The importance of lower-extremity muscle strength for lower-limb functional capacity in multiple sclerosis: Systematic review

12-week melatonin supplementation improved dynamic postural stability and walking performance in persons living with multiple sclerosis: A randomized controlled trial

BACKGROUND

Persons with multiple sclerosis (PwMS) suffer from sleep disturbances, fatigue and pain, which can be due, at least in part, to decreased levels of endogenous melatonin. These alterations could exacerbate postural instability, gait disorders and fall risk. Acute effects of exogenous melatonin on physical disorders have been studied in PwMS but its long-term effects on these parameters have not been explored yet in this population. This study aimed to determine the impact of chronic melatonin intake on dynamic postural stability, walking performance and fall risk in PwMS.

METHODS

This randomized placebo-controlled study included 27 PwMS who were assigned to either melatonin group (MG, n=15) or placebo group (PG, n=12) (3 mg/night for 12 weeks). Dynamic postural balance (force platform), walking performance (locometer) and fall risk (Four Square Step Test) were evaluated pre (T0)- and post (T1)-intervention. Sleep quality (Pittsburgh Sleep Quality Index (PSQI)), fatigue perception (Fatigue Severity Scale (FSS)), neuropathic pain (Neuropathic Pain Questionnaire 4 (DN4)) and quality of life (International Multiple Sclerosis (MS) Quality of Life Questionnaire) were also assessed at T0 and T1.

RESULTS

The center of pressure mean velocity decreased in MG compared with PG in the frontal plane (22.98 %, p=0.028). Stride length and walking speed increased in MG comparatively with PG (18.09 %, p=0.036; 9.65 %, p=0.025, respectively). The PSQI (55.89 %, p<0.001), FSS (32.38 %, p=0.003) and DN4 (32.41 %, p=0.035) scores decreased in MG compared with PG.

CONCLUSION

12-week melatonin supplementation can be recommended for managing MS-related gait disorders and dynamic postural imbalance. This therapy may also be prescribed for PwMS due to its anti-fatigue and analgesic effects as well as its benefits on sleep quality.

CLINICAL REGISTRATION

This study was prospectively recorded in the Pan African Clinical Trial Registry database (PACTR202007465309582) (https://pactr.samrc.ac.za/.).

Lower motor performance is linked with poor sleep quality, depressive symptoms, and grey matter volume alterations

Motor performance (MP) is essential for functional independence and well-being, particularly in later life. However, the relationship between behavioural aspects such as sleep quality and depressive symptoms, which contribute to MP, and the underlying structural brain substrates of their interplay remains unclear. This study used three population-based cohorts of younger and older adults (n=1,950) from the Human Connectome Project-Young Adult (HCP-YA), HCP-Aging (HCP-A), and enhanced Nathan Kline Institute-Rockland sample (eNKI-RS). Several canonical correlation analyses were computed within a machine learning framework to assess the associations between each of the three domains (sleep quality, depressive symptoms, grey matter volume (GMV)) and MP. The HCP-YA analyses showed progressively stronger associations between MP and each domain: depressive symptoms (unexpectedly positive, r=0.13, SD=0.06), sleep quality (r=0.17, SD=0.05), and GMV (r=0.19, SD=0.06). Combining sleep and depressive symptoms significantly improved the canonical correlations (r=0.25, SD=0.05), while the addition of GMV exhibited no further increase (r=0.23, SD=0.06). In young adults, better sleep quality, mild depressive symptoms, and GMV of several brain regions were associated with better MP. This was conceptually replicated in young adults from the eNKI-RS cohort. In HCP-Aging, better sleep quality, fewer depressive symptoms, and increased GMV were associated with MP. Robust multivariate associations were observed between sleep quality, depressive symptoms and GMV with MP, as well as age-related variations in these factors. Future studies should further explore these associations and consider interventions targeting sleep and mental health to test the potential effects on MP across the lifespan.

Blood Flow Restriction and Veterans With Multiple Sclerosis and Advanced Disability: Protocol for a Randomized Controlled Trial

OBJECTIVE

The purpose of this study will be to determine the efficacy of low intensity lower extremity resistance training with and without blood flow restriction (BFR) on quadriceps muscle strength and thickness in veterans with advanced multiple sclerosis (MS).

METHODS

This will be an assessor-blinded, 2-group (1 to 1 allocation) randomized controlled trial targeting an enrollment of 58 participants with advanced MS as defined by Patient-Determined Disease Steps scale levels 4 to 7. Both groups will complete 10 weeks of twice weekly low-load resistance training (20%-30% of 1-repetition max) targeting knee and hip extension, knee flexion, and ankle plantarflexion. The intervention group will perform all training using BFR, with limb occlusion pressures between 60% and 80% of maximal limb occlusion pressure. Primary outcomes will be quadriceps muscle strength and thickness. Secondary outcomes will include knee flexion and ankle plantarflexion strength, functional mobility, physical activity, and patient-reported measures. All outcomes will be assessed at baseline before the intervention, immediately after the intervention, and at a 2-month follow-up assessment. The change between groups postintervention and after the 2-month follow-up will be reported for all outcomes. All analyses will assume a 2-sided test of hypothesis (α = .05).

IMPACT

There is very little evidence for the efficacy of exercise interventions in people with MS who have advanced mobility disability. Resistance training with BFR may be an important approach for people with advanced MS who may not tolerate more conventional, moderate-to-high intensity resistance training. The results of this study will inform clinicians regarding exercise decisions for people with advanced MS and future investigations on the role of BFR in people with MS.

The Association of Age, Sex, and BMI on Lower Limb Neuromuscular and Muscle Mechanical Function in People with Multiple Sclerosis

(1) Background: The countermovement jump (CMJ) on a force plate could be a sensitive assessment for detecting early lower-limb muscle mechanical deficits in the early stages of multiple sclerosis (MS). CMJ performance is known to be influenced by various anthropometric, physiological, and biomechanical factors, mostly investigated in children and adult athletes. Our aim was to investigate the association of age, sex, and BMI with muscle mechanical function using CMJ to provide a comprehensive overview of lower-limb motor function in people with multiple sclerosis (pwMS). (2) Methods: A cross-sectional study was conducted with pwMS (N = 164) and healthy controls (N = 98). All participants performed three maximal CMJs on a force plate. Age, sex, and BMI were collected from all participants. (3) Results: Significant age, sex, and BMI effects were found for all performance parameters, flight time, and negative and positive power for pwMS and HC, but no significant interaction effects with the group (pwMS, HC) were detected. The highest significant effects were found for sex on flight time (η2 = 0.23), jump height (η2 = 0.23), and positive power (η2 = 0.13). PwMS showed significantly lower CMJ performance compared to HC in middle-aged (31-49 years), with normal weight to overweight and in both women and men. (4) Conclusions: This study showed that age, sex, and BMI are associated with muscle mechanical function in pwMS and HC. These results may be useful in developing reference values for CMJ. This is a crucial step in integrating CMJ into the diagnostic assessment of people with early MS and developing individualized and effective neurorehabilitative therapy.

A custom-built step exergame training programme to prevent falls in people with multiple sclerosis: A multicentre randomised controlled trial

BACKGROUND

Cognitive-motor step training can improve stepping, balance and mobility in people with multiple sclerosis (MS), but effectiveness in preventing falls has not been demonstrated.

OBJECTIVES

This multisite randomised controlled trial aimed to determine whether 6 months of home-based step exergame training could reduce falls and improve associated risk factors compared with usual care in people with MS.

METHODS

In total, 461 people with MS aged 22-81 years were randomly allocated to usual care (control) or unsupervised home-based step exergame training (120 minutes/week) for 6 months. The primary outcome was rate of falls over 6 months from randomisation. Secondary outcomes included physical, cognitive and psychosocial function at 6 months and falls over 12 months.

RESULTS

Mean (standard deviation (SD)) weekly training duration was 70 (51) minutes over 6 months. Fall rates did not differ between intervention and control groups (incidence rates (95% confidence interval (CI)): 2.13 (1.57-2.69) versus 2.24 (1.35-3.13), respectively, incidence rate ratio: 0.96 (95% CI: 0.69-1.34, p = 0.816)). Intervention participants performed faster in tests of choice-stepping reaction time at 6 months. No serious training-related adverse events were reported.

CONCLUSION

The step exergame training programme did not reduce falls among people with MS. However, it significantly improved choice-stepping reaction time which is critical to ambulate safely in daily life environment.

Examination of Risk Factors Associated With Falls and Injurious Falls in People With Multiple Sclerosis: An Updated Nationwide Study

OBJECTIVE

To provide an update on risk factors associated with falls and injurious falls among people with multiple sclerosis (PwMS) in the United States.

DESIGN

Nationwide cross-sectional web-based survey.

SETTING

Community setting.

PARTICIPANTS

Adult PwMS (n=965).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Participants completed self-report surveys of demographics, clinical data, concerns about falling, occurrence of falls, factors associated with falls, and injurious falls in the past 6 months. Participants also completed Patient-Reported Outcomes Measurement Information System (PROMIS) measures of depression, pain interference, and physical function, and the Fatigue Severity Scale.

RESULTS

The most common self-reported factors associated with falls included personal factors such as poor balance (75%), muscle weakness (54%), and/or fatigue (35%), environmental factors such as general surface conditions (37%) and/or distraction (15%), and activities-related factors such as urgency to complete a task (35%) and/or multitasking (27%). Logistic regression analyses indicated that higher fatigue severity (OR=1.19, P<.01) and higher pain interference (OR=1.02, P<.01) were associated with higher odds of experiencing at least 1 fall. Any level of concern, even minimal concern about falling was also significantly associated with a higher odd of experiencing at least 1 fall (ORs range 2.78 - 3.95, all P<.01). Fair to very high concerns about falling compared with no concern about falling (ORs range=5.17 - 10.26, all P<.05) was significantly associated with higher odds of sustaining an injurious fall.

CONCLUSIONS

Findings suggest falls prevention approaches in PwMS should be multifactorial and include personal, environmental, and activities-related factors. Particular attention on fatigue, pain, and concern about falling may be needed to reduce incidence of falls and injurious falls in this population.

