The fastest growing market segment in the footwear business is "toning shoes."  You've probably seen the ads on TV for Skechers and Reebox shoes with a rocker bottom design that claims to tone the body just by walking in them.  Ads for the shoes promise you everything from reducing joint stress to burning more calories to increasing the size of your calf muscles.  But do these shoes deliver what they promise? 

The common idea behind all of the "toning shoes" is that the sole has features that create a natural instability that causes the body to work a little harder to maintain its natural balance.  This extra work is supposed to stimulate and exercise the body's supporting muscular system.

Most "toning shoes" are specifically for walking.  However, both Skechers and Reebox have introduced shoes that claim to be suitable for running.  The Skechers ad shown below is interesting for the precision of the claimed benefits, e.g., helps to burn up to precisely 13.2% more calories.  The claim that you will get more by running less in Skechers actually sounds like you will work harder and go slower. 

Skechers Resistance Runner	Reebox RunTone

Reebox also has a "toning shoe" marketed as suitable for running.  The ad for the RunTone claims their patented sole technology "features 8 pods of moving air that force your muscles to work harder, encourages increased muscle activation, toning, strength and endurance."

Even New Balance, a well-respected running shoe company has jumped on the band wagon with a rocker sole product called "rock & tone, a walking shoe that helps you look good even after you take it off."  A legal disclaimer in the ad on the New Balance website cautions, "Product to be used for walking only.  This product is specifically designed for walking and normal daily use.  This product is not intended to be used, nor should it be used, for any other athletic endeavor.  Use of this product in an athletic endeavor, outside of walking, may increase the risk of sustained injury."

Of all the major players in the athletic shoe business, only Nike doesn't have a product in the category and reportedly is not comfortable with the claims being made about what "toning shoes" could do for the consumer.

Nike is most likely right even though it is currently costing them market share, especially with female customers.  A study released by the nonprofit American Council on Exercise (ACE) found that the shoes failed to live up to the promises the manufacturers of the shoes made.  ACE researchers conducted two studies.  The first focused on calorie burning while walking 3.0 to 3.5 miles per hour on a treadmill, with and without incline.  The second looked at muscle activation for all of the muscles the toning shoes say they tone (hamstrings, glutes, abs, quads, etc.)  This independent study found no statistical difference between calorie burning or muscle activation between Skechers Shape-Ups, Reebok EasyTone, MBT and regular New Balance running shoes.  You can check out the study here:  http://www.acefitness.org/getfit/studies/toningshoes072010.pdf

The council's chief science officer Cedric X. Bryant said that the shoes "are not the magic solution consumers were hoping they would be, and simply do not offer any benefits that people cannot reap through walking, running or exercising in traditional athletic shoes."  Others quoted in the study say that not only do the shoes not help, but they also can lead to further injury including strained Achilles tendons.