Article

Outdoor fallers differ from indoor fallers substantially in demographics,
lifestyle, health condition and physical function. Biomechanical predictors of
outdoor falls have not been well characterized. Current validated measures of
postural deficits, which describe only the overall postural behavior, are
predictive of indoor falls but not outdoor falls. We hypothesized that a
model-based description of postural muscle tone and reflexes, particularly during
dual tasking, would predict outdoor falls. We tested whether postural stiffness
and damping from an inverted pendulum model were predictive of future indoor and
outdoor falls among older adults from the MOBILIZE Boston Study. The center of
pressure data during standing were obtained from 717 participants aged 77.9+/-5.3
years. Participants stood barefoot with eyes open for 30s per trial, in two sets
of five standing trials. One set included a serial subtractions task. Postural
stiffness and damping values were determined from the postural sway data. After
the postural measurements, falls were monitored prospectively using a monthly
mail-in calendar over 6-36 months. Associations of postural measures with fall
rates were determined using negative binomial regressions. After covariate
adjustments, postural stiffness (p=0.02-0.05) and damping (p=0.007-0.1) were
associated with lower outdoor falls risk, but not with indoor falls. Results were
invariant by direction (anteroposterior versus mediolateral) or by condition
(quiet standing versus dual task). Outdoor fall risk may be tied to postural
control more so than indoor falls. Dual tasking is likely related to fall risk
among older and sicker older adults, but not those relatively healthy.
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Langue : ANGLAIS