Force-Velocity Profiling: What It Reveals That Sprint Times Can't

A 40m sprint time is useful. It tells you where your athlete ranks against their peers. It gives you a number to improve. But it doesn't tell you why they ran that time, or what to do next to get faster.

Force-velocity profiling does both. It's the single most diagnostic tool in our assessment battery — and the one that most surprises parents and coaches when they see the results.

The Force-Velocity Spectrum

Athletic speed is the product of two physical qualities: the ability to produce force (how much strength and power the muscles generate) and the ability to produce that force at high velocity (how quickly the muscles can contract). These two qualities sit at opposite ends of a spectrum.

At the force end: a powerlifter. Maximum strength, but slow contraction velocity. At the velocity end: a 100m sprinter in maximal acceleration. High contraction speed, lower absolute force. Every athlete sits somewhere on this spectrum — and the position is unique to them.

Why This Matters for Training

This happens constantly in youth football academies and grassroots clubs. Without an FV profile, coaches prescribe general S&C because it's what they know. But a force-dominant athlete doing more force work has a shrinking marginal return. They need velocity-oriented training: assisted sprints, sprint resisted at low loads, ballistic exercises at high velocity.

Conversely, a velocity-dominant athlete (quick, light feet, poor jumping ability) being given only speed drills has the same problem in reverse. They need force production work — plyometrics, weighted hip extension, heavy lower-body compound lifts — to give their fast-twitch muscles something to express.

How We Measure It

Our Photon Sports system captures split times at multiple points across a sprint (5m, 10m, 15m, 20m, 30m and optionally 40m). The velocity at each point is calculated, and using established sprint mechanics models, we derive the force production at each phase of the sprint — from the initial drive phase through to top-end speed.

This produces an FV gradient — a line that shows where on the force-velocity spectrum your athlete sits. A line sloping steeply toward force indicates a force deficit. A line sloping toward velocity indicates a velocity deficit. A well-balanced athlete sits close to the theoretical optimal for their sport.

What We See in Practice

In our Birmingham assessment data, the majority of youth footballers (U12–U16) present with a velocity deficit — they have decent relative strength for their age (often from general play and school PE) but insufficient velocity-specific training. This makes sense: most youth training is technical and tactical, with S&C being informal at best.

Elite academy players and older semi-pro athletes more commonly present with force deficits — they've done a lot of sprint-specific work in their academy environment but haven't developed the muscular strength base to maximise that speed.

Real Case Example

A U16 central midfielder came to us with a coach report that he was "getting turned" in midfield — poor acceleration away from opponents. His 40m sprint time was 5.1 seconds, which sits around the 40th percentile for his age group. Not slow, but not quick enough.

His FV profile showed a significant velocity deficit. Despite training three times a week including gym work, his programme was heavily force-oriented. We redirected training toward velocity work — assisted sprint training, maximal velocity runs, ballistic exercises. At 12-week retest, his 40m time was 4.8 seconds. Same athlete, same gym access. Different training prescription based on data.