How to test: Horizontal Running Force Velocity Profile
Collect a sprint force-velocity profile and interpret the five main metrics for coaching.
A force-velocity profile (FVP) describes how an athlete produces horizontal force as sprint speed increases. Use it alongside sprint times to investigate whether early acceleration or speed capacity deserves more attention in training.
Two athletes can achieve similar sprint times with different acceleration patterns. The profile provides context for those differences; it does not prescribe a training program on its own.
Watch the full force-velocity profiling video on YouTube
Prepare the test
- Choose a flat, non-slippery surface and allow a full warm-up.
- Enter the athlete's height and weight correctly.
- Use a resisted linear sprint with a light load of 1-3 kg and NFW (No Flying Weight) mode.
- Set resisted speed to 14 m/s and assisted speed above 1.5 m/s, following the force-velocity run requirements.
- Allow enough distance to reach top speed and enough clear space to slow down afterward.
The required sprint distance varies with the athlete. Use the distance guidance in Performing a Force Velocity Run, rather than treating a typical 30-yard trial as sufficient for everyone.
Collect and check the profile
- Start from a complete standstill. Avoid preliminary movements that trigger recording before the sprint.
- Sprint with maximum effort throughout the measured run. Continue long enough for speed to plateau.
- Collect one or two quality trials, with recovery between efforts, and select the best valid effort.
- Open the Force Velocity Report.
- Check distance and confidence indicators before interpreting the results. Repeat a trial if the run was too short or the start was poorly captured.
The software's quality levels distinguish run duration from curve-fit confidence. A confidence value of at least 0.985 is the documented good-quality threshold; it does not remove the need to meet the other test requirements.
Understand the five main metrics
| Metric | What it describes | Coaching relevance |
|---|---|---|
| F₀ | Theoretical horizontal force at zero velocity, often expressed relative to body mass in N/kg. | Describes the force end of the profile and helps put early acceleration in context. |
| v₀ | Theoretical velocity intercept, where modeled horizontal force reaches zero. | Describes speed capacity. It is not the athlete's measured top speed. |
| Pmax | Maximum power from the force-velocity relationship; relative power is expressed in W/kg. | Summarizes the combination of force and velocity during acceleration. |
| RFmax | Maximum ratio of horizontal force to total force. | Helps explain how much of the force is directed forward at the start. |
| DRF | How the ratio of horizontal force changes as velocity increases. | A slope closer to zero indicates a smaller reduction in horizontal force ratio as speed rises. |
The report also includes tau (τ), a time constant describing the acceleration curve. It is an additional output, rather than one of the five metrics above. See Understanding F₀ and v₀ for more context on the profile's intercepts.
Use the results in training
Compare profiles collected under consistent conditions and read them alongside actual sprint performance. A relatively strong force end with limited speed capacity may suggest a different emphasis from a profile with stronger speed capacity and limited early force production.
Use the profile to form a coaching question, choose an intervention, and retest. Avoid deciding that an athlete is force- or velocity-deficient from one number alone.
For resisted training, a load-velocity profile answers a separate practical question: which load produces the desired reduction in speed? For higher-speed exposure, see Assisted sprinting and overspeed.
Sources: Force-Velocity Profiling: A Practical Guide for Coaches and Understanding the 5 Main Metrics.