The relationship between concentric and isometric strength of knee flexor and extensor muscles and postural stability in mild stage multiple sclerosis patients

BACKGROUND

Multiple sclerosis (MS) affects muscle strength and postural stability. However, the relationship between concentric and isometric strength of knee flexors and extensors and postural stability in mild stage MS is not well known. The aim of the study was to examine the relationship between concentric and isometric strength of knee flexors and extensors and postural stability in mild stage MS patients.

MATERIALS AND METHODS

The study included 21 mild-stage MS patients with an EDSS score of 4 or less and 21 healthy controls. The concentric and isometric strength of knee flexors and extensors was measured with the Biodex System 4 Dynamometer, and postural stability with the Biodex Balance System under eyes-open and eyes-closed conditions on a rigid surface.

RESULTS

Mild-stage MS patients had reduced concentric strength of knee extensors and flexors and increased postural sway compared with healthy controls (p < 0.05). Isometric strength of knee extensors and flexors in mild stage MS patients were similar to healthy controls (p > 0.05). There was a moderate positive correlation between concentric strength of knee extensors and flexors and isometric strength of knee flexors and open-eye postural stability indexes in mild stage multiple sclerosis patients (p < 0.05).

CONCLUSIONS

While isometric strength of knee extensors and flexors was preserved, concentric strength of knee extensors and flexors was decreased, and postural stability was adversely affected in mild stage MS patients. The increase in the strength of the knee muscles was associated with an increase in their postural sway in mild stage MS patients.

Changes in walking speed following resistance training in people with multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

Reduced walking ability, especially decreased gait speed, is one of the most common and disabling impairments reported by people with multiple sclerosis (MS). Considering the impact of muscle strength on walking ability, resistance training may have the potential to improve walking speed in MS. Therefore, this systematic review and meta-analysis aims to evaluate the effect of lower limb resistance training on walking speed in people with MS.

METHODS

Seven databases (CINAHL, MEDLINE, The Allied and Complimentary Medicine Database, Web of Science, Physiotherapy Evidence Database [PEDro], PsycINFO, and Sports Medicine and Education Index) were searched in March 2024 for studies that met the following eligibility criteria: randomized controlled trials investigating the effects of resistance training interventions on objective measures of walking speed in people with MS. Risk of bias was assessed using the PEDro scale. Meta-analysis was performed to quantify intervention effect using a random effects model.

RESULTS

Twelve randomized controlled trials were included, reporting data on 425 individuals with MS. Participants had mostly relapsing-remitting MS (85%) and a mild-moderate level of disability (Expanded Disability Status Score 1.0-6.0). Results of the meta-analysis (based on 7 of the included studies) indicated a significant yet variable improvement in walking speed in favor of the intervention (0.10 m/s, 95% confidence interval 0.01-0.19, p < .05). Sensitivity analysis indicates that larger improvements in walking speed were found over tests covering shorter distances.

CONCLUSIONS

Resistance training was found to significantly improve walking speed in people with MS. However, variability in results were noted across studies; accordingly, future research should determine how variables-particularly related to resistance training prescription-influence the intervention effect.

Effect of vestibular rehabilitation on kinetic and kinematic parameters of gait in patients with multiple sclerosis: A single-blind randomized controlled study

BACKGROUND

Multiple sclerosis (MS) patients frequently experience gait disturbances, which can be exacerbated in those with vestibular involvement. Various exercise approaches are available to address gait difficulties in this patient population, and the use of vestibular rehabilitation, in particular, has increased recently. However, the effects of this specific exercise approach on gait in MS patients remain unclear. Considering that gait comprises temporospatial, kinetic, and kinematic components, it is evident that existing research in this area is fairly limited. Therefore, our study aimed to evaluate the effect of a vestibular rehabilitation program compared to a conventional exercise program on kinetic and kinematic parameters of gait in patients with MS.

METHODS

MS patients aged 25-60 years with an EDSS score between 3.5 and 6.5 were included in the study. Participants were randomly assigned to either the vestibular rehabilitation group or the conventional exercise group. All participants underwent primary evaluation with Three-dimensional gait analysis and secondary assessments using the 2-Minute Walk Test, 10-Meter Walk Test, 5-Times Sit to Stand Test, and Visual Acuity Test.

