Reebok EasyTone Women’s Footwear Case

Product testing should reflect consumers’ real world experience to ensure performance claims are meaningful.

Basis of Inquiry: As part of its routine monitoring program, NAD requested substantiation for certain performance and establishment claims made by Reebok International, Ltd. in print and Internet advertising for its EasyTone women’s footwear. The following claims formed the basis of the inquiry:

“It’s the shoe proven to work your hamstrings and calves up to 11% harder and tones your butt up to 28% more than regular sneakers just by walking.”

“Discover up to 28% more of a workout for your butt. And up to 11% more toning in your hamstrings and calves.”

“Better legs and a better butt with every step.”

Advertiser’s Position:

The advertiser responded to NAD’s request for claim substantiation by explaining that the Reebok EasyTone shoes are designed for active women aged 25–45 and are the only fitness shoes that incorporate a “balance ball” design (inspired by the BOSU balls) on the soles of the shoes to create instability to each step which, in turn, requires more muscle recruitment than normal shoes in the leg and gluteus maximus (“glutes”). The advertiser noted that it commissioned a study in 2008 at the University of Delaware, conducted by Dr. Todd Royer, Associate Professor and Assistant Chair of the Department of Health, Nutrition, and Exercise¹, and a specialist in exercise science and biomechanics, on the same technology currently found in the Easy Tone shoes. The advertiser asserted that the study was based on years of experience and accepted methodological practice in the field and is consistent with the substantiation provided to NAD in a case concerning another footwear product making toning and strengthening claims.² Dr. Royer’s study included five subjects between the ages of 18 and 35 who were randomly assigned to wear EasyTone shoes, regular walking shoes (Reebok ExpressWalk) or no shoes on an indoor treadmill at a freely chosen pace for five minutes, as electrodes placed on key muscle areas elicited electromyography (EMG) ratings which were recorded for each 30 seconds of each minute of testing. The ratings were averaged for each subject on each shoe condition. The subjects were their own control and thus each subject’s results were compared only against her own results which, the advertiser argued, reduced bias factors and extraneous variables (e.g., body type, gait) and Dr. Royer controlled for possible noise. The advertiser noted that while the study is not published, Dr. Royer’s expertise in this area compensates for this drawback, adding that NAD has never disqualified a study because it was not published and thus should accord as much credence as the studies reviewed in the Earth Footwear case.

The advertiser explained that Dr. Royer assessed the duration and amplitude (or the strength) of the muscular activation as the recorded reading would be the average for each muscle for each subject for each shoe after which he found the average reading for the calf muscle for all subjects wearing each shoe. Dr. Royer reported that average muscle reading for the hamstring was 1.190 microvolts (mv) for the EasyTone shoes versus 1.072 mv for the regular walking shoes, a difference of 11 percent; for the calf muscle, 0.570 mv for EasyTone versus 0.513 mv for regular walking shoes, a difference of 11 percent; and for the glutes, 1.821 mv for the EasyTone compared with 1.420 mv for the regular walking shoes, a difference of 28 percent, which he characterized as “compelling evidence for greater muscle activity.” Dr. Royer also noted increases in activation duration of 14 percent, five percent and 14 percent for the glutes, hamstrings and calves, respectively. Taking these results as a whole, Dr. Royer concluded “[t]he increased muscle activation amplitude and/or activation duration seen in these muscles during the EasyTone shoe condition suggest the potential exists for both greater muscle force generation and greater metabolic energy expenditure.” The advertiser referred to William McInnis, Reebok’s Head of Advanced Innovation, who explained that figures for EMGamp (how hard a muscle...