Visual presentation of simulated muscle activation colors promotes the coordination of complex motor skill learning

Recent studies have shown that AO+MI (Action Observation and Motor Imagery) based on visual-guided demonstration models effectively enhances the learning of complex motor skills. However, the role of essential information in these demonstration models has not been fully explored. Given the importance of visual guidance in AO+MI, we hypothesize that muscle activation color visual guidance can further improve learning efficiency. To test this, we developed demonstration videos using the AnyBody Modeling System. Muscle synergy served as an indicator of motor skill learning efficiency. Twenty-six novice tennis players were randomly assigned to either the experimental group, which used a muscle activation color visual guidance model, or the control group, which did not. Both groups underwent a 6-week tennis serve training program with three sessions per week. Surface electromyography (EMG) was recorded from 10 muscles, and muscle synergies were extracted using non-negative matrix factorization. Results showed that in the control group, upper limb muscle activation was higher during the racquet swing and ball strike. In the experimental group, following the intervention, trunk and lower limb muscles showed increased contribution, with primary activation in the rectus femoris, gluteus maximus, and latissimus dorsi during the backhand and swing phases.