RESULTS

The study was completed with 22 participants [age: 45.18 ± 10.22, EDSS: 4.00 (3.50 - 5.00)]. Pelvic tilt range of motion, knee varus/valgus, ankle maximum external rotation, mean ankle rotation angles and the peak knee extension moment in the 30-60 % cycle of gait showed statistically greater improvement in the vestibular rehabilitation group compared to the conventional exercise group in post-treatment. After exercise trainings, there was no significant difference in temporospatial data between the two groups.

DISCUSSION

It was concluded that supporting the rehabilitation programs of MS patients with VR exercises contributed to the improvement of various kinetic and kinematic parameters of gait.

The relationship of hip strength to walking and balance performance in unilateral lower limb prosthesis users differs by amputation level

BACKGROUND

Safe and efficient locomotion is a frequently stated goal of lower limb prosthesis users, for which hip strength may play a central yet poorly understood role. Additional research to identify associations between hip strength, balance, and mobility among transtibial and transfemoral prosthesis users is required.

OBJECTIVE

To test whether residual and/or intact limb isometric hip strength was associated with lower limb prosthesis users' walking speed, endurance, and balance.

DESIGN

Cross-sectional study.

SETTING

Research laboratory.

PARTICIPANTS

Convivence sample of 14 transtibial and 14 transfemoral prosthesis users.

METHODS

Multiple linear regression was used to evaluate the relationship between isometric measures of residual and intact limb hip strength and walking and balance performance.

MAIN OUTCOME MEASUREMENTS

Measures of isometric hip muscle strength, including peak torque, average torque, torque impulse, and torque steadiness (i.e. consistency with which an isometric torque can be sustained) were derived from maximum voluntary hip flexion, extension, abduction and adduction torque signals collected with a motor-driven dynamometer. Walking speed, endurance, and balance were assessed by administering the 10-meter walk test, 2-minute walk test, Four Square Step Test, and Narrowing Beam Walking Test, respectively.

RESULTS

Residual limb hip extensor max torque and abductor torque steadiness explained between 51% and 69% of the variance in transtibial prosthesis users' walking speed, endurance, and balance. In contrast, intact limb hip abductor torque impulse explained between 33% and 48% of the variance in transfemoral prosthesis users' walking speed, endurance, and balance.

CONCLUSIONS

Our results suggest that unilateral transtibial and transfemoral prosthesis users' walking and balance performance may depend on different hip muscles, and different facets of hip strength. Amputation level-specific hip strength interventions may therefore be required to improve walking and balance performance in unilateral transtibial and transfemoral prosthesis users. The "intact leg strategy" adopted by transfemoral prosthesis users may be due to a variety of prosthesis and biomechanical factors that limit the efficiency with which transfemoral prosthesis users can exploit the strength of their residual limb hip muscles while walking.

Ankle dorsiflexion asymmetry and the relationship with walking performance in people with multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a neurological disease characterized by demyelination disrupting the central nervous system. Persons with MS may exhibit symptomatic strength asymmetry (SA) that impacts motor gait and ankle mobility. The purpose of the present study was to investigate ankle dorsiflexion SA in people with MS and its relationship to functional performance.

RESEARCH QUESTION

Is their a difference in dorsiflexion SA in MS participants compared to healthy individuals and does it impact functional performance?

METHODS

13 MS participants (EDSS 3.5 + 1.8) and 13 age matched NON-MS participants underwent maximal isometric (MVC) dynamometry testing for ankle dorsiflexion in both limbs to determine SA. Participants performed three functional tasks of walking performance.

RESULTS

There was a significant intra-limb MVC difference in the MS group, and significantly greater isometric SA (p < 0.007) and isokinetic SA (p < 0.04) in the MS group compared to healthy individuals. The MS group exhibited significant correlations between outcomes of functional walking performance with isokinetic but not isometric SA. There was no significant correlation between disability status and functional task performance.

SIGNIFICANCE

Ankle dorsiflexion SA is negatively correlated with functional performance in MS participants. MS disability status was not a predictor of functional task performance, and symptom testing may be appropriate to assess walking ability in persons with MS.

