Balance recovery stepping responses during walking were not affected by a concurrent cognitive task among older adults

(2022) 22:289 Paran et al. BMC Geriatrics https://doi.org/10.1186/s12877-022-02969-w Open Access RESEARCH Balance recovery stepping responses during walking were not affected by a concurrent cognitive task among older adults Inbal Paran1, Hadas Nachmani1, Moti Salti2*, Ilan Shelef3 and Itshak Melzer1* Abstract Background: Most of older adults’ falls are related to inefficient balance recovery after an unexpected loss of balance, i.e., postural perturbation. Effective balance recovery responses are crucial to prevent falls. Due to the considerable consequences of lateral falls and the high incidence of falls when walking, this study aimed to examine the effect of a concurrent cognitive task on older adults’ balance recovery stepping abilities from unannounced lateral perturbations while walking. We also aimed to explore whether cognitive performance accuracy is affected by perturbed walking and between task trade-offs. Methods: In a laboratory-based study, 20 older adults (> 70 years old) performed the following test conditions: (1) cognitive task while sitting; (2) perturbed walking; and (3) perturbed walking with a concurrent cognitive task. The cognitive task was serial numbers subtraction by seven. Single-step and multiple-step thresholds, highest perturbation achieved, 3D kinematic analysis of the first recovery step, and cognitive task performance accuracy were compared between single-task and dual-task conditions. Between task trade-offs were examined using dual-task cost (DTC). Results: Single-step and multiple-step thresholds, number of recovery step trials, number of foot collision, multiplestep events and kinematic recovery step parameters were all similar in single-task and dual-task conditions. Cognitive performance was not significantly affected by dual-task conditions, however, different possible trade-offs between cognitive and postural performances were identified using DTC. Conclusions: In situations where postural threat is substantial, such as unexpected balance loss during walking, balance recovery reactions were unaffected by concurrent cognitive load in older adults (i.e., posture first strategy). The study was approved by the Helsinki Ethics Committee of Soroka University Medical Center in Beer-Sheva, Israel (ClinicalTrials.gov Registration number NCT04455607, ID Numbers: Sor 396–16 CTIL; 02/07/2020). *Correspondence: ; 1 Schwartz Movement Analysis & Rehabilitation Laboratory, Department of Physical Therapy, Recanati School of Community Health Professions, Faculty of Health Sciences, Ben-Gurion University of the Negev, P.O.B. 653, 84105 Beer‑Sheva, Israel 2 Scientific Head of the Brain Imaging Research Center (BIRC), Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, 84105 Beer‑Sheva, Israel Full list of author information is available at the end of the article © The Author(s) 2022. 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The Creative Commons Public Domain Dedication waiver (http://creativeco mmons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Paran et al. BMC Geriatrics (2022) 22:289 Page 2 of 13 Keywords: Falls, Dual-task, Balance-perturbations, Compensatory-reactions Introduction Falls among older adults can be catastrophic, as they may lead to serious injuries and medical complications such as head injuries, hip fractures and even death [1]. The majority of falls (approximately 60%) in older adults are related to inefficient recovery after an unexpected balance perturbation (e.g. slips, trips and missteps; collisions or other interactions with the environment; surface translation for instance in public transport) [2]. When balance is lost unexpectedly compensatory recovery responses are evoked in an attempt to regain balance [3], meaning to return the center of mass to the center of base of support [4]. Therefore, effective balance recovery responses are crucial to prevent falls when balance is lost unexpectedly. Selection and engagement of balance recovery response strategies depend on the integration of many sensorimotor processes which tend to deteriorate with age [5] and, in turn, affect recovery response efficacy. For example, older adults use more steps to recover balance (i.e., multiple steps), exhibit more foot-collisions in their recovery responses, as well as unsuccessful balance recovery maneuvers (i.e. fall into a harness) after stance perturbations [3, 6]. In addition, older adults tend to respond with a recovery step at lower perturbation magnitudes [6, 7] and tend to fall sideways which accounts for almost all hip fractures [1]. Compared to young adults, kinematic analyses of older adults’ recovery stepping responses during walking demonstrate slower recovery step initiation time, shorter step length, and larger safety margins of stability [8]. In addition, cognitive abilities also decline with age [9, 10], especially pre-frontal functions such as executive functions and attention [10]. Studies examining interactions between cognitive and postural functions indicate that though pre-frontal cognitive resources are deteriorating, older adults tend to increase reliance on these resources for motor control tasks compared to young adults [11]. The critical role of cognitive resources in postural functions has been demonstrated in imaging studies [12] and in kinematic research applying the dual-task (DT) methodology [13–15]. DT studies allow researchers to explore cognitive-motor interference, often referred to as DT costs or DT effects [16, 17]. DT effects elucidate trade-offs between postural and cognitive tasks as well as task prioritization [16, 17], and thus allow examination of interactions between cognitive recourses and postural functions. In DT studies with both young and older adults, the interaction between cognitive resources and balance recovery responses to stance or walking perturbations, is demonstrated by decreased performance on postural tasks, cognitive tasks, or both [18–24]. Several studies reported situations in which DT conditions did not affect cognitive or balance recovery performance to unexpe (...truncated)