Perturbation-based balance training: Principles, mechanisms and implementation in clinical practice

Virtual obstacle-avoidance training using daily-life obstacles with physical feedback in older people: A cross-over trial

Failures in avoiding environmental hazards can lead to falls. We developed a virtual reality (VR) obstacle-avoidance training system that provides physical feedback upon foot contact with a virtual obstacle. This study aimed to assess whether physical feedback reduces obstacle collisions in older adults within a VR environment. Fifty-six participants (mean age 72.3 ± 5.4 (SD) years) wore an immersive VR head-mounted display and safety harness and walked on a split-belt treadmill in two 8-minute conditions performed in random order. They walked on a virtual suburban footpath, collecting virtual apples and avoiding slip-and-trip obstacles. In the perturbation condition (VR+P), foot-obstacle collisions were accompanied by immediate physical feedback via treadmill belt accelerations/decelerations. In the non-perturbation condition (VR-only), no physical feedback was provided. Obstacle collision rates and subjective acceptability were assessed. In the VR+P condition, participants had fewer obstacle collisions (0.63 versus 0.75), fewer trailing foot collisions (0.57 versus 0.68) and a greater margin of stability compared with the VR-only condition (p < 0.05). Participants reported significantly higher levels of anxiety and greater task difficulty for the VR+P condition (p < 0.05). Motion sickness was rarely reported, and enjoyment ratings were high, with no significant differences between the conditions. In summary, physical feedback reduced obstacle collisions and increased gait stability. The low levels of motion sickness and anxiety and high levels of enjoyment reported suggest that VR obstacle avoidance training is highly acceptable to older people. Future research is required to determine the generalisation of improved motor skills to real-world scenarios.

Effectiveness of various exercise types in reducing fall risk among older adults with diabetic peripheral neuropathy: A systematic review and meta-analysis

Background

Diabetic peripheral neuropathy (DPN) increases fall risk in diabetics. Due to varying variables used to assess fall risk, the impact of exercise on fall prevention remains inconsistent. This study reviews and compares the effects of different exercises on fall risk among older adults with DPN.

Methods

A comprehensive literature search was conducted in PubMed, EBSCO, Web of Science, and Cochrane Library up to February 17th, 2025. Inclusion criteria were: older adults with DPN; exercise intervention only, an inactive or non-exercising control group, and randomized controlled trials with outcome variables: timed up and go (TUG) time, gait speed, Berg Balance Scale (BBS) score, one-legged standing (OLS) time with eye open (EO) and closed (EC). The mean difference (MD) and 95 % confidence interval (CI) were calculated.

Results

A total of 21 articles included five exercise types: balance exercise (BE), multi-component exercise (ME), strength exercise (SE), whole-body vibration (WBV) and foot-ankle functional training (FT). BE reduced TUG time (MD = -1.47, 95 % CI = -1.79 to -1.15) and increased gait speed (0.11, 0.04-0.18), BBS score (0.93, 0.49-1.37), and OLS time (EO: 2.72, 1.86-3.58; EC:1.58, 1.0-2.17). ME reduced TUG time (-1.71, -2.26 to -1.17) and increased BBS score (2.0, 1.28-2.72) and OLS time (EO: 7.07, 4.35-9.79; EC: 2.61, 1.28-3.94); SE reduced TUG time (-1.45, -2.75 to -0.15) and increased gait speed (0.09, 0.06-0.12); WBV increased OLS time (EO: 1.94, 1.32-2.56; EC: 1.86, 0.16-3.56) but did not affect TUG time or gait speed. FT did not affect TUG time or gait speed.

Conclusions

Exercise reduced fall risks among older adults with DPN. BE and ME were effective in reducing fall risks, followed by SE. WBV improved static balance but failed in dynamic balance. FT showed limited effects on fall prevention and was not recommended.

Evaluation of Change in Center of Pressure During Perturbation of Balance Including Blindfolding in Healthy Dogs

Physiotherapy aims to improve postural dysfunction, often using balance exercises. The effects of rehabilitation-based balance exercises on postural control in dogs remains understudied. This study aimed to assess the impact of specific balancing exercises and blindfolding on center of pressure parameters in healthy dogs. Thirteen healthy adult dogs participated in the study. Center of pressure parameters were measured using a pressure platform during quiet standing, external perturbation, head turn, and blindfolded trials. External perturbation significantly increased the area of the elliptical sway, cranio-caudal excursion, and right-left excursion. Head turning led to large effect sizes, but no significant differences compared to quiet standing. Blindfolding led to medium to large effect sizes, though no significant differences were observed. The study confirmed that external perturbation challenges postural stability, resulting in increased sway. Head turning induces sway but may require further training or different methodologies for reliable outcomes. Blindfolding increased sway but was not statistically different. These findings underscore the potential use of perturbation-based exercises in canine rehabilitation to improve balance, while also highlighting the need for further studies to standardize balance challenges and explore the effects in dogs with orthopedic or neurological conditions.

Learning to suppress a balance recovery step: Implications for improving behavioral flexibility in a balance recovery stepping task

BACKGROUND

Research shows compensatory balance responses can be improved with training. The present study is a coincidental finding from a registered report that provides insight into trainability of response inhibition in a balance recovery stepping task.

RESEARCH QUESTION

Can suppression of response inhibition in a rapid balance recovery step be improved with training?

METHODS

Young, healthy participants (N = 20) were released from a supported, forward lean to prompt a rapid balance recovery step. In most trials, participants were instructed to recover balance by quickly stepping forward (i.e., GO trials). However, in 20 % of the trials, a high-pitch tone was randomly played immediately after postural perturbation, signaling participants to suppress a step and relax into a catch harness (i.e., STOP). This balance recovery task was repeated on two separate days. Force plates measured GO reaction time post-perturbation and stepping errors on STOP trials.

RESULTS

Task performance improved on the second day of testing, including faster steps (321 ± 37 ms vs. 348 ± 40 ms; p < 0.001) and more successful inhibition (46 ± 19% vs. 36 ± 19%; p = 0.005). Also, stop signal reaction time was faster on day two (286 ± 41 ms vs. 308 ± 46 ms; p = 0.041), suggesting the cognitive ability to suppress a highly prepotent action was directly influenced.

SIGNIFICANCE

Our results build from past studies where balance reactions improve with practice and we now demonstrate that outright action cancellation within a balance recovery stepping task can be trained, suggesting behavioral flexibility can be improved without compromising response speed.

Dose-response relationship of treadmill perturbation-based balance training for improving reactive balance in older adults at risk of falling: results of the FEATURE randomized controlled pilot trial

BACKGROUND

The inability to appropriately react to balance perturbations is a common cause of falls. Perturbation-based balance training (PBT) is especially beneficial for improving reactive balance and shows high potential for fall prevention. However, its dose-response relationship, feasibility, and acceptability remain to be determined among older adults at risk of falling. The FEATURE study aimed to compare the efficacy of two treadmill PBT protocols with different session numbers to improve reactive balance, and to evaluate their feasibility and acceptability in this population.

METHODS

In this randomized controlled pilot trial, 36 older adults at risk of falling were allocated to receive either six (6PBT) or two treadmill PBT sessions (2PBT). Reactive balance in standing (Stepping Threshold Test [STT]) and walking (Dynamic Stepping Threshold Test [DSTT]) was assessed as primary outcome at baseline (T1), post-intervention (T2), and 6-week follow-up (T3). Secondary outcomes included measures on physical, psychological, and cognitive functioning. Feasibility was assessed via PBT adherence, planned perturbations completed, and adverse events; acceptability via questionnaire. Between-group changes over time were compared using repeated-measures analyses of variance with Bonferroni-corrected post-hoc tests. Data analyses followed the intention-to-treat principle.

RESULTS

A significant time effect was observed for the DSTT (p = 0.008), with both groups significantly improving from T1 to T2 (ps < 0.01). A significant interaction effect (p = 0.027) revealed that only the 6PBT group maintained these improvements (T1 vs. T3: p < 0.001) and scored significantly higher than the 2PBT group at T3 (p = 0.015). No significant interaction effects were found for the STT or any secondary outcome, but improvements over time were observed for dynamic balance, gait capacity, functional mobility, physical activity, concerns about falling, and executive functioning (time effects: ps < 0.05). PBT adherence, planned perturbations completed, and acceptability were high in both groups, with no significant between-group differences. No intervention-related serious adverse events were reported.

CONCLUSIONS

Findings suggest that a low number of treadmill PBT sessions can lead to task-specific improvements in reactive balance during walking, with a higher practice dose enhancing sustainability. Treadmill PBT appears feasible and well-accepted among older adults at risk of falling, regardless of sessions received.

TRIAL REGISTRATION

DRKS00030805 ; prospectively registered December 14, 2022.

