H-reﬂex conditioning during locomotion in people with spinal cord injury

J Physiol, 2021 · DOI: 10.1113/JP278173 · Published: June 19, 2019

Spinal Cord Injury Neurology Neurorehabilitation

Simple Explanation

In individuals with incomplete spinal cord injury (SCI), modifying a spinal reflex through operant conditioning can lead to improved locomotion. This study introduced a new dynamic protocol that aims to change the functioning of the reflex pathway during a specific phase of a complex movement, specifically down-conditioning the soleus H-reflex during the swing-phase of locomotion. This new protocol decreased the reflex much faster and farther than previous steady-state protocols and the reflex decrease persisted for at least 6 months after conditioning ended, also improving locomotion.

Study Duration

Not specified

Participants

13 adults with impaired locomotion due to incomplete SCI

Evidence Level

Not specified

Key Findings

1
Swing-phase conditioning decreased the conditioning H-reﬂex more than did steady-state conditioning.
2
Conditioning during the late-swing phase of walking decreased the control H-reﬂex more than conditioning during standing.
3
Swing-phase conditioning, the average values of the conditioned and control H-reﬂexes for conditioning sessions 7–12 were significantly less than those for the baseline sessions.

Research Summary

This study introduces a new protocol, comprising a dynamic protocol that aims to change the functioning of the reﬂex pathway during a speciﬁc phase of a complex movement. With swing-phase down-conditioning, the H-reﬂex decreased much faster and farther than did the H-reﬂex in all previous animal or human studies with the steady-state protocol, and the decrease persisted for at least 6 months after conditioning ended. These results provide new insight into the factors controlling spinal reﬂex conditioning; they suggest that the conditioning protocols targeting reﬂex function in a speciﬁc movement phase provide a promising new opportunity to enhance functional recovery after SCI or in other disorders.

Practical Implications

Enhanced Functional Recovery

Swing-phase H-reﬂex conditioning can enhance functional recovery after SCI.

Clinical Practicality

The number of conditioning sessions could be considerably reduced, thereby enhancing the clinical practicality and appeal of spinal reﬂex conditioning.

New Therapeutic Approach

Protocols that target reﬂex function in a speciﬁc movement phase offer a focused and ﬂexible new approach to improving functional recovery after SCI or in other disorders.

Study Limitations

1
The improvements were relatively modest, this probably reflected the fact that the participants already walked fairly well.
2
Demands of treadmill walking during conditioning made the swing-phase protocol inaccessible to participants with more severe locomotor impairments.
3
The study did not include a stimulation-only control group.

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