Michelle C Walaszek1, Amanda L Ransom1, Steven Capehart1, Michael B Pohl2, Robert Shapiro1, Lance M Bollinger3. 1. Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, KY, United States. 2. Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, KY, United States; Department of Exercise Science, University of Puget Sound, Tacoma, WA, United States. 3. Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, KY, United States; Center for Muscle Biology, University of Kentucky, Lexington, KY, United States. Electronic address: Lance.bollinger@uky.edu.
Abstract
BACKGROUND: Excess body mass alters gait biomechanics in a distribution-specific manner. The effects of adding mass centrally or peripherally on biomechanics during sitting and rising from a chair are unknown. METHODS: Motion analysis and lower extremity EMG were measured for fifteen healthy, normal weight subjects during sit-to-stand (SitTS) and stand-to-sit (StandTS) from a chair under unloaded (UN), centrally loaded (CL), and peripherally loaded (PL) conditions. RESULTS: Compared to UN, PL significantly increased support width (SitTS and StandTS), increased peak trunk flexion velocity (SitTS), and trended to increase peak trunk flexion angle (SitTS). During StandTS, CL significantly reduced peak trunk flexion compared to UN and PL. EMG activity of the semitendinosus, vastus lateralis and/or medialis was significantly increased in CL compared to UN during SitTS and StandTS. CONCLUSIONS: Adding mass centrally or peripherally induces contrasting biomechanical strategies to successfully sit or rise from a chair. CL limits trunk flexion and increases knee extensor muscle activity whereas; PL increases support width and trunk flexion, thus preventing increased EMG activity.
BACKGROUND: Excess body mass alters gait biomechanics in a distribution-specific manner. The effects of adding mass centrally or peripherally on biomechanics during sitting and rising from a chair are unknown. METHODS: Motion analysis and lower extremity EMG were measured for fifteen healthy, normal weight subjects during sit-to-stand (SitTS) and stand-to-sit (StandTS) from a chair under unloaded (UN), centrally loaded (CL), and peripherally loaded (PL) conditions. RESULTS: Compared to UN, PL significantly increased support width (SitTS and StandTS), increased peak trunk flexion velocity (SitTS), and trended to increase peak trunk flexion angle (SitTS). During StandTS, CL significantly reduced peak trunk flexion compared to UN and PL. EMG activity of the semitendinosus, vastus lateralis and/or medialis was significantly increased in CL compared to UN during SitTS and StandTS. CONCLUSIONS: Adding mass centrally or peripherally induces contrasting biomechanical strategies to successfully sit or rise from a chair. CL limits trunk flexion and increases knee extensor muscle activity whereas; PL increases support width and trunk flexion, thus preventing increased EMG activity.
Authors: Evelien Van Roie; Stijn Van Driessche; Bas Huijben; Remco Baggen; Rob C van Lummel; Christophe Delecluse Journal: PLoS One Date: 2019-01-17 Impact factor: 3.240