Task-oriented exercise effects on walking and corticospinal excitability in multiple sclerosis: protocol for a randomized controlled trial

BACKGROUND

Multiple sclerosis (MS) is a degenerative disease of the central nervous system (CNS) that disrupts walking function and results in other debilitating symptoms. This study compares the effects of 'task-oriented exercise' against 'generalized resistance and aerobic exercise' and a 'stretching control' on walking and CNS function in people with MS (PwMS). We hypothesize that task-oriented exercise will enhance walking speed and related neural changes to a greater extent than other exercise approaches.

METHODS

This study is a single-blinded, three-arm randomized controlled trial conducted in Saskatchewan, Canada. Eligible participants are those older than 18 years of age with a diagnosis of MS and an expanded Patient-Determined Disease Steps (PDDS) score between 3 ('gait disability') and 6 ('bilateral support'). Exercise interventions are delivered for 12 weeks (3 × 60-min per week) in-person under the supervision of a qualified exercise professional. Interventions differ in exercise approach, such that task-oriented exercise involves weight-bearing, walking-specific activities, while generalized resistance and aerobic exercise uses seated machine-based resistance training of major upper and lower body muscle groups and recumbent cycling, and the stretching control exercise involves seated flexibility and relaxation activities. Participants are allocated to interventions using blocked randomization that stratifies by PDDS (mild: 3-4; moderate: 5-6). Assessments are conducted at baseline, post-intervention, and at a six-week retention time point. The primary and secondary outcome measures are the Timed 25-Foot Walk Test and corticospinal excitability for the tibialis anterior muscles determined using transcranial magnetic stimulation (TMS), respectively. Tertiary outcomes include assessments of balance, additional TMS measures, blood biomarkers of neural health and inflammation, and measures of cardiorespiratory and musculoskeletal fitness.

DISCUSSION

A paradigm shift in MS healthcare towards the use of "exercise as medicine" was recently proposed to improve outcomes and alleviate the economic burden of MS. Findings will support this shift by informing the development of specialized exercise programming that targets walking and changes in corticospinal excitability in PwMS.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT05496881, Registered August 11, 2022. https://classic.

CLINICALTRIALS

gov/ct2/show/NCT05496881 . Protocol amendment number: 01; Issue date: August 1, 2023; Primary reason for amendment: Expand eligibility to include people with all forms of MS rather than progressive forms of MS only.

Effect of different types of exercise on fitness in people with multiple sclerosis: A network meta-analysis

BACKGROUND

It is assumed that people with multiple sclerosis (MS) who participate in programs of physical exercise improve their physical fitness.

OBJECTIVE

The aim of this network meta-analysis (NMA) was to analyze the effect of different types of exercise on muscular fitness and cardiorespiratory fitness (CRF) among people with MS and to determine the best type of exercise according to disease severity.

METHODS

MEDLINE, the Physiotherapy Evidence Database, the Cochrane Library, SPORTDiscus, Scopus, and Web of Science were searched from inception to April 2022 to identify randomized controlled trials (RCTs) concerning the effect of physical exercise on fitness in people with MS. We ranked the types of physical exercise by calculating the surface under the cumulative ranking (SUCRA).

RESULTS

We included 72 RCTs involving 2543 MS patients in this NMA. A ranking of five types of physical exercise (aerobic, resistance, combined [aerobic and resistance], sensorimotor training, and mind-body exercises) was achieved. Combined and resistance training had the highest effect sizes (0.94, 95% CI 0.47, 1.41, and 0.93, 95% CI 0.57, 1.29, respectively) and the highest SUCRA (86.2% and 87.0%, respectively) for muscular fitness. The highest effect size (0.66, 95% CI 0.34, 0.99) and SUCRA (86.9%) for CRF was for aerobic exercise.

CONCLUSIONS

Combined and resistance training seem to be the most effective exercises to improve muscular fitness and aerobic exercise for CRF in people with MS.

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.

