Effects of toning shoes on lower extremity gait biomechanics.

BACKGROUND The Reebok Easy Tone shoe concept was developed to induce instability during walking and standing with the primary purpose of increasing muscle activity of the lower extremity muscles. To the authors' knowledge, no scientific work has been published, which analyzed neuromuscular and biomechanical effects when walking and standing with Reebok Easy Tone shoes. Therefore, the purpose of this study was to investigate the immediate effects of using such footwear on gait biomechanics for the lower extremity in healthy participants. METHODS Five healthy female and seven healthy male participants volunteered to participate in this study. During quiet standing, centre of pressure excursion was determined. 3D gait analyses were performed with simultaneously collecting surface electromyography data of the leg muscles when walking with regular shoes and with Reebok Easy Tone shoes. FINDINGS Centre of pressure excursion did not show any significant differences. For walking, only slight differences were found in kinematics and kinetics. When walking with Reebok Easy Tone shoes, the first vertical peak of the ground reaction force was significantly increased as well as the maximum plantarflexion moment during initial contact and loading response. Mean muscle activation for vastus medialis and lateralis showed an increase during the second half of stance, but failed to reach significance. INTERPRETATION Results of this study did not show any increased instability during standing and only a slight increase of vastii activity during stance. Thus, the marketing claims that "toning shoes" could serve as a sort of training devices for lower limb muscles during walking, cannot be supported.