Adaptation to repeated gait-slip perturbations among individuals with multiple sclerosis

Feasibility and preliminary effectiveness of a 2-week in-place reactive balance training program in people with multiple sclerosis

BACKGROUND & PURPOSE

Current treatments for falls in people with multiple sclerosis (PwMS) are incompletely effective. Reactive balance can prevent falls after a loss of balance and is negatively impacted by MS. Perturbation training may improve reactive balance. However, the effects of extended training and its impacts on falls are poorly understood in PwMS.

METHODS

We conducted a task-specific, multi-baseline, in-place reactive balance training program. Over 2 weeks and 6 sessions, participants were exposed to approximately 192 support-surface perturbations in four directions (forward, backward, leftward, and rightward). Reactive stepping was assessed twice before training (Baseline-1 & Baseline-2; [B1, B2], 2-weeks apart), and twice after training (Post-1 & Post-2 [P1, P2], immediately and 2 months after training). Linear mixed models assessed exposure effects (B1-B2), immediate improvement (B2-P1), and retained improvement (B2-P2). Falls were prospectively assessed for 2 months before and after training. Primary outcomes were margin of stability (MOS), latency, and length of the first reactive step after a backwards loss of balance.

RESULTS

Twenty-seven PwMS at risk of falls completed the study through P1 (immediate improvement), with 96.9 % session attendance, and minimal reported adverse events. Of these, 20 participants completed P2 (2-month retention) testing. For backward losses of balance, no significant changes were observed from exposure (B1-B2; p's ≥ 0.603). There were statistically significant immediate improvements in MOS and step latency (B2-P1; p = 0.036 & p = 0.012, respectively) and retained improvement in step latency (B2-P2; p = 0.033). For forward losses of balance, participants exhibited immediate improvement in MOS (p = 0.042) and step latency (p = 0.042). Fall counts were not lower after training compared to pre-training (p = 0.266). No adverse events were observed.

DISCUSSION

PwMS exhibited immediate and retained improvements in reactive stepping after 2-weeks of perturbation training, particularly in reactive step latency. This single-group, non-randomized clinical trial shows feasibility of reactive balance in PwMS and provides preliminary evidence of effectiveness of this intervention.

Recreational older ballet dancers fall less with more effective reactive balance control than non-dancers after a slip during gait

Recent work revealed that recreational ballet practice reduces older adults' fall risk after a standing-slip perturbation. However, whether such ballet practice can lead to decreased falls and better reactive motor control after a gait-slip among older adults remains unclear. This study investigated whether ballet reduces older adults' gait-slip falls and the possible neuromuscular and biomechanical mechanisms responsible for fall risk reduction. Protected by a safety harness, 15 older recreational ballet dancers and 21 age- and sex-matched non-dancers experienced a single unexpected slip while walking on a treadmill. The slip acceleration, duration, and displacement were standardized at 8 m/s2, 0.2 s, and 16 cm, respectively. Motion and electromyography data were collected during the gait-slip trial. The outcomes included slip-faller rate as the primary outcome and the following secondary ones: dynamic gait stability, slipping foot displacement, recovery stepping performance, trunk movement, and recovery leg muscle electromyography latency (rectus femoris, biceps femoris, medial gastrocnemius, and tibialis anterior). The results revealed that fewer dancers fell after the gait-slip (p = 0.029). Dancers displayed better stability at recovery foot touchdown (p = 0.012), a longer (p = 0.002) and faster (p = 0.009) step, shorter slipping foot displacement (p = 0.031), less backward trunk velocity at touchdown (p = 0.011), and shorter latencies for all four muscles (p≤0.038). The results suggest that older dancers are more resilient to an unexpected gait-slip and display better reactive balance control responding to the slip perturbation, which could be related to their more effective recovery stepping, better trunk movement control, and faster leg muscle activations.

Recreational older ballet dancers adapt faster to repeated standing-slips than older non-dancers

BACKGROUND

Falls are a global health concern facing older adults. Ballet emphasizes postural control, coordination, and leg muscle strength. Previous work indicated young professional ballet dancers adapt more effectively to repeated standing-slips than non-dancers as evidenced by better reactive improvements in dynamic gait stability and step latency. However, it remains unknown if older ballet dancers would show a quicker motor learning process than non-dancers. This study tested how older recreational ballet dancers adapt to five repeated standing-slip perturbations compared to non-dancers.

