An exercise treadmill is a belt stretched between two rollers (Figure 12-3). The belt may be driven manually in the least expensive models or by a motor in more expensive ones. Sears, Tunturi, Vitamaster, Voit, DP, Precor, and Proform are among the more common brands of treadmills manufactured for home use. Costs range from $400 to $1000. More expensive machines have a bigger motor, a wider belt, and a faster top speed up to about 5 mph. It is difficult to find a good motor-driven treadmill for under $500. Treadmills subjected to high usage in health clubs cost between $1000 and $12,000. Most of the more expensive motor-driven treadmills allow you to adjust both the speed of the belt and the incline angle to alter intensity.
Machine motors vary in both type and size. The type of motor can be either AC or DC. AC motors run at full speed, all the time relying on a transmission-like pulley system to regulate speed. This means most models start up at full speed and can be somewhat dangerous when getting on. Treadmill motors that are DC can be run at different speeds, thus start-up is not much of a problem. All models come with some type of speed control.
Motor size varies from V2 horsepower to more than1 horsepower. Bigger motors can handle heavier loads and higher speeds. The treadmill must be able to go at least 5 mph to run.