Everyone else calculates force. DynaSled measures it.
Every competing method arrives at a force number by inference, working backwards from something else it can see and then doing the maths. The DynaSled puts a loadcell in the line of pull and reads the actual force directly, from first principles. It is the difference between a clever estimate and the real number.
| Method | How it gets force | Plane |
|---|---|---|
| Barbell VBT (GymAware, Perch) | Force is simply the known weight on the bar | Vertical, in the gym |
| Sprint profiling from radar or timing | Calculated from velocity over time, plus body mass and air-resistance assumptions | Horizontal, inferred |
| Loaded-jump profiling | Calculated backwards from flight time and body mass | Vertical, inferred |
| DynaSled | A loadcell reads the actual push and pull force as it happens. No calculation. | Horizontal, measured |
What sled force actually is
When an athlete drives a sled forward, they apply horizontal force against the ground and into the resistance. That horizontal ground force is the thing that actually moves an athlete down the track. It is made up of the force needed to overcome friction and the force needed to accelerate the load.
Measuring that force directly, rather than working it out afterwards, is the foundation of an honest profile.
Measure force where sport happens
Acceleration, sprinting, change of direction and contact are all horizontal actions. Vertical jump tests and barbell lifts measure force in a different plane to the one the athlete competes in.
They remain useful, but if the goal is to understand how an athlete accelerates, it makes sense to measure force in the direction they are actually producing it. Horizontal force-velocity profiling is sport-specific by design.
Profiling that you can act on
The diagnostic power of force-velocity profiling comes from testing across several loads and reading the relationship between them. When the force at each load is measured rather than reconstructed, the profile does not accumulate modelling error at every step.
The result is a relationship you can act on with confidence, whether the aim is to develop force, develop velocity, or find the load that maximises horizontal power.
Left and right leg contribution
One of the most valuable things a coach can see is whether an athlete produces more horizontal force on one side than the other, which matters most when returning from injury. A single velocity reading cannot reveal this, because it only describes the whole system at once.
Direct, per-side force measurement is the only honest route to a left-right comparison. Where the difference that matters is small, a measured value is the difference between a usable flag and noise.
A loadcell on the sled. Force, measured.
The DynaSled is a friction-resistance sled instrumented with a loadcell. It measures horizontal push and pull force directly, like a moving force plate, across natural and indoor surfaces. It brings measured-force horizontal profiling out of the lab and onto the track and field.
Common questions
Can you measure force on a sled?
Yes. The DynaSled uses a loadcell to measure the actual horizontal push and pull force the athlete produces, rather than estimating it from velocity.
What is the difference between measured and estimated force?
Measured force is read directly by a force sensor. Estimated force is calculated from something else, usually velocity or flight time, plus assumptions about mass and air resistance. Estimates can be good, but they depend on those assumptions holding.
Is a force-measuring sled an alternative to a force plate?
It measures horizontal force in the movement athletes actually compete in, which a fixed force plate cannot do during a sprint. The two are complementary, with the sled covering the horizontal, sport-specific picture.
Is horizontal VBT the same as barbell VBT?
No. Barbell velocity-based training is vertical and gym-based, and its force is the known weight on the bar. Horizontal force-velocity profiling applies the same measurement-led philosophy to sprinting, where the force has to be measured rather than assumed.