Gender differences in lower extremity gait biomechanics during walking using an unstable shoe.

BACKGROUND In recent years several unstable shoe designs that cause increased instability at the ankle joint have been developed with the aims of training static and dynamic posture and postural control. However, earlier research found significant gender differences in the generation of ankle torque and in the reaction times after a perturbation. Therefore it is possible that men and women are affected differently by the instability that unstable shoes create. The purpose of this study was to investigate if gender differences exist a) during bilateral quiet stance or b) in lower extremity gait kinematics and kinetics when using unstable shoes. METHODS Seventeen females and seventeen males were included in this study. Masai Barefoot Technology shoes were used as test shoes. Center of pressure excursion was recorded during 30s bilateral quiet stance trials using a force plate. Joint angles, resultant joint moments and joint moment impulses during walking were determined using standard gait analysis methods. FINDINGS In bipedal stance, female subjects had significantly greater anterior-posterior center of pressure excursion than male subjects. In the stance phase of the gait cycle gender differences were found in the ankle joint moments which had not been reported in earlier studies using barefoot or normal shoe conditions. INTERPRETATION The results suggest that women and men use different strategies to control the ankle joint when standing or walking in unstable shoes. Gender effects should therefore be taken into consideration if functional or therapeutic effects of unstable shoes are assessed.