Perturbation Training for Fall-Risk Reduction in Healthy Older Adults: Interference and Generalization to Opposing Novel Perturbations Post Intervention.

Tanvi Bhatt,Yiru Wang,Shuaijie Wang,Lakshmi Kannan

doi:10.3389/fspor.2021.697169

Tanvi Bhatt, Yiru Wang + Show 2 more

Open Access

https://doi.org/10.3389/fspor.2021.697169

Copy DOI

Abstract

This study examined the effects of perturbation training on the contextual interference and generalization of encountering a novel opposing perturbation. One hundred and sixty-nine community-dwelling healthy older adults (69.6 ± 6.4 years) were randomly assigned to one of the three groups: slip-perturbation training (St, n = 67) group received 24 slips, trip-perturbation training (Tt, n = 67) group received 24 trips, and control (Ctrl: n = 31) group received only non-perturbed walking trials (ClinicalTrials.gov NCT03199729; https://clinicaltrials.gov/ct2/show/NCT03199729). After training, all groups had 30 min of rest and three post-training non-perturbed walking trials, followed by a reslip and a novel trip trial for St, a retrip and a novel slip trial for Tt, and randomized novel slip and trip trials for Ctrl. The margin of stability (MOS), step length, and toe clearance of post-training walking trials were compared among three groups to examine interferences in proactive adjustment. Falls, MOS at the instant of recovery foot touchdown, and hip height of post-training perturbation trials were investigated to detect interferences and generalization in reactive responses. Results indicated that prior adaptation to slip perturbation training, resulting in walking with a greater MOS (more anterior) and a shorter step length (p < 0.01) than that of the Ctrl group, would be associated with a greater likelihood to forward balance loss if encountered with a trip. The trip adaptation training mainly induced a higher toe clearance during walking (p < 0.01) than the Ctrl group, which could lead to reduced effectiveness of the reactive response when encountered with a novel slip. However, there was no difference in the reactive MOS, limb support, and falls between the control group and the slip and trip training groups on their respective opposing novel perturbation post-training (MOS, limb support, and falls for novel slip: Tt = Ctrl; for the novel trip: St = Ctrl, both p > 0.05). Current findings suggested that, although perturbation training results in proactive adjustments that could worsen the reactive response (interference) when exposed to an unexpected opposing perturbation, older adults demonstrated the ability to immediately generalize the training-induced adaptive reactive control to maintain MOS, to preserve limb support control, and to reduce fall risk.

Highlights

Falls are the leading cause of injury-related deaths among older adults regardless of their physical function and activity level (Rubenstein et al, 1994; Morley, 2002; Spaniolas et al, 2010)
Our prior preliminary results from young adults showed that post-perturbation training, adaptation within proactive control, which is involved with the upcoming context prediction, will be prone to a greater interference when exposed to an opposing perturbation (Bhatt et al, 2013)
Our central hypothesis was that the central nervous system (CNS) can still recalibrate its motor strategies based on the commonalities in the reactive control of stability to generalize the previously learned strategies and to mitigate or overcome any negative interference in the proactive control of stability induced by the opposing perturbation

Summary

Introduction

Falls are the leading cause of injury-related deaths among older adults regardless of their physical function and activity level (Rubenstein et al, 1994; Morley, 2002; Spaniolas et al, 2010). Large environmental postural disturbances most often lead to slip- or trip-related falls, which comprise 28–53% of outdoor falls (Luukinen et al, 2000; Talbot et al, 2005; Antes et al, 2013). The subsequent cost is high after fatal or non-fatal falls (Milat et al, 2011; Towne et al, 2014), and the induced fear of falling leads to activity reduction (Tinetti et al, 1986), diminishing the quality of life of older adults. Due to such vast consequences of falls (social and economic), strengthening the defenses of older adults against falls is imperative

Objectives

Methods

Results

Conclusion