After scaling to body size hip strength of the residual limb exceeds that of the intact limb among unilateral lower limb prosthesis users

BACKGROUND

Hip muscles play a prominent role in compensating for the loss of ankle and/or knee muscle function after lower limb amputation. Despite contributions to walking and balance, there is no consensus regarding hip strength deficits in lower limb prosthesis (LLP) users. Identifying patterns of hip muscle weakness in LLP users may increase the specificity of physical therapy interventions (i.e., which muscle group(s) to target), and expedite the search for modifiable factors associated with deficits in hip muscle function among LLP users. The purpose of this study was to test whether hip strength, estimated by maximum voluntary isometric peak torque, differed between the residual and intact limbs of LLP users, and age- and gender-matched controls.

METHODS

Twenty-eight LLP users (14 transtibial, 14 transfemoral, 7 dysvascular, 13.5 years since amputation), and 28 age- and gender-matched controls participated in a cross-sectional study. Maximum voluntary isometric hip extension, flexion, abduction, and adduction torque were measured with a motorized dynamometer. Participants completed 15 five-second trials with 10-s rest between trials. Peak isometric hip torque was normalized to body mass × thigh length. A 2-way mixed-ANOVA with a between-subject factor of leg (intact, residual, control) and a within-subject factor of muscle group (extensors, flexors, abductors, adductors) tested for differences in strength among combinations of leg and muscle group (α = 0.05). Multiple comparisons were adjusted using Tukey's Honest-Difference.

RESULTS

A significant 2-way interaction between leg and muscle group indicated normalized peak torque differed among combinations of muscle group and leg (p < 0.001). A significant simple main effect of leg (p = 0.001) indicated peak torque differed between two or more legs per muscle group. Post-hoc comparisons revealed hip extensor, flexor, and abductor peak torque was not significantly different between the residual and control legs (p ≥ 0.067) but torques in both legs were significantly greater than in the intact leg (p < 0.001). Peak hip abductor torque was significantly greater in the control and residual legs than the intact leg (p < 0.001), and significantly greater in the residual than control leg (p < 0.001).

CONCLUSIONS

Our results suggest that it is the intact, rather than the residual limb, that is weaker. These findings may be due to methodological choices (e.g., normalization), or biomechanical demands placed on residual limb hip muscles. Further research is warranted to both confirm, expand upon, and elucidate possible mechanisms for the present findings; and clarify contributions of intact and residual limb hip muscles to walking and balance in LLP users.

CLINICAL TRIAL REGISTRATION

N/A.

Criterion validity of muscle strain analyses of skeletal muscle function in patients with multiple sclerosis

BACKGROUND

Despite the wide range of existing performance measures to evaluate functional status of patients with multiple sclerosis, the heterogeneous nature of the disease hinders clinical characterization and monitoring of disease severity. Speckle tracking ultrasonography is a non-invasive technique to assess isolated muscle function by evaluating the contractile properties of muscle tissue, i.e. muscle strain. The aim of this study was to investigate whether muscle strain measured by speckle tracking ultrasonography could be a useful quantitative measure of muscle function in patients with multiple sclerosis. The criterion validity of muscle strain was compared to that of validated performance measures of upper and lower extremity function.

METHODS

This cross-sectional study used baseline data from an explorative observational cohort study (the MUST study). Participants recruited from a hospital outpatient MS clinic underwent speckle tracking ultrasonography of the biceps brachii, supraspinatus, and soleus muscles of the dominant side according to pre-defined submaximal isometric contractions. Participants also completed the Timed 25-Foot Walk Test, the Six Spot Step Test, the 2-minute walking test, the Nine-Hole Peg Test, the 12-item Multiple Sclerosis Walking Scale, and the Oxford Shoulder Score. Gaussian distribution was investigated by visual inspection of normal probability plots and the Shapiro-Wilk test. The Timed 25-Foot Walk Test and Nine-Hole Peg Test were selected as gold standards for function of the lower and upper extremities, respectively. Criterion validity was assessed using Spearman's rank-order correlation coefficient ρ (rho), comparing the muscle strain and performance measures against predefined gold standards. Differences in criterion validity were estimated using squared correlations on the Fischer's Z-scale, with non-parametric bootstrapping to obtain bias-corrected, accelerated bootstrap confidence intervals (95% BCa).

RESULTS

Criterion validity showed good to excellent correlations between the gold standard for lower extremity function and the 2-minute walking test and Six Spot Step Test, and a fair correlation to the 12-item Multiple Sclerosis Walking Scale. No significant correlation was found between the gold standard for upper extremity function and the performance measure. There were no significant correlations between the gold standards and muscle strain.

