Ilan Kurz , Yoav Gimmon , Amir Shapiro , Ronen Debi , Yoram Snir and Itshak Melzer Background: Falls are common among elderly, most of them occur while slipping or tripping during walking. We aimed to explore whether a training program that incorporates unexpected loss of balance during walking able to improve risk factors for falls. Methods: In a double-blind randomized controlled trial 53 community dwelling older adults (age 80.1±5.6 years), were recruited and randomly allocated to an intervention group (n = 27) or a control group (n = 26). The intervention group received 24 training sessions over 3 months that included unexpected perturbation of balance exercises during treadmill walking. The control group performed treadmill walking with no perturbations. The primary outcome measures were the voluntary step execution times, traditional postural sway parameters and Stabilogram-Diffusion Analysis. The secondary outcome measures were the fall efficacy Scale (FES), self-reported late life function (LLFDI), and Performance-Oriented Mobility Assessment (POMA). Results: Compared to control, participation in intervention program that includes unexpected loss of balance during walking led to faster Voluntary Step Execution Times under single (p = 0.002; effect size [ES] =0.75) and dual task (p = 0.003; [ES] = 0.89) conditions; intervention group subjects showed improvement in Short-term Effective diffusion coefficients in the mediolateral direction of the Stabilogram-Diffusion Analysis under eyes closed conditions (p = 0.012, [ES] = 0.92). Compared to control there were no significant changes in FES, LLFDI, and POMA. Conclusions: An intervention program that includes unexpected loss of balance during walking can improve voluntary stepping times and balance control, both previously reported as risk factors for falls. This however, did not transferred to a change self-reported function and FES. Trial registration: ClinicalTrials.gov Registration number: NCT01439451.

Shimada, Hiroyuki PhD, PT; Obuchi, Shuichi PhD, PT; Furuna, Taketo PT; Suzuki, Takao MD, PhD Am J Phys Med Rehabil (2004);83:493–499. Objective: To determine the effects of a perturbed walking exercise using a bilateral separated treadmill in physically disabled elderly. Method: Participants of the study were 32 long-term care facility residents and outpatients aged 66–98 years. Participants were randomly assigned to a usual exercise group or to a treadmill exercise group. Perturbed gait exercise on a treadmill continued for 6 months. Number of falls and time to first fall during a 6-month period, balance and gait functions, and reaction time were evaluated before and after intervention. Results: The treadmill exercise group showed significant improvement in balance and reaction time when compared with the usual exercise group. Number of falls in the treadmill exercise group was 21% lower than that in the usual exercise group. Conclusions: Gait training with unexpected perturbation seems to have a beneficial impact on physical function in disabled elderly individuals. The results suggest that this program may be used as an exercise intervention to reduce falls in institutional settings.

Michael J. Pavol, Eileen F. Runtz, Beatrice J. Edwards  and Yi-Chung Pai J Gerontol A. Biol Sci Med Sci (2002);57(8) Background: Fall incidence in older adults might be reduced through learning to better recover from or adjust to perturbations. Extents of age-related declines and limitations in the ability to recover are not well established. Methods: Slips were induced, using bilateral low-friction platforms, during a sit-to-stand task in 60 young and 41 older, healthy, safety-harnessed adults. Subjects underwent five slips, a block of non-slipping trials, then two re-exposures to the slip. The first slip was novel and unexpected. Age-group and trial effects on fall incidence (evidenced by excessive hip descent) and on the direction of the initial protective step were examined. Results: More older than young adults fell upon the first slip (73% vs 28%;p < .001). With repeated exposure, fall incidence decreased at similar exponential rates in both age groups. All but one subject eventually learned to slip without falling, and two-thirds of fallers fell only once. Repeat fallers fell without stepping in 63% of falls. Upon later slip re-exposure, more older than young adults fell (20% vs 2%), but fewer falls occurred than did originally (p = .001). Likelihoods of forward and backward stepping during successful recovery changed with repeated slip exposure and upon re-exposure, but did not differ between age groups. Conclusions: Older adults are more likely to fall upon initial, unexpected perturbation exposure, but, upon repeated exposure, healthy young and older adults rapidly learn to avoid falling at a similar rate. Healthy older adults appear fully capable of learning to better recover from or adjust to a perturbation through repeated exposure.

