Force-Velocity Profiling — Personalising Power Development in Football

Introduction

Not all football players have the same power deficit. Some players produce high forces but limited velocity — they accelerate powerfully but top-end speed is constrained. Others generate high velocities but lack force — fast but lacking drive force at initial sprint steps. Prescribing the same sprint and strength training for both profiles is suboptimal. Force-velocity (F-V) profiling identifies each player’s individual power production constraints, enabling targeted training that specifically addresses their limiting factor — an approach that produces superior speed and power development compared to generic programming.

The Science

The force-velocity relationship: Muscle generates maximum force at zero velocity (isometric contraction) and maximum velocity at zero force (unloaded contraction). Between these extremes, force and velocity are inversely related: the faster a muscle contracts, the less force it can produce, and vice versa. This relationship is linear at the whole-body locomotion level, creating an individual F-V profile describable by two variables: F0 (maximal force) and V0 (maximal velocity).

Mechanical power: Peak mechanical power (Pmax) occurs at intermediate force-velocity combinations — approximately 50% of F0 and 50% of V0. An athlete’s Pmax represents their maximal power output capacity. But two athletes can have identical Pmax with very different F-V profiles:

• Force-deficit profile: High V0, relatively low F0 — the athlete can produce high velocities but is force-limited. Needs heavy strength training to shift F0.
• Velocity-deficit profile: High F0, relatively low V0 — the athlete produces high drive forces but velocity is limited. Needs high-velocity and plyometric training to shift V0.
• Well-balanced profile: Optimal F0-V0 balance for mechanical power production. Targeted to maintain balance while increasing absolute output.

Measuring the F-V profile: Field-based sprinting methods (Samozino et al., 2016) allow F-V profiling from simple sprint timing data. Using split times from a maximal sprint effort (timing gates at 5, 10, 20, 30, 40m), and player body mass, the F-V profile can be calculated from the acceleration-velocity relationship without laboratory equipment. This makes F-V profiling feasible in applied football settings.

The F-V imbalance index: The optimal F-V slope for an individual athlete can be calculated from their body mass and height. The deviation of their actual slope from this optimal represents their F-V imbalance — the training priority. Greater imbalance from the optimal predicts a larger potential performance gain from targeted training.

What Research Says

Samozino et al. (2016) published the original field-based F-V profiling methodology in Scandinavian Journal of Medicine & Science in Sports, demonstrating that mechanical output (force, velocity, power) during sprinting can be accurately calculated from split-time data and body mass — enabling F-V profiling without force plates or laboratory equipment.

Jiménez-Reyes et al. (2016) applied F-V profiling to jump training in Frontiers in Physiology, demonstrating that athletes with higher F-V imbalance showed significantly greater jump performance improvement after individually targeted (force- vs velocity-directed) training compared to non-individualised training.

Cross et al. (2017) compared force-directed and velocity-directed training protocols in rugby players in International Journal of Sports Physiology and Performance, finding that athletes who trained according to their identified F-V deficit achieved significantly greater improvements in sprint performance and countermovement jump than those who underwent generic training, confirming the practical value of profiling.

Did You Know? GPS-based force-velocity profiling is now commercially available — several GPS companies have integrated acceleration-velocity modelling into their analysis platforms, allowing clubs to generate F-V profiles for every player from their normal GPS match and training data without additional testing sessions. This means clubs with existing GPS infrastructure can access F-V profiling for their entire squad, updated weekly throughout the season, at no additional hardware cost.

Applied to Football

Implementing F-V profiling in football strength and conditioning:

1. Profile all players at pre-season using maximal sprint tests. 40m sprint with split times at 5, 10, 20, 30m. Input mass and height. Calculate F0, V0, and F-V slope using Samozino’s free calculation tools.
2. Classify each player’s imbalance direction. Force-deficit or velocity-deficit. Players within 10% of optimal slope are well-balanced — focus on increasing absolute output.
3. Direct strength training by F-V profile. Force-deficit players: heavy back squat, hip thrust, loaded sled (80–90% 1RM emphasis). Velocity-deficit players: plyometrics, resisted sprint at low resistance, assisted sprint.
4. Reassess every 4–6 weeks. F-V profiles shift with training — a force-deficit player who responds to heavy loading will shift toward balance. Re-profile and adjust training emphasis accordingly.
5. Use F-V profiling to individualise warm-up and activation. Force-deficit players benefit from heavy isometric pre-activation; velocity-deficit players from dynamic sprint warm-up. Pre-match protocols can be individualised by profile.

Key Takeaways

• The F-V profile describes an athlete’s force-velocity imbalance: force-deficit (needs strength) or velocity-deficit (needs speed)
• Field-based profiling from sprint split times is validated and requires no laboratory equipment
• Targeted training addressing the specific imbalance produces superior sprint improvement vs. generic programmes
• GPS-based F-V profiling enables continuous monitoring from match and training data
• F-V imbalance index quantifies the magnitude of the training priority and potential performance gain

References

• Samozino, P., Rabita, G., Dorel, S., Slawinski, J., Peyrot, N., Saez de Villarreal, E., & Morin, J. B. (2016). A simple method for measuring power, force, velocity properties, and mechanical effectiveness in sprint running. Scandinavian Journal of Medicine & Science in Sports, 26(6), 648–658.
• Jiménez-Reyes, P., Samozino, P., Brughelli, M., & Morin, J. B. (2016). Effectiveness of an individualized training based on force-velocity profiling during jumping. Frontiers in Physiology, 7, 677.
• Cross, M. R., Brughelli, M., Samozino, P., Brown, S. R., & Morin, J. B. (2017). Optimal loading for maximising power during sled-resisted sprinting. International Journal of Sports Physiology and Performance, 12(8), 1069–1077.