Get Healthy!

• Posted April 16, 2026

Why Walking Remains Unsteady After Partial Spinal Cord Injury

People who’ve recovered from a spinal cord injury enough to walk continue to have trouble standing, balancing or moving smoothly – and researchers now think they know why.

The way the human body compensates for a spinal injury appears to result in herky-jerky movement on the muscular level, researchers recently reported in the Journal of NeuroEngineering and Rehabilitation.

The nervous system struggles to spread signals smoothly across muscles when people engage at low levels of muscle exertion, researchers found.

And at the other end of the scale, the nervous system overcompensates at higher levels of exertion, producing louder, less refined signals.

“After spinal cord injury the nervous system becomes more rigid and less able to change its approach as the muscles work harder,” said senior researcher Ruoli Wang, an associate professor in biomechanics at the KTH Royal Institute of Technology in Stockholm.

“A healthy nervous system on the other hand is able to adapt its strategy as force demands, to adjust the shared neural drive level," she said in a news releae.

For the study, researchers tracked muscle movement and motor coordination among 15 people recovering from partial spinal cord injuries and 10 heathy participants.

The team used skin electrical sensors to track individual motor units – the nerve-to-muscle connections that create movement. A single muscle requires hundreds of motor units to move, with each unit turning off and on precisely to create smooth force.

Participants were asked to push lightly or moderately against a force measurement device with their legs, while researchers tracked electrical activity in their calf muscles.

At 20% effort, fewer of the motor units in spinal patients’ calf muscles worked in a shared, coordinated way, resulting in shaky and unstable movements.

"They were much less being driven by the same coordinated signal from the nervous system,” lead researcher Zhihao Duan, a doctoral student at the KTH Royal Institute of Technology, said in a news release.

At 50% effort, spinal cord patients showed stronger low-frequency synchronization in calf muscles, causing the body to lose flexibility and precision, researchers said.

"This could be a sign of the nervous system compensating by sending louder, less refined signals," Duan said.

Although more study is needed in a larger number of patients, these results could help inform how a spinal cord injury reshapes motor control in people, researchers said.

"This finding may open the door to a new rehabilitation biomarker, helping clinicians and researchers design new neurorehabilitation strategies to re-tune the spinal cord control and to restore coordinated neural input," Wang said.

More information

The National Institutes of Health has more on spinal cord injury.

SOURCE: KTH Royal Institute of Technology, news release, April 14, 2026