MATERIALS AND METHODS

Twenty older recreational dancers and 23 age- and sex-matched non-dancers experienced five unexpected slips while standing on a treadmill. The primary outcome was the slip-faller rate. Secondary outcomes included the percent change from first to last slip in kinematic measurements: dynamic gait stability, recovery stepping (step latency, duration, length), and trunk angle.

RESULTS

Dancers showed a faster reduction in the slip-faller rate from the first to last standing-slip compared to the non-dancers (p = 0.004). The dancers improved dynamic gait stability at the recovery step touchdown more than the non-dancers (p = 0.002). The dancers increased their step duration (p = 0.006) more than the non-dancers across the five standing-slips, and dancers exhibited better improvement in trunk angle at recovery touchdown (p = 0.028).

CONCLUSIONS

Older ballet dancers adapt faster to repeated standing-slips and can improve their slip-faller rate more quickly compared to non-dancers. Dancers also improve their step duration and trunk angle as related to balance loss recovery, which may be attributed to their ballet practice.

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.

Ballet practice improves neuromuscular and biomechanical responses to an unexpected standing-slip in older adults

Falls and fall-induced injuries are common and consequential in older adults. Ballet emphasizes full-body coordination, leg strength, and postural control. However, it remains unknown whether ballet can indeed reduce falls in older adults. This study examined biomechanical and neuromuscular responses of older recreational ballet dancers to an unexpected standing-slip. Twenty older ballet dancers (17 females, 3 males) and 23 age- and sex-matched nondancers (19 females, 4 males) were exposed to an unexpected slip during treadmill standing. The slip-faller rate was the primary outcome. The secondary outcomes were kinematic measurements, including dynamic gait stability, slip distance, and recovery stepping performance (step latency, duration, length, and speed). The tertiary outcome was the electromyography latency of leg muscles (bilateral tibialis anterior, medial gastrocnemius, rectus femoris, and biceps femoris). Fewer dancers fell than nondancers after the standing-slip (45% vs. 83%, P = 0.005, d = 0.970). Dancers displayed better stability at recovery foot liftoff (P = 0.006) and touchdown (P = 0.012), a shorter step latency (P = 0.020), shorter step duration (P = 0.011), faster step speed (P = 0.032), and shorter slip distance (P = 0.015) than nondancers. They also exhibited shorter latencies than nondancers for the standing leg rectus femoris (P = 0.028) and tibialis anterior (P = 0.002), and the stepping leg biceps femoris (P = 0.031), tibialis anterior (P = 0.017), and medial gastrocnemius (P = 0.030). The results suggest that older ballet dancers experience a lower fall risk and are more stable than nondancers following an unexpected standing-slip. The greater stability among dancers could be attributed to more biomechanically effective recovery stepping, possibly associated with the ballet-induced neuromuscular benefit-an earlier leg muscle activation.NEW & NOTEWORTHY This is the first study to examine how older ballet dancers respond to an unexpected external slip perturbation while standing. The results suggest that older ballet dancers experience a reduced fall risk after the slip than their nondancer counterparts. The lower fall risk can be accounted for by dancers' quicker neuromuscular reactions to the slip that result in a more effective recovery step and thus higher stability against backward falls due to the slip.

Dynamic gait stability in people with mild to moderate Parkinson's disease

BACKGROUND

Falls are a serious health threat for people with Parkinson's disease. Dynamic gait stability has been associated with fall risk. Developing effective fall prevention interventions requires a sound understanding of how Parkinson's disease affects dynamic gait stability. This study compared dynamic gait stability within the Feasible Stability Region framework between people with and without Parkinson's disease during level walking at a self-selected speed.

METHODS

Twenty adults with Parkinson's disease and twenty age- and gender-matched healthy individuals were recruited. Dynamic gait stability at two gait instants: touchdown and liftoff, was assessed as the primary outcome measurement. Spatiotemporal gait parameters, including stance phase duration, step length, gait speed, and cadence were determined as explanatory variables.

