Spinal neuromotor rehabilitation using a portable isokinetic training robot

Most lower-extremity assistive robots are designed to actively assist gait 1-7 without considering long-term neuromuscular adaptations 8-11 . In this study, we present a lightweight (0.96 kg) robot that administers isokinetic resistance training to sustain neuromuscular rehabilitation after removal. The device integrates a variable stiffness mechanism with a back-drivable damping motor to make available safe, portable, and customizable resistance training to juveniles with Spinal Muscular Atrophy (SMA) type II. In a study involving 6 such juvenile participants, significant improvements in lower-extremity motor ability were observed after 6 weeks of robot-assisted training in a clinical trial (NCT06648486). Participants gained the ability to perform sit-to-stand transitions with hands on knees but without external support from an average seated knee flexion angle of 111° to 104°, representing a 7° improvement from pre-intervention. This improvement was accompanied by significantly increased bilateral knee joint function (peak torque: +130%; range of motion: +51%; work: +97%). Significant physiological quadriceps muscle hypertrophy was observed (anatomical cross-sectional area: +12%; volume: +19%; physiological cross-sectional area: +21%) alongside enhanced femoral nerve conduction (compound muscle action potential: +19%), representing physiological changes consistent with the observed functional improvements. …