Selective orthotic constraint of lower limb movement during walking reveals new insights into neuromuscular adaptation.
Christopher F Hovorka, Géza F Kogler, Young-Hui Chang and 1 others
PMID 38994331WHAT IT FOUND
Walking in a rigid ankle orthosis caused immediate and progressive drops in muscle activation on the treated leg, while the untreated leg showed increased activity.
This reveals a bilateral neuromuscular adaptation to mechanical constraint in healthy adults, not a treatment effect for patients.
Key findings
01In the final 5 minutes of walking with maximal ankle constraint, soleus muscle activation on the treated leg declined to 67.9% of the control condition, while tibialis anterior activation during stance declined to 88.8%.
02The untreated leg showed increased muscle activation on the treated side, with soleus iEMG rising to 102.1% and tibialis anterior iEMG rising to 109.1% of the control condition during stance.
03During the swing phase of the constrained condition, tibialis anterior activation on the treated leg increased to 106.6% of the control, contrasting with the declines seen during stance.
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 involved only 14 healthy young adults, so findings cannot be generalized to patients with stroke, cerebral palsy, or other conditions that typically require AFOs. The experimental orthosis was heavy (1.76 kg) and custom-built, which may not reflect the weight or design of commercially available devices. The walking duration was only 15 minutes, which captures early adaptation but not long-term effects or learned non-use over weeks. The study did not measure clinical outcomes like gait efficiency or patient-reported comfort, focusing solely on biomechanical and EMG data.
Declared interests
The research was supported by grants from the American Orthotic and Prosthetic Association, the National Science Foundation, and the Oak Ridge Institute for Science and Education.
The easy way to misread this
Do not assume this orthosis improves walking for patients. The study tested healthy adults, not patients with deficits, and it showed reduced muscle activation on the treated leg, which could theoretically lead to weakness or dependence if used long-term without appropriate therapy.