Electrical muscle stimulation or EMS is an exercise aid that uses very mild electrical current to cause your muscles to contract, under the auspices of increasing tone and fitness. Historically, EMS has been used in medical situations to help relieve muscle pain. For several years now, EMS devices have been available commercially to the general public as supplements to an exercise program.

While many manufacturers claim that EMS systems will cause people who lead a sedentary lifestyle to get into shape, there actual effectiveness is a subject of debate.

In 2002 the American Council on Exercise, a nonprofit fitness advocate, published a study on EMS in its magazine. According to the study, the type of EMS used by manufactures of abdominal exercise belts was ineffective, time consuming and often painful.

This led to injunctions against the makers of certain EMS products for false and misleading advertisements. The manufacturers were claiming their products would lead to a loss in body fat and an increase in muscle tone, helping people achieve ideal "six-pack" abs. During the study, subjects underwent EMS "training," according to the guidelines of the products' manufacturer for eight weeks. The subjects did not lose any body fat or gain any muscle strength from using EMS alone. The researchers who conducted the study implied that EMS had no intrinsic value and could not serve as a replacement for weight training and other conventional forms of exercise.

That said, EMS does have its proponents. Olympic sprinting coach Charlie Francis published an article in Testosterone magazine about the history and benefits of EMS.

He recommends EMS as a supplement to a weight-lifting and exercise program, citing its effectiveness in conjunction with conventional exercise.

Francis said he encourages athletes to use EMS as a low-intensity exercise to help them increase circulation and recover form their more intense, regular exercise routines. He also recommended EMS as a way for bodybuilders to increase muscle density or burn off a tiny layer of fat before an exhibition.

However, Charlie Francis explicitly says EMS alone will not lead to the same results as a conventional exercise and weight lifting program. He says that EMS has use as a training device and for muscle rehabilitation, but that the idea that one can use EMS in place of good, old-fashioned weight lifting, running, calisthenics and other forms of resistance training and gain a rock hard, weight-lifter's body does not make sense.

So, we can now see that the value of EMS is a subject of discussion and research. Many people believe EMS machines are dangerous and not very useful, a scam promising to make sedentary couch potatoes think they can get fit without moving. Others see EMS as a medical technology appropriate for rehabilitation or a fitness technology useful for professional athletes, bodybuilders and hardcore fitness buffs.

Whatever the uses of EMS may be, it seems that the experts can agree on one thing. Using EMS alone is not a replacement for weight-lifting. If you're considering spending hundreds of dollars on an EMS machine, your money might be better spent on a gym membership or a nice set of weights.