Validity and reliability of newly developed hip muscle strength tests

Abstract

healthy subjects. The work is made with regard to have a reference for analyzing subjects with lower limb prostheses and balancing arm movements. Patients/materials and methods: Ten healthy subjects (22–43 years, 7males, 3 females)with no histories for neurologic, orthopedic and vestibular diseases participated in the study. 3D-kinematic data is collected with a 12-camera Vicon system while walking on level ground as well as ascending and descending (2.5◦/5.0◦/7.5◦ inclined surfaces) at their normal self-selected speed. The Vicon’s lowerbody “Plugin-Gaitmodel” is combinedwithanupperextremity model [1] for fullbody gait analysis. A “gait-line” is defined as projection of the pelvis center (mid point of the three markers placed on the pelvis) to the floor. Step width is determined as orthogonal distance of the “foot midpoint” (mid point between ankle joint center and toe marker) to the gait-line at foot strike. Stride width is defined as sum of corresponding left and right step width. A combined center of mass for both arms together (ArmsCoM) is calculated and its position relative to the upright is determined as a projection angle in the frontal plane (ad/abduction). Results: Stride width and standard deviation is enhanced with increased inclination angle, e.g. between level walking and uphill walking on 7.5◦ inclined surface there is a mean difference about (10±20)%. The figure shows ad-/abductionmovement of the ArmsCoM normalized to 100% of a gaitcycle for different strides of the same subject. No differences are found in ArmsCoM pattern between level and up-/downhill walking on inclined surfaces with different inclination angles. Furthermore no differences are found in the amplitudes of the maximum in stance phase and the minimuminswingphaseandalsonodifferencesare found in itsposition in the gaitcycle. Discussion and conclusions: Larger stride width compensate forhigherneeds to achievemediolateral balanceduring slopewalking. Increased standard deviation can be interpreted to show less stability but for healthy subjects the arms are not involved in compensation.