The Relationship between Gait Kinetics and Normalized Gait Kinematics

Purpose: Falls in the elderly are a significant problem threatening the emotional, financial and physical well-being of older adults. As intrinsic risk factors have gained traction as significant contributors to increased falls risk, one problem with parameters such as biomechanical variables is that they are difficult to compare across individuals in raw form. To combat this issue, it may benefit researchers to focus on how scaled biomechanical variables in an effort to increase comparison capabilities. The purpose of this study was to correlate selected gait kinetics with the normalized gait kinematic measure of stride length to leg length ratio. Methods: Data collection sessions were conducted separately across 36 areas in the United States, producing an initial pool of 850 subjects. Subjects first completed a non-extensive medical history form that included a history of past falls then lengths of the right and left legs of each subject were measured to the nearest 0.01cm and recorded. Lastly, gait data were collected by The Electronic Caregiver Co. (ECG), Mobile Fall-Risk Assessment Unit from a pressure sensitive walkway (Tekscan, Boston, MA.) where each subject walked across at their own pace. After trials, all data was converted to digital format in a deidentification process by the Electronic Caregiver® Mobile Falls Risk Assessment Laboratory team then sent to New Mexico State University Laboratorio de Biomechanica (NMSU-LdB) for subsequent analysis. Results: Impulse, maximum force, and peak pressure with regards to standard deviation showed to be only slightly varied (≤1 difference) while the other variables had a greater difference in standard deviation when comparing the right and left leg. There was greater overall deviation in the right leg than left excluding max peak pressure which shows a minimal of 3.2% greater in the left leg than the right leg. All variables were correlated to stride length to leg length ratio, but the normalized variables had a stronger correlation (p < 0.01) than the non-normalized variables on both the right and left sides. Conclusion: These data indicate there are significant correlations between right and left leg maximum resultant ground force reaction, maximum peak pressure and impulse and stride length to leg length ratio. These relationships may provide a possible normalization factor allowing gait characteristics to be compared across individuals of different builds.