Between-Day Reliability of the Gait Characteristics and Their Changes During the 6-Minute Walking Test in People With Multiple Sclerosis

BACKGROUND

Gait characteristics and their changes during the 6-minute walking test (6MWT) in people with multiple sclerosis (pwMS) have been described in the literature, which one may refer to as walking fatigability in the body function level of the International Classification of Functioning, Disability, and Health. However, whether these metrics are reliable is unknown.

OBJECTIVE

To investigate the between-day reliability of the gait characteristics and their changes in pwMS and healthy controls (HCs).

METHODS

Forty-nine pwMS (EDSS 4.82 ± 1.22 and 54.7 ± 9.36 years) and 23 HCs (50.6 ± 6.1 years) performed the 6MWT, as fast as possible but safely while wearing Inertial Measurement Units. Gait characteristics were measured in the pace, rhythm, variability, asymmetry, kinematics, coordination, and postural control domains and were obtained in intervals of 1 minute during the 6MWT. In addition, gait characteristics change in the last minute compared with the first minute were calculated for all gait variables using a fatigability index (ie, distance walking index). The intraclass correlation coefficient (ICC), Bland-Altman Plots, and Standard error of measurement were applied to investigate reliability.

RESULTS

Reliability of gait characteristics, minute-by-minute, and for their changes (ie, using the fatigability index) ranged from poor to excellent (pwMS: ICC 0.46-0.96; HC: ICC 0.09-0.97 and pwMS: ICC 0-0.72; HC: ICC 0-0.77, respectively).

CONCLUSION

Besides coordination, at least 1 variable of each gait domain showed an ICC of moderate or good reliability for gait characteristics changes in both pwMS and HC. These metrics can be incorporated into future clinical trials and research on walking fatigability.Clinical Trial Registration: NCT05412043.

Safety and efficacy of blood flow restriction exercise in individuals with neurological disorders: A systematic review

OBJECTIVES

This systematic review evaluated the safety and efficacy of blood flow restriction exercise (BFRE) on skeletal muscle size, strength, and functional performance in individuals with neurological disorders (ND).

METHODS

A literature search was performed in PubMed, CINAHL, and Embase. Two researchers independently assessed eligibility and performed data extraction and quality assessments.

ELIGIBILITY CRITERIA

Study populations with ND, BFRE as intervention modality, outcome measures related to safety or efficacy.

RESULTS

Out of 443 studies identified, 16 were deemed eligible for review. Three studies examined the efficacy and safety of BFRE, one study focused on efficacy results, and 12 studies investigated safety. Disease populations included spinal cord injury (SCI), inclusion body myositis (sIBM), multiple sclerosis (MS), Parkinson's disease (PD), and stroke. A moderate-to-high risk of bias was presented in the quality assessment. Five studies reported safety concerns, including acutely elevated pain and rating of perceived exertion levels, severe fatigue, muscle soreness, and cases of autonomic dysreflexia. Two RCTs reported a significant between-group difference in physical function outcomes, and two RCTs reported neuromuscular adaptations.

CONCLUSION

BFRE seems to be a potentially safe and effective training modality in individuals with ND. However, the results should be interpreted cautiously due to limited quality and number of studies, small sample sizes, and a general lack of heterogeneity within and between the examined patient cohorts.

Feasibility of Low-Load Resistance Training Using Blood Flow Restriction for People With Advanced Multiple Sclerosis: A Prospective Cohort Study

OBJECTIVE

The objective of this study was to determine the feasibility of low-load resistance training with blood flow restriction (BFR) for people with advanced disability due to multiple sclerosis (MS).

METHODS

In this prospective cohort study, 14 participants with MS (Expanded Disability Status Scale [EDSS] score = 6.0 to 7.0; mean age = 55.4 [SD = 6.2] years; 71% women) were asked to perform 3 lower extremity resistance exercises (leg press, calf press, and hip abduction) bilaterally twice weekly for 8 weeks using BFR. Feasibility criteria were as follows: enrollment of 20 participants, ≥80% retention and adherence, ≥90% satisfaction, and no serious adverse events related to the intervention. Other outcomes included knee extensor, ankle plantar flexor, and hip abductor muscle strength, 30-Second Sit-to-Stand Test, Berg Balance Scale, Timed 25-Foot Walk Test, 12-Item MS Walking Scale, Modified Fatigue Impact Scale, Patient-Specific Functional Scale, and daily step count.

RESULTS

Sixteen participants consented, and 14 completed the intervention, with 93% adherence overall. All participants were satisfied with the intervention. A minor hip muscle strain was the only intervention-related adverse event. There were muscle strength improvements on the more-involved (16%-28%) and less-involved (12%-19%) sides. There were also changes in the 30-Second Sit-to-Stand Test (1.9 repetitions; 95% CI = 1.0 to 2.8), Berg Balance Scale (5.3 points; 95% CI = 3.2 to 7.4), Timed 25-Foot Walk Test (-3.3 seconds; 95% CI = -7.9 to 1.3), Modified Fatigue Impact Scale (-8.8 points; 95% CI = -16.5 to -1.1), 12-Item MS Walking Scale (-3.6 points; 95% CI = -11.5 to 4.4), Patient-Specific Functional Scale (2.9 points; 95% CI = 1.9 to 3.8), and daily step count (333 steps; 95% CI = -191 to 857).

CONCLUSION

Low-load resistance training using BFR in people with MS and EDSS scores of 6.0 to 7.0 appears feasible, and subsequent investigation into its efficacy is warranted.

IMPACT

Although efficacy data are needed, combining BFR with low-load resistance training may be a viable alternative for people who have MS and who do not tolerate conventional moderate- to high-intensity training because of more severe symptoms, such as fatigue and weakness.

LAY SUMMARY

Low-load strength training with BFR was feasible in people who have advanced disability due to MS. Using BFR may provide an alternative for people with MS who do not tolerate higher intensity training due to more severe symptoms, such as fatigue and weakness.

The combined deleterious effects of multiple sclerosis and ageing on neuromuscular function

BACKGROUND

The prevalence of older (>60 years) people with multiple sclerosis (pwMS) is increasing. This introduces numerous challenges, as both MS and ageing independently contribute to the deterioration of neuromuscular function.

AIM

The aim was to compare the neuromuscular function in pwMS and healthy controls (HC) across three age groups: young, middle-aged, and old.

METHODS

Using a cross-sectional study design, the maximal muscle strength (Fmax) and rate of force development (RFD) of the knee extensors (KE) and plantar flexors (PF) were assessed using an isokinetic dynamometer. In addition, voluntary activation (VA) and resting twitch (RT) were measured using the interpolated twitch technique.

RESULTS

The Fmax, RFD, and VA of the KE were reduced in pwMS compared to HC across age groups. In pwMS, reductions were observed in PF Fmax, RFD, and RT, predominantly in the middle-aged and old age groups. Reductions increased with age in KE for both groups (except for VA) but in PF only for pwMS. The "trajectory" differed between pwMS and HC, as pwMS showed reductions from young to middle age, while HC showed reductions from middle to old age in KE.

CONCLUSION

The combined negative effects of MS and ageing on neuromuscular function were especially present in the PF but also substantial in the KE. RFD showed large deficits for pwMS compared to HC across age groups. The findings can partly be explained by a reduction in VA and RT, but further investigations of neural regulation are needed to explain large RFD deficits.

Investigation of parameters related to lower extremity muscle strength and proprioception in Patients with Multiple Sclerosis: a cross-sectional study

BACKGROUND

Patients with Multiple Sclerosis (PwMS) may experience a decline in balance, gait, and mobility as well as an increase in fear of falling (FoF) and fatigue due to weaker muscles and proprioceptive loss in their lower limbs. The study aimed to compare lower extremity muscle strength and proprioception, balance, functional mobility, gait, FoF, and fatigue between PwMS and healthy controls and to investigate the relationship between lower extremity muscle strength and proprioception and balance, functional mobility, gait, FoF, and fatigue in PwMS.

METHODS

The study was completed with 35 PwMS and 35 healthy controls with matching age and gender. The 5 Repetition Sit-to Stand Test (5-STS-test), knee and ankle reposition tests (using a digital inclinometer), the Berg Balance Scale (BBS), the Timed Up and Go (TUG) test, the Dynamic Gait Index (DGI), the Falls Efficacy-International (FES-I), and the Fatigue Severity Scale (FSS) were used for evaluations.

RESULTS

The 5-STS test, knee and ankle reposition tests, TUG, FES-I, and FSS Test scores were higher and BBS and DGI scores were lower in PwMS compared to healthy controls (p < 0.05). BBS, DGI, TUG, FES-I, and FSS were associated with 5-STS test and knee and ankle reposition tests except for some nondominant reposition tests in PwMS (r between 0.342 and -0.714; p < 0.05 for all).

CONCLUSION

Lower extremity muscle strength and proprioception were associated with balance, functional mobility, gait, FoF, and fatigue in PwMS. These results suggested that detailed assessment of neuromuscular parameters in lower extremity function is important in determining the appropriate rehabilitation programs.

Predictors of performance and perceived fatigability in people with multiple sclerosis

BACKGROUND AND OBJECTIVE

Fatigability is a distinct construct from fatigue that has been reported to contribute to activity limitations in people with multiple sclerosis (PwMS). Identifying predictors of performance and perceived fatigability may guide the development of interventions to mitigate fatigability. This study investigated predictors of performance and perceived fatigability among PwMS.

METHODS

PwMS (N = 51) completed self-report measures of demographics, clinical history, symptoms severity (Modified Fatigue Impact Scale), and functioning (PROMIS Physical Function and PROMIS Cognitive Function Abilities). Performance fatigability measures included Ambulatory Fatigue Index (AFI), Deceleration Index (DI), and Distance Walking Index (DWI). Perceived fatigability measures included Pittsburgh Fatigability Scale (PFS), Perceived Physical Exertion, and Perceived Fatigue Intensity. Performance and perceived fatigability measures were calculated based on the Timed 25-Foot Walk Test and the 6-Minute Walk Test.

RESULTS

Multivariable linear regression analyses indicated that PROMIS Cognitive Function was a significant independent predictor of performance fatigability measured with AFI (β = -0.515, p = 0.007), DI (β = -0.511, p = 0.008), and DWI (β = -0.516, p = 0.007). Regarding perceived fatigability, PROMIS Pain Intensity predicted Perceived Fatigue Intensity (β = 0.325, p = 0.035). PROMIS Physical Function predicted PFS Mental fatigability (β = -0.503, p < 0.001). PROMIS Physical Function (β = -0.619, p < 0.001) and Cognitive Function (β = -0.249, p = 0.037) predicted PFS Physical fatigability.