Virtual reality obstacle avoidance training can be enhanced by physical feedback via perturbations: A proof-of-concept study

BACKGROUND

Fall injuries resulting from trips are a major health concern. Virtual reality (VR) offers an effective way of training obstacle avoidance while walking due to its ability to provide safe and meaningful real-time feedback during rehabilitation. This proof-of-concept study examined the benefit of providing physical feedback during obstacle avoidance gait training using VR.

METHODS

Twenty-six young adults walked on an instrumented treadmill while wearing a head-mounted display in two 8-min conditions. Virtual obstacles to be avoided were presented in a VR-only condition and a VR + Perturbation (VR + P) condition where additional rapid belt acceleration simulated tripping on an obstacle.

RESULTS

A lower obstacle collision rate, greater step length and height of the leading foot over the obstacles were found in the VR + P condition compared to the VR-only condition (p < 0.05). Step height of the trailing foot over the obstacles significantly decreased over time during the VR-only condition (p < 0.01) but not during the VR + P condition. The margin of stability significantly improved over time during the VR + P condition only (p < 0.01).

CONCLUSIONS

Immediate physical feedback via treadmill belt acceleration can improve obstacle avoidance performance in a virtual environment. Future research is required to examine the generalizability of this finding to other populations and real-world falls.

Dual task reactive balance control in older adults with mild cognitive impairment: does the cognitive task domain make a difference?

Older adults with mild cognitive impairment (OAwMCI) demonstrate higher cognitive-motor interference (CMI) than cognitively intact older adults (CIOA) during dual tasking. However, studies have rarely examined how dual tasking affects reactive balance control in OAwMCI, or the effect of different cognitive task domains. This study compared how four cognitive tasks affected CMI during reactive balance control in OAwMCI vs. CIOA. In this study, 38 OAwMCI [Montreal Cognitive Assessment (MoCA): 18-25] and 38 CIOA (MoCA ≥ 26) were included and exposed to anterior support surface perturbations in single task and while performing four cognitive tasks: two visuomotor tasks (Target, Track), auditory clock test (ACT), and letter number sequencing (LNS). Cognitive tasks were also completed during unperturbed standing. In both single and dual task conditions, OAwMCI had a higher fall rate and lower reactive center of mass (COM) stability than CIOA. Reactive balance performance deteriorated in both groups while performing Target and Track, although was not affected by ACT or LNS. Cognitive performance was lower in dual vs. single task on the Target, Track, and LNS for both groups, although OAwMCI had higher cognitive costs than CIOA. These findings suggest that dual tasking could increase fall risk in both OAwMCI and CIOA, although visuomotor tasks induced greater CMI than executive function/working memory tasks, suggesting greater sharing of resources with reactive balance control. Furthermore, OAwMCI could experience higher CMI due to damage in sensorimotor areas involved in triggering/executing reactive balance responses, along with multidomain cognitive decline. Comprehensive dual task assessments could identify domain-specific cognitive decline in OAwMCI.NEW & NOTEWORTHY Although OAwMCI have higher CMI than CIOA during volitional balance tasks, it is unclear how dual tasking involving different cognitive domains affects reactive balance control in OAwMCI. This study showed that dual tasking could impair reactive balance responses in both CIOA and OAwMCI, although OAwMCI experienced greater performance deteriorations in dual vs. single task conditions. Furthermore, visuomotor tasks induced higher CMI than executive function/working memory tasks, suggesting greater sharing of resources with reactive balance control.

Dominant or nondominant leg, which one is used to recover balance after a simulated slip during standing?

BACKGROUND

Standing-slips are used as a fall reduction training modality or fall risk assessment tool. It is unclear whether the trainees prefer one leg over the other to recover their balance after a standing-slip.

RESEARCH QUESTIONS

1) Do the trainees always adopt the dominant leg to recover balance following an unexpected standing-slip perturbation? and 2) What are the determinants for the recovery leg selection?

METHODS

Eighty-six participants were exposed to a large-scale slip with varying peak belt speed while standing on a treadmill. Depending on the agreement between the recovery leg and the dominant leg, 54 participants were classified into the congruent group and the other 32 in the conflictive group. The demographic information and peak belt speed were compared between these two groups.

RESULTS

The peak belt speed was significantly different between the two groups (1.47 ± 0.49 m/s for conflictive vs. 1.26 ± 0.37 m/s for congruent, p = 0.026). Individuals tended to use their dominant leg to recover balance after the slip when the peak belt speed was small. The selection of the recovery leg became random when the peak belt speed was increased. The receiver operating characteristics analysis revealed a high accuracy of the peak belt speed in predicting the group classification (the area under the curve = 0.891). The Youden index identified the cutoff value of the peak belt speed (1.2 m/s) that maximized the prediction accuracy.

SIGNIFICANCE

The identified threshold of the peak belt speed could provide practical guidance for designing standing-slip-based perturbation training programs for diverse populations.

The effect of incorporating whole body vibration into exercise therapy on the corticomotor excitability of the quadriceps in athletes following anterior cruciate ligament reconstruction

Previous studies have shown that athletes recovering from anterior cruciate ligament (ACL) reconstruction experience a decline in motor cortex excitability and injury-related cortical reorganization, potentially leading to ongoing complications and a higher risk of subsequent injuries. Therefore, incorporating an intervention that consistently delivers sensory inputs to the central nervous system and enhances excitability at both spinal and supra-spinal levels, in addition to exercise therapy, may offer greater benefits. The purpose of this study was to explore whether combining whole body vibration (WBV) with exercise therapy enhances motor cortical excitability in athletes undergoing ACL reconstruction more effectively than exercise therapy alone. Additionally, it aimed to assess whether this combination improves quadriceps strength and reduces functional limitations in daily activities. This study is a randomized, single-blinded, controlled trial. Twenty-six participants were assigned to either the WBV plus exercise therapy group (intervention group) or the exercise therapy-only group (control group). Outcome measures, assessed before and after treatment, included motor cortex excitability [active motor threshold (AMT) and motor-evoked potential amplitude of the quadriceps], isometric peak torque of the quadriceps, and daily functional disabilities using the knee outcome survey activities of daily living scale (KOS-ADL scale). The treatment period consisted of 12 sessions (4 weeks, with 3 sessions per week). A two-way mixed ANOVA was conducted to examine the main effects of group, time and their interactions. The results showed that in the intervention group (WBV plus exercise therapy), AMT significantly decreased (F(1, 12) = 11.35, P = 0.006, η2 = 0.486), while the control group (exercise therapy only) showed no significant change (F(1, 12) = 0.252, P = 0.625, η2 = 0.021). In the intervention group, AMT decreased by 19.47% post-treatment. Both groups showed significant improvements in isometric peak torque and KOS-ADL scores (P < 0.001), with large effect sizes for these parameters. The study concluded that adding WBV to exercise therapy is more effective in increasing motor cortex excitability compared to exercise therapy alone. However, since both groups showed significant improvements in quadriceps peak torque and KOS-ADL scores, it suggests that the addition of WBV did not provide substantial added benefits in enhancing quadriceps strength and improving daily functional abilities. The observed improvements may primarily be attributed to exercise therapy. Nonetheless, it is important to consider the small sample size and low statistical power when interpreting these results.RCT registration: On the Iranian Registry of Clinical Trials (IRCT20220220054078N1).

Proactive modifications to walking stability under the threat of large, anterior or posterior perturbations

Biomechanically, falling after a walking perturbation may be influenced by: (1) the pre-perturbation state of mechanical stability (e.g., stability margins) and (2) the response to a perturbation (i.e., recovery skill). Walking stability margins must be modifiable to serve as a target for fall-prevention interventions. We investigated if neurotypical adults could proactively modulate pre-perturbation anteroposterior stability margins while walking. Eleven adults walked on a treadmill at three speeds with and without anterior and posterior perturbations. We measured stability margins anteriorly at mid-swing and posteriorly at foot strike for pre-perturbation steps. A repeated-measures factorial ANOVA evaluated main effects and interactions of walking speed (0.6, 0.8, 1.0 stats/s) and perturbation type (anterior, none, posterior). With posterior perturbation threats, the posterior stability margins were more positive at foot strike (p < 0.01) compared to trials without perturbations. With anterior perturbation threats, the anterior stability margins were not different at mid-swing compared to trials without perturbations (p > 0.05). With any perturbation threat, step lengths shortened (p < 0.01) and step rates increased (p < 0.01). Step width was not different (p > 0.11). At slow speeds with posterior perturbation threats, double-support time decreased (p = 0.04). Proactive modifications to stability margins are indeed possible in a neurotypical population. Consequently, anteroposterior stability margins may be a feasible target for fall-prevention interventions by targeting decreased step lengths or increased step rates within a given walking speed. We do not know the extent to which the observed effects have a meaningful effect on perturbation recovery.

