Walking with a powered ankle-foot orthosis: the effects of actuation timing and stiffness level on healthy users.
Marta Moltedo, Tomislav Baček, Ben Serrien and 4 others
PMID 32680539WHAT IT FOUND
Walking with a powered ankle orthosis increased metabolic cost compared to normal walking, though it reduced soleus muscle activity.
Later push-off timing and softer stiffness settings appeared more efficient, but no single configuration significantly outperformed others in healthy users.
Key findings
01Assisted walking trials had higher net metabolic costs than normal walking at the first minute, with significant increases in specific conditions.
02Soleus muscle activity was significantly reduced in assisted walking trials compared to normal walking at the last minute.
03Later push-off onset timings and more compliant actuator settings showed a trend toward better metabolic efficiency, though differences between assisted trials were not statistically significant.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only eight healthy male subjects, limiting generalizability to clinical populations or females. The sample size resulted in low statistical power for hypothesis testing. Subjects may not have reached a steady state during the 10-minute walking trials, affecting metabolic cost measurements. EMG data required manual synchronization, which could introduce errors. The study tested a unilateral device on healthy users, so findings may not apply to bilateral devices or impaired users.
Declared interests
None reported.
The easy way to misread this
Do not conclude that this device reduces metabolic cost compared to normal walking. In this study, assisted walking always had a higher metabolic cost than normal walking, even if it was lower than walking with the unpowered device.