Time-dependent tuning of balance control and aftereffects following optical flow perturbation training in older adults.
Jackson T Richards, Brian P Selgrade, Mu Qiao and 3 others
PMID 31262319WHAT IT FOUND
In 13 older adults, 10 minutes of treadmill walking with virtual hallway sideways visual disturbances initially made steps wider, shorter, and legs stiffer.
Over time, step size and stiffness returned toward normal, and after stopping they took longer, narrower steps with less leg stiffness.
Key findings
01At the start of optical flow perturbations, older adults took wider and shorter steps, had much more variable step width and length, and showed roughly twice the antagonist leg muscle coactivation.
02During prolonged exposure, step length increased and leg coactivation decreased toward baseline, but step width and length variability and margin of stability variability at heel-strike stayed above baseline.
03After perturbations stopped, older adults tended to take longer and narrower steps, had 18% larger step width variability, 43% less minimum margin of stability variability, 13% more margin of stability variability at heel-strike, and less leg coactivation than at baseline.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study had 13 older adults, so the findings are too small to support clinic-wide conclusions. Participants were community-independent walkers without assistive aids and without reported neurological, musculoskeletal, cardiovascular, ophthalmological, or orthopedic disorders, so it says little about patients who need walking aids or have those conditions. Four participants had reported one fall in the previous year, but all participants were analyzed together, so fall history could not be examined as a separate group. No electromyography was collected during the control session, so reduced leg coactivation after perturbations could also have happened after prolonged unperturbed treadmill walking. The virtual hallway perturbations were not designed to resemble a specific everyday balance challenge. The study did not determine how long aftereffects last after perturbations stop. One participant had some electromyography and margin of stability data excluded.
Declared interests
The supplied text reports funding by the National Institute on Aging and does not include a conflict-of-interest declaration.
The easy way to misread this
Do not read the 10-minute virtual hallway perturbation session as proven balance training for older adults. The study had 13 independent older adults, used lab measures of step size, balance margin, and leg muscle activity, and the authors call it proof-of-concept and say larger clinical trials are needed.