Avril Mansfield, Amy L. Peters,Barbara A. Liu and Brian E. Maki. Physical Therapy, April (2010); 90 (4) 476-49. Background: Compensatory stepping and grasping reactions are prevalent responses to sudden loss of balance and play a critical role in preventing falls. The ability to execute these reactions effectively is impaired in older adults. Objective: The purpose of this study was to evaluate a perturbation-based balance training program designed to target specific age-related impairments in compensatory stepping and grasping balance recovery reactions. Method: This was a double-blind randomized controlled trial.  The study was conducted at research laboratories in a large urban hospital. Thirty community-dwelling older adults (aged 64–80 years) with a recent history of falls or self-reported instability participated in the study. Participants were randomly assigned to receive either a 6-week perturbation-based (motion platform) balance training program or a 6-week control program involving flexibility and relaxation training. Features of balance reactions targeted by the perturbation-based program were: (1) multi-step reactions, (2) extra lateral steps following anteroposterior perturbations, (3) foot collisions following lateral perturbations, and (4) time to complete grasping reactions. The reactions were evoked during testing by highly unpredictable surface translation and cable pull perturbations, both of which differed from the perturbations used during training. Results Compared with the control program, the perturbation-based training led to greater reductions in frequency of multi-step reactions and foot collisions that were statistically significant for surface translations but not cable pulls. The perturbation group also showed significantly greater reduction in handrail contact time compared with the control group for cable pulls and a possible trend in this direction for surface translations. Conclusion Perturbation-based training shows promise as an effective intervention to improve the ability of older adults to prevent them from falling when they lose their balance.

Avril Mansfield, Jennifer S. Wong, Jessica Bryce, Svetlana Knorr and Kara K. Patterson Physical Therapy (2015); 95 (5) 700-709. Background: Older adults and individuals with neurological conditions are at an increased risk for falls. Although physical exercise can prevent falls, certain types of exercise may be more effective. Perturbation-based balance training is a novel intervention involving repeated postural perturbations aiming to improve control of rapid balance reactions. Objective: The purpose of this study was to estimate the effect of perturbation-based balance training on falls in daily life. Data Sources: MEDLINE (1946–July 2014), EMBASE (1974–July 2014), PEDro (all dates), CENTRAL (1991–July 2014), and Google Scholar (all dates) were the data sources used in this study. Study Selection Randomized controlled trials written in English were included if they focused on perturbation-based balance training among older adults or individuals with neurological conditions and collected falls data post-training. Data Extraction Two investigators extracted data independently. Study authors were contacted to obtain missing information. A PEDro score was obtained for each study. Primary outcomes were proportion of participants who reported one or more falls (ie, number of “fallers”) and the total number of falls. The risk ratio (proportion of fallers) and rate ratio (number of falls) were entered into the analysis. Data Synthesis Eight studies involving 404 participants were included. Participants who completed perturbation-based balance training were less likely to report a fall (overall risk ratio=0.71; 95% confidence interval=0.52, 0.96; P=.02) and reported fewer falls than those in the control groups (overall rate ratio=0.54; 95% confidence interval=0.34, 0.85; P=.007). Conclusions Perturbation-based balance training appears to reduce fall risk among older adults and individuals with Parkinson disease.

Avril Mansfield, PhD, Elizabeth L. Inness, MSc, Jennifer S. Wong, Julia E. Fraser and William E. McIlroy, PhD. Neural Repair  (2013); 27 (6) 526-533 Background: Individuals with stroke fall more often than age-matched controls. Although many focus on the multifactorial nature of falls, the fundamental problem is likely the ability for an individual to generate reactions to recover from a loss of balance. Stepping reactions to recover balance are particularly important to balance recovery, and individuals with stroke have difficulty executing these responses to prevent a fall following a loss of balance. Objective: The purpose of this study is to determine if characteristics of balance recovery steps are related to falls during inpatient stroke rehabilitation. Methods: We conducted a retrospective review of individuals with stroke attending inpatient rehabilitation (n = 136). Details of falls experienced during inpatient rehabilitation were obtained from incident reports, nursing notes, and patient interviews. Stepping reactions were evoked using a “release-from-lean” postural perturbation. Poisson regression was used to determine characteristics of stepping reactions that were related to increased fall frequency relative to length of stay. Results: In all, 20 individuals experienced 29 falls during inpatient rehabilitation. The characteristics of stepping reactions significantly related to increased fall rates were increased frequency of external assistance to prevent a fall to the floor, increased frequency of no-step responses, increased frequency of step responses with inadequate foot clearance, and delayed time to initiate stepping responses. Conclusions: Impaired control of balance recovery steps is related to increased fall rates during inpatient stroke rehabilitation. This study informs the specific features of stepping reactions that can be targeted with physiotherapy intervention during inpatient rehabilitation to improve dynamic stability control and potentially prevent falls.

