Aging effects on leg joint variability during walking with balance perturbations.
Mu Qiao, Jody A Feld, Jason R Franz
PMID 29510323WHAT IT FOUND
Older adults did not scale their hip, knee, and ankle joint adjustments to increasing visual perturbations, unlike younger adults.
They showed disproportionately large variability even at the smallest disturbance, suggesting a saturated or misgraded balance response.
Key findings
01Older adults did not scale their joint-level responses progressively with increasing perturbation amplitude and were disproportionately susceptible to even the smallest amplitude perturbation.
02Compared to young adults, 20 cm perturbations increased sagittal plane hip, knee, and ankle joint variabilities by an average of 211%, 140%, and 94% more, respectively, in older adults.
03Leg joint variability was gait phase-dependent, with step-to-step adjustments in hip, knee, and ankle joint kinematics occurring predominantly during push-off and early swing.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
Small sample size (11 per group) may have affected statistical power. Continuous optical flow perturbations may elicit different responses than acute, unexpected loss of balance. Stride-averaged data from the second minute of walking may have muted immediate perturbation responses. Regression analyses cannot establish causal links between joint angle adjustments and foot placement. Fixed treadmill speed limited the capacity to respond by changing walking speed, unlike daily life. Young adult data were reanalyzed from a previous study, and treadmill speeds differed slightly between cohorts (1.25 m/s vs 1.19 m/s), though this difference was not significant.
Declared interests
None declared in the provided text.
The easy way to misread this
Do not interpret the 211% increase in sagittal hip variability as a clinical outcome or a fall prediction. This is a kinematic measure in a small laboratory sample walking on a treadmill with continuous visual perturbations, not a validated clinical test or a demonstration of a treatable deficit.