CONCLUSIONS

Preliminary findings suggest that self-reported functioning levels, including physical and perceived cognitive function, are potential predictors of performance and perceived fatigability in MS. Notably, perceived fatigue impact showed no association with performance or perceived fatigability. Future studies are warranted to confirm and extend our findings.

Reliability and validity of the glittre activities of daily living test in fully ambulatory multiple sclerosis patients

BACKGROUND

Evaluation of activities of daily living (ADL) and functional exercise capacity in patients with multiple sclerosis (pwMS) is crucial in demonstrating the effectiveness of interventions.

AIMS

To investigate the reliability and validity of the Glittre ADL Test in pwMS.

METHODS

Twenty-five pwMS and 26 healthy adults were included in this methodological study. The Glittre ADL Test was applied. Six-Minute Walk Test (6MWT) and Nottingham Extended Activities of Daily Living Index (NEADL) were applied for concurrent validity. Expanded Disability Status Scale (EDSS), Fatigue Severity Scale (FSS), Mini Balance Evaluation Systems Test (Mini BESTest), Multiple Sclerosis Quality of Life Scale-54 (MSQoL-54), and Five Times Sit-to-Stand Test (5 STST) were applied for construct validity. The Glittre ADL Test was repeated after 3-6 days for test-retest reliability.

RESULTS

The test-retest reliability of the Glittre ADL Test was excellent (ICC = 0.941). There was strong correlation of the Glittre ADL Test with 6MWT (rho = - 0.710, p < 0.001), NEADL (rho = - 0.841, p < 0.001), EDSS, (rho = 0.836, p = < 0.001), Mini BESTest (rho = 0.792, p < 0.001), and 5 STST scores (rho = 0.720, p < 0.001). There was a moderate correlation between the Glittre ADL Test and the physical health sub-item score of the MSQoL-54 (rho = - 0.591, p = 0.002). No correlation was found between the Glittre ADL Test and FSS (rho = 0.348, p = 0.096). There was a difference in the Glittre ADL Test results between the pwMS and the healthy adults (p = 0.001).

CONCLUSIONS

The Glittre ADL Test has excellent reliability and strong construct and criterion validity for assessing functional exercise capacity and ADL in fully ambulatory pwMS.

TRIAL REGISTRATION

TRN: NCT04182269.

The rate of force relaxation scaling factor is highly sensitive to detect upper and lower extremity motor deficiencies in mildly affected people with multiple sclerosis

BACKGROUND

The motor symptoms affecting upper and lower extremity functioning in people with multiple sclerosis (PwMS) are considered the cardinal symptoms of multiple sclerosis. There is still a need for outcome measures that can sensitively evaluate these symptoms. We aimed to investigate the sensitivity of the isometric outcomes (maximum force; Fmax, maximum rate of force development; RFDmax, rate of force development scaling factor; RFD-SF, and rate of force relaxation scaling factor; RFR-SF) and standard clinical tests (9-hole peg test; 9HPT and timed 25-feet walk test; T25FW) in detecting the upper and lower extremity motor deficiencies in PwMS and also in a subgroup of mildly affected PwMS whose performance in standard clinical tests were similar to controls.

METHODS

Twenty-nine PwMS (age: 47.9 (8.6) years, relapsing-remitting type, expanded disability status scale: 2.5 (1.5)) and their age- and gender-matched controls completed an identical testing protocol in the upper (grip force muscles) and lower (knee extensors) extremities. For each extremity, we assessed Fmax, RFDmax, RFD-SF, and RFR-SF. Additionally, participants completed standard clinical tests for the evaluation of upper- (9HPT) and lower-extremity (T25FW) function. Comparisons were made between controls and PwMS 1) using all study participants and 2) including only mildly affected PwMS whose performance in standard functional tests was comparable to controls. Independent sample t-tests were utilized to compare groups, with a p-value set at 0.01 to correct for multiple comparisons. P-values and effect sizes were used to evaluate the sensitivity of the outcome measures in detecting group differences.

RESULTS

Our results indicate that most isometric outcomes and standard functional tests were sensitive in detecting motor deficiencies in both upper and lower extremities between groups (p<0.001). Among participants, 16 PwMS in 9HPT and 11 PwMS in T25FW demonstrated performance similar to that of the control group (9HPT: 18.85 (2.20) s vs 17.81 (2.19) s; p=0.19) and (T25FW: 3.60 (0.42) s vs 3.58 (0.29) s; p=0.92). The results of the comparisons between mildly affected PwMS and their controls indicate that RFR-SF is the only sensitive isometric outcome to detect differences between groups in the upper (-8.24 (0.76) 1/s vs -8.93 (0.6) 1/s; p=0.008) and lower extremity (-5.86 (1.13) 1/s vs -7.71 (1.11) 1/s; p<0.001).

CONCLUSION

The rate of force relaxation scaling factor, which assesses the ability to rapidly relax muscle forces after quick contractions, demonstrates high sensitivity in detecting motor deficiencies in PwMS, even when the current standard clinical outcomes fail to detect these differences. Our findings emphasize the importance of future randomized controlled trials focusing on rehabilitative and therapeutic interventions that specifically target muscle force relaxation to enhance motor functioning in PwMS.

Feature selection, construction and test of model for estimating lower extremity strength of older adults using foot motion measured by an in-shoe motion sensor

Lower extremity strength (LES) is essential to support activities in daily living. To extend healthy life expectancy of elderly people, early detection of LES weakness is important. In this study, we challenge to develop a method for LES assessment in daily living via an in-shoe motion sensor (IMS). To construct the estimation model, we collected data from 62 subjects. We used the outcome of the five-times-sit-to-stand test to represent the performance of LES as the target variable. Predictors were constructed from the subjects' foot motions measured by the IMS during straight path walking. We used the leave-one-subject-out least absolute shrinkage and selection operator algorithm to select features and construct respective models for the males and females. As a result, the models achieved fair and a good intra-class correlation coefficient agreement between the true and estimation values, with mean absolute errors of 2.14 and 1.21 s (variation of 23.6 and 16.0%), respectively. To validate the models, we separately collected data from 45 subjects. The models successfully predicted 100% and 90% of the male and female subjects' data, respectively, which suggests the robustness of the constructed estimation models. The results suggested that LES can be identified more effectively in daily living by wearing an IMS, and the use of an IMS has the potential for future frailty and fall risk assessment applications.

Ultrasound measures of muscle morphology in people with multiple sclerosis are associated with muscle performance and functional mobility

BACKGROUND

Neurologically-based muscle weakness is a common symptom in people with multiple sclerosis MS (MS), who may also exhibit muscle morphology changes and intrinsic muscle dysfunction. Diagnostic ultrasound (sonography) is a non-invasive, inexpensive, and clinically feasible method to measure muscle morphology. The purpose of this study was to investigate possible asymmetries in lower limb muscle morphology and performance in people with MS, and to assess the relationships of muscle morphology measures with individual patient characteristics, muscle performance, and functional mobility.

METHODS

This cross-sectional study was conducted at the Washington, DC Veterans Affairs Medical Center. The study participants were 29 Veterans with MS (52% female, 79% African-American, 48.6 ± 11.2 years old, Mean Expanded Disability Status Scale: 3.6 ± 1.4) who completed seated knee extension isokinetic strength and power tests, functional assessments (Timed 25-Foot Walk - T25FW, 5-Times Sit-to-Stand - 5STS), and quantitative B-mode ultrasound image acquisition of the rectus femoris muscle to derive morphology measures (thickness and echogenicity). The limb with weaker knee extension strength was identified as the more-involved limb. Differences between the more and less-involved limb were quantified using a t-test for all muscle morphology and muscle performance measures. Relationships between muscle morphology and patient characteristics, muscle performance, and functional mobility were evaluated using bivariate and multivariate analyses.

RESULTS

The rectus femoris thickness from the more-involved limb was lower (p<0.001) than that of the less-involved limb, whereas echogenicity was not different between the two limbs (p=0.147). Rectus femoris thickness of the more-involved limb was directly related to age (r=-0.63, p<0.001), muscle strength (r=0.53, p=0.003) and power (r=0.53, p=0.003), and gait speed (r=0.42, p=0.024); whereas its echogenicity was positively associated only with muscle strength (r=-0.46, p=0.013) and power (r=-0.50, p=0.006). Together rectus femoris thickness and echogenicity of the more involved limb explained 44% and 48% of the variance in muscle strength and power, respectively (p<0.001).

CONCLUSION

This study supports the ability of sonography to measure muscle morphology in people with MS, identify asymmetries, and quantify associations with important clinical correlates. Compared with more invasive and costly alternatives, sonography is a clinically feasible, relatively low-cost tool that can be used to assess muscle morphology in people with MS. Further research is warranted to determine the potential clinical utility of sonographic measures of muscle morphology in evaluating changes due to disease progression or therapeutic interventions in this population.

Establishment of regression-based normative isometric strength values for major lower limb muscle groups in persons with multiple sclerosis

BACKGROUND

Limb weakness is a major impairment that affects mobility in persons with multiple sclerosis (PwMS). Specifically, lower limb (LL) weakness can greatly affect gait and balance, while increasing fall risk and decreasing quality of life. Numerous studies have compared LL strength of PwMS to healthy controls, however none have objectively measured strength in all major LL joints (hip, knee, and ankle) in a large number of PwMS. Additionally, while discrete normative values exist for knee extensors in PwMS, there has yet to be regression-based normative isometric strength values for all major LL muscle groups. Therefore, this study aimed to develop gender-specific regression-based normative prediction equations, with 95% confidence intervals, for maximal isometric peak torque of major LL muscles in PwMS. A secondary aim was to characterize the prevalence of LL weakness in PwMS, defined as ≥ 2 SD below values reported for healthy individuals.