Avril Mansfield, Elizabeth L. Inness, Janice Komar, Louis Biasin, Karen Brunton, Bimal Lakhani and William E. McIlroy. Physical Therapy (2011) 91 (6) 958-969 Background: Compensatory stepping reactions are important responses to prevent a fall following a postural perturbation. People with hemiparesis following a stroke show delayed initiation and execution of stepping reactions and often are found to be unable to initiate these steps with the more-affected limb. This case report describes a targeted training program involving repeated postural perturbations to improve control of compensatory stepping in an individual with stroke. Case Description: Compensatory stepping reactions of a 68-year-old man were examined 52 days after left hemorrhagic stroke. He required assistance to prevent a fall in all trials administered during his initial examination because he showed weight-bearing asymmetry (with more weight borne on the more-affected right side), was unable to initiate stepping with the right leg (despite blocking of the left leg in some trials), and demonstrated delayed response times. The patient completed 6 perturbation training sessions (30–60 minutes per session) that aimed to improve preperturbation weight-bearing symmetry, to encourage stepping with the right limb, and to reduce step initiation and completion times. Results: Improved efficacy of compensatory stepping reactions with training and reduced reliance on assistance to prevent falling were observed. Improvements were noted in preperturbation asymmetry and step timing. Blocking the left foot was effective in encouraging stepping with the more-affected right foot. Conclusion: This case report demonstrates potential short-term adaptations in compensatory stepping reactions following perturbation training in an individual with stroke. Future work should investigate the links between improved compensatory step characteristics and fall risk in this vulnerable population.

Ilan Kurz, Yoav Gimmon, Ronen Debi and Itshak Melzer Schwartz Movement Analysis and Rehabilitation Laboratory, Physical Therapy Department, Recanati School for Community Health Professions, Faculty of Health Sciences, Ben-Gurion University, Be’er-Sheva, Israel, Orthopedic Department Barzilai Medical Center, Ashkelon, Israel Introduction: Age-related deterioration of gait and balance increases the risk of falls. Fall related injuries are a serious public health problem in terms of the high costs to society and in terms of human suffering. To this date most fall prevention training programs did not include perturbation training while walking in their training protocol and, thus, ignored the important aspect of training postural recovery reactions during gait. We propose a novel training program using an innovative Balance Measure and Perturbation system (BaMPer system) that combines unexpected perturbation of balance during walking. Aim: To evaluate the effect of perturbation training while walking on balance and voluntary step functions in independent older adults. We hypothesized that the novel training program can improve balance while standing as well as during voluntary stepping and decrease the fear of falling. Method: In a randomized controlled trial of 57 elderly persons. The intervention group received 24 training sessions over three months that included unexpected perturbations during treadmill walking. The level of perturbations during the training was progressed according to the patient’s abilities to cope with unexpected perturbation of balance during walking. The control group received similar intervention including dual task exercises while walking but with no perturbations. Postural stability in upright standing (e.g. ML sway, AP sway, sway velocity and sway area) and voluntary step during single and dual task conditions (e.g. step reaction and step times) were evaluated using a force plate (Kistler Ltd) before and after the intervention period. Results: Forty volunteers completed the 12 week training program (twice a week for 20-30 minutes each workout) with seventeen drop outs (9 in the experimental and 8 in the controls). Results show significant improvement among both experimental and control group subjects. The experimental group showed significant improvement compare with the control group in: postural sway parameters especially in the eyes closed condition and voluntary step execution times in both single and dual task conditions. Compensatory stepping reactions during walking and during standing and fall rates in the following year are currently analyzed. Conclusions: Current results are promising, suggesting that significant benefits can be achieved using a specific and personally tailored training program that includes unexpected perturbations of balance while walking. This training program can improve several markers of balance control, parameters previously found to be related to increased risk of falls and injury in older adults. Those benefits could not be attributed to walking alone and even to walking while preforming a secondary cognitive task. The importance of the specificity of a prevention training program is thus shown. Further work is needed to determine whether a maintenance training program would help retain the training effects and to assess whether these benefits reduce falls in daily life.

