Low body fat and a smart exercise program are the keys to trim and toned abdominals.
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Electrical muscle stimulation devices promise to work your abdominal muscles while you just sit there. Models sporting chiseled midsections tout their benefits, but as with many such products, there is little scientific evidence to back this up. While a 2005 University of Wisconsin Study found that one commercial device did stimulate muscles enough to improve abdominal strength, no fat loss occurred.
How EMS Works
Electrical muscle stimulation devices deliver an electrical impulse to muscle fibers, causing the fibers to contract. When this is done repeatedly for a number of minutes, the muscle fibers become fatigued enough for some minor physiological adaptations to occur. In a clinical setting, EMS devices are used on patients who have lost the ability to perform muscle contractions on their own, as in the case of spinal cord injury. Clinical devices have many small individual electrode pads or even tiny, needle-like probes reaching directly into the muscle tissue. These are very different, and much more effective, than the large pads or belts commonly seen on commercial products.
Even with expensive medical equipment, EMS devices do not build muscle. Rather, they slow or prevent muscle atrophy in newly injured individuals so that they can start a more comprehensive exercise program once they regain the ability to move. A 2005 University of Wisconsin study found that subjects using a commercial EMS device did experience significant gains in both abdominal strength and endurance. It also found that waist circumference decreased by nearly 1.5 inches on average. However, the smaller waists were not attributed to fat loss, as no changes in body mass index, body weight or skin-fold thickness occurred. It is thought that the increased muscle strength allowed subjects to better hold their stomachs in.
A 2002 study, also conducted at the University of Wisconsin, came to the same conclusion as the 2005 study: The EMS devices did stimulate the targeted muscles in study subjects but not enough to achieve any of the physiological changes promised. No decrease in body fat percentage resulted from using an EMS device. The managing director of Slendertone USA, a manufacturer of EMS devices, specifically noted in a the Wall Street Journal article that abdominal stimulation devices don't work at all for obese individuals. This is because the electrical impulse cannot penetrate through the fat to reach the muscles.
Some users of EMS devices have reported pain and, in a few cases, even shocks, burns and bruises. The Food and Drug Administration, which regulates both commercial and medical EMS devices, warned that there are devices on the market that had not undergone FDA review. This does not necessarily mean those devices are dangerous. However, they note that the FDA is not aware of scientific information supporting many of the claims used to promote these devices in advertising.