METHODS

A convenience sample of 175 (women: n = 135) PwMS participated in a prospective, cross-sectional study where isometric peak torque of hip flexors, extensors, and abductors, knee flexors and extensors, and ankle plantarflexors and dorsiflexors were measured using the Biodex System 4 Pro-Dynamometer®. Demographics (age, height, and weight) and disease characteristics (disease duration and disability) were collected. Performances were separated for each muscle group into strongest limb and weakest limb. For each gender, regression-based equations were generated for the LL muscle groups by limb with age, height, weight, disability, and disease duration as the covariates. Descriptive statistics were used to examine the frequency of LL weakness by gender and disability level. For comparison purposes, age-stratified (<30, 30-39, 40-49, 50-59, 60-69, >70 years) and disability-stratified (mild, moderate, and severe ambulant) discrete peak torque values were also generated for each gender.

RESULTS

Regression-based normative data are presented for men and women, accounting for age, height, weight, disability, and disease duration. Men were significantly stronger (P < 0.001) than women for all LL, with the men's models accounting for a greater percent of muscle strength variation than women's models for all muscle groups, except for hip extension. Disability was inversely related to strength in all of the models. LL weakness was prevalent in hip flexion (m: 47.5%; w: 63.0%) and extension (m: 92.5%; w: 88.1%), knee extension (m: 30.0%; w: 33.3%) and flexion (m: 25.0%; w: 34.8%), and ankle plantarflexion (m: 15.0%; w: 10.4%) and dorsiflexion (m: 100.0%; w: 96.3%). PwMS with mild disability had a high prevalence of ankle dorsiflexion (94.9-100.0%) and hip extension (81.4-90.0%) weakness.

CONCLUSIONS

This study is the first to provide regression-based normative data of bilateral strength in all major LL muscle groups and clinically useful prevalence data on the occurrence of weakness in these muscles. Of note, PwMS had a high prevalence of ankle dorsiflexion and hip extension weakness even when they were only mildly disabled. These findings can help guide the direction of future interventions and treatments to improve muscle function in PwMS.

Influence of Transcranial Direct Current Stimulation and Exercise on Physical Capacity and Gait in Multiple Sclerosis: A Cross-Over Pilot Study

Physical capacity provides a link between disease or impairment and limitations in activity; in multiple sclerosis (MS), it is limited and decreased. The aim of this study was to study the effects of exercise and transcranial direct current stimulation (tDCS) on the left dorsolateral prefrontal cortex area in MS patients with fatigue and an impaired gait ability. A cross-over design was carried out on fifteen patients with two disability associations, but three were excluded. Before and after each intervention, the 6 min walk test (6MWT) and the 2 min walk test (2MWT) were used to assess walking ability and the Modified Fatigue Impact Scale (MFIS) was used to assess fatigue. A total of twelve patients were enrolled (48.0 median age, Kurtzke Disability Scale (EDSS) 3.66 ± 1.3): five females and seven males. After the application of the exercise program, significant improvements were observed in the 6MWT (p < 0.001, g = 0.159) and 2MWT (p < 0.001, g = 0.182). Furthermore, fatigue was significantly reduced after the application of the exercise program (p < 0.05, g = 0.742) and after tDCS (p < 0.05, g = 0.525). We could consider therapeutic exercise in the future to improve the walking ability and fatigue in MS patients. Furthermore, tDCS did not exert a significant improvement in walking ability, but it appeared to influence fatigue. Clinical trial registration code: ACTRN12622000264785.

Neuromuscular rate of force development discriminates fallers in ambulatory persons with multiple sclerosis - an exploratory study

BACKGROUND

Falls as well as fall-related injuries (e.g., bone fractures) are common in persons with multiple sclerosis (pwMS). Whilst some studies have identified lower extremity maximal muscle strength (Fmax) as one among several risk factors, no previous studies have investigated the association between rate of force development (RFD; ability to generate a rapid rise in muscle force) and falls in pwMS. Not only is RFD substantially compromised (and more so than Fmax) in pwMS, studies involving other neurodegenerative populations have shown that RFD - to a greater extent than Fmax - is crucial for counteracting unexpected perturbations and avoiding falling.

OBJECTIVE

To explore whether knee extensor RFD (and Fmax) can discriminate fallers from non-fallers in pwMS.

METHODS

Knee extensor neuromuscular function (comprising RFD_50ms and RFD_200ms (force developed in the interval 0-50 ms and 0-200 ms, respectively) as well as Fmax) of the weaker leg was assessed by isokinetic dynamometry. Falls were determined by 1-year patient recall, with pwMS subsequently being classified as non-fallers (0 falls), fallers (1-2 falls), or recurrent fallers (≥3 falls).

RESULTS

A total of n=53 pwMS were enrolled in the study, with n=24 classified as non-fallers (63% females, 48 years, EDSS 2.2), n=16 as fallers (88% females, 57 years, EDSS 3.3), and n=13 as recurrent fallers (46% females, 60 years, EDSS 4.2). Compared with non-fallers, neuromuscular function was reduced in both fallers (RFD₅₀ -4.42 [-7.47;-1.37] Nm^.s^-1.kg^-1, -48%; RFD₂₀₀ -1.45 [-2.98;0.07] Nm^.s^-1.kg^-1, -24%; Fmax -0.42 [-0.81;-0.03] Nm^.kg^-1, -21%) and recurrent fallers (RFD₅₀ -5.69 [-8.94;-2.43] Nm^.s^-1.kg^-1, -62%; RFD₂₀₀ -2.26 [-3.89;-0.63] Nm^.s^-1.kg^-1, -38%; Fmax -0.38 [-0.80;0.03] Nm^.kg^-1, -19%). Across all participants, associations were observed between RFD_50ms and falls (r_s = -0.46 [-0.67;-0.24], between RFD_200ms and falls (r_s = -0.34 [-0.59;-0.09]), and between Fmax and falls (r_s = -0.24 [-0.48;0.01]).

CONCLUSION

In this exploratory study, knee extensor neuromuscular function was able to discriminate fallers from non-fallers in pwMS, with RFD being superior to Fmax. Routine assessment of lower extremity neuromuscular function (RFD_50ms in particular) may be a helpful tool in identifying pwMS at future risk of falling.

Clinical utility of the Trendelenburg Test in people with multiple sclerosis

BACKGROUND

The clinical utility of the Trendelenburg Test remains unknown in people with multiple sclerosis (MS).

OBJECTIVE

To measure (1) intra-rater reliability, (2) agreement of goniometer-assessed Trendelenburg pelvis-on-femur angle (POF) with motion capture, and (3) concurrent validity of Trendelenburg POF and hip abduction strength with POF during walking and step negotiation.

METHODS

Trendelenburg POF was measured in 20 people with MS using goniometry and motion analysis. In addition, peak POF was measured using motion analysis during walking, step ascent, and step descent. Intra-rater reliability of goniometer-assessed Trendelenburg POF and agreement with motion analysis-assessed POF were analyzed. Pearson's r was used to determine the relationships between Trendelenburg POF and hip abduction strength with peak POF during each functional activity.

RESULTS

Goniometer-assessed Trendelenburg POF demonstrated very strong reliability (ICC: 0.948), strong agreement with 3D motion analysis (ICC: 0.792), correlated moderately with peak POF during walking (r = 0.519) and step ascent (r = 0.572), and weakly with step descent (r = 0.463). Hip abductor strength correlated weakly with peak POF during step ascent (r = -0.307) and negligibly during walking (r = -0.270) and step descent (r = -0.249).

CONCLUSIONS

Goniometer-assessed Trendelenburg POF was reliable, agreed with motion analysis, and may provide insight into hip abduction muscle performance during functional activities in people with MS.

Reliability of the Five Times Sit to Stand Test performed remotely by multiple sclerosis patients

INTRODUCTION

Multiple Sclerosis, known main cause of non-traumatic neurological disability in adults, leads to changes in muscle strength, especially in the lower limbs. Assessing muscle strength in these patients is thus essential and can be achieved by the Five Times Sit to Stand Test (FTSST), commonly performed in person. Due to the COVID-19 pandemic and social distancing measured adopted, Brazilian physiotherapists turned to remote monitoring and assessment, supported by Resolution n° 516/2020, which required proving the reliability of tests. Given this scenario, this study sought to evaluate the intra- and inter-rater reliability of the Five Times Sit to Stand Test performed remotely and synchronously by multiple sclerosis patients.

METHODS

A sample of 33 individuals with relapsing-remitting Multiple Sclerosis (18 women and 15 men, mean age 43.7 ± 13.4 years) were remotely and synchronously by video call. Inter-rater reliability was evaluated by analyzing FTSST execution time, in seconds, timed by two different raters on the same video call. In turn, intra-rater reliability was assessed by analyzing the execution time recorded in two different video calls made by the same rater, within a 24-28-h interval. Descriptive and inferential data analysis were performed using SPSS 20.0 software. Means and standard deviation were calculated for descriptive statistic. Intraclass correlation coefficient (ICC), with a 0.05 significance level, standard error of measurement (SEM) and minimal detectable change (MDC) were calculated for inferential analysis.

RESULTS

Data analysis showed excellent ICC values and low SEM and MDC values regarding inter-rater reliability (ICC: 0.993 (0.986-0.996); p-value: <0.001; SEM: 0.6 s; MDC: 1.6 s) and intra-rater reliability (ICC: 0.962 (0.925-0.981); p-value: <0.001; SEM: 1.4 s; MDC: 3.8 s).

CONCLUSION

Based on these values, FTSST performed remotely and synchronously by relapsing-remitting Multiple Sclerosis patients is reliable and can be used both by different raters, for assessment, or by the same rater, in pre- and post-test situations.

Validity of the 30-Second Sit-to-Stand test as a measure of lower extremity function in persons with multiple sclerosis: Preliminary evidence

BACKGROUND

The 30-Second Sit-To-Stand (30SSTS) is a quick, inexpensive, safe, and widely used clinical measure of lower extremity function. To date, there is limited evidence regarding the use of 30SSTS in multiple sclerosis (MS). The purpose of this study was to examine the construct validity of the 30SSTS test in persons with MS compared with non-MS healthy controls.

METHODS

Twenty ambulatory persons with MS and twenty age- and sex-matched healthy controls completed the 30SSTS, Timed 25-Foot Walk (T25FW), Timed Up and Go (TUG), Six-Minute Walk (6MW), and Godin Leisure-Time Exercise Questionnaire (GLTEQ). Persons with MS also completed the Patient Determined Disease Steps (PDDS) and 12-item MS Walking Scale (MSWS-12).

