Estimation of muscle and bone-to-bone forces by electromyography-assisted optimization in stair-climbing

Abstract

[Purpose] The purpose of this study was to estimate muscle forces during stair-climbing using electromyography-assisted optimization (EAO), to evaluate the validity of estimated muscle forces and to calculate bone-to-bone forces at the knee joint. [Subjects] Subjects were 6 healthy males. [Method] The muscle forces were initially estimated from electromyography (EMG) and physiological muscle properties. Joint torques obtained from the estimated muscle forces were adjusted using EAO. The bone-to-bone force at the knee joint was calculated based on the adjusted muscle forces. [Result] Applying EAO, the muscle forces exhibited good correlation with corresponding EMG patterns. The bone-to-bone force at the knee joint showed maximum values in the stance phase, 39.4±3.3 N/kg (mean±SD) in step-over-step, and 17.4±4.5 N/kg in step-by-step. [Conclusion] Our results suggest the use of EAO in estimating muscle forces during dynamic tasks is valid. © 2013 by the Society of Physical Therapy Science.