Pavol MJ, Runtz EF and Pai YC. J Gerontol A Biol Sci Med Sci. (2004); 59(5):494-502 Background: A previous study found that, with repeated exposure to slipping during a sit-to-stand task, fall incidence decreased at a similar exponential rate in young and older adults. This study investigated the adaptations responsible for this decrease. Methods: Slips were induced, using bilateral low-friction platforms, during a sit-to-stand in 60 young and 41 older healthy safety-harnessed adults. Participants underwent 5 slips, then a 6th slip (re-slip) after 3-4 non-slipping trials. Between-trial adjustments in body center of mass state at seat-off were examined and correlated to the likelihoods of falling and stepping. Changes in reactive response between the first slip and re-slip were investigated. Results: With repeated slipping, both young and older adults adjusted to increase their center of mass anterior position and forward velocity at seat-off (p <.001), contributing to decreased fall incidence and changes in step incidence and direction (p <.001). These proactive adjustments predicted fall incidence well in later trials, but under predicted fall incidence upon the first slip by 9%-21%, suggesting that reactive response deficiencies also initially contributed to falls by both age groups. Ten participants who initially fell without stepping adapted by stepping to recover upon the re-slip. Thirty-six participants who stepped backward initially and upon the re-slip altered their non-stepping limb reactive response to reduce hip vertical descent during the step (p <.001). Conclusions: Young and older adults rapidly learned to avoid falling through similar proactive and reactive adaptations that persisted in the short term. Both proactive and reactive adaptations should be targeted in interventions to reduce older adult fall incidence.

Mansfield, J.S. Wong, W.E. McIlroy, L. Biasin, K. Brunton, M. Bayley and E.L. Inness. Physiotherapy (2015); 101 (4) 373 – 380 Objective: To determine if reactive balance control measures predict falls after discharge from stroke rehabilitation. Setting: Rehabilitation hospital and community.Participants: Independently ambulatory individuals with stroke who were discharged home after inpatient rehabilitation (n = 95). Main outcome measures: Balance and gait measures were obtained from a clinical assessment at discharge from inpatient stroke rehabilitation. Measures of reactive balance control were obtained: (1) during quiet standing; (2) when walking; and (3) in response to large postural perturbations. Participants reported falls and activity levels up to 6 months post-discharge. Logistic and Poisson regressions were used to identify measures of reactive balance control that were related to falls post-discharge. Results: Decreased paretic limb contribution to standing balance control [rate ratio 0.8, 95% confidence interval (CI) 0.7 to 1.0; P = 0.011], reduced between-limb synchronization of quiet standing balance control (rate ratio 0.9, 95% CI 0.8 to 0.9; P < 0.0001), increased step length variability (rate ratio 1.4, 95% CI 1.2 to 1.7; P = 0.0011) and inability to step with the blocked limb (rate ratio 1.2, 95% CI 1.0 to 1.3; P = 0.013) were significantly associated with increased fall rates when controlling for age, stroke severity, functional balance and daily walking activity. Conclusions: Impaired reactive balance control in standing and walking predicted increased risk of falls post-discharge from stroke rehabilitation. Specifically, measures that revealed the capacity of both limbs to respond to instability were related to increased risk of falls. These results suggest that post-stroke rehabilitation strategies for falls prevention should train responses to instability, and focus on remediating decontrol in the more-affected limb.

