title: A systematic review of gait perturbation paradigms for improving reactive stepping responses and falls risk among healthy older adults.
abstract: BACKGROUND
  Falls are a leading cause of injury among older adults and most often occur during walking. While strength and balance training moderately improve falls risk, training reactive recovery responses following sudden perturbations during walking may be more task-specific for falls prevention. The aim of this review was to determine the variety, characteristics and effectiveness of gait perturbation paradigms that have been used for improving reactive recovery responses during walking and reducing falls among healthy older adults.
  
  
  METHODS
  A systematic search was conducted in PubMed, Web of Science, MEDLINE and CINAHL databases in December 2015, repeated in May 2016, using sets of terms relating to gait, perturbations, adaptation and training, and ageing. Inclusion criteria: studies were conducted with healthy participants of 60 years or older; repeated, unpredictable, mechanical perturbations were applied during walking; and reactive recovery responses to gait perturbations or the incidence of laboratory or daily life falls were recorded. Results were narratively synthesised. The risk of bias for each study (PEDro Scale) and the levels of evidence for each perturbation type were determined.
  
  
  RESULTS
  In the nine studies that met the inclusion criteria, moveable floor platforms, ground surface compliance changes, or treadmill belt accelerations or decelerations were used to perturb the gait of older adults. Eight studies used a single session of perturbations, with two studies using multiple sessions. Eight of the studies reported improvement in the reactive recovery response to the perturbations. Four studies reported a reduction in the percentage of laboratory falls from the pre- to post-perturbation experience measurement and two studies reported a reduction in daily life falls. As well as the range of perturbation types, the magnitude and frequency of the perturbations varied between the studies.
  
  
  CONCLUSIONS
  To date, a range of perturbation paradigms have been used successfully to perturb older adults' gait and stimulate reactive response adaptations. Variation also exists in the number and magnitudes of applied perturbations. Future research should examine the effects of perturbation type, magnitude and number on the extent and retention of the reactive recovery response adaptations, as well as on falls, over longer time periods among older adults.
authors.affiliation: NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Department of Human Movement Science, Maastricht, The Netherlands.|Institute of Movement and Sport Gerontology, German Sport University Cologne, Cologne, Germany.
authors.forename: Christopher
authors.identifier: 0000-0002-4927-1114
authors.initials: C
authors.lastname: McCrum
authors.affiliation: NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Department of Human Movement Science, Maastricht, The Netherlands.|azM Herstelzorg Centre for Geriatric Rehabilitation and Care, Maastricht, The Netherlands.
authors.forename: Marissa H G
authors.initials: MHG
authors.lastname: Gerards
authors.affiliation: Institute of Movement and Sport Gerontology, German Sport University Cologne, Cologne, Germany.|Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, London, UK.
authors.forename: Kiros
authors.initials: K
authors.lastname: Karamanidis
authors.affiliation: Institute of Movement and Sport Gerontology, German Sport University Cologne, Cologne, Germany.
authors.forename: Wiebren
authors.initials: W
authors.lastname: Zijlstra
authors.affiliation: NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Department of Human Movement Science, Maastricht, The Netherlands.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Meijer
keywords: Adaptation; Aged; Ageing; Biomechanics; Falls; Locomotion; Motor learning; Postural balance; Rehabilitation; Systematic review