use this calculator
- Measure body mass on the day of the test.
- Run six maximal 35-meter sprints with 10 seconds of recovery between efforts.
- Enter each sprint time in seconds, preferably to the nearest hundredth.
- Review the peak, minimum, average, relative power, fatigue, and six-sprint table.
How the RAST calculation works
The Running-based Anaerobic Sprint Test, usually shortened to RAST, converts six timed 35-meter sprints into field estimates of anaerobic power and power decline. The fixed distance is 35 meters, and the standard protocol uses six maximal efforts separated by 10-second recovery periods.
For each sprint, this calculator uses the Draper and Whyte power equation:
P = m × d² ÷ t³
- P is sprint power in watts.
- m is body mass in kilograms.
- d is 35 meters.
- t is that sprint's time in seconds.
Each sprint also gets a speed value, v = d ÷ t, and a relative power value, RP = P ÷ m. Peak power is the greatest of the six sprint-power values, minimum power is the lowest, and average power is the arithmetic mean of all six values.
Fatigue measures
The original RAST fatigue index is a rate of power decline:
FI = (Pmax − Pmin) ÷ total sprint time
It is reported in watts per second, so it is not the same as a percentage loss. The calculator also reports peak-to-minimum power loss as 100 × (Pmax − Pmin) ÷ Pmax.
Percentage decrement is a separate repeated-sprint measure. It compares the athlete's total sprint time with an ideal total formed by repeating the fastest sprint six times:
Sdec = 100 × (total time ÷ (6 × fastest time) − 1)
If all six sprint times are identical, the fatigue index, peak-to-minimum loss, and percentage decrement are all zero. The calculator does not assume the first sprint is best or the last sprint is worst; it finds the peak and minimum power from all six trials.
What moves the result most
Sprint time dominates the calculation because time is cubed. A small timing error, a rolling start, a different surface, or a change from hand timing to timing gates can noticeably change power. Body mass scales absolute watts, while watts per kilogram helps compare repeated tests when body mass changes.
What this calculator leaves out
RAST is a field estimate. It does not directly measure force on the ground, mechanical work, blood lactate, oxygen uptake, or laboratory Wingate performance. It also cannot judge whether the warm-up, starting technique, recovery interval, weather, footwear, or motivation were standardized well enough for comparison.
Worked example
Suppose an 80 kg athlete records six 35-meter times of 5.00, 5.20, 5.40, 5.60, 5.80, and 6.00 seconds. The first sprint power is 80 × 35² ÷ 5.00³ = 784 W, and the sixth sprint power is 80 × 35² ÷ 6.00³ = 453.70 W.
Across all six sprints, peak power is 784 W, minimum power is 453.70 W, and average power is 602.89 W. Relative peak power is 9.80 W/kg, relative average power is 7.54 W/kg, the RAST fatigue index is 10.01 W/s, peak-to-minimum power loss is 42.13%, and sprint percentage decrement is 10.00%.
Common questions
How do you perform the six-sprint RAST protocol?
Set a straight 35-meter course, warm up thoroughly, then run six maximal sprints with 10 seconds of recovery between efforts. Record each sprint time in seconds, ideally with timing gates or the same careful timing method each session.
What is a good RAST fatigue index?
A lower fatigue index means less power drop across the six sprints, but a useful target depends on sport, age, training status, and timing method. Compare an athlete against their own repeated tests under the same conditions before treating a number as good or poor.
Why is sprint time cubed in the power formula?
The RAST equation estimates power from body mass, fixed distance, and sprint duration. Because time is raised to the third power, small timing differences can create large changes in calculated watts.
What is the difference between fatigue index and percentage decrement?
RAST fatigue index is the drop from peak power to minimum power divided by total sprint time, reported in watts per second. Percentage decrement compares total sprint time with the ideal total if the fastest sprint were repeated six times, so it describes repeated-sprint slowing in percent.
Why report watts and watts per kilogram?
Absolute watts show the estimated power output for the whole athlete. Watts per kilogram divides by body mass, which is useful when tracking body-mass changes or comparing athletes whose sports reward power relative to mass.
Can hand-timed RAST results be compared with timing-gate results?
They should not be compared directly. Manual stopwatch error is magnified by the cubed time term, so use the same timing system, start procedure, surface, footwear, and recovery interval whenever you want a meaningful trend.