Reebok Easy Tones promise a nice posterior, Skechers Shape-Ups claim to give Joe Montana better posture and myriad knock-offs at stores like Target and Wal-Mart offer all the benefits at half the price.
But can so-called "fitness shoes" actually tone muscles on the walk to class? Dr. Damian Dieter, a podiatrist at the Portage Foot Clinic in South Bend, has treated some patients who have worn the shoes and has tried out a pair himself.
"It's not a cookie-cutter answer, that it's good or really bad," he said.
From working muscles to increasing circulation, the benefits described in the commercials and other promotional materials are mostly true, he said, but there are some caveats.
Dieter said people with foot problems — such as plantar fasciitis, heel spurs, bunions or arthritis — should be careful when trying out the shoes, since it might aggravate their discomfort.
"If you've got a really whacked-out foot and you think going around in these shoes, all your prayers and questions are answered, that's not the case," he said.
The most important part of any walking shoe is the heel counter, Dieter said. This "cup" in the shoe that surrounds a person's heel has to be stiff in order to keep the arch of the foot from wobbling.
Most fitness shoes do have this heel support, Dieter said. However, in most of the designs, instability in the rest of the body of the shoe is the whole point.
For example, the Reebok Easy-Tone shoes have two air chambers (what the commercials call "balance ball technology"). Dieter said the air cushion is forced from heel-to-toe, heel-to-toe, in the reverse direction of the force of the step, so the wearer is constantly working against normal walking motion.
Dieter said he tried out the Skechers Shape-Ups in a store for about 15 minutes, but did not feel stable in them.
"I constantly had to hold onto something," he said. "Now, if I wore them for a week straight, I probably would get used to it."
Forcing wearers to overcome that unsteadiness is an intentional part of the shoes' design, he said.
"Well, if you're unsteady, you clench up muscles," he said. "It's like sea legs. When you're on a boat, the boat is constantly moving, so even without thinking, you're clenching your leg muscles to stay on balance, that's why you get stronger legs."
The Skechers' website recommends going through some warm-up and adjustment exercises when first putting on the shoes, in order to adjust to the new form of walking. Re-learning how to walk shouldn't be the goal of any exercise routine, he said, especially just for one pair of shoes.
"You shouldn't have to tell your body what to do when you walk," he said. "Walking should be like breathing. You shouldn't have to say to yourself, time to breathe in now. It's an automatic response."
Additionally, Dieter said "rocker bottom" shoes like the Skechers Shape-Ups, with a curved sole, actually shorten the wearer's gait. The shoes force people to shorter, faster steps.
"It increases blood flow just because you're walking fast," he said.
But he added, "You can just do jumping jacks to get your blood flowing, too."
"People that are going to go work out with any shoe, yeah, they're going to have better circulation," he said.
While Dieter said the instability and gait-changing aspects of these shoes will help some people with posture or circulation, just wearing a different kind of footwear won't replace eating healthy or breaking a sweat.
"The marketing thing is that everybody wants to sell you something that, if you do this, you don't have to go to the gym, you don't have to watch what you eat," he said. "Everybody's got a gimmick."
