How they tested

Most exercise infomercials we examined refer to "scientific research" or "university studies" that show their product is a winner. It's true that fitness devices, including some of those we used, are often tested in labs at colleges or elsewhere. But the results may not be as impressive as they sound.

Such tests are typically small and commissioned by the company, which can choose the test parameters and the exercises with which its device is compared. The maker of a machine that works the oblique muscles might ask the lab to compare it with a basic crunch, which doesn't target the obliques. Then the company could use its product's higher oblique scores to imply superiority in its exercise infomercials. The tests don't represent an endorsement by the university, and the company can use (or not use) the results in any way it chooses.

Curious about evidence behind the claims of the tested devices, we contacted each manufacturer. If the product made a specific research claim, we asked for a copy of the research; otherwise, we asked for any evidence to back up claims from the product's infomercial, Web site, or packaging.

The founders of two companies, makers of the Ab-Doer and the Fluidity Bar, called promptly to suggest that the technology behind their products was too advanced for our experts, or even most scientists, to understand. The company that markets the AirClimber sent two free samples, which we sent back. (We accept no freebies.) The company ultimately provided the study we'd asked for. Fitness Quest, which makes the Easy Shaper Ultimate, responded that its test information is proprietary, though it provided the name and credentials of the researcher.

In the end, one maker of of the seven products that made specific research claims in infomercials, the AirClimber, turned over summaries of its data. The tests, conducted at an undisclosed lab, were adequate to back up the claims. But only one of the 11 people in the AirClimber study burned the 950 calories an hour cited in the infomercial. The average number was more like 490. (An online version of the infomercial appearing after our tests cited that average.)

The Urban Rebounder's Web site includes a description of a study mentioned prominently in the company's promotional materials—a 1980 NASA report comparing trampoline jumping with treadmill running. We obtained a copy of the study, which identified benefits to jumping but didn't name specific products. Nowhere in the NASA study did the authors call rebounding a "miracle exercise," as the Web site claims.


How we tested

We asked five fit people, three men and two women, to use each device. For abdominal and bun-and-thigh machines, we measured muscle activity in the claimed target areas by attaching electrodes to the skin over those areas. That process, called electromyography, records activity in key muscle groups. Then we measured muscle activity when panelists did other, no-cost exercises such as the bicycle maneuver, jackknife sit-ups, and crunches for abdominal muscles, and lunges and modified leg lifts for the lower body. We also used a metabolic gas analyzer to record calories burned during part of the workout that's packaged with each device. If multiple workouts were included, we typically used the most advanced ones. We estimated expected weight loss from those calorie measurements, assuming no change in daily calorie intake or additional aerobic activity.