Effects of Different Stiffness Settings During Robotic Isokinetic Training in Children With SMA

This randomized, within-participant, contralateral-limb-controlled clinical trial will compare individually optimized compliant and rigid stiffness settings of a portable isokinetic knee training robot in children with spinal muscular atrophy. At least 13 children aged 6 to 12 years will be enrolled. For each participant, one leg will be randomly assigned to the compliant setting and the contralateral leg to the rigid setting using sequentially numbered, opaque, sealed envelopes. Both legs will receive the same training volume, number of repetitions, and angular velocity for up to 8 weeks. The primary outcome is the between-setting difference in the change from baseline in peak isokinetic knee-extension torque. Secondary outcomes include knee-extension range of motion, quadriceps cross-sectional area on magnetic resonance imaging, femoral nerve conduction measures, and sit-to-stand performance. Knee pain, suprapatellar skin temperature, fatigue, and other adverse events will be monitored throughout the study.