ABSTRACT
The objective of this pilot study was to explore nonlinear synchronization of biceps and triceps muscles during maximum voluntary contraction (MVC) protocol for biceps muscles. Generalized synchronization indexes (S-, H-, and N-index) were utilized to explore synchronization and interdependence of bivariate biceps and triceps time series data. It was found that the more robust H-and N-index were able to distinguish the dynamical changes in three stages (pre-MVC, MVC, and postMVC) ofMVC protocol. According to the H-and N-index values, synchronization between biceps and triceps muscles was more pronounced in pre and post-MVC stage than in MVC. ANOV A analyses confirmed the significant difference (p < 0.01) of those index values between pre-, MVC, and post-MVC stages. A linear synchronization measure, cross-correlation, was utilized that failed to capture any
synchronization patterns between biceps and triceps muscles. It is argued that that nonlinear synchronization indexes could provide useful insight to the synergistic muscle activities and their relationships with respect to the task, posture control and stability.
