Fall-recovery training applied to individuals with chronic stroke
Date
2019
Authors
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Journal ISSN
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Publisher
University of Delaware
Abstract
Individuals with chronic stroke have a fall risk that is twice that of age- and sex-matched peers. A third of falls in this population are from a trip or a slip. An impaired ability to recover from anterior and posterior falls likely contributes to this high risk of trip- and slip-related falls. Although neural factors underlie the impaired fall-recovery response of those with stroke, the subsequent effects of lower-extremity impairment on fall-recovery kinematics are not well understood. Such kinematics are important, as they are determinants of fall-recovery success. By addressing this unknown, we hope to identify specific targets for interventions to improve recovery from common fall causes. ☐ Traditional exercise has not reduced falls in those with chronic stroke. Perturbation-based balance training, a specific form of exercise that targets fall-recovery, has reduced falls in other at-risk populations. The extent to which, and specific means by which fall-recovery training benefits those with chronic stroke, however, is not known. If the fall-recovery response of this population is improved with practice, then the efficacy of exercise in reducing falls may be improved. ☐ The purpose of this study was to determine the effects of lower limb, stroke-related impairment on anterior and posterior fall-recovery performance, and then determine the benefits of exercise focused specifically on improving fall-recovery skill. We hypothesized that compensatory steps with the paretic limb would be associated with worse fall-recovery performance and kinematics. We also hypothesized that such aspects would improve with specific fall-recovery training. Performance was quantified as the proportion of successful recoveries within a series of perturbations, as well as the highest perturbation magnitude within that series. “Worse” kinematic features included shorter and wider recovery steps relative to the CoM, as well as larger peak trunk rotation angles and angular velocities. ☐ Fifteen relatively high-functioning individuals (29-77 years old, 2-15 years post stroke, 76-100 Activities Specific Balance Confidence Scale, 36-56 Berg Balance Scale) with chronic stroke performed up to six sessions of fall-recovery training. Each session consisted of four progressions of treadmill-induced perturbations. The four progressions focused on responding to anterior or posterior falls with the initial step being the paretic or non-paretic limb. Fall-recovery performance as well as step and trunk kinematics were compared between the initial stepping limbs in the first session. Limb-specific outcomes were also compared between the first and last training sessions. ☐ There were no between-limb differences in anterior fall-recovery performance in the first session, however, there were between-limb differences in compensatory step placement. In response to an anterior fall, steps with the paretic limb were wider and shorter relative to the center of mass (p’s < .056, d’s > 0.61). With training, participants successfully recovered from a higher proportion of anterior falls (p’s = .011, Cohen’s d’s > 0.73), progressed to larger perturbation magnitudes (p’s < .065, d’s > 0.54), initial paretic limb steps became longer (p = .034, d = 0.66), and trunk forward rotation was reduced when first stepping with the non-paretic limb (p = .029, d = 0.62). ☐ There were between-limb difference in posterior fall-recovery performance in the first session. Initial posterior steps with the non-paretic limb were associated with a higher proportion of success than initial steps with the paretic limb (p = .015, Cohen’s d = 1.26). In response to a posterior fall, steps with the paretic limb were wider relative to the center of mass (p = .011, d = 1.50). With training, participants successfully recovered from a higher proportion posterior falls (p’s < .049, d’s > 0.54), as well as progressed to larger perturbation magnitudes (p’s < .042, d’s > 0.61). There were no significant changes in kinematic variables with posterior fall-recovery training (p’s > .071, d’s < 0.51). ☐ The initial stepping limb affects relevant step kinematics during anterior and posterior fall recovery of high-functioning individuals with chronic stroke. We demonstrated that, because we saw performance-based and kinematic adaptations to the fall-recovery response, our fall-recovery training is a potentially beneficial exercise intervention for those with chronic stroke. Anterior fall-recovery training improved performance and select kinematic outcomes. Although this study provides evidence that the skill of posterior stepping in response to a fall can be improved with practice in those with chronic stroke, we were not able to identify the underlying kinematic mechanisms behind this adaptation. Further study is required to determine if this form of training is effective at reducing trip- and slip-related falls in the free-living environment in survivors of stroke. ☐