Lay Summary by Frank Yeung
Edited by Rona Herzog
In 2019, researchers from ICORD studied a new passive training protocol that used the Lokomat robotic gait device. As opposed to many neurorehabilitation strategies that focus on active interventions, including inducing and strengthening motor function, the training protocol used in this study was passive. The passive intervention focused on the recovery of sensory function in individuals with spinal cord injury (SCI). Specifically, this training protocol was designed to recover proprioception. Proprioception refers to our ability to recognize the position and movement of our body, and it plays a critical role in human movement control.
What were the objectives of this study?
The study had two objectives:
- The main objective was to test the effects of the researchers’ proprioception training protocol on lower limb proprioceptive sense in people with incomplete SCI.
- The secondary objective was to assess whether the benefits from training transferred to a precision stepping task for people with incomplete SCI.
The Training Protocol:
The training protocol used in this study focused on improving two aspects of proprioception, which were end-point discrimination and knee joint position sense.
- For the end-point discrimination task, the Lokomat moved one of the participant’s entire lower limb twice, resulting in a change in the participant’s heel position; the participant reported if the final position was either higher or lower relative to the starting position.
- For the knee joint position sense task, the Lokomat flexed or extended the knee, and the participant had to position the knee back to the starting position using a joystick to control the Lokomat.
Visual feedback was provided for learning after each response in the proprioception training. After the proprioception training, the participants performed a precision stepping task, where they walked on a treadmill and trained their ability to raise their foot to a target height during the swing phase.
How was the research conducted?
The researchers recruited 15 participants with incomplete SCI and 10 able-bodied participants. Participants with incomplete SCI were asked to determine the leg for which they had greater difficulty sensing position; this leg was then used in the training protocol. For able-bodied participants, their non-dominant leg was used. Before the training protocol, all participants assessed their baseline ability to sense their knee joint position and heel position. For the participants who were able to walk safely to some degree, researchers also assessed their ability to carry out the precision stepping task on the treadmill. The participants used the training protocol over two consecutive days to improve in the three tasks. Researchers tested if the participants improved their scores after the training protocol was completed.
What did the researchers find?
Researchers found that both end-point discrimination and knee joint position sense could be improved after a small amount of proprioceptive training. The extent of an individual’s improvement was related to their proprioceptive sense prior to the training protocol, where individuals who had larger deficits in proprioceptive sense showed larger improvements following training. The results also demonstrated that improvements in proprioceptive sense transferred from the end-point discrimination task to the joint position sense task, and also the precision stepping task.
Why are these findings important?
The findings of this study indicated that passive training was beneficial and had potential to become a rehabilitation intervention alongside the other protocols focused on improving limb strength, walking speed and endurance. This matched results from previous studies that also demonstrated the possibility of training an individual’s ability to sense the position of their limbs; an ability that has importance in precisely controlling the path of their feet while walking. Researchers note the importance of further studies in order to determine the long-lasting effects of such training, interactions with other therapies, and effects on rehabilitation outcomes.
Motor function: The ability to learn or demonstrate control over one’s movements and posture.
Sensory function: The ability to perceive and interpret the world around us.