RESULTS

Persons with MS had significantly worse performance on the TUG (mean difference [95% confidence interval] = 1.4 [0.5, 2.3] sec) and 6MW (-259.2 [-450.8, -67.6] ft), but not on the 30SSTS (-1.6 [-1.5, 4.6] reps) and T25FW (-0.59 [-0.1, 1.2] ft/sec) compared with controls. There were significant moderate-to-strong correlations between the 30SSTS with T25FW, TUG, and 6MW scores in persons with MS (r = 0.48, -0.65 and 0.61, respectively), whereas the 30SSTS was only significantly associated with 6MW scores (r = 0.43) in controls. The 30SSTS was negatively associated with MS-related walking disability assessed by the PDDS and MSWS-12 (r_s = -0.52 and -0.64, respectively), but was not significantly associated with the GLTEQ in MS and controls (r = 0.30 and 0.17, respectively).

CONCLUSION

This study provides initial support for the construct validity of the 30SSTS as a measure of lower extremity function in persons with MS. Our findings warrant the inclusion of the 30SSTS as a feasible and valid measure of physical function in clinical research and practice involving persons with MS.

Motor performance, motor impairments, and quality of life after eccentric resistance training in neurological populations: A systematic review and meta-analyses

BACKGROUND

Many overlapping factors impair motor performance and quality of life in neurological patients. Eccentric resistance training (ET) has potential benefits for improving motor performance and treating motor impairments better than some traditional rehabilitation approaches.

OBJECTIVE

To estimate the effect of ET in neurological settings.

METHODS

Seven databases were reviewed up to May 2022 according to PRSIMA guidelines to find randomized clinical trials involving adults with a neurological condition, who underwent ET as set by the American College of Sports Medicine. Motor performance (main outcome) was assessed as strength, power and capacities during activity. Secondary outcomes (impairments) were muscle structure, flexibility, muscle activity, tone, tremor, balance and fatigue. Tertiary outcomes were risk of fall, and self-reports of quality of life.

RESULTS

Ten trials were included, assessed using Risk of Bias 2.0 tool, and used to compute meta-analyses. Effective effects in favour of ET were found for strength and power, but not for capacities during activity. Mixed results were found for secondary and tertiary outcomes.

CONCLUSION

ET may be a promising intervention to better improve strength/power in neurological patients. More studies are needed to improve the quality of evidence underlying changes responsible for these results.

EFFECTS OF BRAKE TRAINING ON LOWER LIMBS OF SOCCER PLAYERS

ABSTRACT Introduction: As sports skills and attacking techniques evolved rapidly, so did sports offense and defense, requiring new techniques for improving sports performance on the field. One technique that has been empirically highlighted is braking training, with little scientific research on its practical results. Objective: Study the effects of brake training on lower limb agility in soccer players. Methods: Male soccer athletes participated in the experiment, and patients were divided into experimental and control groups, where lower limb demand and fracture resistance were tested. Results: After 8 weeks of training, the quality of sensitivity and explosive strength of the lower extremities were checked, where the experimental group showed a highly significant difference in training (P<0.01). The sensitivity index scores were all significantly changed. In the control group, there was a variation in bone density before and after exercise but little significant difference in performance. Conclusion: Compared to traditional resistance training, extending and focusing on lower limb braking training can effectively develop explosive strength and agility in soccer players. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

INFLUENCE OF DOUBLE JUMP ROPES ON ATHLETES’ LOWER LIMBS

ABSTRACT Introduction: The double jump rope swing is a rope jumping technique that combines the technology of vertical jump and rope swing, requiring participants to jump twice in a row with the soles of their feet. Objective: Study the effect of double-balance jump rope training on athletes’ muscular strength in the lower limbs. Methods: Through the experimental process, the dynamic and kinematic parameters generated during the process of vertical jump of the participants before and after the double balance rope jump exercise were tested; the effects of double balance rope jump on the biomechanical characteristics of the lower limbs and hip, knee and ankle joints of the participants were analyzed. Results: Compared to pre-training, subjects in the experimental group improved significantly (p = 0.05). Conclusion: After double rope jump training, the subjects obtained an increase in lower limb strength and ground reaction force at the extension stage in the vertical jump. They produced greater force in less time, suggesting that the lower limb burst strength was enhanced. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Application of eccentric training in various clinical populations: Protocol for a multi-centered pilot and feasibility study in people with low back pain and people with multiple sclerosis

Physical activity and exercise are effective approaches in prevention and therapy of multiple diseases. Although the specific characteristics of lengthening contractions have the potential to be beneficial in many clinical conditions, eccentric training is not commonly used in clinical populations with metabolic, orthopaedic, or neurologic conditions. The purpose of this pilot study is to investigate the feasibility, functional benefits, and systemic responses of an eccentric exercise program focused on the trunk and lower extremities in people with low back pain (LBP) and multiple sclerosis (MS). A six-week eccentric training program with three weekly sessions is performed by people with LBP and MS. The program consists of ten exercises addressing strength of the trunk and lower extremities. The study follows a four-group design (N = 12 per group) in two study centers (Israel and Germany): three groups perform the eccentric training program: A) control group (healthy, asymptomatic); B) people with LBP; C) people with MS; group D (people with MS) receives standard care physiotherapy. Baseline measurements are conducted before first training, post-measurement takes place after the last session both comprise blood sampling, self-reported questionnaires, mobility, balance, and strength testing. The feasibility of the eccentric training program will be evaluated using quantitative and qualitative measures related to the study process, compliance and adherence, safety, and overall program assessment. For preliminary assessment of potential intervention effects, surrogate parameters related to mobility, postural control, muscle strength and systemic effects are assessed. The presented study will add knowledge regarding safety, feasibility, and initial effects of eccentric training in people with orthopaedic and neurological conditions. The simple exercises, that are easily modifiable in complexity and intensity, are likely beneficial to other populations. Thus, multiple applications and implementation pathways for the herein presented training program are conceivable. Trial registration: DRKS00020483 (DRKS, German Clinical Trials Register; 24th January 2020 -retrospectively registered; https://www.drks.de/DRKS00020483).

Effects of an 8-week lunge exercise on an unstable support surface on lower-extremity muscle function and balance in middle-aged women

PURPOSE

This study aimed to develop a more effective exercise program for lower extremity muscle function by evaluating the effects of an 8-week lunge exercise performed on an unstable support surface on lower extremity muscle function, body composition, and body balance in middle-aged women.

METHODS

Twenty participants were divided into two groups (control group: exercise on a stable support surface, n=10; experimental group: exercise on an unsta ble support surface, n=10). Each participant performed the exercise program for 8 weeks (three sessions a week, 50 min/session).

RESULTS

The results revealed that body fat percentage decreased significantly in the experimental group (p&lt;0.01). Additionally, lower-extremity muscle mass and function increased significantly in both groups (p&lt;0.05), but with no significant difference between the groups. Moreover, the results of the static and dynamic balance tests indicated that balance improved in both groups, with significantly greater improvements in the experimental group than in the control group (p&lt;0.05).

CONCLUSION

Lunge exercise on stable and unstable support surfaces improves muscle function and static balance in middle-aged women. In particular, lunge exercise on an unstable support surface was more effective at reducing body fat than lunge exercise on a stable support surface and was also found to improve dynamic balance. Therefore, a program consisting of lunge exercises on an unstable support surface may be suitable for body improvements in middle-aged women.

Effects of fast-velocity concentric resistance training in people with multiple sclerosis: A randomized controlled trial

OBJECTIVES

To analyze the effects of a fast-velocity concentric resistance training (FVCRT) program on maximum strength of upper and lower limb, gait speed, walking endurance, fatigue, physical self-perception, and catastrophizing pain in people with multiple sclerosis (MS).

MATERIALS AND METHODS

Participants were randomized to either an experimental [EG] (n = 18) or a control [CG] (n = 12) group. The EG carried out 10-weeks of lower limb FVCRT. The CG did not perform any intervention. The maximum isometric voluntary contraction (MVIC) during knee extension, hand-grip strength, gait speed, walking endurance, fatigue, physical self-perception, and catastrophizing pain were measured.

RESULTS

Inter-group differences after intervention were found on the right and left sides in MVIC (p = .032; ES = -0.7 and p = .009; ES = -0.9), and hand grip strength (p = .003; ES = -1.0 and p = .029; ES = -0.7). After FVCRT, there was in increase in MVIC (p < .001; ES = -1.7 and p < .001; ES = -1.3) and hand grip strength (p < .001; ES = -1.3 and p < .001; ES = -1.3) on both right and left sides, respectively. In addition, gait speed (p = .023; ES = 1.3), walking endurance (p < .001; ES = -1.0), symptomatic fatigue (p = .004; ES = 0.6), and catastrophizing pain (p < .001; ES = 1.0) improved in EG.

CONCLUSION

Lower limb FVCRT improved the upper and lower limb strength, walking, symptomatic fatigue, and catastrophizing pain in MS participants.

Functional Performance, Leg Muscle Strength, and Core Muscle Endurance in Multiple Sclerosis Patients With Mild Disability: A Cross-Sectional Study

This study aimed to investigate the relationship of sit-to-stand and walking performance with leg muscle strength and core muscle endurance in people with multiple sclerosis (PwMS) with mild disabilities. In this study, 49 PwMS (Expanded Disability Status Scale score = 1.59 ± 0.79) and 26 healthy controls were enrolled. The functional performances, including sit-to-stand and walking performances, were evaluated with the five-repetition sit-to-stand test, timed up and go test, and 6-min walking test. The PwMS finished significantly slower five-repetition sit-to-stand, timed up and go, and 6-min walking test than the healthy controls. In addition, the significant contributors were the weakest trunk lateral flexor endurance for five-repetition sit-to-stand; the Expanded Disability Status Scale score, and the weakest hip adductor muscle for timed up and go; the weakest hip extensor muscles strength for 6-min walking test. The functional performances in PwMS, even with mild disabilities, were lower compared with healthy controls. Decreases in both leg muscle strength and core muscle endurance are associated with lower functional performance in PwMS.

