Sensory Modulation of Gait Balance in Human Locomotion: A Neuromusculoskeletal Modeling Study

Maintaining balance during gait relies on intricate sensorimotor processes, engaging compensatory muscle actions and reflex modulations to counteract external perturbations and prevent falls. This study aims to identify possible muscle reflex parameters that are modulated to maintain balance in the face of external perturbations through neuromechanical simulations. A reflex-based neuromusculoskeletal model is utilized and subjected to four distinct sagittal-plane perturbation types (two whole body linear momentum (WBLM) and two whole body angular momentum (WBAM) applied to the torso at five different timings. Analysis of the correlation between reflex parameters and their impact on perturbation recovery indicates seven key reflex parameters as strong candidates for modulating gait balance. For WBLM perturbations, our findings indicated the contribution of both stance and swing phase strategies by modulating Soleus positive force feedback and Iliopsoas activity. In WBAM perturbations, Vasti positive force feedback emerged as a crucial reflex contributing to knee joint stability in backward torque perturbation. The study suggests leg adjustments as a primary strategy for recovering from forward torque perturbations, achieved by modulating hamstring positive force feedback and increasing Iliopsoas muscle activation during the swing phase. These findings provide new insights into the underlying mechanisms of reflex modulation and its significance in balancing and recovering from perturbations during locomotion.