The effects of different challenge-level balance tasks on stroke cortical responses and balance assessment using EEG

Previous studies have validated that different balance tasks induce different cortical responses, which are key indexes of balance assessment. Assessing balance is crucial for stroke survivors to prevent falls and improve rehabilitation outcomes. However, it was unclear whether these tasks may affect the balance assessment, particularly regarding the relationship between task difficulty and the corresponding cortical responses involved in balance control. Therefore, we sought to explore the effects of different challenge-level balance tasks on balance assessment. Eighteen participants with stroke and thirteen healthy individuals were recruited in this study. The EEG was collected during sitting, standing and perturbation tasks. The pairwise-derived Brain Symmetry Index (pdBSI), and Granger Causality (GC) were analyzed with a two-way (task ×group) RMANOVA. Finally, a multiple linear regression analysis was applied to predict the BBS score with the above parameters. We found a significant interaction effect on pdBSI and GC. In the frontal lobe, participants with stroke exhibited significantly higher pdBSI (standing: p=0.042, perturbation: p=0.013) and lower GC (standing: p<0.001, perturbation: p=0.028) compared to healthy controls. Similarly, in the parietal lobe, stroke survivors showed markedly higher pdBSI (standing: p = 0.006, perturbation: p=0.012) and lower GC (standing: p=0.030, perturbation: p=0.011). Finally, The Berg Balance Scale (BBS) scores could be reliably predicted using parietal BSI and frontal GC metrics recorded during standing (p<0.001, adjusted R²=0.938) and perturbation tasks (p=0.001, adjusted R²=0.644). It was discovered that the more challenging balance tasks better revealed the difference in the power distribution and the directional functional connection between groups. The pdBSI and GC during standing and perturbation tasks, could be used as biomarkers for stroke balance assessment.

Human motor performance assessment with lower limb exoskeletons as a potential strategy to support healthy aging-a perspective article

With increasing age, motor performance declines. This decline is associated with less favorable health outcomes such as impaired activities of daily living, reduced quality of life, or increased mortality. Through regular assessment of motor performance, changes over time can be monitored, and targeted therapeutic programs and interventions may be informed. This can ensure better individualization of any intervention approach (e.g. by considering the current motor performance status of a person) and thus potentially increase its effectiveness with regard to maintaining current performance status or delaying further decline. However, in older adults, motor performance assessment is time consuming and requires experienced examiners and specific equipment, amongst others. This is particularly not feasible in care facility/nursing home settings. Wearable robotic devices, such as exoskeletons, have the potential of being used to assess motor performance and provide assistance during physical activities and exercise training for older adults or individuals with mobility impairments, thereby potentially enhancing motor performance. In this manuscript, we aim to (1) provide a brief overview of age-related changes of motor performance, (2) summarize established clinical and laboratory test procedures for the assessment of motor performance, (3) discuss the possibilities of translating established test procedures into exoskeleton-based procedures, and (4) highlight the feasibility, technological requirements and prerequisites for the assessment of human motor performance using lower limb exoskeletons.

Effect of a Perturbation-Based Balance Training Session on Adaptive Locomotor Response in Older Adults With a History of Falls

AIM

To assess the adaptive response of older adults with a history of falls in a single Perturbation-Based Balance Training (PBT) session by examining the margin of stability (MoS) and the number of falls.

METHODS

Thirty-two older adults with a history of falls underwent a treadmill walking session lasting 20-25 min. During the PBT protocol, participants experienced 24 unexpected perturbations delivered in two ways: acceleration or deceleration of the treadmill belt, with 12 perturbations in each direction. The MoS in the anteroposterior direction was assessed for the first and last perturbations of the session, during the perturbation step (N) and the recovery step (REC), along with the number of falls during the training session.

RESULTS

There was no statistically significant difference in MoS between the first and last perturbations (acceleration and deceleration) for steps N and REC. Regarding the number of falls, a significant reduction was found when comparing the first half with the second half of the training session (p = .033). There were 13 falls in the first half and only three in the second half of the PBT session.

CONCLUSION

Older adults with a history of falls exhibited an adaptive response with a reduction in the number of falls during a single session of PBT despite not showing changes in the MoS.

Action observation with motor simulation of reactive stepping: A randomized study in older adults with a history of falls

BACKGROUND

Perturbation-based training improves reactive stepping responses to prevent falling following a loss-of-balance. As there is currently no safe and feasible method for home-based practice, this randomized study investigated whether action observation with motor simulation (AOMS) of balance recovery improves reactive stepping in older adults with a history of falls. Additionally, we evaluated whether effects differ between AOMS of a human actor in the same experimental context or of an avatar in a virtual world.

METHODS

Seventy participants with a history of falls (68.3 ± 5.2y/o;52f) were subjected to 20 balance perturbations eliciting backward reactive steps. The AOMS group was tested after simulation of 20 reactive steps demonstrated by either a human actor (HumanAOMS) or a virtual avatar (AvatarAOMS). The control group was tested without prior observation. The primary outcome was reactive step quality, quantified as the leg angle at stepping-foot contact.

RESULTS

Differences between groups in the first perturbation trial were not significant. Upon repeated trials, both AOMS groups improved reactive step quality substantially faster than the control group. AOMS participants required on average five repetitions to achieve a reactive step quality that was no longer different from final performance in the last trial, whereas the control group needed ten. Both HumanAOMS and AvatarAOMS yielded similar gains.

CONCLUSIONS

The lack of effect in the first trial suggests that AOMS alone may not be sufficient for preventing real-life falls in this population. A next step would be to investigate whether this could be achieved by combining brief real perturbation practice with AOMS.

Effects of Stroboscopic Goggles on Standing Balance in the Spatiotemporal and Frequency Domains: An Exploratory Study

Balance training paradigms have been shown to effectively reduce fall risk. Visual feedback is an important sensory mechanism for regulating postural control, promoting visual perturbations for balance training paradigms. Stroboscopic goggles, which oscillate from transparent to opaque, are a form of visual perturbation, but their effect on standing balance has not been assessed. In this study, 29 participants stood in bilateral and tandem stances as the center of pressure was recorded for 6 consecutive minutes wherein there were no stroboscopic perturbations in the first and last minutes. Spatial-temporal, frequency domain, and nonlinear standing balance parameters were calculated for each period. More differences in spatial-temporal parameters due to the strobe were found in the medial-lateral direction than the anterior-posterior direction. More differences in frequency domain parameters were observed in the anterior-posterior direction than the medial-lateral direction, but this did not occur for each variable. The nonlinear parameters were strongly affected by the strobe. Stroboscopic perturbations did not affect the bilateral and tandem stances equally. Spatial-temporal parameters for the tandem stance were greater in magnitude during the strobe period than the no strobe periods. This effect was not seen with the bilateral stance. This indicates that the efficacy of stroboscopic perturbations for challenging standing balance depends on task difficulty. Balance training paradigms that utilize stroboscopic perturbations will need to harmonize these perturbations with task difficulty.

Neuromuscular Mechanisms of Motor Adaptation to Repeated Treadmill-Slip Perturbations During Stance in Healthy Young Adults

Treadmill-based repeated perturbation training (PBT) induces motor adaptation in reactive balance responses, thus lowering the risk of slip-induced falls. However, little evidence exists regarding intervention-induced changes in neuromuscular control underlying motor adaptation. Examining neuromuscular changes could be an important step in identifying key elements of adaptation and evaluating treadmill training protocols for fall prevention. Moreover, identifying the muscle synergies contributing to motor adaptation in young adults could lay the groundwork for comparison with high fall-risk populations. Thus, we aimed to investigate neuromuscular changes in reactive balance responses during stance slip-PBT. Lower limb electromyography (EMG) signals (4/leg) were recorded during ten repeated forward stance (slip-like) perturbations in twenty-six young adults. Muscle synergies were compared between early-training (slips 1-2) and late-training (slips 9-10) stages. Results showed that 5 different modes of synergies (named on dominant muscles: WTA, W , W , W , and W were recruited in both stages. 3 out of 5 synergies (WTA, W , and W showed a high similarity (r >0.97) in structure and activation between stages, whereas W and W showed a lower similarity (r <0.83) between the two stages, and the area of activation in WTA, the peak value of activation in W and the activation onset in W showed a reduction from early- to late-training stage (p <0.05). These results suggest that a block of stance slip-PBT resulted in modest changes in muscle synergies in young adults, which might explain the smaller changes seen in biomechanical variables. Future studies should examine neuromuscular changes in people at high risk of falls.

