Bowflex offers two pulley-based resistance mechanisms for its home gyms: Progressive resistance from flexible Power Rods, which offer more resistance the more you flex them; and trademarked SpiraFlex resistance plates, which contain flexible polymers that flex and twist to create linear -- that is, constant -- resistance as you lift. These technologies are patented, and there's nothing else quite like them on the market. Still, you can approximate some characteristics of the Bowflex experience with other home gym brands.
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Linear vs. Progressive
If you like the feel of the progressive resistance from Bowflex's Power Rods, you might enjoy working out with elastic resistance bands, which also provide progressive resistance.
If you prefer the linear resistance of SpiraFlex plates, Soloflex offers simplistic home gyms with heavy-duty polymer weight bands that also produce linear resistance. Bio Force also offers linear resistance from a hydraulic system.
Another trademark of Bowflex gyms is their pulley system, which forces your body to stabilize the handles as you push or pull. The Total Gym offers a similar feel, with your body -- perched on the gym's gliding board -- acting as the resistance. Other home gym manufacturers such as Weider usually offer a couple of pulley stations too, mixed in with the lever-based stations that characterize its home gyms.