Reliability of Isometric Muscle Strength Measurement and Its Accuracy Prediction of Maximal Dynamic Force in People with Multiple Sclerosis

Background and Objectives: Multiple sclerosis (MS) is a disease that manifests with varied neurological symptoms, including muscle weakness, especially in the lower extremities. Strength exercises play an important role in the rehabilitation and functional maintenance of these patients. The individualized prescription of strength exercises is recommended to be based on the maximum force determined by the one-repetition maximum (1RM), although to save time and because it requires less equipment, it is often determined by the maximum voluntary isometric contraction (MVIC). The purpose of this work was to study, in patients with MS (pwMS), the reliability of MVIC and the correlation between the MVIC and 1RM of the knee extensors and to predict the MVIC-based 1RM. Materials and Methods: A total of 328 pwMS participated. The study of the reliability of MVIC included all pwMS, for which MVIC was determined twice in one session. Their 1RM was also evaluated. The sample was randomized by MS type, sex, and neurological disability score into a training group and a testing group for the analysis of the correlation and prediction of MVIC-based 1RM. Results: MVIC repeatability (ICC, 2.1 = 0.973) was determined, along with a minimum detectable change of 13.2 kg. The correlation between MVIC and 1RM was R2 = 0.804, with a standard error estimate of 12.2 kg. The absolute percentage error of 1RM prediction based on MVIC in the test group was 12.7%, independent of MS type and with no correlation with neurological disability score. Conclusions: In patients with MS, MVIC presents very good intrasubject repeatability, and the difference between two measurements of the same subject must differ by 17% to be considered a true change in MVIC. There is a high correlation between MVIC and 1RM, which allows estimation of 1RM once MVIC is known, with an estimation error of about 12%, regardless of sex or type of MS, and regardless of the degree of neurological disability.

Implications of lower extremity muscle power and force for walking and fatigability in multiple sclerosis - An exploratory pilot-study

BACKGROUND

Limitations in physical function are common in Multiple Sclerosis (MS), yet it is neither clear how muscle power implicates physical function and walking-fatigability. This pilot-study aims to investigate (1) deficits in muscle power/force alongside walking in persons with MS; (2) associations between muscle power/force and physical functions and (3) the impact of prolonged walking in muscle power/force.

METHODS

30 relapse-remitting persons with MS and 28 healthy controls performed chair rise and plantar flexion on a force platform before and after 12-minutes of intermittent walking to measure lower extremity muscle power/force. GaitRite measured walking speed. The percentage change in distance walked was also calculated. Persons with MS were classified into subgroups according to walking-fatigability and mobility disability status (Patient Determined Disease Steps).

FINDINGS

Higher deficits in muscle power compared to force were observed in persons with MS vs. healthy controls particularly in persons with MS having higher disability. Muscle power and force were associated with walking capacity, mobility disability and subjective fatigue, but not with percentage change in distance walked. Persons with MS slowed down over the course of the 12-min intermittent walking, whereas decrements in walking speed and muscle power/force (derived from chair rise) were observed in persons with MS presenting walking-fatigability only.

INTERPRETATION

Muscle power and force are impaired in persons with MS and appear to be critical for physical function in MS. This exploratory pilot study further suggests that muscle power/force from chair rise could contributes to walking-fatigability which therefore offer future treatment targets.

Efficacy of prolonged-release fampridine versus placebo on walking ability, dynamic and static balance, physical impact of multiple sclerosis, and quality of life: an integrated analysis of MOBILE and ENHANCE

Background:

MOBILE and ENHANCE were similarly designed randomized trials of walking-impaired adults with relapsing-remitting or progressive multiple sclerosis (MS) who received placebo or 10 mg prolonged-release (PR)-fampridine twice daily for 24 weeks. Both studies showed sustained and clinically meaningful improvement in broad measures of walking and balance over 24 weeks of PR-fampridine treatment.

Objective:

To evaluate the functional benefits and safety of PR-fampridine versus placebo using a post hoc integrated efficacy analysis of MOBILE and ENHANCE data.

Methods:

Data from the intention-to-treat (ITT) populations of MOBILE and ENHANCE studies were pooled in a post hoc analysis based on the following outcome measures: 12-item MS Walking Scale (MSWS-12), Timed Up and Go (TUG) speed, Berg Balance Scale (BBS), MS Impact Scale physical impact subscale (MSIS-29 PHYS), EQ-5D utility index score, visual analogue scale (VAS), and adverse events. The primary analysis was the proportion of people with MS (PwMS) with a mean improvement in MSWS-12 score (⩾8 points) from baseline over 24 weeks. A subgroup analysis based on baseline characteristics was performed.

Findings:

In the ITT population (N = 765; PR-fampridine, n = 383; placebo, n = 382), a greater proportion of PR-fampridine–treated PwMS than placebo-treated PwMS achieved a clinically meaningful improvement in the MSWS-12 scale over 24 weeks (44.3% versus 33.0%; p < 0.001). PR-fampridine MSWS-12 responders demonstrated greater improvements from baseline in TUG speed, BBS score, MSIS-29 PHYS score, and EQ-5D utility index and VAS scores versus PR-fampridine MSWS-12 nonresponders and placebo. Subgroup analyses based on baseline characteristics showed consistency in the effects of PR-fampridine.

Conclusion:

The pooled analysis of MOBILE and ENHANCE confirms previous evidence that treatment with PR-fampridine results in clinically meaningful improvements in walking, mobility and balance, self-reported physical impact of MS, and quality of life and is effective across a broad range of PwMS.

Objectively assessed physiological, physical, and cognitive function along with patient-reported outcomes during the first 2 years of Alemtuzumab treatment in multiple sclerosis: a prospective observational study

INTRODUCTION

In persons with multiple sclerosis (pwMS), little evidence exist on the effects of Alemtuzumab on physiological, physical, and cognitive function along with patient-reported outcomes, despite these domains are being rated as highly important. Therefore, our purpose was to perform a prospective observational study to examine these outlined outcomes during the first two years of Alemtuzumab treatment in pwMS.

METHODS

In n = 17 relapsing-remitting pwMS, physiological function [body composition; bone mineral content; muscle strength; aerobic capacity], physical function [6-min walk test (6MWT, primary outcome); timed 25 ft walk test (T25FWT); six spot step test (SSST); 9-step stair ascend (9SSA); timed up and go test (TUG); 5 × sit to stand test (5STS)], cognitive function [selective reminding test (SRT); symbol digit modalities test (SDMT)], and patient-reported outcomes [multiple sclerosis impact scale-29 (MSIS29); 12-item multiple sclerosis walking scale (MSWS12); modified fatigue impact scale (MFIS); hospital anxiety and depression scale (HADS)] were assessed prior to Alemtuzumab treatment initiation as well as 3, 6, 12, and 24 months into the treatment.

RESULTS

Improvements were observed at 24-month follow-up in T25FWT (+ 8%), SSST (+ 10%), SDMT (+ 5.2 points, 53% improved more than the clinical cut-off score) and SRT, whereas the primary outcome 6MWT, and all other remaining outcomes, remained stable throughout the Alemtuzumab treatment period.

CONCLUSION

The present findings suggest that Alemtuzumab treatment in relapsing-remitting pwMS can improve certain domains of physical function (short distance walking) and cognitive function (processing speed, memory), and furthermore stabilize physiological and physical function along with patient-reported outcomes.

TRIAL REGISTRATION

Registered at clinicaltrials.gov: NCT03806387.

Embodied learning in multiple sclerosis using melodic, sound, and visual feedback: a potential rehabilitation approach

Given the prevalence of motor and cognitive functions in persons with multiple sclerosis (PwMS), we proposed that the theoretical framework of embodiment could provide a rehabilitation avenue to train these functions as one functional unit. PwMS (n = 31) and age- and gender-matched healthy controls (n = 30) underwent an embodied learning protocol. This involved learning a cognitive sequence while performing it through bodily stepping movement under three feedback conditions (melody, sound, and visual). Cognitive and movement performance was assessed by a delayed recall 15 min after undergoing the embodied learning protocol. Half of participants correctly recalled the sequence in all three conditions, while 70% of healthy controls achieved correct recall within the melody condition. Balance impairment predicted the speed of executing the sequence irrespective of learning, most apparent in the melody condition. Information processing speed predicted the speed of executing the sequence in the melody and sound conditions between participants as well as over time. Those who learned performed the sequence faster in the melody condition only and overall were faster over time. We propose how embodied learning could expand the current context of rehabilitation of cognitive and motor control in PwMS.

Six-Minute Walk Performance and Related Factors in Pediatric-Onset Multiple Sclerosis

OBJECTIVE

To investigate functional exercise capacity and its relationship between physical activity levels, muscle strength, balance, fatigue, and quality of life in patients with pediatric-onset multiple sclerosis.

METHODS

Fifteen patients with pediatric-onset multiple sclerosis were included. The 6-minute walk test was used to determine functional exercise capacity and walking distance. The Godin Leisure-Time Exercise Questionnaire and pedometer were used to evaluate physical activity, Timed-Up and Go for dynamic balance, isokinetic testing for lower extremity muscle strength, Fatigue Severity Scale for fatigue, and the Pediatric Quality of Life Inventory (PedsQL) for quality of life.

RESULTS

The 6-minute walking distance was positively correlated with GLTEQ and the School-Work subgroup score of the PedsQL-Self-report, and negatively correlated with Timed-Up and Go and Fatigue Severity Scale. Dynamic balance, physical activity, and fatigue were significant predictors of 6-minute walking distance.

CONCLUSIONS

Our results showed that 6-minute walk test is influenced by physical activity, dynamic balance, and fatigue, and related to quality of life in patients with pediatric-onset multiple sclerosis.

Impact of Lockdown during COVID-19 Pandemic on Central Activation, Muscle Activity, Contractile Function, and Spasticity in People with Multiple Sclerosis

Background

People with multiple sclerosis (MS) suffer from symptoms related to neural control, such as reduced central activation, lower muscle activity, and accentuated spasticity. A forced 9-week home confinement related to COVID-19 in Spain may have worsened these symptoms. However, no study has demonstrated the impact of home confinement on neuromuscular mechanisms in the MS population. This study was aimed at analyzing the effects of a 9-week home confinement on central activation, muscle activity, contractile function, and spasticity in MS patients.

