Biophysical Society Thematic Meeting | Canterbury 2023

Towards a More Perfect Union: Multi-Scale Models of Muscle and Their Experimental Validation

Thursday Speaker Abstracts

MODELING MUSCLE COORDINATION IN WHOLE BODY MOVEMENT Anne Silverman 1,2 ; 1 Colorado School of Mines, Mechanical Engineering, Golden, CO, USA 2 Colorado School of Mines, Quantitative Biosciences and Engineering, Golden, CO, USA Muscle action drives movement dynamics. The functional roles of muscles are dependent on movement task, and organisms have a remarkable ability to achieve a wide variety of movements by adapting coordination of multiple muscles. Movement tasks have multiple and changing objectives including maintaining stability, supporting body weight, and accelerating body segments. Muscle mechanics are challenging to characterize, however, as their forces and velocities are difficult to directly measure. Musculoskeletal modeling and simulation techniques incorporate multiple muscles that coordinate to drive observed movement. We use optimization approaches to determine the muscle recruitment solution for the redundant musculoskeletal system. These approaches allow investigation of impaired and at-risk populations to evaluate device design and treatment interventions. We have identified muscle compensations that help achieve challenging task dynamics in the face of musculoskeletal deficits, but may also contribute to long-term risk of injury in muscles and joints. For example, runners with a unilateral transtibial amputation compensate for lost energy generation from the ankle plantar flexors using their hip extensors to generate positive muscle work to run faster. This greater muscle force generation contributes to higher hip joint loading compared to runners without an amputation, which may result in greater levels of joint degeneration and pain over long durations. In military service members, the demand for hip extensor muscle forces is especially high when carrying heavy backpacks up steep walking slopes. Due to their differing architecture, hamstring muscles produce different levels of concentric and eccentric muscle work, explaining disparate injury prevalence in these muscles. To maximize human performance and minimize injury risk, we must characterize multi-muscle coordination effectively at the organism level. Furthermore, incorporating variation across individuals will improve personalized training and treatment.

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