FINDINGS

People with Parkinson's disease walked more slowly (p < 0.001) with a shorter step (p = 0.05), and prolonged stance phase (p = 0.04) than their healthy peers with moderate to large effect sizes. Dynamic gait stability did not show any group-associated differences (p > 0.36).

INTERPRETATION

Despite the different gait parameters between groups, people with Parkinson's disease exhibited similar dynamic gait stability to their healthy counterparts. To compensate for the potential dynamic gait stability deficit resulting from slow gait speed, individuals with Parkinson's disease adopted a short step length to shift the center of mass motion state closer to the Feasible Stability Region. Our findings could provide insight into the impact of Parkinson's disease on the control of dynamic gait stability.

Perturbation-based Balance Training to improve postural responses and falls in people with multiple sclerosis: a randomized controlled trial

PURPOSE

To determine the effects of Perturbation-based Balance Training (PBT) on postural responses and falls in people with multiple sclerosis (PwMS) and compare the results with conventional balance training (CBT).

MATERIALS AND METHODS

Thirty-four PwMS were randomized to receive 4 weeks of PBT or CBT. Latency of postural responses to external perturbations, Timed-Up-and-Go (TUG), 10-meter-walk (10MW), Berg Balance Scale (BBS), and Activities-specific Balance Confidence Scale (ABC) were measured at baseline and post-training. Also, the proportion of fallers and fall rate were assessed at a 3-month follow-up.

RESULTS

The latency of postural responses significantly decreased in PBT compared to CBT. TUG, 10MW, BBS, and ABC, at post-training, and relative risk of falls and fall rate at 3-month follow-up had no statistically significant between-group differences.

CONCLUSIONS

The results show that PBT is at least as effective as CBT in improving balance and decreasing falls, while it has superiority over CBT whenever the clinicians mainly aim to improve reactive balance strategies. Future studies with a larger sample size are warranted to complement the results of this study.Implication for rehabilitationPerturbation-based Balance Training is at least as effective as conventional balance training (CBT) in improving proactive postural control in people with multiple sclerosis (PwMS).Perturbation-based Balance Training has superiority over CBT in improving reactive postural control in PwMS.Perturbation-based Balance Training has no superiority over CBT in improving fall-related outcomes.

Preliminary race-ethnicity-based analyses of fall risk among people with multiple sclerosis

BACKGROUND

Mounting evidence suggests differences in the disease characteristics of multiple sclerosis (MS) across ethnic and racial groups. Although it is widely recognized that falls are a significant concern for people with MS (PwMS), no study has explored if the fall risk is related to race/ethnicity in PwMS. The primary purpose of this pilot study was to examine whether the risk of falls is different between age-matched White, Black, and Latinx PwMS.

METHODS

Fifteen White, 16 Black, and 22 Latinx, age-matched ambulatory PwMS were selected from previous studies. Demographic and disease information, the fall risk (annual fall prevalence, proportion of recurrent fallers, and the number of falls) in the preceding year, and a battery of fall risk factors (including the disability level, gait speed, and cognition) were compared between race/ethnicity groups. The fall history was gathered using the valid fall questionnaire. The disability level was assessed by the Patient Determined Disease Steps score. Gait speed was measured using the Timed 25-Foot Walk test. The short Blessed Orientation-Memory-Concentration test evaluates participants' cognitive function. SPSS 28.0 was used for all statistical analyses and a significance level of 0.05 was applied.

RESULTS

Among the demographic measurements, age (p = 0.052), sex (p = 0.17), body mass (p = 0.338), age at diagnosis (p = 0.623), and disease duration (p = 0.280) were comparable across groups while the body height was significantly different between racial groups (p < 0.001). Binary logistic regression analysis did not detect a significant relationship between the faller status and racial/ethnic group (p = 0.571) after controlling the body height and age. Similarly, the recurrent faller status was not associated with our participants' race/ethnicity (p = 0.519). There was no difference in the number of falls in the past year between racial groups (p = 0.477). The fall risk factors of disability level (p = 0.931) and gait speed (p = 0.252) were similar among the groups. However, the White group had a significantly better Blessed Orientation-Memory-Concentration score than the Black (p = 0.037) and Latinx (p = 0.036) groups. No significant difference in the Blessed Orientation-Memory-Concentration score was observed between the Black and Latinx groups (p = 0.857).

