Displacement MMG-based estimation of dynamic muscle viscoelasticity in the quadriceps during passive pedaling

We explore the correlation between muscle viscoelasticity and displacement mechanomyography (DMMG) during passive joint movement. Current methods for assessing muscle viscoelasticity (which is essential for rehabilitation and sports conditioning) are limited in terms of simplicity, objectivity, and portability. We introduce a novel methodology employing DMMG during passive pedaling to evaluate these properties. Participants engaged in passive pedaling at various cadences, while DMMG signals were recorded from the quadriceps, and knee joint angles measured. DMMG signals were consistent across different cadences and unaffected by muscle temperature changes due to thermal stimulation. However, the phase difference between DMMG and knee joint angle increased with cadence, reflecting an increase in the particularly viscous component of the muscle. An increase in muscle temperature reduced this phase difference, indicating that temperature influences the viscous properties of muscle as detected by DMMG. The findings suggest that the combination of DMMG and knee joint angle measurement during passive pedaling could provide a simple, quantitative method to estimate muscle viscoelasticity. Analyzing the phase difference between DMMG and joint angle may facilitate the assessment of changes in muscle viscoelasticity without the need for complex equipment. These findings can enhance the evaluation of muscle performance, contracture, atrophy, and injury prevention in both rehabilitation and sports settings.