Adapting spatiotemporal gait symmetry to functional electrical stimulation during treadmill walking

Individuals with neurological impairments often exhibit asymmetrical gait patterns. This study explored the potential of using functional electrical stimulation (FES) as a perturbation method during treadmill walking to promote gait symmetry adaptation by investigating whether the FES perturbation could induce gait adaptation concerning spatial and temporal gait symmetry in healthy subjects. In the FES perturbation, both legs received electrical pulses at the same period as the subjects' initial stride duration, and the temporal gap between the two pulses for each leg was manipulated over a 7-min period. Following this, subjects continued to walk for another 5 minutes without FES. Subjects participated in two trials: implicit and explicit. In the implicit trial, they walked comfortably during FES perturbation without consciously adjusting their gait. In the explicit trial, they voluntarily synchronized their toe-off phase to the stimulation timing. To examine the effects of the FES perturbation, we measured step length and stance time and then analyzed changes in step length and stance time symmetries alongside their subsequent aftereffects. During the explicit trial, subjects adapted their gait patterns to the electrical pulses, resulting in a directional change in stance time (temporal) symmetry, with the left stance becoming shorter than the right. The stance time asymmetry induced by FES perturbation showed a slight residual effect. In the implicit trial, the directional change trend was slightly observed but not statistically significant. No consistent trend in step length (spatial) symmetry changes was observed in either condition, indicating that subjects may adapt their spatial gait patterns independently of their temporal patterns. Our findings suggest that the applied FES perturbation strategy under explicit condition can induce adaptations in subjects' temporal gait asymmetry, particularly in stance. The implicit condition showed a similar slight trend but was not statistically significant. Further experiments would provide deeper understanding into the mechanism behind subjects' response to FES perturbations, as well as the long-term effects of these perturbations on the spatial and temporal aspects of gait symmetry.

The Stepping Threshold Test for assessing reactive balance discriminates between older adult fallers and non-fallers

Introduction

The ability to respond effectively to external perturbations is crucial for avoiding falls. The Stepping Threshold Test (STT) has been developed to assess this reactive balance, but its ability to discriminate between fallers and non-fallers is still unsubstantiated. This study aimed to evaluate the discriminant validity of the STT in distinguishing fallers and non-fallers and its convergent validity.

Methods

Thirty-six older adults (age = 80 ± 5 years), with 13 (36%) of them reporting a fall history in the past year, completed the STT on a perturbation treadmill. They received surface perturbations of progressively increasing magnitude while standing. Single- and multiple-step thresholds were assessed using an all-step count evaluation (STT-ACE), and a direction-sensitive evaluation strategy (STT-DSE). Receiver operating characteristics and area under the curves (AUC) were analyzed to evaluate the discriminative accuracy. Convergent validity was explored by 13 hypothesized associations with other mobility, psychological, and cognitive assessments.

Results

Fallers and non-fallers significantly differed in the STT-DSE (p = 0.033), but not in the STT-ACE or other commonly used mobility assessments. Acceptable discriminative accuracy was obtained for the STT-DSE (AUC = 0.72), but not for the STT-ACE and other mobility assessments (AUC = 0.53-0.68). Twelve (92%) associations were consistent with our hypotheses for the STT-DSE, and ten (77%) for the STT-ACE.

Conclusion

Our findings provide preliminary evidence that the STT, when using the STT-DSE, may discriminate between older adult fallers and non-fallers. The STT appears to be a valid tool for assessing reactive balance, with its STT-DSE being recommended due to its better discriminant and convergent validity compared to the STT-ACE.

Subconscious vibrotactile stimulation improves mobility and balance in patients with bilateral vestibulopathy: adherence over 2 years

Objective

To investigate the effect of daily use of subconscious vibrotactile stimulation in bilateral vestibulopathy (BVP) patients, who judged the effect of vestibular rehabilitation as insufficient.

Methods

BVP patients were asked to wear a subconscious vibrotactile stimulation belt for 2 h. Patients who reported benefit after 2 h of use, were instructed to wear a subconscious vibrotactile stimulation belt in daily life, for up to more than 2 years. Follow-up consultations (mostly by telephone calls) were scheduled after 2 weeks, 2 months, 1 year, and 2 years of use. During these consultations, adherence and the self-reported overall Balance and Mobility Score (BMS) were evaluated.

Results

One hundred twenty-one BVP patients were included. Regarding adherence, 74% of patients (n = 89) wanted to proceed with daily use at home after 2 h of try out. Of these patients, 90% (n = 80) was still wearing the belt daily after 2 months, and at least 81% (n = 72) after 1 year and 73% (n = 65) after 2 years. It should be noted that lack of adherence after 1 and 2 years resulted from a loss to follow-up. All patients responding to telephone consultations in the 2 years follow up were wearing a subconscious vibrotactile stimulation belt daily. The median BMS score significantly improved within 2 h of use, from 4 to 6 points (p < 0.0001). Compared to baseline, the median BMS score significantly improved with >=3 points after 2 weeks, 2 months, 1 year, and 2 years of daily use (p < 0.0001). Long-term adherence was high in patients who experienced an increase of two or more points on the BMS, after 2 weeks of daily use.

Conclusion

The Subconscious vibrotactile stimulation improves self-reported balance and mobility in a subgroup of motivated BVP patients in which vestibular rehabilitation is insufficient.

Clinician acceptability of the ReacStep reactive balance training program for fall prevention

AIM

To examine if a novel reactive balance training program (ReacStep) designed for clinical settings is acceptable to clinicians prescribing balance and mobility training.

METHODS

ReacStep consists of tether-release reactive step training, volitional trip and slip training, and functional strength training. An open survey comprising 11-point visual analog scale items (0 = strongly disagree to 10 = strongly agree) based on the Theoretical Framework of Acceptability was sent to clinicians working in balance and mobility training. Items evaluated the acceptability of ReacStep across seven domains (intervention coherence, perceived efficacy, self-efficacy, ethicality, affective attitude, burden and opportunity cost).

RESULTS

Two hundred and seven clinicians (169 Physiotherapists, 22 Exercise Physiologists, 11 Occupational Therapists and five others) completed the survey. Respondents considered ReacStep to have good overall acceptability, intervention coherence, effectiveness, ethicality and self-efficacy (mean acceptability scores >7). However, respondent's ratings of ReacStep's affective attitude, burden and opportunity cost were more variable (mean acceptability scores 2-8) due to concerns about client anxiety, the need for a safety harness and staffing and training requirements. Respondents considered that ReacStep would be more effective and safer to conduct in geriatrics clients compared with neurological clients, and that it would be more appropriate for rehabilitation and private practice settings compared to home settings.

CONCLUSIONS

ReacStep was generally acceptable from the perspective of clinicians who prescribe balance and mobility training in various clinical settings, and was deemed more effective and safer for older clients without neurological conditions, and beneficial in outpatient rehabilitation and private practice settings.

Neuromuscular adaptations to perturbation-based balance training using treadmill belt accelerations do not transfer to an obstacle trip in older people: A cross-over randomised controlled trial

BACKGROUND

This study examined (i) adaptations in muscle activity following perturbation-based balance training (PBT) using treadmill belt-accelerations or PBT using walkway trips and (ii) whether adaptations during treadmill PBT transfer to a walkway trip.

METHODS

Thirty-eight older people (65+ years) undertook two PBT sessions, including 11 treadmill belt-accelerations and 11 walkway trips. Surface electromyography (EMG) was measured bilaterally on the rectus femoris (RF), tibialis anterior (TA), semitendinosus (ST) and gastrocnemius medial head (GM) during the first (T1) and eleventh (T11) perturbations. Adaptations (within-subjects - 1st vs 11th perturbations for treadmill and walkway PBT) and their transfer (between-subjects - 1st walkway trip after treadmill PBT vs 1st walkway trip with no prior training) effects were examined for the EMG parameters.

RESULTS

Treadmill PBT reduced post-perturbation peak muscle activation magnitude (left RF, TA, ST, right RF, ST, GM), onset latency (right TA), time to peak (right RF) and co-contraction index (knee muscles) (P < 0.05). Walkway PBT reduced post-trip onset latencies (right TA, ST), peak magnitude (left ST, right GM), time to peak (right RF, ST) and pre-perturbation muscle activity (right TA) (P < 0.05). Those who undertook treadmill PBT were not different to those without prior training during the first walkway trip (P > 0.05).

CONCLUSIONS

Both treadmill and walkway PBT induced earlier initiation and peak activation of right limb muscles responsible for the first recovery step. Treadmill PBT also reduced co-contraction of the knee muscles. Adaptations in muscle activity following treadmill PBT did not transfer to a walkway trip.

Impact of Reactive Balance Training on a Perturbation Treadmill on Physical Performance in Geriatric Patients:Results of a Single-Center, Assessor Blinded Randomized Controlled Trial

Background/Objectives: Falls and related injuries are a frequent and serious health problem in older persons. Among the various strategies, different forms of active physical training, in particular, have demonstrated success in reducing fall risk. A task-specific training approach is perturbation-based training of reactive balance. Performing this training modality on a perturbation treadmill, secured with a safety harness, is an innovative new approach facilitating task-specific training with unannounced perturbations in a safe environment. The aim of this study was to investigate the feasibility and effectiveness of this specific training in multimorbid older hospitalized patients with prefrailty and frailty. Methods: The trial was conducted as a prospective single-center, assessor-blinded randomized controlled trial. A total of 127 acute-care geriatric hospitalized patients were enrolled in a program either involving a minimum of 60 min perturbation-based treadmill training or treadmill training without perturbations on the identical device and for a comparable training period. Results: Participants were 81 ± 6 years old (64% female) with a baseline FRAIL Scale, SPPB, and MoCA scores of 3.5 ± 1.6, 8.3 ± 2.6, and 21 ± 5 points, respectively. The training was performed on six occasions with an average total training period of 89 min during a mean hospital stay of 17 ± 3 days. Between the baseline and up to 2 days after the last training, the Short Physical Performance Battery score, which was considered the primary endpoint, improved by 1.4 ± 2.1 points in the intervention group compared to 0.5 ± 1.7 in the control group, with a 0.9-point difference between the groups (p < 0.001). Conclusions: a relatively short training period of approximately 90 min on a perturbation treadmill led to a significant and clinically meaningful increase in the physical performance of frail and prefrail hospitalized geriatric patients. However, its effectiveness in reducing fall risk is yet to be proven in this population.