CONCLUSION

As the initial attempt, our preliminary study suggests that the annual risk of being a faller or recurrent faller may not be affected by PwMS' race/ethnicity. Similarly, the physical functions (quantified by the Patient Determined Disease Steps and the gait speed) are comparable between racial/ethnic groups. However, the cognitive function may differ among age-matched racial groups of PwMS. Given the small sample size, caution is warranted when interpreting our findings. Despite the limitations, our study provides pilot knowledge about how race/ethnicity affects the fall risk in PwMS. Due to the limited sample size, it is too soon to definitively conclude that race/ethnicity has ignorable impacts on fall risk in PwMS. Further studies with larger sample sizes and more fall risk metrics are needed to clarify the effects of race/ethnicity on fall risk in this population.

Adaptation to repeated standing-slips in professional ballet dancers

Ballet training is being increasingly used to improve physical functions in older adults. Our previous work showed that ballet dancers react to a novel standing-slip more effectively than their non-dancer counterparts through better control of the recovery step and trunk movement. The purpose of this study was to test if and to what extent ballet dancers adapt differently to repeated standing-slips relative to non-dancers. Protected by a harness, twenty young adults (10 professional ballet dancers and 10 age/sex-matched non-dancers) experienced five repeated and standardized standing-slips on a treadmill. Changes from the first slip (S1) to the fifth slip (S5) in dynamic gait stability (primary outcome) and other variables, including the center of mass position and velocity, step latency, slip distance, ankle angle, and trunk angle (secondary outcomes) were compared between groups. Results revealed that both groups adopted similar proactive controls to improve dynamic gait stability by using the ankle and hip strategies. However, dancers showed a better reactive improvement in stability after the repeated slips than non-dancers. From S1 to S5, dancers reactively improved their dynamic gait stability more than non-dancers at the recovery step liftoff (p = 0.003). Dancers decreased their recovery step latency (p = 0.004) and shortened the slip distance (p = 0.004) significantly more than non-dancers from S1 to S5. These findings suggest that ballet dancers could facilitate the adaptation to repeated slips, which may be attributed to their ballet practice experience. This finding augments our understanding of the underlying mechanisms of ballet practice reducing falls.

Training reactive balance using trips and slips in people with multiple sclerosis: a blinded randomised controlled trial

BACKGROUND

This study examined the feasibility and efficacy of reactive balance training for improving stepping performance and reducing laboratory-induced falls in people with multiple sclerosis (MS).

METHODS

Thirty people diagnosed with MS (18-70 years) participated in a blinded randomized controlled trial (ACTRN12618001436268). The intervention group (n = 14) underwent two 50-minute sessions (total 100 min) that exposed them to a total of 24 trips and 24 slips in mixed order, over one week. The control group (n = 16) received sham training (stepping over foam obstacles) with equivalent dosage. The primary outcome was falls into the harness (defined as >30% body weight) when exposed to trips and slips that were unpredictable in timing, location and type at post-assessment. Physical and psychological measures were also assessed at baseline and post assessments.

RESULTS

The intervention and control groups completed 86% and 95% of the training protocols respectively. Incidence rate ratios (95% confidence intervals) of the intervention group relative to the control group were 0.57 (0.25, 1.26) for all falls, 0.80 (0.30, 2.11) for slip falls and 0.20 (0.04, 0.96) for trip falls in the laboratory. Kinematic analyses indicated the intervention participants improved dynamic stability, with higher centre of mass position and reduced trunk sway during recovery steps following a trip, compared to control. There were no significant differences between the intervention and control participants at post-assessment for other secondary outcome measures.

CONCLUSIONS

Reactive balance training improved trip-induced dynamic stability, limb support, trunk control and reduced falls in people with MS. More research is required to optimise the training protocol and determine whether the beneficial effects of reactive balance training can be retained long term and generalize to fewer daily-life falls.

Vibration training reducing falls in community-living older adults: a pilot randomized controlled trial

BACKGROUND

Although vibration training has been applied in older adults, it remains unclear if it can reduce falls.

AIMS

This pilot randomized-controlled trial aimed to test the effects of an 8-week vibration training program on reducing falls among community-dwelling adults.