Radzinski M, Bukowczan S, Stożek J, Zajdel K, Mirek E, Chwała W, Wójcik-Pędziwiatr M, Banaszkiewicz K and Szczudlik A. Neurol Neurochir Pol. (2013);47(5):431-7. Background: Although Parkinson disease (PD) patients suffer falls more frequently than other old people, only a few studies have focused on identifying the specific risk factors for falls in PD patients. The aim of this study was to assess the incidence and risk factors of falls in a prospective study in comparison to a control group. Methods: One hundred patients with PD were recruited to the study along with 55 gender- and age-matched healthy controls. Both groups were examined twice; the second examination took place one year after the first one. Examination of the PD group included: medical history including falls, neurological examination, assessment of the severity of parkinsonism [Unified Parkinson’s Disease Rating Scale (UPDRS), Schwab and England scale (S&E), Hoehn and Yahr scale (H&Y), Mini-Mental State Examination (MMSE)], Hamilton scale and quality of life scales (SF-36, EQ-5D) and Freezing of Gait Questionnaire (FOG-Q). In both groups falls were recorded over the 12 months. Frequent fallers are defined as having more than 3 falls a year. Results: Over the year falls occurred in 54% of PD patients and 18% of controls. In a prospective study 28% of PD patients fell more frequently than in retrospective analysis. Frequent fallers were found in 20% of patients and in 7% of controls. Fallers showed higher scores in UPDRS, H&Y, S&E, MMSE, and Hamilton scale than non-fallers. Independent risk factors for falls were: age, previously reported falls and higher score in the FOG-Q. Conclusions: Falls in PD patients occurred three times more frequently than in controls. Independent risk factors for falls were: high score in FOG-Q, older age and presence of falls in medical history.

Background: Dynamic knee stabilization strategies of people who successfully compensate for the absence of an anterior cruciate ligament (ACL) (“copers”) are different from those of people who do not compensate well for the injury (“noncopers”). Early after injury, certain patients (“potential copers”) can increase the likelihood of successfully compensating for the injury by participating in 10 sessions of perturbation training. The purpose of this study was to determine how perturbation training alters muscle co-contraction and knee kinematics in potential copers. Subjects: Seventeen individuals with acute, unilateral ACL rupture who were categorized as potential copers and 17 subjects without injuries who were matched by age, sex, and activity level were recruited for this study Methods:Motion analysis and electromyographic data were collected as subjects walked across a stationary or moving platform (horizontal translation) before and after perturbation training Results:Before training, potential copers had higher co-contraction indexes and lower peak knee flexion angles than subjects without injuries. After training, potential copers’ movement patterns more closely resembled those of subjects without injuries (ie, they showed reduced co-contraction indexes and increased peak knee flexion angles during stance). Conclusions: Perturbation training reduced quadriceps femoris-hamstring muscle and quadriceps femoris-gastrocnemius muscle co-contractions and normalized knee kinematics in individuals with ACL rupture who were classified as potential copers. Findings from this study provide evidence for a mechanism by which perturbation training acts as an effective intervention for promoting coordinated muscle activity in a select population of people with ACL rupture. [Chmielewski TL, Hurd WJ, Rudolph KS, et al. Perturbation training improves knee kinematics and reduces muscle co-contraction after complete unilateral anterior cruciate ligament injuries. Phys Ther. 2005;85:740 –754.] FULL RESEARCH

Scott M. Lephart,* PhD, ATC, Danny M. Pincivero, MEd, Jorge L. Giraido, MD, and Freddie H. Fu, MD ABSTRACT Rehabilitation continues to evolve with the increased emphasis on patient management and proprioceptive training. Proprioception can be defined as a specialized variation of the sensory modality of touch that encompasses the sensation of joint movement (kinesthesia) and joint position (joint position sense). Numerous investigators have observed that afferent feedback to the brain and spinal pathways is mediated by skin, articular, and muscle mechanoreceptors. Examining the effects of ligamentous injury, surgical intervention, and proprioceptiveiy mediated activities in the rehabilitation program provides an understanding of the complexity of this system responsible for motor control. It appears that this neuromuscular feedback mechanism becomes interrupted with injury and abnormalities, and approaches restoration after surgical intervention and rehabilitation. Rehabilitation programs should be designed to include a proprioceptive component that addresses the following three levels of motor control: spinal reflexes, cognitive programming, and brainstem activity. Such a program is highly recommended to promote dynamic joint and functional stability. Thus far, current knowledge regarding the basic science and clinical application of proprioception has led the profession of sports medicine one step closer to its ultimate goal of restoring function FULL RESEARCH

