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Adaptive resistance doesn’t mean the machine adapts to you. That’s the whole secret.
“It’s crucial that it does not adapt, because it’s only when it doesn’t care about what you do to it—it’s going to continue at the constant velocity—that it can then provide the adaptive resistance we use to deliver the stimulus.” — Jim Keen, Director of Training at FastFit®
Jim Keen is back after a long detour of functional medicine episodes and he’s here to untangle something that has confused a lot of people, including members of our own team.
Here’s the question I posed to him: if the machine is isokinetic—constant velocity, variable force—how can we call it “adaptive”? After all, you can start a set, stand up, walk away, and the machine keeps moving at the exact same pace. It doesn’t care if you’re there. It isn’t responding to you at all. So where’s the adaptation?
Jim’s answer reframes everything. The machine itself does not adapt. And that’s the entire point. He uses two analogies. A thermos keeps hot things hot and cold things cold, but there’s no algorithm inside; it’s just a cylinder of metal whose nature slows entropy. The earth pushes back with exactly the force you put into it—stand on it and it supports your weight, jump and it absorbs two or three times your weight—but the earth isn’t “deciding” anything. It’s just its nature.
The FastFit® machine works the same way. Because it holds a constant velocity and refuses to speed up no matter how hard you push, the resistance you feel automatically matches the force you produce. Push harder, feel more. Ease off, feel less. The resistance is what adapts—not the machine. And it’s precisely the machine’s refusal to adapt that makes that perfectly matched resistance possible.
This is why the team has sent out a clear directive to trainers and marketing: stop saying the machine “responds to you in real time” or “adapts to you.” It doesn’t. It’s isokinetic. It moves at a constant velocity so that you can always apply as much force as you want for optimal tension. For stimulus-rich workouts that drive results. Compare that to a barbell, which adapts in speed (push harder, it moves faster) but never in resistance, because 100 pounds is always 100 pounds.
In this episode, you’ll learn:
- Why the FastFit machine purposely does not adapt to the user—and why that’s a feature, not a flaw
- The thermos and earth analogies that explain how something can provide adaptive resistance without “adapting”
- The crucial distinction: the machine holds constant velocity, so the resistance is what adapts to your force
- Why describing the machine as “responding to you in real time” is inaccurate—and what to say instead
- How isokinetic exercise differs fundamentally from barbell training (which adapts in speed, never in resistance)
- Why most strength research comes with an unspoken asterisk: “…with weights”
- A preview of the next episode, going deeper on why weight-based research doesn’t automatically apply to isokinetic resistance exercise
🎧 Listen to the episode now:
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