METHODS

Forty-eight older adults were randomized to two groups: training and control. The training group received three weekly training sessions over eight weeks while the control group maintained their normal lifestyle over the 8-week period. Immediately before (or baseline), following (post-training), and three months after (retest) the 8-week training course, a group of fall risk factors were assessed for all participants. Each participant was also exposed to an unexpected gait-slip on a treadmill during post-training and retest sessions. Their daily-living fall incidence was collected for 12 months after the baseline test. The slip fall was the primary outcome, prospective all-cause falls were the secondary outcome, and fall risk factors acted as the tertiary ones.

RESULTS

The vibration training program significantly reduced the risk of slip-falls and improved all fall risk factors immediately after the training course. The training effect may be carried over for three months. The 8-week training program could also lower the number of falls between the baseline test and retest and reduce the recurrent faller rate across the 12 months after the baseline test.

DISCUSSION

This study indicates that vibration training might have some effects on fall-related measures in older adults.

CONCLUSIONS

An 8-week vibration training program could be effective to reduce falls in older adults.

CLINICALTRIALS

GOV REGISTRATION NUMBER

NCT02694666.

Training-dependent plasticity and far transfer effect enhanced by Bobath rehabilitation in Multiple Sclerosis

BACKGROUND

Multiple Sclerosis (MS) is a disease that often results in motor and/or cognitive disability. Despite the increasing availability of effective drug therapies, rehabilitation is very important means of counteracting the progression of disability and improving physical function, impacting social participation and improving quality of life. Several rehabilitation approaches can be used in the context of neuro-motor rehabilitation, but there is insufficient evidence for them in the literature.

OBJECTIVES

This study has the twofold purpose of: (i) investigate whether rehabilitation according to Bobath Concept can improve balance and some aspects of cognitive function in MS patients; (ii) explore whether the ability to improve postural control, an indirect index of adaptive neuroplasticity, is preserved in MS patients and whether it can be improved with rehabilitation.

METHOD

This is an independent wait-listed study. Forty people with MS (pwMS) were enrolled: patients in the Bobath group underwent 8 weeks of rehabilitation according to the Bobath Concept. For aim 1, pwMS were assessed at baseline (T0), at the end of the 8 weeks of treatment (T1) and after 8 weeks of observation (T2) with motor and cognitive scales. For aim 2, the same 40 pwMS were matched with healthy controls and were subjected to a postural learning task using the force platform at T0, T1 and T2.

RESULTS

Patients in Bobath group scored better on balance and cognitive function at T1, but this improvement was not maintained at T2. All patients were less accurate than controls in the postural learning task at each assessment; however, patients also demonstrated an increase in accuracy after training, similar to that of healthy controls. The learning curve was better for patients randomized to the active group than the waitlist at T1 time, but this advantage was not maintained at the T2 assessment.

CONCLUSION

In light of the results, this study supports the use of rehabilitation according to Bobath Concept to improve balance control and some executive functions in MS. Despite worse baseline performance, pwMS were able to learn a postural control task on par with healthy controls. Also, supports the hypothesis that adaptive plasticity is preserved despite MS and can be promoted by rehabilitation.

Reactive balance responses to a trip and slip during gait in people with multiple sclerosis

BACKGROUND

To examine reactive balance responses to a trip and slip during gait in people with multiple sclerosis (MS).

METHODS

This cross-sectional laboratory study involved 29 participants with MS (50.6 ± 13.4 years) and 29 gender-and-aged-matched healthy controls (50.9 ± 19.2 years). Falls following an induced trip and slip along a 10 m walkway, approach (e.g. gait speed, step length, foot contact angle) and recovery strategies (e.g. response time, extrapolated centre of mass position, margin of stability) were compared between the two groups.

FINDINGS

The rate of falls was significantly higher in the participants with MS relative to healthy controls (rate ratio=2.82, 95% confidence interval [CI]=1.42, 5.61). Participants with MS also experienced more trip falls (odds ratio [OR]=3.90, 95% CI=1.16, 13.08) and more slip falls (OR=6.27, 95% CI=1.95, 20.22) than the heathy controls. Participants with MS had significantly slower gait speed, step length, cadence, and foot contact angle during approach (P < 0.05). Following slips, participants with MS had significantly greater stance limb knee flexion (P < 0.05), suggesting inadequate lower limb support to recover balance post-slip. Following trips, participants with MS had significantly delayed response initiation, lower toe clearance, shorter step length, and greater trunk sway (P < 0.05). Fewer participants with MS showed a hopping response to clear the obstacle (P < 0.05).

