Evaluation of Quadriceps Femoris by Simultaneous Measurement of Mechanomyography and Electromyography

Abstract

Athletic capability in sports and rehabilitation scenarios is generally evaluated based on parameters such as maximum muscle strength, number of repetitions, and maximum time. However, the performance of individual target muscles is not evaluated directly in many cases. It is difficult to express muscle quality quantitatively. The purpose of this study was to simultaneously perform electromyography （EMG） and mechanomyography （MMG） using an MMG/EMG hybrid transducer developed by us, and to evaluate muscle performance during pedaling exercise based on the electrical/mechanical transformations during muscle contraction. Nine healthy adult men participated in the experiment. The pedaling exercise was performed using a recumbent bicycle that can be seated and exercised. The target muscles were the vastus medialis （VM） and vastus lateralis （VL） of the quadriceps femoris, and EMG and displacement MMG （dMMG） were performed during pedaling. The cadence was constant at 30 rpm, and the pedaling work rate was varied from 30 W to 150 W in five steps of 30 W each. The measurement was performed for 30 s with a sampling frequency of 1 kHz. The study demonstrated the following: （1） The VL contributes more to pedaling than VM. This is based on the mechanical aspect of muscle contraction. （2） The correlation between EMG and dMMG indicates that the MMG / EMG ratio of VL is higher than that of VM. In conclusion, it is indicated that the combined evaluation of EMG and MMG may yield an index that reflects the muscle performance during exercise.