By Chris Valuck

KeiserResidents have expressed interest in how Keiser strength training equipment functions and why it’s different from traditional strength training equipment.  The information below, taken from their website, explains their technology.


Keiser’s pneumatic strength training equipment was designed by mechanical engineer, Dennis Keiser,  and his brother Randy in 1978.  They have worked with Olympic athletes, as well as NASA to create  equipment for long-duration space flights, and with the Council on Aging and Adult Development to support research on aging and exercise.


How It’s Different From Traditional Weight Training Equipment

Keiser exercise equipment uses compressed air rather than a weight stack to provide resistance.  The resistance applied by each machine varies throughout the range of motion so that the muscle must maintain a constant level of exertion to complete the exercise.  With a traditional “weight stack” machine, more effort is required at the beginning of the movement to move the mass (weight stack) and at the end of the movement to slow it down.

Graph:  Keiser Pneumatic Machine (Blue) – Traditional Weight Stack Machine (Red)
Keiser graph

Additional Research

It can be seen in the graph that the acceleration forces of inertia increase dramatically with a weight stack machine depending upon the speed of movement. Also the weight stack shows a loss of resistance because of gravity and momentum. Keiser pneumatic resistance strength curve remains consistent at all three training speeds. Weight stack cam machines were designed to take into consideration the forces due to acceleration and deceleration (starting and stopping the weight stack) so it can counteract the effects of inertia and momentum. The problem with weight stack machines is that they were designed to work at one restricted speed of movement to counteract the effects of inertia and momentum.

There are several research studies involving older adults and fitness using Keiser equipment.  Results show significant improvements in strength and endurance, bone density, and physical frailty.  For more information on these studies, go to the link: