Speed, resistance, and unexpected accelerations modulate feed forward and feedback control during a novel weight bearing task.
Shih-Chiao Tseng, Keith R Cole, Michael A Shaffer and 3 others
PMID 28043056WHAT IT FOUND
In healthy adults, faster single-leg squat tracking and more brake resistance increased knee movement errors.
Unexpected brake release produced larger error and force responses at high speed and resistance. Quadriceps activity increased and hamstrings inhibited.
Key findings
01During unperturbed cycles, increasing movement speed produced a linear increase in movement error.
02When the brake was released unexpectedly, error and force changed at a greater rate when speed or resistance was higher.
03During the perturbation response, quadriceps activity increased with higher resistance, while lateral hamstrings decreased relative to the knee extensors.
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 healthy adults with no acute or ongoing orthopedic, neuromuscular, or neurological deficits. Only the dominant leg was tested. The order of the nine conditions was fixed across subjects. Each condition was tested in one trial per subject. The study was a single session. EMG was collected in a subset of subjects. Subjects received real-time visual feedback during the task. The study did not test people with gait or posture impairments.
Declared interests
The authors reported no conflict of interest.
The easy way to misread this
Do not read this as evidence that perturbation training improves patient balance or function. The study tested healthy adults in a laboratory task and did not measure patient outcomes.