Methods

Eighteen participants were enrolled in the study. Left and right knee extensor maximum voluntary isometric contraction (MVIC), maximal neural drive via peak surface electromyography (EMG) of the vastus lateralis, central activation ratio (CAR), and muscle contractile function via electrical stimulation of the knee extensor muscles, as well as spasticity using the pendulum test, were measured immediately before and after home confinement.

Results

Seventeen participants completed the study. CAR significantly decreased after lockdown (ES = 1.271, p < 0.001). Regarding spasticity, there was a trend to decrease in the number of oscillations (ES = 0.511, p = 0.059) and a significant decrease in the duration of oscillations (ES = 0.568, p = 0.038). Furthermore, in the left leg, there was a significant decrease in the first swing excursion (ES = 0.612, p = 0.027) and in the relaxation index (ES = 0.992, p = 0.001). Muscle contractile properties, MVIC, and EMG variables were not modified after confinement.

Conclusions

The results suggest that a home confinement period of 9 weeks may lead to an increase in lower limb spasticity and a greater deficit in voluntary activation of the knee extensors.

The Validity of the Single-Leg Heel Raise Test in People With Multiple Sclerosis: A Cross-Sectional Study

Background: The single-leg heel raise test is a common clinical assessment; however, little is known about its validity in people with multiple sclerosis (MS). This study investigated the validity of the single-leg heel raise test in a group of people with MS and a healthy control group (CTL).

Materials and Methods: Twenty-one people with MS (49 ± 12 years, Expanded Disability Status Scale 1.5–5.5) and 10 healthy controls (48 ± 12 years) performed the single-leg heel raise test, ankle plantarflexion isometric strength assessment using electromechanical dynamometry, and mobility measures (Timed 25-Foot Walk, 2-Min Walk Test, Functional Stair Test).

Results: Convergent validity between the heel raise test and strength was moderate for participants with MS completing <20 heel raises (r = 0.63, p = 0.001) but weak for the entire sample (r = 0.30, p = 0.020). Compared to the average CTL group values, the heel raise test differentiated between groups on the MS groups' weaker (p < 0.001) and stronger (p = 0.003) limbs, while strength only differentiated between groups on the weaker limb (p = 0.010). Considering the weaker and strong limbs from the MS group and the CTL group average values, the mobility measures had moderate-to-strong correlations with the heel raise test on the weaker MS limb + CTL (r = 0.71–0.78) and stronger MS limb + CTL (r = 0.62–0.70), and weak-to-moderate correlations with strength on the weaker MS limb + CTL (r = 0.49–0.58, p = 0.001–0.007).

Discussion: In people with MS, the single-leg heel raise test may be clinically useful as it identified impaired muscle performance and differentiated muscle performance from a healthy control group and, together with the control group, correlated with functional mobility.

The impact of COVID-19 home confinement on neuromuscular performance, functional capacity, and psychological state in Spanish people with Multiple Sclerosis

Background

The COVID-19 pandemic caused a global confinement of more than 2 months in Spain. As a result, the general population has significantly decreased their physical activity levels. The consequences of this abrupt, sedentary lifestyle in Spanish people with Multiple Sclerosis (pwMS) were unknown. Our aim was to examine the impact of COVID-19 home confinement on neuromuscular performance, functional capacity, physical self-perception, and anxiety in pwMS.

Methods

Eighteen pwMS (8:10 men/women, age: 43.41±10.88 years, Expanded Disability Status Scale: 2.85±1.34) participated in the study. Rate of force development (RFD) and maximal voluntary isometric contraction during knee extension in both legs, Timed-Up and Go test (TUG), sit-to-stand test, 6 min walk test, 10 m walk test, Physical-Self Perception Questionnaire (PSPQ) and State-Train Anxiety Inventory (STAI) were performed just before and after home confinement.

Results

A non-significant moderate effect (p = 0.07; ES = -0.48) was observed in the time in the sit-to-stand test compared to pre-home confinement. There was a significant increase in the time in TUG (p = 0.02; ES = -0.67). The PSQP score decreased (p = 0.01; ES = 0.79) and STAI-state increased (p = 0.01; ES = -0.65) following home confinement.

Conclusion

Home confinement had an impact on functional capacity, physical self-perception and state anxiety. However, neuromuscular performance was not altered after home confinement.

Comparison Between Isometric and Concentric Motor Fatigability in Persons With Multiple Sclerosis and Healthy Controls - exploring central and peripheral contributions of motor fatigability

BACKGROUND

Motor fatigability (i.e. contraction-induced reduction in muscle strength) from a concentric task associate stronger to walking and perception of fatigue in persons with multiple sclerosis (pwMS), compared with an isometric task. However, the central and peripheral contributions of motor fatigability between these tasks have not been investigated.

OBJECTIVE

Compare the central and peripheral contributions of motor fatigability in the knee extensors in a sustained isometric fatigability protocol versus a concentric fatigability protocol and in pwMS versus healthy controls (HCs).

METHODS

Participants (n=31 pwMS; n=15 HCs) underwent neuromuscular testing before and immediately after two knee extensor fatigability tasks (sustained isometric and concentric) in an isokinetic dynamometer. Neuromuscular testing of fatigability consisted of maximal voluntary contraction, voluntary activation (central/neural contributor), and resting twitch (peripheral/muscular contributor) determined by the interpolated twitch technique.

RESULTS

Sustained isometric and concentric fatigability protocols resulted in motor fatigability for both pwMS and HCs, with no between-protocols differences for either group. Regression analysis showed that motor fatigability variance in pwMS was mainly attributed to central fatigability in the sustained isometric protocol and to both central and peripheral fatigability in the concentric protocol. In HCs, the variance in sustained isometric and concentric fatigability were attributed to both peripheral and central fatigability.

CONCLUSION

Central and peripheral contributions of motor fatigability differed between sustained isometric and concentric protocols as well as between pwMS and HCs. These between-protocol differences in pwMS provide a neuromuscular dimension to the reported difference in the strength of associations of concentric and isometric tasks to walking and perception of fatigue in pwMS.

Lower extremity muscle power - A critical determinant of physical function in aging and multiple sclerosis

BACKGROUND AND PURPOSE

In aging, lower extremity muscle power is undoubtedly one of the most important parameters of neuromuscular function implicating lower extremity physical function (e.g. walking capacity). However, no previous studies have examined the combined effects of aging and multiple sclerosis (MS) on lower extremity muscle power concomitant with lower extremity physical function. The aim of this cross-sectional study was to examine potential decrements in pwMS vs. healthy controls (HC) across the adult lifespan in these outcomes.

METHODS

In the present explorative cross-sectional study, n = 42 pwMS (females n = 29 (69%); age = 53 ± 12 years (mean ± SD), range 31-78; patient determined disease steps score = 3.7 ± 1.7, range 0-7) and n = 49 age-matched HC (females n = 34 (69%); age = 56 ± 16 years, range 24-78) were enrolled, and divided into groups of young (≤ 44 years), middle-aged (45-59 years), and old (≥ 60 years). Muscle power was obtained from bilateral leg press (Power_LegPressPeak) and maximal chair rise (Power_ChairRise) using a linear encoder. Associations were assessed between muscle power and measurements of lower extremity physical function (5 x sit-to-stand (5STS); timed 25-foot-walk-test (T25FWT)).

RESULTS

Muscle power was reduced in pwMS vs. HC (Power_LegPressPeak -23[-34:-12]% (mean[95%CI]); Power_ChairRise -26[-35:-17]%) and was negatively associated with advanced age in both pwMS (decline per decade -0.40 W.kg^-1 and -2.53 W.kg^-1, respectively) and HC (decline per decade -0.42 W.kg^-1 and -2.03 W.kg^-1, respectively). Muscle power was strongly associated with physical function in pwMS (r²_range = 0.45-0.61, p < 0.01) yet only moderately associated in HC (r²_range = 0.18-0.39, p < 0.01).

CONCLUSION

The combined effects of MS and aging reveal substantial decrements in lower extremity muscle power that is accompanied by (and strongly associated with) decrements in lower extremity physical function. Consequently, lower extremity muscle power should be viewed as a clinically important factor (i.e. a critical determinant of lower extremity physical function) in pwMS. We propose that lower extremity muscle power should be specifically targeted by preventive and rehabilitative exercise strategies, especially in older pwMS.

Kinematic Analysis of Lower Limb Joint Asymmetry During Gait in People with Multiple Sclerosis

The majority of people with Multiple Sclerosis (pwMS), report lower limb motor dysfunctions, which may relevantly affect postural control, gait and a wide range of activities of daily living. While it is quite common to observe a different impact of the disease on the two limbs (i.e., one of them is more affected), less clear are the effects of such asymmetry on gait performance. The present retrospective cross-sectional study aimed to characterize the magnitude of interlimb asymmetry in pwMS, particularly as regards the joint kinematics, using parameters derived from angle-angle diagrams. To this end, we analyzed gait patterns of 101 pwMS (55 women, 46 men, mean age 46.3, average Expanded Disability Status Scale (EDSS) score 3.5, range 1–6.5) and 81 unaffected individuals age- and sex-matched who underwent 3D computerized gait analysis carried out using an eight-camera motion capture system. Spatio-temporal parameters and kinematics in the sagittal plane at hip, knee and ankle joints were considered for the analysis. The angular trends of left and right sides were processed to build synchronized angle–angle diagrams (cyclograms) for each joint, and symmetry was assessed by computing several geometrical features such as area, orientation and Trend Symmetry. Based on cyclogram orientation and Trend Symmetry, the results show that pwMS exhibit significantly greater asymmetry in all three joints with respect to unaffected individuals. In particular, orientation values were as follows: 5.1 of pwMS vs. 1.6 of unaffected individuals at hip joint, 7.0 vs. 1.5 at knee and 6.4 vs. 3.0 at ankle (p < 0.001 in all cases), while for Trend Symmetry we obtained at hip 1.7 of pwMS vs. 0.3 of unaffected individuals, 4.2 vs. 0.5 at knee and 8.5 vs. 1.5 at ankle (p < 0.001 in all cases). Moreover, the same parameters were sensitive enough to discriminate individuals of different disability levels. With few exceptions, all the calculated symmetry parameters were found significantly correlated with the main spatio-temporal parameters of gait and the EDSS score. In particular, large correlations were detected between Trend Symmetry and gait speed (with rho values in the range of −0.58 to −0.63 depending on the considered joint, p < 0.001) and between Trend Symmetry and EDSS score (rho = 0.62 to 0.69, p < 0.001). Such results suggest not only that MS is associated with significantly marked interlimb asymmetry during gait but also that such asymmetry worsens as the disease progresses and that it has a relevant impact on gait performances.

