Potential benefits include balance
So-called toning shoes may be best known for ads promising a better butt, but research presented in June at the annual meeting of the American College of Sports Medicine suggests the real benefits may lie outside the gluteus maximus.
By Jordana Bieze Foster
Toning shoe designs vary, but most feature an outsole sole with either a rocker shape or convex half-spheres positioned under the forefoot and rearfoot. Both types of outsole construction are designed to challenge stability during gait, theoretically promoting muscle activation and improving balance.
Of three studies on the topic presented at the ACSM meeting, only one found significantly greater muscle activation in toning shoes than in control walking shoes, and that increase was seen in the gastrocnemius lateralis. But researchers did report that toning shoes were associated with significant kinematic and kinetic changes during walking that likely reflect wearers’ efforts to maintain stability while wearing the shoes.
Two separate studies presented at ACSM, one from Utah Valley University in Orem, UT, and another from the University of Puget Sound in Tacoma, WA, found that toning shoes were associated with significantly decreased single-limb contact time during walking compared with control shoes.
The 19-participant UPS study also found that the toning shoes affected ground reaction forces, but in ways that seemed to be dependent on outsole design. A rocker-sole toning shoe was associated with significantly higher forces at midstance when compared to a control shoe or a toning shoe with a double-pod outsole. The rocker-sole shoe also had higher anterior forces than a control shoe. The double-pod shoe was associated with significantly higher forces at heel strike and higher posterior forces than the other two shoe conditions.
“I think the real potential for these shoes is in improving balance,” said Heidi Orloff, PhD, a professor of exercise science at UPS. “Balance is such an important risk factor for women over 50. If we can just get away from what these shoes are being advertised for it might make a difference.”
The 10-participant Utah Valley study found that toning shoes affected other aspects of gait mechanics as well. While wearing the toning shoes, participants walked with less rearfoot displacement, greater rearfoot angular velocity, and a foot-fall angle that was more in line with the direction of gait in the sagittal plane. The former two findings are likely related to instability, while the third suggests there may be less torque on the knee while wearing toning shoes.
But these gait changes also offer some insight into anecdotal reports of overuse-type injuries associated with toning shoes, particularly in recent converts.
“What happens is that people are so excited to have the shoes that they go out and use them all the time,” said Talin Louder, a graduate student in exercise science at UVU and coauthor of the study. “But, because their gait isn’t what they’ve been used to, that could lead to overuse injury.”
The ACSM studies were less revealing with regard to toning shoes and muscle activity, however. The UPS study analyzed electromyographic activity for five lower extremity muscles and found significant increases associated with toning shoes only for the lateral gastroc. And a six-person study from the University of Nevada, Las Vegas found that EMG activity for four calf muscles did not differ significantly between toning shoes and control shoes.
But EMG may not tell the whole story, said John Mercer, PhD, associate professor of biomechanics at UNLV.
“Will the shoe give you any added benefit? Probably not,” Mercer said. “But to me if you’re not out walking now and wearing this shoe will make you do it, then that’s a good thing. As long as you’re walking, that’s what I care about.”