Effects of a powered ankle-foot orthosis on perturbed standing balance.

Only ten healthy adults took part, and none had a clinical balance impairment, so the results cannot be generalized to patients. The task used forward pushes at the pelvis and instructed no stepping, so it does not test everyday multidirectional balance or step responses. The authors state the exposure to the controllers may have been too short to demonstrate feed-forward adaptation. The EMG changes were normalized to the zero-impedance condition, and the authors state they cannot tell whether total muscle activity increased or decreased. The powered orthosis was tested with a backpack and a pusher in a research setup, not as a standalone clinical device for patients. The study had a twofold goal rather than a clearly labelled primary outcome, and the balance-performance goal was null while torque and EMG goals showed differences.

The supplied text names FP7 as funder and does not include a separate conflict-of-interest declaration.

Do not conclude that a powered ankle-foot orthosis improves standing balance or makes balancing easier for patients. In ten healthy adults, body sway and recovery time did not differ between the body-sway controller and the other conditions. For large perturbations, the person's own ankle torque decreased, but soleus activity fell while tibialis anterior activity rose, so total muscle effort was not clear.