Validation of forward simulations to predict the effects of bilateral plantarflexor weakness on gait

Background: Bilateral plantarflexor muscle weakness is a common impairment in many neuromuscular diseases. However, the way which severity of affects gait terms walking energy cost and speed not fully understood. Predictive simulations are an attractive alternative to human experiments as allow systematic alterations weakness. pathological have yet been validated against experimental data, limiting their applicability. Research question: Our first aim was validate predictive simulation framework for with bilateral by comparing predicted data patients Secondly, we aimed evaluate how incremental levels affect gait. Methods: We used planar musculoskeletal model 9 degrees freedom Hill-type muscle-tendon units per leg. A state-dependent reflex-based controller optimized function combining cost, activation squared head acceleration simulate For validation, strength plantarflexors reduced 80 % simulated compared 16 subjects Subsequently, stepwise its effect on kinematics kinetics, speed. Results: Simulations matched well hip ankle kinetics (R > 0.64), but less knee 0.82) strength. Significance: most changes due weakness, indicates that features emerge especially when exceeds 60 %. may support future research into pathologies or assistive devices