INTERPRETATION

Multiple sclerosis impairs reactive balance responses to a trip and slip associated with reduced lower limb function and delayed postural responses. Neurorehabilitation targeting reactive balance may facilitate fall prevention in people with multiple sclerosis.

Motor sequence learning in a goal-directed stepping task in persons with multiple sclerosis: a pilot study

Motor sequence learning in persons with multiple sclerosis (pwMS) and healthy controls (HC) under implicit or explicit learning conditions has not yet been investigated in a stepping task. Given the prevalent cognitive and mobility impairments in pwMS, this is important in order to understand motor learning processes and optimize rehabilitation strategies. Nineteen pwMS (the Expanded Disability Status Scale = 3.4 ± 1.2) and 18 HC performed a modified serial reaction time task by stepping as fast as possible on a stepping tile when it lit up, either with (explicit) or without (implicit) knowledge of the presence of a sequence beforehand. Motor sequence learning was studied by examining response time changes and differences between sequence and random blocks during the learning session (acquisition), 24 h later (retention), and in three dual-task (DT) conditions at baseline and retention (automaticity) using subtracting sevens, verbal fluency, and vigilance as concurrent cognitive DTs. Response times improved and were lower for the sequenced compared with the random blocks at the post- and retention tests (P's < 0.001). Response times during DT conditions improved after learning, but DT cost improved only for the subtracting sevens DT condition. No differences in learning were observed between learning conditions or groups. This study showed motor sequence learning, by acquisition and retention, in a stepping task in pwMS with motor impairments, to a similar degree as HC and regardless of learning conditions. Whether automaticity increased remains unclear.

Change in 'first-trial' performance after protective step practice in people with multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a debilitating, neurodegenerative disorder causing considerable gait and balance dysfunction. Reactive balance (i.e., quick movements in response to a loss of balance) is particularly important for fall risk and is impaired in people with MS compared to neurotypical peers. Therefore, improving reactive balance among those with MS is critical. However, for maximum ecological validity, improvements in reactive balance through training would be demonstrable upon first loss-of-balance, rather than an average of several trials as is typically reported. This study evaluated changes in performance on the first stepping trial in people with MS after one day of practice.

METHODS

Fourteen people with MS underwent two, consecutive days of support-surface perturbations from stance. On day 1, participants underwent a single backward-stepping trial, followed by 35 practice trails (forward and backward). Approximately 24 h later, participants were again exposed to a single backward stepping perturbation. Protective stepping outcomes were step length, step latency, and margin of stability at first foot contact. The backward step performance on the first trial of days one and two were compared, and difference scores were evaluated for relationships with correlates based on theoretical considerations.

FINDINGS

First-trial margin of stability increased (improved) from day 1 to day 2 (P = .016). Steps were also faster on average by approximately 5 ms on day 2, although this improvement was not significant (P = .062).

INTERPRETATIONS

Although preliminary, these findings provide evidence that individuals with MS may be able to experience first-trial improvements after a low dose of perturbation training.

Occupational Therapy Interventions in Adults with Multiple Sclerosis or Amyotrophic Lateral Sclerosis: A Scoping Review

This scoping review aims to describe occupational therapy interventions carried out with multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS) patients in occupational therapy. A peer review of the literature was conducted in different databases: Pubmed, Scopus, Web of Science and Embase, and in some occupational therapy journals. A search of the literature published was carried out before December 2019. The inclusion criteria were as follows: (1) articles evaluating the intervention of occupational therapy in MS or ALS including experimental, randomized, nonrandomized and exploratory studies; (2) written in English or Spanish; (3) adult population (over 18 years old). The initial search identified 836 articles of which we included 32 divided into four areas of intervention: fatigue-targeted interventions, cognitive interventions, physical interventions and others. Only 16 studies were carried out exclusively by occupational therapists. Most occupational therapy interventions are aimed at fatigue and physical rehabilitation. The majority of the studies in our review included MS patients, with little representation from the ALS population. These interventions have shown an improvement in perceived fatigue, manual dexterity, falls prevention and improvement in cognitive aspects such as memory, communication, depression and quality of life in the MS and ALS populations.

