Operant down-conditioning of the soleus H-reflex in people after stroke.
Aiko K Thompson, Christina R Gill, Wuwei Feng and 1 others
PMID 36188979WHAT IT FOUND
Half of stroke survivors successfully reduced a spinal reflex through training.
Those who succeeded walked faster by 0.14 m/s on average. The other half did not improve reflex size, but their walking speed did not worsen either.
Key findings
01Operant down-conditioning successfully reduced the soleus H-reflex in 6 of 12 participants with chronic stroke.
02Participants who successfully reduced the reflex increased their 10-meter walking speed by 0.14 ± 0.13 m/s, while those who did not reduce the reflex showed no consistent change in speed.
03There was a strong negative correlation between the final reflex size and walking speed gain, meaning those with larger reflex reductions had larger walking improvements.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
The study included only 12 participants, making it a small pilot with limited generalizability. Only half of the participants responded to the conditioning, and the reasons for this difference are unknown. The study did not measure clinical spasticity (e.g., Modified Ashworth Scale) after conditioning, so the direct link to spasticity reduction is not confirmed. Walking speed data was missing for two participants. The intervention required specialized equipment for electrical stimulation and EMG feedback, which is not typically available in standard clinical settings.
Declared interests
The authors declared no commercial or financial conflicts of interest. The work was funded by various National Institutes of Health grants and the New York State Spinal Cord Injury Research Trust.
The easy way to misread this
Do not assume that this training reduces clinical spasticity in all patients. Only half the participants achieved the reflex reduction, and the study did not measure standard spasticity outcomes. Furthermore, the non-responders showed an increase in baseline reflex excitability, suggesting the neural response to this training is complex and variable.