Similarity of muscle synergies in human walking and cycling: preliminary results

Recent investigations on how the Motor System coordinates different tasks in humans have indicated that a low-dimensional structure of muscle synergies is sufficient to explain specific spatiotemporal components underlying such behaviors. In this work, we tested the hypothesis that pedaling and walking share common modular features by using the muscle synergies paradigm. Seven healthy subjects walked on a treadmill at their maximum speed and also cycled in an ergometer, set at the same walking cadence. EMG activity was recorded from 10 muscles of the most dominant leg. A Non-Negative Matrix Factorization algorithm was applied to extract synergies. Four synergies were sufficient to explain 90% of the EMG variability during walking and cycling. There were statistically significant correlations (higher than 71%) across similar synergies for each task (walking and pedaling). These preliminary results support the hypothesis of modular control across different human motor tasks and may indicate that some synergies are shared amongst different rhythmic movements.