Which Are the Key Kinematic and Kinetic Components to Distinguish Recovery Strategies for Overground Slips Among Community-Dwelling Older Adults?

Slip outcomes are categorized as either a backward loss of balance (LOB) or a no loss of balance (no-LOB) in which an individual does not take a backward step to regain their stability. LOB includes falls and nonfalls, while no-LOB includes skate overs and walkovers. Researchers are uncertain about which factors determine slip outcomes and at which critical instants they do so. The purpose of the study was to investigate factors affecting slip outcomes in proactive and early reactive phases by analyzing 136 slip trials from 68 participants (age: 72.2 [5.3] y, female: 22). Segment angles and average joint moments in the sagittal plane of the slipping limb were compared for different slip outcomes. The results showed that knee flexor, hip extensor, and plantar flexor moments were significantly larger for no-LOB than for LOB in the midproactive phase, leading to smaller shank-ground and foot-ground angles at the slip onset, based on forward dynamics. In the early reactive phase, the hip extensor and plantar flexor moments were larger for no-LOB than for LOB, and all segment angles were smaller for no-LOB. Our findings indicate that the shank angle and knee moment were the major determinants of slip outcomes in both proactive and reactive phases.

Reactive Balance Adaptability and Retention in People With Multiple Sclerosis: A Systematic Review and Meta-Analysis

Aim. To compare reactive balance in people with multiple sclerosis (MS) with healthy controls and to examine the ability of people with MS to adapt their reactive balance and retain training effects. Data Sources. Electronic databases (PubMed, EMBASE, PsychINFO) and reference lists of included articles from inception to February 25, 2019. Study Selection. Case-control and intervention studies that assessed reactive balance using mechanical perturbations in people with a confirmed diagnosis of MS. Results. Meta-analyses of 9 studies (n = 342) showed that people with MS have significantly worse reactive balance than healthy controls (standardized mean difference [SMD] 0.78, 95% CI 0.44-1.11, P < .0001, I² = 47%). Specifically, people with MS have greater center of mass displacements (SMD 0.41, 95% CI 0.05-0.77, P = .02, I² = 9%) and longer response times (MD (ms) 31.45, 95% CI 19.91-42.98, P < .0001, I² = 75%) in response to standing perturbations than healthy controls. Subsequent meta-analyses revealed training comprising repeated exposure to perturbations improved response times (P < .001) and training effects on response times could be retained for 24 hours (P < .001) in people with MS. Conclusions. Reactive balance assessments can highlight functional impairments related to falls in people with MS, and perturbation training can acutely improve reactive balance control and such improvements can be retained for 24 hours in this population. Systematic review registration number: CRD42019126130.

Influence of multiple sclerosis on dynamic gait stability

Falls are a serious health threat for people with multiple sclerosis (MS). Dynamic gait stability has been identified as a key risk factor of falls. The development of effective interventions for preventing falls requires a sound understanding of how MS affects dynamic gait stability. The purpose of the study was to compare dynamic gait stability within the framework of Feasible Stability Region between people with and without MS during level walking at a self-selected speed. Twenty adults with MS and 25 age- and sex-matched healthy individuals were recruited. Dynamic gait stability at touchdown and liftoff on both the strong and weak sides was assessed as the primary outcome measurement. Spatiotemporal gait parameters, including step times, step length, step frequency, and foot landing angle, were determined as explanatory variables. People with MS exhibited lower stability at both gait events bilaterally than their healthy counterparts. The lower stability was mainly attributable to the slower gait speed in MS than in the healthy control. To compensate for the dynamic gait stability deficit resulting from the slow gait speed, individuals with MS adopted a short step length to shift the center of mass motion state closer to the feasible stability region. For people with MS, the stability value was higher on the weak side than on the strong side at touchdown, but not liftoff. The findings from this study could provide insight into the impact of MS on the control of dynamic gait stability.