A portable exercise bike is a small piece of fitness equipment, similar in concept to a stationary bicycle, but very different in design. Though there are some foldable stationary bicycles that are sometimes referred to as portable exercise bikes, the term "portable exercise bike" usually refers to a small device that the user pedals while sitting in a chair. This type of mini bike can be one way to get some exercise in the legs and buttocks, but is generally not sufficient enough for an entire workout.
A portable exercise bike sits flat on the floor and features two bicycle pedals attached to a flywheel, which uses friction for resistance, or a magnetized wheel. The whole piece of equipment is typically no more than 2 feet (.6 meters) high, and does not feature a seat. Instead, the user sits in a chair, places his or her feet on the pedals, and pushes the pedals as if sitting on a bicycle. This piece of fitness equipment is not safe to stand on.
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Sitting straight up in a chair will theoretically mimic the workout from a standard upright bicycle, whereas leaning back in the chair is similar to using a recumbent bicycle, which works the abdominal muscles as well as the legs. The obvious upside to a portable exercise bike is that it is so small and easy to move, and can be used anywhere. One can sit in a chair watching television and pedaling the bicycle at the same time.
A portable exercise bike may feature an LCD screen that displays information such as the time spent exercising and the calories burned, but this feature is more common on more expensive versions. Some are also able to connect to a computer and be used with a computer game; i.e., when one pedals faster, one's character in the game runs faster. There are a few downsides to exercising this way, however. First, the portable stationary bike is often not very stable, and may wobble during use, which could cause the feet to slip off the pedals.
Second, while it is true that one is exercising the muscles of the legs while using this piece of equipment, it is still difficult to get the heart rate up while relaxing in a chair. A portable exercise bike should probably be just one component of a fitness routine that also includes aerobic activity such as brisk walking, jogging, or swimming, as well as strength training activities.