Motor slacking during resisted treadmill walking: Can visual feedback of kinematics reduce this behavior?
Edward P Washabaugh, Luis H Cubillos, Alexandra C Nelson and 3 others
PMID 34564007WHAT IT FOUND
During resisted treadmill walking, knee angle dropped 17.0 degrees without feedback.
Visual feedback kept knee angle near baseline, raised muscle activity compared with no feedback, and produced larger changes that carried over.
Key findings
01Without visual feedback, resisted treadmill walking reduced knee angle by 17.0 degrees compared with baseline.
02With visual feedback, knee angle was close to baseline, and muscle activation was higher than during training without feedback.
03After training with visual feedback, peak knee flexion increased by 3.9 degrees compared with baseline; after training without feedback, it did not change significantly.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 13 participants were analysed after one exclusion, and the planned sample was 17, so the study may not have been powered for effects smaller than about 1.08. The conditions were presented in a fixed order, not randomized, and no washout was provided between the no-feedback and feedback conditions. Each training bout was only 300 seconds, shorter than a typical intervention, so longer training could change engagement or aftereffects. The two training conditions had different instructions, because participants walked naturally without feedback but matched targets with feedback, so differences may reflect task demands. Participants were able-bodied adults, not people with gait impairment.
Declared interests
Two authors are inventors on a patent for the resistive device used in the study. The article also lists NIH and U.S. government research support.
The easy way to misread this
Do not conclude that visual feedback improves clinical gait or strength. The study tested short bouts of resisted treadmill walking in 13 able-bodied adults and measured immediate knee angle, muscle activity, and aftereffects, not clinical outcomes.