Stroke survivors are at high risk for falls in all poststroke stages. Falls may have severe consequences, both physically and psychosocially. Individuals with stroke have an increased risk for hip fractures, and after such a fracture, they less often regain independent mobility. In addition, fear of falling is a common consequence of falls, which may lead to decreased physical activity, social deprivation and, eventually, loss of independence. Important risk factors for falls are balance and gait deficits. Stroke-related balance deficits comprise reduced postural stability during quiet standing and delayed and less coordinated responses to both self-induced and external balance perturbations. Gait deficits include reduced propulsion at push-off, decreased hip and knee flexion during the swing phase, and reduced stability during the stance phase. Interventions addressing these deficits can be expected to prevent falls more successfully. Preliminary evidence shows that task-specific exercise programs targeting balance and gait deficits can indeed reduce the number of falls in individuals with stroke. Technological advances in assistive devices are another promising area. More research is needed, however, to provide conclusive evidence of the efficacy of these interventions regarding the prevention of falls in individuals with stroke.

A fter stroke, a main goal of rehabilitation is to promote independence in activities of daily living. An important determinant of activities of daily living performance is standing balance, which is a strong predictor of functional recovery 1,2 and walking capacity 3,4 and an important risk factor for falls 5 after stroke. Although the vast majority (75%) of people after stroke regain independent standing-balance capacity, 6 weightbearing asymmetry and increased postural sway often persist, as well as a diminished capacity to voluntarily shift body weight or to withstand external perturbations. 7 Hence, a keyBackground and Purpose-The purpose of this systematic review and meta-analysis was to investigate the effects of exercise training on balance capacity in people in the chronic phase after stroke. Furthermore, we aimed to identify which training regimen was most effective. Methods-Electronic databases were searched for randomized controlled trials evaluating the effects of exercise therapy on balance capacity in the chronic phase after stroke. Studies were included if they were of moderate or high methodological quality (PEDro score ≥4). Data were pooled if a specific outcome measure was reported in at least 3 randomized controlled trials. A sensitivity analysis and consequent subgroup analyses were performed for the different types of experimental training (balance and/or weight-shifting training, gait training, multisensory training, high-intensity aerobic exercise training, and other training programs). Results-Forty-three randomized controlled trials out of 369 unique hits were included. A meta-analysis could be conducted for the Berg Balance Scale (28 studies, n=985), Functional Reach Test (5 studies, n=153), Sensory Organization Test (4 studies, n=173), and mean postural sway velocity (3 studies, n=89). A significant overall difference in favor of the intervention group was found for the Berg Balance Scale (mean difference 2. Previous meta-analyses of the effects of exercise therapy on improving balance capacity have been inconclusive. [8][9][10][11] There seemed to be an effect of biofeedback training on postural sway and of repetitive task training on sit-to-stand activities, 8 but both types of training did not result in better performance on clinical tests of balance capacity. 9 In addition, it remained unclear which type of training regimen would be most effective. Furthermore, previous meta-analyses did not address whether training effects differed between poststroke stages. One systematic review reported that favorable effects of balance exercises were restricted to the chronic phase (≥6 months post onset), but a meta-analysis was not included to substantiate this statement. 12Nevertheless, several studies that have been published since suggest that exercise therapy may yield significant improvements in balance capacity in individuals in the chronic phase of stroke. 13,14 Evaluating the effects of exercise therapy in the chronic phase of stroke is of particular interest because the resu...

Even in persons who were only mildly affected by stroke, gait adaptability may be reduced, which may place them at risk of falling. Delayed and decreased muscle responses were identified as one possible mechanism with diminished ability to adapt the length of the avoiding stride. Rehabilitation interventions could focus on these impairments.

Movement execution is speeded up when a startle auditory stimulus is applied with an imperative signal in a simple reaction time task experiment, a phenomenon described as StartReact. The effect has been recently observed in a step adjustment task requiring fast selection of specific movements in a choice reaction time task. Therefore, we hypothesized that inducing a StartReact effect may be beneficial in obstacle avoidance under time pressure, when subjects have to perform fast gait adjustments. Twelve healthy young adults walked on a treadmill and obstacles were released in specific moments of the step cycle. On average the EMG onset latency in the biceps femoris shortened by 20% while amplitude increased by 50%, in trials in which an auditory startle accompanied obstacle avoidance. The presentation of a startle increased the probability of using a long step strategy, enlarged stride length modifications and resulted in higher success rates, to avoid the obstacle. We also examined the effects of the startle in a condition in which the obstacle was not present in comparison to a condition in which the obstacle was visibly present but it did not fall. In the latter condition, the obstacle avoidance reaction occurred with a similar latency but smaller amplitude as in trials in which the obstacle was actually released. Our results suggest that the motor programmes used for obstacle avoidance are probably stored at subcortical structures. The release of these motor programmes by a startling auditory stimulus may combine intersensory facilitation and the StartReact effect.

Introduction: People with stroke often have impaired stepping responses following balance perturbations, which increases their risk of falling. Computer-controlled movable platforms are promising tools for delivering perturbation-based balance training under safe and standardized circumstances.Purpose: This proof-of-concept study aimed to identify whether a 5-week perturbation-based balance training program on a movable platform improves reactive step quality in people with chronic stroke.Materials and Methods: Twenty people with chronic stroke received a 5-week perturbation-based balance training (10 sessions, 45 min) on a movable platform. As the primary outcome, backward, and forward reactive step quality (i.e., leg angle at stepping-foot contact) was assessed with a lean-and-release (i.e., non-trained) task at pre-intervention, immediately post-intervention, and 6 weeks after intervention (follow-up). Additionally, reactive step quality was assessed on the movable platform in multiple directions, as well as, the percentage side steps upon sideward perturbations. To ensure that changes in the primary outcome could not solely be attributed to learning effects on the task due to repeated testing, 10 randomly selected participants received an additional pre-intervention assessment, 6 weeks prior to training. Clinical assesments included the 6-item Activity-specific Balance Confidence (6-ABC) scale, Berg Balance Scale (BBS), Trunk Impairment Scale (TIS), 10-Meter Walking Test (10-MWT), and Timed Up and Go-test (TUG).Results: After lean-and-release, we observed 4.3° and 2.8° greater leg angles at post compared to pre-intervention in the backward and forward direction, respectively. Leg angles also significantly improved in all perturbation directions on the movable platform. In addition, participants took 39% more paretic and 46% more non-paretic side steps. These effects were retained at follow-up. Post-intervention, BBS and TIS scores had improved. At follow-up, TIS and 6-ABC scores had significantly improved compared to pre-intervention. No significant changes were observed between the two pre-intervention assessments (n=10).Conclusion: A 5-week perturbation-based balance training on a movable platform appears to improve reactive step quality in people with chronic stroke. Importantly, improvements were retained after 6 weeks. Further controlled studies in larger patient samples are needed to verify these results and to establish whether this translates to fewer falls in daily life.Trial registration: The Netherlands National Trial Register (NTR3804). http://www.trialregister.nl/trialreg/admin/rctview.aspTC=3804