Unveiling the underlying motor control mechanism of arm-trunk-leg coordinated humanoid exoskeletal interlimb locomotor robotic neurorehabilitation

Background Arm-leg coordinated humanoid exoskeletal robots offer a solution to the ‘unnatural’ gait patterns seen in current leg-only exoskeletons, but their neuromechanical control mechanisms require further exploration. Objective This study investigates the neuromechanical properties and modulation of cervical and lumbar central pattern generators (CPGs) across different gait training conditions. Methods Eleven healthy adults (mean age: 25.27 ± 1.95 years; 5 females, 6 males) participated in gait analysis involving kinematics, kinetics, and electromyography during treadmill-based arm-leg interlimb coordination (TIT), robot-assisted arm-leg coordination (RIT), and robot-assisted leg-only coordination (RLT). Results Trunk counterrotation and shoulder, hip, and knee kinematics in RIT closely resembled those in TIT (5–10% variance) but significantly differed from RLT (30–40% variance). Electromyography revealed normalized reciprocal activation between the anterior and posterior deltoids (r = -0.48), tibialis anterior, and gastrocnemius (r = -0.68) during RIT, while RLT showed altered agonist-antagonist co-activation (r = 0.84). Conclusions These findings highlight the importance of cervical and lumbar CPG interaction in natural locomotion, suggesting that arm-leg coordinated exoskeletons could improve neurorehabilitation for individuals recovering from stroke or spinal cord injury.