Faculty Mentor(s)

Dr. Brooke Odle, Engineering

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Lower back pain is one of the most common injuries involving healthcare workers who perform manual patient-handling tasks. Currently, no freely available subject-specific model to explore internal joint loading during these tasks exists. A proof-of-concept study to simulate squatting tasks with the OpenSim Lifting Full-Body (LFB) Model is presented. Thirty-nine reflective markers were placed on bony landmarks of the upper and lower body of a 20-year old able-bodied female volunteer. Ten electromyography (EMG) sensors were placed bilaterally on the following muscles; lumbar erector spinae, thoracic erector spinae, rectus femoris, rectus abdominis, and the external obliques. Position (100 Hz), ground reaction forces (1000 Hz), and muscle activity (1000 Hz) data were synchronized and captured while the subject performed five squats for four trials. Kinetic data were down-sampled to 100 Hz. Kinematic, kinetic, and EMG data (after rectification) were filtered with a fourth order Butterworth filter with a cut-off frequency of 6 Hz. EMG signals for each muscle were normalized to its average maximum peak value across all four trials and resampled to 100% of the squat. Scaling, Inverse Kinematics, Inverse Dynamics, and Static Optimization were performed in OpenSim. The left lumbar erector spinae and bilateral rectus femoris were the most active during the exercise, which suggests quadriceps should be included in the model. Reserve actuators were added to the model to help the static optimization simulations to converge. The values for each joint coordinate of the reserve actuators are less than 5 percent which suggests the reserve actuators did not contribute too much to the movement and these results are acceptable. Pilot results suggest that the LFB Model may be used to simulate simple squatting tasks. After some modifications, the LFB Model may ultimately be used to simulate patienthandling tasks and provide insight on low back loading during patient-handling tasks.


Research reported in this publication was supported in part by funding provided by the National Aeronautics and Space Administration (NASA), under award number NNX15AJ20H, Michigan Space Grant Consortium and the Ernest Haight Summer Research Fund in Engineering.

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