Perturbation-based balance training of older adults and effects on physiological, cognitive and sociopsychological factors: a secondary analysis from a randomised controlled trial with 12-month follow-up

BACKGROUND

Perturbation-based balance training (PBT) has shown promising, although diverging, fall-preventive effects; however, the effects on important physical, cognitive and sociopsychological factors are currently unknown. The study aimed to evaluate these effects on PBT at three different time points (post-training, 6-months and 12-months) in community-dwelling older adults compared with regular treadmill walking.

METHODS

This was a preplanned secondary analysis from a randomised, controlled trial performed in Aalborg, Denmark, between March 2021 and November 2022. Community-dwelling older adults aged ≥65 were randomly assigned to participate in four sessions (lasting 20 min each) of either PBT (intervention) or regular treadmill walking (control). All participants were assigned to four testing sessions: pretraining, post-training, 6-month follow-up and 12-month follow-up. At these sessions, physical, cognitive and sociopsychological measures were assessed.

RESULTS

In total, 140 participants were randomly allocated to either the PBT or control group. Short-term (pretraining to post-training) between-group differences were seen for choice stepping reaction time (-49 ms, 95% CI -80 to -18), dual-task gait speed (0.05 m/s, 95% CI 0.01 to 0.09) favouring the PBT group. However, these improvements were not sustained at the 6-month and 12-month follow-up. No significant between-group differences were found in other physical, cognitive or sociopsychological factors.

CONCLUSIONS

This study showed that PBT, in the short term, improved choice stepping reaction time and dual-task gait speed among community-dwelling older adults. Yet, these improvements were not retained for 6- or 12-months. The healthy state of the study's population may have imposed a ceiling effect limiting the ability to show any clinically relevant effects of PBT.

TRIAL REGISTRATION NUMBER

NCT04733222.

Reduced adaptability to balance perturbations in older adults with probable cognitive impairment after a severe fall

Falls in older individuals often result from unexpected balance disturbances during walking, necessitating the analysis of recovery strategies for effective falls prevention. This becomes particularly crucial for individuals with cognitive impairment, who face a higher fall risk compared to cognitively healthy adults. Hence, our study aimed to compare the recovery response to standardized walking perturbations on a treadmill between older adults with cognitive impairment and cognitively healthy older adults. 36 individuals with a recent history of a severe fall, leading to an emergency department visit without subsequent admission, were stratified into two groups (with and without probable cognitive impairment) based on scores of the Montreal Cognitive Assessment. Recovery performance was quantified using force plate data from a perturbation treadmill (M-Gait, Motek Medical B.V., Amsterdam, the Netherlands), specifically evaluating the number of steps needed to restore step length and width to pre perturbation baseline across two trials of nine different perturbations. Individuals with cognitive impairment (n = 18, mean age: 74.7) required significantly (p = 0.045, Cohen's d = 0.69) more steps to recover total steps after perturbations compared to cognitively healthy individuals (n = 18, mean age: 69.7). While step width recovery was similar between the groups, those with probable cognitive impairment required significantly more steps to recover their step length (p = 0.039, Cohen's d = 0.72). Thus, our findings indicate that older adults with probable cognitive impairment manifest inferior gait adaptability, especially in adapting step length, potentially underscoring a critical aspect for effective falls prevention in this population.

Acceptability of Two Perturbation-Based Balance Training Paradigms: Perturbation Treadmill versus Dynamic Stability Training in the Presence of Perturbations

INTRODUCTION

Perturbation-based balance training (PBT) is promising for fall prevention in older adults, mimicking real-life fall situations at a person's stability thresholds to improve reactive balance. Hence, it can be associated with anxiety, but knowledge about the acceptability of PBT is scarce.

METHOD

This is a secondary analysis of a randomized controlled trial comparing the effects of two different PBT paradigms that aims to evaluate and compare the acceptability of those training paradigms in fall-prone older adults. Participants (74.9 ± 5.7 years) who completed the training (6 weeks, 3x/week) on either a perturbation treadmill (PBTtreadmill: n = 22) or unstable surfaces in the presence of perturbations (PBTstability: n = 27) were surveyed on the acceptability of PBT using a 21-item questionnaire addressing seven domains (perceived effectiveness, tailoring, demand, safety, burden, devices, affective attitude), based on the theoretical framework of acceptability and context-specific factors. Relative scores (% of absolute maximum) for single items and domains were calculated.

RESULTS

Median domain scores of perceived effectiveness, tailoring, safety, devices, and affective attitude were all ≥70% for both paradigms. The highest scores were obtained for tailoring (both paradigms = 100% [interquartile range 80-100%]). Domain scores of demand and burden were in the medium range (40-45%) for both paradigms. No significant differences between paradigms were found for any domain score. Two single items of safety differed significantly, with PBTtreadmill perceived as needing less support (p = 0.015) and leading less often to balance loss (p = 0.026) than PBTstability.

CONCLUSION

PBT conducted on a perturbation treadmill or unstable surfaces is well accepted in this fall-prone older sample, even though it is conducted at individual stability thresholds. Tailoring may play a key role in achieving high levels of perceived effectiveness, appropriate levels of demand and burden, and a high sense of safety. PBT delivered on treadmills might be more appropriate for more anxious persons.

Treadmill induced belt-accelerations may not accurately evoke the muscle responses to obstacle trips in older people

BACKGROUND

Treadmill belt-accelerations are a commonly utilised surrogate for tripping, but their physiological validity is unknown. This study examined if a treadmill belt-acceleration induces lower limb muscle activation responses similar to a trip on a walkway.

METHODS

38 older people (65+ years) experienced one treadmill belt-acceleration and one walkway obstacle trip in random order. Muscle responses were assessed bilaterally using surface electromyography on the rectus femoris (RF), tibialis anterior (TA), semitendinosus (ST) and gastrocnemius medial head (GM). Unperturbed muscle activity, post-perturbation onset latency, peak magnitude, time to peak and co-contraction index (CCI) were examined.

RESULTS

Muscle activity in the right ST was greater during unperturbed walking on the treadmill compared to walkway (P=0.011). Compared to a treadmill belt-acceleration, a walkway trip elicited faster onset latencies in all muscles; greater peak magnitudes in the left RF, TA, GM and right GM; faster time to peaks in the left TA and right GM; and lower knee and ankle muscle CCI (P<0.05).

CONCLUSIONS

Walkway trips and treadmill belt-accelerations elicit distinct muscle activation patterns. While walkway trips induced faster and larger muscle responses, treadmill belt-accelerations involved greater co-contraction. Therefore, treadmill belt-accelerations may not accurately simulate the muscle responses to trips.

Curvilinear walking elevates fall risk and modulates slip and compensatory step attributes after unconstrained human slips

While much attention has been paid to understanding slip-related falls in humans, little has been focused on curvilinear paths despite their prevalence, distinct biomechanical demands and increased slipping threat. We determined the mechanics, compensatory stepping reactions and fall risk associated with slips during fixed-speed walking across ranges of path curvature, slipped foot and slip onset phase contexts possible in the community, which builds upon previous work by examining speed-independent effects of curvilinear walking. Twenty-one participants experienced 15 unconstrained slips induced by a wearable friction-reducing device as motion capture and harness load cell data were recorded. Falls were most likely after early stance slips to the inside foot and increased at tighter curvatures. Slip distance and peak velocity decreased as slips began later in stance phase, did not differ between feet, and accelerated on tighter paths. Slipping foot directions relative to heading transitioned from anterior (forward) to posterior (backward) as slips began later in stance, were ipsilateral (toward the slipping foot side) and contralateral (toward the opposite side) for the outside and inside foot, respectively, and became increasingly ipsilateral/contralateral on tighter curvatures. Compensatory steps were placed anteriorly and ipsilaterally after outside and inside foot slips, respectively, and lengthened at later onset phases for outside foot slips only. Our findings illustrate slip magnitude and fall risk relationships that suggest slip direction may influence the balance threat posed by a slip, imply that walking speed may modify slip likelihood, and indicate the most destabilizing curved walking contexts to target in future perturbation-based balance training approaches.

