Bowflex is a brand of home fitness equipment manufactured and marketed by Nautilus, a company long known for exercise machines used extensively in gyms. The home gyms for which Bowflex is best known work by means of Bowflex's Power Rod progressive resistance technology. Working with progressive resistance is like pulling back the string of a bow, where the resistance grows greater as the movement progresses, according to PEERtrainer.
As Vanderbilt University Health Psychology explains, the Bowflex workout is a version of circuit training, in which a high number of repetitions of an exercise is done in a short period of time to increase the heart rate, thus combining an aerobic and anaerobic workout. While some of the TV infomercials selling Bowflex equipment insist that exercisers only need to work out 20 minutes a day for three days a week, in reality a greater commitment to exercise is needed to gain strength or add muscle mass. PEERtrainer points out that those wishing to gain muscle mass should move up to a more complex and expensive Bowflex home gym, the Bowflex Revolution, which uses a technology that makes the workout feel more like lifting free weights.
Bowflex home gyms accommodate from 70 to over 100 different exercises at several levels of resistance, according to Wikipedia. Bowflex provides workout manuals suggesting exercises and repetition levels.