We have all seen advertisements on television or in magazines pertaining to some fitness machine or device that pledges to melt fat from your midsection, thighs or butt.
Familiar infomercials promise that fat will be burned in the abdomen by performing a certain amount of crunches on this specialized exercise device. Some of the exercises that are commonly represented by these products are abdominal crunches, assisted sit-ups, hip adduction and abduction for inner and outer thighs, as well as hip flexion and extension motions for hip flexors and gluteus muscles. Selectively targeting certain body parts for fat burn through exercise is called spot reduction, and it is a myth.
This myth aligns with people’s tendency to find quicker ways to meet their fitness goals. Many people are busy and cannot devote enough time to properly exercise. Companies exploit this concept in order to encourage the marketability of its product. Who wouldn’t want to do a set number of crunches each day and burn stomach fat with ease? Not only is this idea attractive, but it also believable. For many people, it seems plausible that the fat burn occurs in the region of the specific muscle contraction. Exercise and fat burn do not work this way, however. These machines encourage strength training of these target areas. Strength training results in hypertrophy, or muscle growth, below the layers of fat. Therefore, the same amount of fat tissue remains.
For instance, in one study, the circumference and fat composition of tennis players’ dominant arms were compared with that of their non-playing arms, in order to test the validity of spot reduction. While the individuals’ playing arms grew in circumference due to muscular hypertrophy, the skinfold thickness did not differ significantly between the active and inactive arms. Thus, there was no evidence supporting that spot reduction occurred.