Comparison of estimated OpenSim muscle activations with EMG data of the ankle joint muscles during elderly treadmill gait

Biomechanical motion analysis approaches, such as OpenSim, are useful tools for simulating movement and estimating muscle forces and activations.In order to develop prevention strategies for elderly falls, it is important to study the mechanisms behind them, which can be achieved through motion analysis.. While OpenSim has been validated for young people, it is important to check the validity of the calculated muscle activations for elderly subjects. Therefore, this study aimed to compare the muscle activations evaluated through OpenSim’s Static Optimization tool with their EMG recordings obtained during the gait of elderly individuals, using the Cosine Similarity approach. Two healthy male elderly subjects were asked to walk at their normal pace for a minute on a split belt treadmill, while data was collected using a 3D motion capture system, two force platforms and four surface EMG sensors securely placed at the lateral gastrocnemius (LG), soleus (S), tibialis anterior (TA), and peroneus longus (PL) muscles of the left leg. Motion data collected, for ten gait cycles of each subject’s left limb, was used for OpenSim calculations with a generic full body musculoskeletal model. Finally, OpenSim Static Optimization analyses were performed to determine the muscle activations of the left limb for each gait cycle. The results showed that the calculated muscle activations had low similarity with the recorded activations, which could be due to the time shift difference between the recorded and calculated data. Therefore, further research with a larger group of participants and a wider range of muscles is needed to validate the use of OpenSim for elderly subjects.

A. Gkrekidis, G. Giarmatzis, D. Menychtas, V. Karakasis, A. Kanavaki, E. Kouli, I. Smilios, V. Gourgoulis, M. Michalopoulou, E. Douda, G. Sirakoulis, N. Aggelousis