Stiffness estimation of the vastus lateralis muscle in quiet standing

Abstract

This study aims to estimate stiffness of the vastus lateralis muscle in quiet standing using a system identification technique. Six healthy males (age 22) participated the experiment. The electrical stimulation, monopolar rectangle pulse of 500 μs and approximately 30 mA, was applied to the vastus lateralis muscle. The electrically induced reaction force was measured with a force plate. The transfer function from the electrical stimulation to the induced reaction force was identified as the 5th-order model. The model consists of two 2nd-order models and one 1st-order model. One of the 2nd-oder model provided the muscle stiffness which was 630 to 1119 N/m.