Reproducibility and Convergent Validity of the Sitting-Rising Test in People With Multiple Sclerosis

OBJECTIVE

To evaluate the test-retest reproducibility and convergent validity of the sitting-rising test (SRT) in people with multiple sclerosis (PwMS).

DESIGN

Observational study comprising a test-retest design.

SETTING

Multiple Sclerosis Center, Rehabilitation Hospital at Sheba Medical Center, Tel-Hashomer, Israel.

PARTICIPANTS

A total of 50 PwMS (32 women, 18 men, N=50), mean age 44.8±7.6 years and mean disease duration of 13.8±8.5 years since diagnosis, were enrolled in the study. The median Expanded Disability Status Scale score was 4.5, indicating a mild-moderate neurologic disability.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

SRT, posturography measures, 10-repetion sit-to-stand test (10STS), timed Up and Go (TUG) test, hand grip strength, strength of hip flexion/extension/abduction, knee flexion/extension, and Fall Status Questionnaire.

RESULTS

The intraclass correlation coefficient value for the intrarater test-retest reproducibility (7- to 10-day interval between tests) of the SRT test, was 0.931 (95% confidence interval, 0.796-0.977). Strong correlations were found between the SRT, TUG test (ρ=-0.709), and 10STS (ρ=-0.719), and moderate correlations were found between the SRT and postural control measures (ρ∼0.4). Moderate correlations were found between the SRT and the hip and knee strength (combined) of the weaker limb (ρ=0.344). No differences were found in the SRT score between fallers and nonfallers.

CONCLUSIONS

The current study supports the convergent validity and test-retest reproducibility of the SRT in PwMS.

Is maximal muscle strength and fatigability of three lower limb muscle groups associated with walking capacity and fatigability in multiple sclerosis? An exploratory study

BACKGROUND

Both muscle fatigability and walking fatigability are prevalent in persons with MS (pwMS), but their associations remains unclear. The aim of this study was to examine the association of muscle strength and fatigability from both isometric and concentric protocols of three different muscle groups, and their association to walking capacity and walking fatigability.

METHODS

Twenty-seven pwMS and 13 Healthy Controls (HC) were included in this exploratory study. All participants performed a six-minute walking test (6MWT), where the distance walked index (DWI) was calculated to measure walking fatigability with a cut-off score of -10%. In three different muscle groups (knee extensors (KE), knee flexors (KF), ankle dorsiflexors (DF)), isometric and concentric muscle fatigability protocols (FI_isometric or FI_concentric) were used to quantify maximal voluntary contraction (MVC) and muscle fatigability. Pearson or Spearman correlation coefficients and linear regression models were calculated to establish the association between muscle strength/fatigability and walking capacity/fatigability.

RESULTS

Higher MVCs values for all muscle groups were found in HC compared to pwMS (mainly those having walking fatigability) (p < 0.05). FI_isometric of DF was lower in pwMS having walking fatigability compared to no walking fatigability. MVC of KE, KF and DF had a low to moderate association with walking capacity (range r = 0.52-0.56; p < 0.05) and walking fatigability in pwMS (range r-r_s: 0.39-0.50; p<0.05). FI_concentric of KF and DF, but not of KE, were associated with walking fatigability (r = 0.39 and r_s = 0.47, respectively; p < 0.05). In contrast, FI_isometric for all muscle groups were not related to walking capacity or walking fatigability.

CONCLUSION

MVC of KE, KF and DF are associated with walking capacity and walking fatigability, while concentric (but not isometric) muscle fatigability of KF and DF are associated with walking fatigability.

Impaired central drive to plantarflexors and minimal ankle proprioceptive deficit in people with multiple sclerosis

BACKGROUND

A common and disruptive symptom of multiple sclerosis is difficulty in walking. Deficits in ankle proprioception and in plantarflexor muscle function may contribute to these mobility issues. In this study, ankle proprioceptive ability and plantarflexor performance of people with multiple sclerosis (PwMS) were compared to healthy controls to determine whether multiple sclerosis causes impairments in these systems.

METHODS

PwMS (n = 30, median EDSS 4.0, IQR 2) were compared to age- and sex-matched healthy controls (n = 30) across tests of ankle proprioception and plantarflexor muscle performance. Proprioceptive tests: detection of passive movement, reaction time and ankle joint position sense. Plantarflexor performance: strength, fatigue, recovery and voluntary activation (level of neural drive) of the plantarflexor muscles, assessed through brief and sustained fatiguing (2 min) isometric maximal voluntary contractions with nerve stimulation to evoke superimposed and resting muscle twitches.

RESULTS

PwMS had unimpaired movement detection and joint position sense but had a slower reaction time to respond with plantarflexion to an imposed ankle movement (between group difference = 0.11 [95% CI; 0.05 to 0.17] s). During brief, maximal contractions PwMS produced lower torque (difference = -25.1 [-42.0 to -8.2] Nm) with reduced voluntary activation (difference = -14.6 [-25.1 to -4.1]%) but no impairment of the muscle itself (resting twitch torque difference = 0.3 [-2.8 to 2.2] Nm). At the end of the fatiguing contraction, neural drive decreased for PwMS (-19.5 [-27.1 to -11.9]%, p <0.0001) but not for controls (-2.5 [-6.9 to 1.8]%, p = 0.242). Fatigue did not affect the resting twitch size for controls (-1.3 [-2.7 to -0.03] Nm, p = 0.134) or PwMS (-0.1 [-1.1 to 1.0] Nm, p = 0.90).

CONCLUSIONS

PwMS showed no deficit in their ability to sense ankle position or imposed movements but were slow when a motor response was required. Their plantarflexor muscles produced similar torque with electrical stimulation but voluntary strength was impaired.  Both groups experienced overall fatigue following the 2-minute maximal voluntary contraction but PwMS also had significantly reduced neural drive indicating central fatigue. PwMS showed mainly central deficits in motor output at the ankle with little impairment of proprioceptive acuity.

Perceived fatigue, lower limb muscle force and performance fatigability after a rehabilitation program in Multiple Sclerosis

Muscle weakness and fatigue represent frequent disabling symptoms for Multiple Sclerosis (MS) patients. We evaluated the effects of an intensive task-oriented circuit training (TOCT) on perceived fatigue, muscle strength and changes in motor performance fatigability in mildly impaired MS patients. Fifteen MS patients performed different functional scales, self-reported questionnaires and instrumental evaluations before (T0) and after (T1) TOCT. Strength and performance fatigability were analyzed during isometric knee extension and ankle dorsiflexion through an isokinetic dinamometer, recording surface EMG signals of Vastus Medialis and Tibialis Anterior. The Dinamic Gait Index, Multiple Sclerosis Impact Scale-29, Modified Fatigue Impact Scale and Multiple Sclerosis Walking Scale-12 significantly improved after training. An increase of exerted force during isometric knee extension was observed, whereas no significant changes were revealed on mechanical and electrical fatigue. Moreover, the improvement in perceived disability after treatment was related to strength increase in knee mechanical force output. The TOCT positively modifies perceived fatigue, perceived ambulatory function and knee force output in mildly impaired MS subjects, suggesting a virtuous circle between strength levels, recovery of functional skills and improved quality of life.

Reference Values for Isometric, Dynamic, and Asymmetry Leg Extension Strength in Patients with Multiple Sclerosis

Having recognized the value of resistance training in patients with multiple sclerosis (PwMS), there are a lack of lower limb normative reference values for one repetition maximum (1RM) and maximal voluntary isometric contraction (MVIC) in this population. Hence, the purposes of this study were to provide reference values for 1RM and MVIC of knee extensors in PwMS across the disability spectrum and to examine knee extension strength asymmetry. Three hundred and ninety PwMS participated in the study, performing MVIC and 1RM tests of bilateral (both legs together at once) and unilateral (each leg singly) knee extensors. There was no difference in 1RM according to the disease course of MS, but there was according to the degree of neurological disability, being more preserved in those with a lower degree of disability. MVIC tends to be higher in patients with relapsing-remitting MS respect those with progressive MS, and in patients with lower levels of neurological disability. Asymmetry above the values considered normal in 1RM was present in 20-60% of patients and 56-79% in the MVIC test, depending on the type of MS and tended to be lower in those with less disability. Reference values are given by quartiles for 1RM, MVIC, and asymmetry.

Neurophysiological impairments in multiple sclerosis-Central and peripheral motor pathways

A systematic review of the literature was conducted comparing neurophysiological outcomes in persons with multiple sclerosis (PwMS) to healthy controls (HC), in studies of the central nervous system (CNS) function comprising motor evoked potentials (MEP) elicited by transcranial magnetic stimulation (TMS) and in studies of the peripheral nervous system (PNS) function comprising electroneuronography (ENG) outcomes elicited by peripheral nerve stimulation. Studies comparing neuromuscular function, assessed during maximal voluntary contraction (MVC) of muscle, were included if they reported muscle strength along with muscle activation by use of electromyography (EMG) and/or interpolated twitch technique (ITT). Studies investigating CNS function showed prolonged central motor conduction times, asymmetry of nerve conduction motor pathways, and prolonged latencies in PwMS when compared to HC. Resting motor threshold, amplitude, and cortical silent periods showed conflicting results. CNS findings generally correlated with disabilities. Studies of PNS function showed near significant prolongation in motor latency of the median nerve, reduced nerve conduction velocities in the tibial and peroneal nerves, and decreased compound muscle action potential amplitudes of the tibial nerve in PwMS. ENG findings did not correlate with clinical severity of disabilities. Studies of neuromuscular function showed lower voluntary muscle activation and increased central fatigue in PwMS, whereas EMG showed divergent muscle activation (ie, EMG amplitude) during MVC. When comparing the existing literature on neurophysiological motor examinations in PwMS and HC, consistent and substantial impairments of CNS function were seen in PwMS, whereas impairments of the PNS were less pronounced and inconsistent. In addition, impairments in muscle activation were observed in PwMS.