Do Rocker-Bottom 'Shape-Up' Shoes Actually Work?

A class-action lawsuit challenges the technology's vaunted health claims.


You know those sneakers with the thick, rounded soles that look like worn-down platform shoes? Your mother's friend Eileen probably wears them? Yes, those. They're supposed to be really good for you. To hear the manufacturers tell it, these miracles of modern engineering will make your extra weight slide off like melted butter and give you calves of steel. If that's the case -- aside from the fact that the wearers all look like astronauts out for a spacewalk -- it's a wonder we haven't all converted to wearing them.

But it turns out they don't work as advertised -- at least, according to a class-action lawsuit filed against Skechers, the company that's been among the most aggressive at marketing their Shape-up and Tone-up sneakers to consumers. Skechers has agreed to a $40 million settlement, but it hasn't admitted to any fault or wrongdoing in its toning-shoe promotion.

Rocker-soled shoes operate on a simple logic. Flat-soled shoes don't challenge your body much in that they're pretty stable on even terrain. But rocker-bottoms throw off your balance, demanding that your body constantly adjust to the instability. The theory, so it goes, is that your body's attempt to compensate activates muscles in ways you don't ordinarily. More activation means more muscle tone.

Skechers says its promotional claims are grounded in good science. As part of a statement in response to the class-action suit, the company's provided a list of eight studies that it argues defends its statements in advertising materials like this chart:


The text is (in)conveniently difficult to make out, but on the x-axis are speeds (3 kph, 4 kph, 5 kph and so on), while the y-axis displays what's evidently meant to be the percentage improvement over flat-soled athletic shoes (marked by the red line at 100 percent).

The FTC challenged the research, arguing that Skechers is playing fast and loose with the data:

An ad that claims consumers who wear Resistance Runner shoes will increase "muscle activation" by up to 85 percent for posture-related muscles, 71 percent for one of the muscles in the buttocks, and 68 percent for calf muscles, compared to wearing regular running shoes. The FTC alleges that in citing the study that claimed to back this up, Skechers cherry-picked results and failed to substantiate its ad claims.

Whether the research is solid is a question for other scientists to answer conclusively -- but it's worth pointing out that none of the highlighted papers make a funding disclosure, and no study had a sample size larger than 20. The paper that produced the chart you see above was the result of a six-person test in which each subject walked for three minutes at varying speeds.

In this commercial, Kim Kardashian dumps her personal trainer for a pair of Shape-ups.

From a presentation perspective, the ad is pretty misleading. Problematically, neither axis on the chart is clearly defined, leaving the impression of scientific credibility without actually spelling out what it's trying to say. Beneath the chart is an even weirder claim: "Get in shape without setting foot in a gym" -- a statement that implies there's something uniquely fitness-enhancing about rocker-bottoms that its wearers can ditch their memberships if they just buy a pair of Shape-ups. But it's also perfectly true that you can get fit without Shape-ups, without gyms, and, indeed, without any shoes at all. 

Even when you give Skechers the benefit of the doubt when it comes to the science of rocker-bottoms, the carefully worded attempt at making the mundane special without telling any untruths should give consumers pause.

Luckily, the lawsuit's settlement means that consumers who bought a pair of Shape-ups between August 1, 2008, and August 13, 2012 will be able to get their money back. The more pressing question: how will Skechers compensate us for all that time people spent looking like idiots?

Presented by

Brian Fung is the technology writer at National Journal. He was previously an associate editor at The Atlantic and has written for Foreign Policy and The Washington Post.

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