In vivo estimation of dynamic muscle-tendon moment arm length using a wearable sensor system

In this research, the dynamic moment arm length of legpsilas muscle-tendon groups, including Soleus (SO), Tibilis Anterior (TA), Biceps Femoris Caput Breve (BS), Glusteus (GU), Vastus (VA), Iliopsoas (IL), Gastrocnemius (GA), Rectus Femoris (RF) and Hamstring (HA), was estimated in the sagittal plane based on a wearable sensor system. The wearable sensor system for body motion analysis in daily environment was used to measure kinematical data of lower extremities during gait instead of optical camera system that is laboratory-restricted. A serious of regression equations by inputting morphological parameters of lower extremities osteology was used to calculate a muscle-tendon origin-insertion coordinates in a coordinates system of musculoskeletal model. The morphological parameters of lower extremities osteology can be easily and directly measured by in vivo human body. By integration of the kinematical data and the musculoskeletal model, an algorithm was developed to estimate dynamic muscle-tendon moment arm length not only suitable for the simple articular muscles but also for the biarticular muscles. The result suggested the method in our study is feasible to estimate dynamic muscle-tendon moment arm length in human daily activities.