Engineering: 2nd Place (The Ohio State University Edward F. Hayes Graduate Research Forum)Due to weakened muscles or diseased joints, more than 2 million Americans over the age of 64 have difficulty accomplishing a sit-to-stand (STS) transfer independently. Previous studies have examined joint torques and muscle activations during STS by using motion capture or rigid body models. However, individual muscle forces during STS have yet to be investigated, and such knowledge will potentially inform rehabilitation strategies for patients with weakened muscles to improve performance with STS transfer. The first step toward accomplishing this goal was to examine individual muscle forces as well as inter-limb differences in muscle forces during STS transfer in a young, healthy population. Subject-specific simulations were created for each subject’s STS trial with a custom three-dimensional musculoskeletal model. Static optimization was implemented to estimate individual muscle forces. We found that vastus lateralis generated the largest force, reaching its peak value after maximum hip flexion occurred, while the medial gastrocnemius generated the smallest force out of all the muscles examined throughout STS once maximum hip flexion was reached. Inter-limb differences, quantified as a percent difference, showed high variability between subjects as the standard deviation values were over 100% for some of the muscles examined across the phases of STS. Understanding individual muscle forces as well as symmetry of muscle forces between legs during STS transfer in healthy subjects is the first step to analyzing muscle function and weakness in patients with pathologic conditions such as osteoarthritis and may potentially inform rehabilitation strategies that could improve these patients’ functional performance with this task.A one-year embargo was granted for this item
