Resisted sprinting has worked more or less the same way for a long time. Pick a simple amount of load, the athlete runs, then repeat. Although simple and effective, it has a built-in limitation. 15kg of resistance doesn’t feel the same at step 2 as it does at step 20. It's the same load but different stimulus depending on where it is in the run.
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Motorized resistance opens up a new solution for this problem. Coaches can not only control how much load the athlete feels, but also when in the run the load changes. This is called variable loading and it’s one of the first real evolutions in resisted sprinting that hasn't been accessible until now.
What Variable Loading Actually Is
Variable loading means the load changes within a single sprint rep. The load smoothly transitions from one load to the next across the run, with the change being as quick or slow or big or small as you want.
And this supports the core idea of most resistance training, including the weight room: the load isn’t the stimulus, the velocity is. For sprinting specifically, it’s the velocity decrement, or how much slower the resistance makes the athlete relative to their top speed.
Throughout an unresisted sprint, the kinetics and kinematics change dramatically from the first step to top speed. If the sprint itself changes across the run, the load should be able to change with it. (Constant loading still has real value, but it’s one tool, not the only one.)
A Brief History (and Why They Fall Short)
Variable loading itself isn’t new. Coaches have been changing load across a sprint for decades:
-Elastic bands and bungees: ascending load profile (increases over time) as the band stretches, very hard to quantify or repeat
-Parachutes and drag implements: ascending profile, but resistance depends on the athlete’s speed and environmental conditions
-Resist and release: descending profile technically (decrease over time), but the abrupt unloading is hard to prescribe cleanly and introduces some biomechanical risk
Each of these changes load across a rep, but none of them are precise, individualizable, or measurable in a meaningful way. Which means the training process itself can’t be consistent, leading to more guessing and hoping than objective decision-making.
How Variable Loading Works on the 1080
Motorized resistance delivers any load profile, both ascending and descending, that's precise, repeatable, and measurable. Here are the 3 variables that define the prescription:
-Start load: what the athlete feels at step one
-Target load: what the load transitions to across the rep
-Target speed: the speed at which the target load is fully transitioned
These are combined to change both how fast and how much the transition is. Change any one of them and the shape of the stimulus changes. This gives you the exact control you need to ensure the training reps match the training goals.
Prescribing by velocity decrement (Vdec) is what makes variable loading individualized. For example, a start load of 50% Vdec and target load of 25% Vdec. When each athlete has their own load-velocity profile, the software pulls the specific loads and target speed for that athlete automatically.
Two Loading Profiles in Practice
Case Study 1: Ascending. Light load at the start lets the athlete get up to the target speed quicker so more of the rep is spent at the target load and speed.
-Start load: 5% Vdec (3kg)
-Target load: 30% Vdec (15kg)
-Target speed: 6 m/s
A constant 15kg load would get the athlete to 6 m/s eventually too, but much later in the run. With variable loading, more of each rep exposes the athlete to the intended stimulus.
Case Study 2: Descending. Start heavy then transition to light so the resistance models what an unresisted sprint would look like.
-Start load: 55% Vdec (24.7kg)
-Target load: 10% Vdec (5.1kg)
-Target speed: 7.7 m/s
A constant 24kg load would plateau the athlete’s speed and leave a lot of velocity on the table. The first few steps would be the right stimulus but the rest of the rep would be too slow.
More Applications
Although we only mentioned resisted sprinting, the applications of variable loading go well beyond this. A few other examples include:
-Variable assistance, a descending profile for assisted sprinting: more pull at the start to get the athlete up to top speed, then less pull once they’re there so the top speed is more them doing the work
-Resisted skating, an ascending profile: lets the athlete create speed under light load while having no friction on the ice
-And more
Where to Start
The honest answer: variable loading gets a lot more powerful with a load-velocity profile.
You can experiment with regular loads by estimating them and still learn a lot. But estimated loads don’t account for the athlete’s specific ability to sprint against resistance, which is what makes variable loading programmable rather than guesswork.
If you don’t have an LVP yet, here’s our full guide on how to collect one: VIDEO and ARTICLE
For starting ranges when you’re new to variable loading, check out the table below.
Beyond that: play around with ascending vs descending, feel the transitions, see how athletes respond to dial in your processes over time.
Software Demo
Adam walked through the software setup during the live webinar, showing which exact buttons to push both on your 1080 Sprint 2 and tablet. If you want to watch this, it starts at 38:42 or use this specific link HERE.
Conclusion
Variable loading isn’t about just changing to more or less load. It’s about controlling how much load challenges the athlete at specific points within a sprint.
The published research on this is still limited. It’s a relatively new capability, and coaches and researchers are both still figuring out everything it can do. That’s part of what makes the conversation worth opening: if you try it, experiment, and see what your athletes respond to, let us know what you find.
This is one of the places where the field is being built in real time.
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Published: November 9, 2026