A Quasi-Randomized Clinical Trial to Compare the Effects of Suspension Versus Instability Training on Balance

CONTEXT

Suspension training devices are becoming increasingly popular. Most studies analyzed the effectiveness according to diverse measures in patients with or without conditions at any age. The characteristics of suspension training are very specific and can increase instability and; therefore, enhance balance. The goal was to determine the effects of suspension training on balance by comparing it with instability training.

DESIGN

Two-arm, randomized trial.

METHODS

44 young adults, aged 22.4 years old, with no musculoskeletal condition, took part. There were 2 interventions, suspension and instability training, designed with 12 sessions in 4 weeks. The primary outcome was the Y-Balance test. Other balance outcomes were the Emery and jumping sideways tests, and platform measures while standing.

RESULTS

Suspension and instability training were effective in enhancing balance in terms of the primary outcome, the Y-Balance test, with no between-group differences. Instability training enhanced the Emery test over suspension training (P = .018), but the latter was more effective in the jumping sideways test (P = .003). Neither of the training improved static balance measures.

CONCLUSIONS

Training with suspension devices is effective in enhancing dynamic balance, with similar improvements to instability training. Importantly, the magnitude of change and the frequency of responders to intervention in terms of motor coordination and keeping balance in unstable conditions appear to be sensitive to the type of training.

A meta-analysis of previous falls and subsequent fracture risk in cohort studies

The relationship between self-reported falls and fracture risk was estimated in an international meta-analysis of individual-level data from 46 prospective cohorts. Previous falls were associated with an increased fracture risk in women and men and should be considered as an additional risk factor in the FRAX® algorithm.

INTRODUCTION

Previous falls are a well-documented risk factor for subsequent fracture but have not yet been incorporated into the FRAX algorithm. The aim of this study was to evaluate, in an international meta-analysis, the association between previous falls and subsequent fracture risk and its relation to sex, age, duration of follow-up, and bone mineral density (BMD).

METHODS

The resource comprised 906,359 women and men (66.9% female) from 46 prospective cohorts. Previous falls were uniformly defined as any fall occurring during the previous year in 43 cohorts; the remaining three cohorts had a different question construct. The association between previous falls and fracture risk (any clinical fracture, osteoporotic fracture, major osteoporotic fracture, and hip fracture) was examined using an extension of the Poisson regression model in each cohort and each sex, followed by random-effects meta-analyses of the weighted beta coefficients.

RESULTS

Falls in the past year were reported in 21.4% of individuals. During a follow-up of 9,102,207 person-years, 87,352 fractures occurred of which 19,509 were hip fractures. A previous fall was associated with a significantly increased risk of any clinical fracture both in women (hazard ratio (HR) 1.42, 95% confidence interval (CI) 1.33-1.51) and men (HR 1.53, 95% CI 1.41-1.67). The HRs were of similar magnitude for osteoporotic, major osteoporotic fracture, and hip fracture. Sex significantly modified the association between previous fall and fracture risk, with predictive values being higher in men than in women (e.g., for major osteoporotic fracture, HR 1.53 (95% CI 1.27-1.84) in men vs. HR 1.32 (95% CI 1.20-1.45) in women, P for interaction = 0.013). The HRs associated with previous falls decreased with age in women and with duration of follow-up in men and women for most fracture outcomes. There was no evidence of an interaction between falls and BMD for fracture risk. Subsequent risk for a major osteoporotic fracture increased with each additional previous fall in women and men.

CONCLUSIONS

A previous self-reported fall confers an increased risk of fracture that is largely independent of BMD. Previous falls should be considered as an additional risk factor in future iterations of FRAX to improve fracture risk prediction.

Recovering whole-body angular momentum and margin of stability after treadmill-induced perturbations during sloped walking in healthy young adults

Although humans are well-adapted to negotiating sloped terrain, balance recovery after a disturbance on slopes is poorly understood. This study investigated how slope affects recovery from unanticipated simulated trips and slips. Eighteen healthy young adults walked on a split-belt treadmill at 1.25 m/s and three slope angles (downhill: - 8°; level: 0°; uphill: + 8°), with slip- and trip-like perturbations applied randomly at heel-strike. We evaluated balance recovery using whole-body angular momentum (WBAM) and perturbation response (PR), for which larger PR values indicate greater deviation of the margin of stability from baseline, therefore, greater destabilisation after perturbation. Overall, trips were more destabilising than slips, producing larger PR and greater range and integral of WBAM across all tested slopes, most significantly in the sagittal plane. Contrary to expectation, sagittal-plane PR post-trip was greatest for level walking and smallest for downhill walking. Heightened vigilance during downhill walking may explain this finding. Recovery strategy in both frontal and sagittal planes was consistent across all slopes and perturbation types, characterized by a wider and shorter first recovery step, with trips requiring the greatest step adjustment. Our findings advance understanding of the robustness of human locomotion and may offer insights into fall prevention interventions.

Advances in balance training to prevent falls in stroke patients: a scoping review

Objective

To summarize the status and characteristics of the available evidence, research gaps, and future research priorities for preventing falls in stroke patients through balance training.

Methods

We used a scoping review framework. A systematic search of PUBMED, Embase, and Cochrane databases for main articles was conducted. Our study only included articles that on balance training and fall-related indicators in stroke patients. Two researchers independently screened the literature according to the inclusion and exclusion criteria. The data of demographic, clinical characteristics, intervention, sample, and outcome indicators were extracted. The characteristics and limitations of the included literature were comprehensively analyzed.

Results

Of the 1,058 studies, 31 were included. The methods of balance training include regular balance training, Tai Chi, Yoga, task balance training, visual balance training, multisensory training, aquatic balance training, perturbation-based balance training, cognitive balance training, system-based balance training, and robot-assisted balance training. The commonly used outcome measures include clinical balance test, such as Berg balance scale (BBS), Timed Up-and-Go Test (TUG), Fall Risk Index assessment (FRI), Fall Efficacy Scale score (FES), and instrumented balance tests.

Conclusion

This scoping review summarizes the existing primary research on preventing falls in stroke patients by balance training. Based on the summary of the existing evidence, the characteristics of balance training and their relation to falls in stroke patients were found. The future researches should explore how to develop personalized training program, the sound combination of various balance training, to more effectively prevent falls.

Does the effect of walking balance perturbations generalize across contexts?

Balance perturbations are used to study locomotor instability. However, these perturbations are designed to provoke a specific context of instability that may or may not generalize to a broader understanding of falls risk. The purpose of this study was to determine if the effect of balance perturbations on instability generalizes across contexts. 29 younger adults and 28 older adults completed four experimental trials, including unperturbed walking and walking while responding to three perturbation contexts: mediolateral optical flow, treadmill-induced slips, and lateral waist-pulls. We quantified the effect of perturbations as an absolute change in margin of stability from unperturbed walking. We found significant changes in mediolateral and anteroposterior margin of stability for all perturbations compared to unperturbed walking in both cohorts (p-values ≤ 0.042). In older adults, the mediolateral effects of lateral waist-pulls significantly correlated with those of optical flow perturbations and treadmill-induced slips (r ≥ 0.398, p-values ≤ 0.036). In younger adults but not in older adults, we found positive and significant correlations between the anteroposterior effect of waist-pull perturbations and optical flow perturbations, and the anteroposterior and mediolateral effect of treadmill-induced slips (r ≥ 0.428, p-values ≤ 0.021). We found no "goldilocks" perturbation paradigm to endorse that would support universal interpretations about locomotor instability. Building the most accurate patient profiles of instability likely requires a series of perturbation paradigms designed to emulate the variety of environmental contexts in which falls may occur.

The Acceptability of a Community-Based Perturbation-Based Balance Training to Older Adults and Healthcare Professionals

Background: Perturbation-based balance training (PBT) is a promising fall risk reduction method that involves inducing unexpected perturbations to balance to train participants reactive balance control. Due to the unpredictable nature of PBT, its acceptability to older adults could present a barrier to the implementation of PBT in the community. Aim/Purpose: The purpose of this study was to assess the perceived acceptability of a community-based PBT program to both older adults and healthcare professionals (HCPs). Methods: Nineteen older adults (aged 69.6 ± 6.6 years, 17 women, 2 men) and three HCPs participated in the qualitative study. Participants completed four PBT sessions facilitated in conjunction with HCPs. Interviews, based on the theoretical framework of acceptability, were conducted before and after PBT and analyzed using template analysis. Results: PBT was perceived as effective by older adults and HCPs. However, HCPs perceived the equipment cost as a substantial barrier to feasibility in the community.

