Keiser Resistance Technology

Engineered for human performance.

A better way to train

Lifting mass, such as iron, is the traditional standard of resistance training. But if you use a standard approach, you get standard results.

Keiser’s Pure Resistance Technology™ doesn’t rely on mass and gravity. It’s a purer resistance that is more effective at a wider variety of training tempos.

Lifting mass has limitations.

Mass, such as iron, works very well at slow tempos to build strength. But it has properties that limit the ways you can use it effectively.

• Mass has inertia — a resistance to change in its state of motion.
• Mass has momentum once in motion — a tendency to continue moving independent of the force you use.

When you lift iron, as in a bench press, iron’s inertia requires you to use additional force at the beginning of the rep — just to get the weight moving. There is actually more resistance than the true weight of the mass. But it’s the point at which you’re at your weakest.

Once you get the iron moving, it has momentum. The faster you move, the greater the momentum. More momentum means less resistance, less than the actual weight you’re lifting. But as you continue through the concentric lifting phase, you’re mechanically stronger. You need more resistance, not less.

If you move fast enough, you’ll have to apply force in the opposite direction to slow the bar and change direction. It’s possible to move so fast that it leaves your hands —— you throw it. At that point, the weight offers no resistance.

These factors also create shock loading — the sudden application of force to connective tissue during exercise. Shock loading can place tendons and ligaments at high risk of strain or injury.

Low-inertia resistance is more effective across a wider variety of training themes. Keiser’s Pure Resistance Technology (PRT) minimizes mass, inertia, and momentum as a factor.

• It’s more effective at faster tempos when training for power and speed.
• It’s just as effective at slower tempos when training for strength.

We remove as much mass as possible.

Keiser’s PRT gives you a pure, highly versatile resistance.

We engineer the connections between you and the resistance to have as little mass as possible. With less mass, there’s less inertia and momentum.

We use compressed air under digital control instead of iron resistance. It has almost no mass, inertia, or momentum. No matter how fast you move, you can’t throw it and you don’t have to slow it.

With almost no inertia, your resistance is more effective and safer at a wide variety of speeds. This gives you more ways to train and rehab.