Dimensionality effect of myoelectric-controlled interface on the coordination of agonist and antagonist muscles during voluntary isometric elbow flexion and extension

This study aimed to investigate the dimensionality effect of myoelectric-controlled interface (MCI) on the coordination of agonist and antagonist muscles during voluntary isometric elbow flexion and extension. Eighteen healthy subjects were recruited to control a controllable cursor to track a target cursor by real-time modulating the biceps and triceps activities within one-dimensional and two-dimensional MCIs. Electromyographic (EMG) signals were collected to calculate the normalized muscle activation, while the slope of the best-fitting linear relationship between the normalized agonist and antagonist activations was used to quantify the muscle co-activation. The tracking error and the normalized net torque of the elbow joint were also calculated. Results showed that no significant difference was found in the tracking error between one-dimensional and two-dimensional MCIs. The normalized antagonist activation, the muscle co-activation and the normalized net torque were significantly lower within two-dimensional MCI than within one-dimensional MCI. In addition, significant decrease in the normalized agonist activation was also found during elbow extension. These results implied that within two-dimensional MCI, subjects were able to modulate the coordination of agonist and antagonist precisely by inhibiting unnecessary muscle activities. Therefore, two-dimensional MCI might be applied as a rehabilitation tool aiming at fine control of abnormal muscle coordination.