Utilizing mobile robotics for pelvic perturbations to improve balance and cognitive performance in older adults: a randomized controlled trial

Late-life balance disorders remain a severe problem with fatal consequences. Perturbation-based balance training (PBT), a form of rehabilitation that intentionally introduces small, unpredictable disruptions to an individual's gait cycle, can improve balance. The Tethered Pelvic Assist Device (TPAD) is a cable-driven robotic trainer that applies perturbations to the user's pelvis during treadmill walking. Earlier work showcased improved gait stability and the first evidence of increased cognition acutely. The mobile Tethered Pelvic Assist Device (mTPAD), a portable version of the TPAD, applies perturbations to a pelvic belt via a posterior walker during overground gait, as opposed to treadmill walking. Forty healthy older adults were randomly assigned to a control group (CG, n = 20) without mTPAD PBT or an experimental group (EG, n = 20) with mTPAD PBT for a two-day study. Day 1 consisted of baseline anthropometrics, vitals, and functional and cognitive measurements. Day 2 consisted of training with the mTPAD and post-interventional cognitive and functional measurements. Results revealed that the EG significantly outperformed the CG in several cognitive (SDMT-C and TMT-B) and functional (BBS and 4-Stage Balance: one-foot stand) measurements while showcasing increased confidence in mobility based on FES-I. To our knowledge, our study is the first randomized, large group (n = 40) clinical study exploring new mobile perturbation-based robotic gait training technology.

Effects of protective step training on proactive and reactive motor adaptations in Parkinson's disease patients

The aim of this study was to investigate to what extent PD affects the ability to walk, respond to balance perturbations in a single training session, and produce acute short-term effects to improve compensatory reactions and control of unperturbed walking stability. Understanding the mechanism of compensation and neuroplasticity to unexpected step perturbation training during walking and static stance can inform treatment of PD by helping to design effective training regimens that remediate fall risk. Current rehabilitation therapies are inadequate at reducing falls in people with Parkinson's disease (PD). While pharmacologic and surgical treatments have proved largely ineffective in treating postural instability and gait dysfunction in people with PD, studies have demonstrated that therapy specifically focusing on posture, gait, and balance may significantly improve these factors and reduce falls. The primary goal of this study was to assess the effectiveness of a novel and promising intervention therapy (protective step training - i.e., PST) to improve balance and reduce falls in people with PD. A secondary goal was to understand the effects of PST on proactive and reactive feedback responses during stance and gait tasks. Multiple-baseline, repeated measures analyses were performed on the multitude of proactive and reactive performance measures to assess the effects of PST on gait and postural stability parameters. In general, the results indicate that participants with PD were able to use experiences with perturbation training to integrate and adapt feedforward and feedback behaviors to reduce falls. The ability of the participants with PD to adapt to changes in task demands suggests that individuals with PD could benefit from the protective step training to facilitate balance control during rehabilitation.

Prevention of Falls in Parkinson's Disease: Guidelines and Gaps

Background

People living with Parkinson's disease (PD) have a high risk for falls.

Objective

To examine gaps in falls prevention targeting people with PD as part of the Task Force on Global Guidelines for Falls in Older Adults.

Methods

A Delphi consensus process was used to identify specific recommendations for falls in PD. The current narrative review was conducted as educational background with a view to identifying gaps in fall prevention.

Results

A recent Cochrane review recommended exercises and structured physical activities for PD; however, the types of exercises and activities to recommend and PD subgroups likely to benefit require further consideration. Freezing of gait, reduced gait speed, and a prior history of falls are risk factors for falls in PD and should be incorporated in assessments to identify fall risk and target interventions. Multimodal and multi-domain fall prevention interventions may be beneficial. With advanced or complex PD, balance and strength training should be administered under supervision. Medications, particularly cholinesterase inhibitors, show promise for falls prevention. Identifying how to engage people with PD, their families, and health professionals in falls education and implementation remains a challenge. Barriers to the prevention of falls occur at individual, environmental, policy, and health system levels.

Conclusion

Effective mitigation of fall risk requires specific targeting and strategies to reduce this debilitating and common problem in PD. While exercise is recommended, the types and modalities of exercise and how to combine them as interventions for different PD subgroups (cognitive impairment, freezing, advanced disease) need further study.

Treadmill Training Plus Semi-Immersive Virtual Reality in Parkinson's Disease: Results from a Pilot Study

Parkinson's disease (PD) is one of the most common neurodegenerative disorders that causes postural instability and gait alterations, such as reduced walking speed, shorter step length, and gait asymmetry, exposing patients to a higher risk of falling. Recently, virtual reality (VR) was added to a treadmill, in order to promote motor functional recovery and neuroplastic processes. Twenty PD patients were enrolled and randomly assigned to two groups: the experimental group (EG) and the control group (CG). In particular, patients in the EG were trained with the C-Mill, an innovative type of treadmill, which is equipped with semi-immersive VR, whereas the CG performed conventional physiotherapy. Patients in both groups were evaluated through a specific motor assessment battery at baseline (T0) and after the training (T1). Comparing pre-(T0) and post-(T1) treatment scores, in the EG, we found statistical significances in the following outcome measures: 6 Minutes Walking Test (6MWT) (p < 0.0005), Timed up and go (TUG right) (p < 0.03), Berg Balance Scale (BBS) (p < 0.006), Tinetti Scale (TS) (p < 0.002), Falls Efficacy Scale- International (FES-I), (p < 0.03) Unified PD Rating Scale-III (UPDRS) (p < 0.002), and Functional Independence Measure (FIM) (p < 0.004). Also, the CG showed statistical significances after the training. Between-group (EG and CG) analysis showed significative statistical differences in 6MWT (p < 0.006), BBS (p < 0.006), TS (p < 0.008), FES-I (p < 0.01), and FIM (p < 0.009). From our results it emerges that both groups (EG and CG) achieved better outcome scores after the treatment, suggesting that both physiotherapy interventions were effective. However, the EG training using VR seemed to have induced more improvements, especially in gait and balance skills. Then, C-Mill could be a valid adjunctive treatment in the context of gait and balance disturbances, which are very common in the PD population.

Feasibility, effectiveness and acceptability of two perturbation-based treadmill training protocols to improve reactive balance in fall-prone older adults (FEATURE): protocol for a pilot randomised controlled trial

INTRODUCTION

Perturbation-based balance training (PBT) targets the mechanism of falls (eg, slipping, tripping) to specifically train the recovery actions needed to avoid a fall. This task-specific training has shown great promise as an effective and efficient intervention for fall prevention in older adults. However, knowledge about the dose-response relationship of PBT, as well as its feasibility and acceptability in older adults with increased risk of falling is still limited. Thus, the aim of this study is to compare the effectiveness of two different treadmill PBT protocols for improving reactive balance control in fall-prone older adults, and to evaluate the feasibility and acceptability of these protocols.

METHODS AND ANALYSIS

The study is designed as a pilot randomised controlled trial with a 6-week intervention and 6-week follow-up period. Thirty-six community-dwelling, fall-prone (Timed Up and Go >12 s, habitual gait speed <1.0 m/s and/or fall history) older adults will be randomised (1:1) to receive six (weeks 1-6) or two treadmill PBT sessions (weeks 1+6) plus four conventional treadmill training sessions (weeks 2-5). Training sessions are conducted 1×/week for 30 min. Each PBT will include 40 perturbations in anterior-posterior and mediolateral directions. Reactive balance after perturbations in standing (Stepping Threshold Test (STT)) and walking (Dynamic Stepping Threshold Test (DSTT)) will be assessed as the primary outcome for effectiveness. Secondary outcomes are spatiotemporal and kinematic parameters collected during STT, DSTT and PBT, maximum perturbation magnitude for each PBT session, static and dynamic balance, physical capacity, physical activity, concerns with falling and executive functions. Feasibility will be assessed via training adherence, drop-out rate, perturbations actually performed and adverse events; and acceptability via self-designed questionnaire and focus groups.

ETHICS AND DISSEMINATION

The study has been approved by the Ethics Committee of the Medical Faculty Heidelberg (S-602/2022). Findings will be disseminated through publications in peer-reviewed journals and conference presentations.

TRIAL REGISTRATION NUMBER

DRKS00030805.

"Biofeedback-based return to sport": individualization through objective assessments

Elite athletes are regularly exposed to high and repetitive mechanical stresses and impacts, resulting in high injury rates. The consequences of injury can range from time lost from training and competition to chronic physical and psychological burden, with no guarantee that the athlete will return to preinjury levels of sport activity and performance. Prominent predictors include load management and previous injury, highlighting the importance of the postinjury period for effective return to sport (RTS). Currently, there is conflicting information on how to choose and assess the best reentry strategy. Treating RTS as a continuum, with controlled progression of training load and complexity, seems to provide benefits in this process. Furthermore, objectivity has been identified as a critical factor in improving the effectiveness of RTS. We propose that assessments derived from biomechanical measurements in functional settings can provide the objectivity needed for regular biofeedback cycles. These cycles should aim to identify weaknesses, customize the load, and inform on the status of RTS progress. This approach emphasizes individualization as the primary determinant of RTS and provides a solid foundation for achieving it.