Gregory M. Gutierrez, PhD, Thomas W. Kaminski, PhD, ATC, FACSM, Al T. Douex, MS, ATC Lateral ankle sprains (LAS) are common injuries in athletics and daily activity. Although most are resolved with conservative treatment, others develop chronic ankle instability (AI)—a condition associated with persistent pain, weakness, and instability—both mechanical (such as ligamentous laxity) and functional (neuromuscular impairment with or without mechanical laxity). The predominant theory in AI is one of articular deafferentation from the injury, affecting closed-loop (feedback/reflexive) neuromuscular control, but recent research has called that theory into question. A considerable amount of attention has been directed toward understanding the underlying causes of this pathology; however, little is known concerning the neuromuscular mechanisms behind the development of AI. The purpose of this review is to summarize the available literature on neuromuscular control in uninjured individuals and individuals with AI. Based on available research and reasonable speculation, it seems that open-loop (feedforward/anticipatory) neuromuscular control may be more important for the maintenance of dynamic joint stability than closed-loop control systems that rely primarily on proprioception. Therefore, incorporating perturbation activities into patient rehabilitation schemes may be of some benefit in enhancing these open-loop control mechanisms. Despite the amount of research conducted in this area, analysis of individuals with AI during dynamic conditions is limited. Future work should aim to evaluate dynamic perturbations in individuals with AI, as well as subjects who have a history of at least one LAS and never experienced recurrent symptoms. These potential findings may help elucidate some compensatory mechanisms, or more appropriate neuromuscular control strategies after an LAS event, thus laying the groundwork for future intervention studies that can attempt to reduce the incidence and severity of acute and chronic lateral ankle injury. FULL RESEARCH

F. B. HORAK AND L. M. NASHNER SUMMARY AND CONCLUSIONS 1. We studied the extent to which automatic postural actions in standing human subjects are organized by a limited repertoire of central motor programs. Subjects stood on support surfaces of various lengths, which forced them to adopt different postural movement strategies to compensate for the same external perturbations. We assessedwhether a continuum or a limited set of muscle activation patterns was used to produce different movement patterns and the extent to which movement patterns were influenced by prior experience. 2. Exposing subjects standing on a normal support surface to brief forward and backward horizontal surface perturbations elicited relatively stereotyped patterns of leg and trunk muscle activation with 73- to 1IO-ms latencies. Activity began in the ankle joint muscles and then radiated in sequence to thigh and then trunk muscles on the same dorsal or ventral aspect of the body. This activation pattern exerted compensatory torques about the ankle joints, which restored equilibrium by moving the body center of mass forward or backward. This pattern has been termed the ankle strategy because it restores equilibrium by moving the body primarily around the ankle joints. 3. To successfully maintain balance while standing on a support surface short in relation to foot length, subjects activated leg and trunk muscles at similar latencies but organized the activity differently. The trunk and thigh muscles antagonistic to those used in the ankle strategy were activated in the opposite proximal-to-distal sequence, whereas the ankle muscles were generally unresponsive. This activation pattern produced a compensatory horizontal shear force against the support surface but little, if any, ankle torque. This pattern has been termed the hip strategy, because the resulting motion is focused primarily about the hip joints. 4. Exposing subjects to horizontal surface perturbations while standing on support surfaces intermediate in length between the shortest and longest elicited more complex postural movements and associated muscle activation patterns that resembled ankle and hip strategies combined in different temporal relations. These complex postural movements were executed with combinations of torque and horizontal shear forces and motions of ankle and hip joints. 5. During the first 5-20 practice trials immediately following changes from one support surface length to another, response latencies were unchanged. The activation patterns, however, were complex and resembled the patterns observed during well-practiced stance on surfaces of intermediate lengths. During the course of practice, the relative amplitudes and timing of the ankle and hip strategy components changed progressively. 6. Our results have demonstrated that subjects can synthesize a continuum of different postural movements by combining two distinct strategies in different magnitudes and temporal relations. The combination of strategies used in a particular instance is influenced not only by the current support-surface conditions but also by the subject’s recent experiences. These observations are consistent with the hypothesis that postural actions are organized by a limited repertoire of central programs selected in advance of movement. FULL RESEARCH