Many people do feel that these shoes work because of soreness in different muscles. Don't be fooled, Bryant says. The shoe's unstable sole design does cause wearers to use slightly different muscles to maintain balance, resulting in temporary soreness that will subside as the body adjusts to the shoe, he says.
That said, "If these shoes are serving as a motivator for individuals to walk or get moving more often, that is a good thing, even if they don't produce the dramatic toning and calorie-burning results people think they are getting," Bryant says.
Additional studies looking at how toning shoes affect balance over time are under way, he says.
Shoe Companies React
Shoe makers are unshaken by the ACE study on toning shoes. Leonard Armato, president of Skechers' fitness group, in Manhattan Beach, Calif, stands behind his product 100%. "I have not a doubt that the Shape-Up technology requires you to make a little more effort with each step, burn more calories, and activate more muscles," he says.
Armato does, however, have some doubts about the new study results. "This study is not published in a peer-reviewed journal, and only involved 12 young, fit women who walked for five minutes on a treadmill," he tells WebMD. "ACE represents fitness trainers who are at odds with the toning industry, and don't want toning to take root."
It's a turf war, he says. "They have the most to lose if people start walking around in these shoes as opposed to going to a gym and hiring a personal trainer."
Bill McInnis, the head of advanced innovation for Reebok, based in Canton, Mass., created the technology used in Reebok's EasyTone line. "We looked at stability balls from the gym and incorporated that same thinking into a shoe," he says. "The idea was that introducing soft, micro-instability in the shoe would cause you to have to rebalance a bit with every single step and cause your muscles to work a little harder all day long," he says.
"The new study makes bold statements without the data to back it up," he tells WebMD.