Utilizing Mobile Robotics for Pelvic Perturbations to Improve Balance and Cognitive Performance in Older Adults: A Randomized Controlled Trial

Late-life balance disorders remain a severe problem with fatal consequences. Perturbation-based balance training (PBT), a form of rehabilitation that intentionally introduces small, unpredictable disruptions to an individual's gait cycle, can improve balance. The Tethered Pelvic Assist Device (TPAD) is a cable-driven robotic trainer that applies perturbations to the user's pelvis during treadmill walking. Earlier work showcased improved gait stability and the first evidence of increased cognition acutely. The mobile Tethered Pelvic Assist Device (mTPAD), a portable version of the TPAD, applies perturbations to a pelvic belt via a posterior walker during overground gait, as opposed to treadmill walking. Forty healthy older adults were randomly assigned to a control group (CG, n = 20) without mTPAD PBT or an experimental group (EG, n = 20) with mTPAD PBT for a two-day study. Day 1 consisted of baseline anthropometrics, vitals, and functional and cognitive measurements. Day 2 consisted of training with the mTPAD and post-interventional cognitive and functional measurements. Results revealed that the EG significantly outperformed the CG in cognitive and functional tasks while showcasing increased confidence in mobility. Gait analysis demonstrated that the mTPAD PBT significantly improved mediolateral stability during lateral perturbations. To our knowledge, our study is the first randomized, large group (n = 40) clinical study exploring new mobile perturbation-based robotic gait training technology.

Rehabilitation of Gait and Balance in Cerebral Palsy: A Scoping Review on the Use of Robotics with Biomechanical Implications

Cerebral palsy (CP) is a congenital and permanent neurological disorder due to non-progressive brain damage that affects gross motor functions, such as balance, trunk control and gait. CP gross motor impairments yield more challenging right foot placement during gait phases, as well as the correct direction of the whole-body center of mass with a stability reduction and an increase in falling and tripping. For these reasons, robotic devices, thanks to their biomechanical features, can adapt easily to CP children, allowing better motor recovery and enjoyment. In fact, physiotherapists should consider each pathological gait feature to provide the patient with the best possible rehabilitation strategy and reduce extra energy efforts and the risk of falling in children affected by CP.

Comparing the Effects of Two Perturbation-Based Balance Training Paradigms in Fall-Prone Older Adults: A Randomized Controlled Trial

INTRODUCTION

There is increasing evidence that perturbation-based balance training (PBT) is highly effective in preventing falls at older age. Different PBT paradigms have been presented so far, yet a systematic comparison of PBT approaches with respect to feasibility and effectiveness is missing. Two different paradigms of PBT seem to be promising for clinical implementation: (1) technology-supported training on a perturbation treadmill (PBTtreadmill); (2) training of dynamic stability mechanisms in the presence of perturbations induced by unstable surfaces (PBTstability). This study aimed to compare both program's feasibility and effectiveness in fall-prone older adults.

METHODS

In this three-armed randomized controlled trial, seventy-one older adults (74.9 ± 6.0 years) with a verified fall risk were randomly assigned into three groups: PBTtreadmill on a motorized treadmill, PBTstability using unstable conditions such as balance pads, and a passive control group (CG). In both intervention groups, participants conducted a 6-week intervention with 3 sessions per week. Effects were assessed in fall risk (Brief-BEST), balance ability (Stepping Threshold Test, center of pressure, limits of stability), leg strength capacity, functional performance (Timed Up and Go Test, Chair-Stand), gait (preferred walking speed), and fear of falling (Short FES-I).

RESULTS

Fifty-one participants completed the study. Training adherence was 91% for PBTtreadmill and 87% for PBTstability, while no severe adverse events occurred. An analysis of covariance with an intention-to-treat approach revealed statistically significant group effects in favor of PBTstability in the Brief-BEST (p = 0.009, η2 = 0.131) and the limits of stability (p = 0.020, η2 = 0.110) and in favor of PBTtreadmill in the Stepping Threshold Test (p < 0.001, η2 = 0.395). The other outcomes demonstrated no significant group effects.

CONCLUSION

Both training paradigms demonstrated high feasibility and were effective in improving specific motor performances in the fall-prone population and these effects were task specific. PBTtreadmill showed higher improvements in reactive balance, which might have been promoted by the unpredictable nature of the included perturbations and the similarity to the tested surface perturbation paradigm. PBTstability showed more wide-ranging effects on balance ability. Consequently, both paradigms improved fall risk-associated measures. The advantages of both formats should be evaluated in light of individual needs and preferences. Larger studies are needed to investigate the effects of these paradigms on real-life fall rates.

Evaluation of a novel technology-supported fall prevention intervention - study protocol of a multi-centre randomised controlled trial in older adults at increased risk of falls

BACKGROUND

Increasing number of falls and fall-related injuries in an aging society give rise to the need for effective fall prevention and rehabilitation strategies. Besides traditional exercise approaches, new technologies show promising options for fall prevention in older adults. As a new technology-based approach, the hunova robot can support fall prevention in older adults. The objective of this study is to implement and evaluate a novel technology-supported fall prevention intervention using the hunova robot compared to an inactive control group. The presented protocol aims at introducing a two-armed, multi-centre (four sites) randomised controlled trial, evaluating the effects of this new approach on the number of falls and number of fallers as primary outcomes.

METHODS

The full clinical trial incorporates community-dwelling older adults at risk of falls with a minimum age of 65 years. Including a one-year follow-up measurement, all participants are tested four times. The training programme for the intervention group comprises 24-32 weeks in which training sessions are scheduled mostly twice a week; the first 24 training sessions use the hunova robot, these are followed by a home-based programme of 24 training sessions. Fall-related risk factors as secondary endpoints are measured using the hunova robot. For this purpose, the hunova robot measures the participants' performance in several dimensions. The test outcomes are input for the calculation of an overall score which indicates the fall risk. The hunova-based measurements are accompanied by the timed-up-and-go test as a standard test within fall prevention studies.

DISCUSSION

This study is expected to lead to new insights which may help establish a new approach to fall prevention training for older adults at risk of falls. First positive results on risk factors can be expected after the first 24 training sessions using the hunova robot. As primary outcomes, the number of falls and fallers within the study (including the one-year follow-up period) are the most relevant parameters that should be positively influenced by our new approach to fall prevention. After the study completion, approaches to examine the cost-effectiveness and develop an implementation plan are relevant aspects for further steps.

TRIAL REGISTRATION

German Clinical Trial Register (DRKS), ID: DRKS00025897. Prospectively registered 16 August 2021, https://drks.de/search/de/trial/DRKS00025897 .

Compensatory stepping responses during real-life falls in older adults

BACKGROUND

Laboratory studies of postural responses suggest that stepping is a common strategy for balance recovery. Yet little is known about the frequency and characteristics of stepping responses during real-life falls in older adults.

RESEARCH QUESTIONS

(1) Among falls experienced by older adults in long-term care (LTC), what is the prevalence of attempts to recover balance by stepping? (2) How often are steps aligned to the direction of the fall? (3) Do the prevalence and characteristics of steps associate with intrinsic and situational factors?

METHODS

We collected and analyzed video footage of 1516 falls experienced by 515 residents of LTC (of mean age 82.7 years). Using generalized estimating equations, we tested whether the prevalence, direction and size of steps associated with sex, age, fall direction, activity at the time of falling, cause of imbalance, and holding or grasping objects.

RESULTS

Stepping after imbalance was observed in 76% of falls, and 80% of these cases involved multiple steps. The direction of steps aligned with the initial fall direction in 81% of cases. The size of the first step was less than one-half foot length in 64% of cases. Secondary steps tended to be similar in size to the first step. Steps were more common for falls during walking than standing, and for sideways falls. Steps were less common in falls involving held objects, and steps were less likely to be aligned with the fall direction when reach-to-grasp responses were observed.

SIGNIFICANCE

Older adults in LTC tended to respond to falls with multiple compensatory steps. Steps were tailored to the direction of the fall, but small in size (less than one-half foot length in size). Exercise programs for fall prevention in older adults should focus on increasing step size to enhance the effectiveness of step recovery responses.

Provoking Artificial Slips and Trips towards Perturbation-Based Balance Training: A Narrative Review

Humans' balance recovery responses to gait perturbations are negatively impacted with ageing. Slip and trip events, the main causes preceding falls during walking, are likely to produce severe injuries in older adults. While traditional exercise-based interventions produce inconsistent results in reducing patients' fall rates, perturbation-based balance training (PBT) emerges as a promising task-specific solution towards fall prevention. PBT improves patients' reactive stability and fall-resisting skills through the delivery of unexpected balance perturbations. The adopted perturbation conditions play an important role towards PBT's effectiveness and the acquisition of meaningful sensor data for studying human biomechanical reactions to loss of balance (LOB) events. Hence, this narrative review aims to survey the different methods employed in the scientific literature to provoke artificial slips and trips in healthy adults during treadmill and overground walking. For each type of perturbation, a comprehensive analysis was conducted to identify trends regarding the most adopted perturbation methods, gait phase perturbed, gait speed, perturbed leg, and sensor systems used for data collection. The reliable application of artificial perturbations to mimic real-life LOB events may reduce the gap between laboratory and real-life falls and potentially lead to fall-rate reduction among the elderly community.