I recently read an intriguing piece in the New York Times about the growing popularity of "toning shoes", the bizarrely soled trainers that manufacturers claim will shape your butt while you just walk around. See New Balance's ad for the shoe.

Despite no independent research verifying claims of increased effectiveness, this market segment has experienced meteoric growth from sales of $17 million in 2008, to $145 million in 2009, to a projected $1.5 billion in 2010.  What has caused this growth in a category that had little growth since its definition in 1996?

A new set of 'toning' shoes with an increased focus on form factor.

You read that correctly. This specific exercise shoe segment has increased 100-fold inside two years by making cuter shoes with no proven health benefits.  Perhaps that won't surprise many given the U.S. market for exercise equipment has a strong affinity for fads and silver bullets.  

That said, the incredibly success of companies like Reebok, New Balance and Skechers provides an object lesson on the importance of listening to your prospective customers: selling consumers what they 'want to believe' doesn't require convincing them with hard data.

Companies marketing these shoes have successfully connected with consumer pathos and re-invented a product whose technology hasn't changed in over a decade.  The results may not be typical, but the players in this market are taking them to the bank, and by any measure those kinds of growth numbers mean this is good marketing.