CONCLUSION

The absence of criterion validity for muscle strain alongside fair to strong criterion validity for the performance measures indicates that speckle tracking ultrasonography assessment of muscle strain is either invalid or evaluates other constructs of multiple sclerosis. Muscle strain assessed by speckle tracking ultrasonography cannot be recommended for the evaluation of treatment effects or disease progression in multiple sclerosis.

Determination of five times-sit-to-stand test performance in patients with multiple sclerosis: validity and reliability

PURPOSE/AIM

Although Five Times-Sit-To-Stand test (FTSST) performance is known to be a valid and reliable method in people with chronic stroke, Parkinson's disease, and balance disorder, it has not been widely studied in patients with Multiple sclerosis (MS). The main aim of this study was to evaluate validity and reliability of the FTSST in patients with MS.

METHODS

The first outcome measure of the study was the FTSST, which was conducted by two different researchers. Secondary outcome measures were Biodex Stability System (BSS), 10-meter walk test, time up go test (TUG), EDSS scoring, Fatigue Severity Scale (FSS), Barthel Index, Quadriceps Muscle strength test, Functional Reach test. Intraclass correlation coefficient (ICC) was used for the validity and reliability of the FTSST, which was made by two different researchers, and Pearson Correlation Analysis was used to determine its relationship with other measurements.

RESULTS

Interrater and test-retest reliability for the FTSST were excellent (Intraclass correlation coefficients of 0.98 and 0.99, respectively). A statistically significant correlation was found between all secondary outcome measures and FTSST (p < 0.05).

CONCLUSION

FTSST is considered to be a valid, reliable, easy, and rapid method for evaluating lower extremity muscle strength and balance in patients with MS.

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.

Normalization alters the interpretation of hip strength in established unilateral lower limb prosthesis users

BACKGROUND

Valid comparisons of muscle strength between individuals or legs that differ in size requires normalization, often by simple anthropometric variables. Few studies of muscle strength in lower-limb prosthesis users have normalized strength data by any anthropometric variable, potentially confounding our understanding of strength deficits in lower-limb prosthesis users. The objective of this pilot study was to determine the need for as well as effectiveness and impact of normalizing hip strength in lower-limb prosthesis users.

METHODS

Peak isometric hip extension and abduction torques were collected from 28 lower-limb prosthesis users. Allometric scaling was used to determine if hip torque values were significantly associated with, and therefore needed to be adjusted for, body mass, thigh length, or body mass x thigh length, and whether normalization was effective in reducing any associations. Between limb differences in peak hip torque, and correlations with balance ability, were inspected pre- and post-normalization.

FINDINGS

Hip torques were consistently and significantly associated with body-mass x thigh length. Associations between peak hip torque and body-mass x thigh length were reduced by normalization. After normalization by body-mass x thigh length, between limb differences in hip extension torque, as well as the correlation between hip abduction torque and balance ability, changed from non-significant to significant.

INTERPRETATION

In the absence of normalization, hip strength (i.e., peak torque) in lower-limb prosthesis users remains dependent on basic anthropometric variables, masking relationships between hip strength and balance ability, as well as between limb differences.

Effects and optimal dosage of resistance training on strength, functional capacity, balance, general health perception, and fatigue in people with multiple sclerosis: a systematic review and meta-analysis

PURPOSE

To analyze the effectiveness of resistance training programs (RTP) on strength, functional capacity, balance, general health perception, and fatigue for people with Multiple Sclerosis (MS) and to determine the most effective dose of RTP in this population.

METHODS

Studies examining the effect of RTP on strength, functional capacity, balance, general health perception, and fatigue in MS patients were included. 44 studies were included. The meta-analysis, subgroup analysis and meta-regression methods were used to calculate the mean difference and standardized mean difference.

RESULTS

Significant group differences were observed in knee extensor (p = 0.01) and flexor (p < 0.001), but not in 1-repetition maximum. Regarding functional capacity and balance, differences between groups, in favour of the RTP group, were found in the Timed Up and Go Test (p = 0.001), walking endurance, (p = 0.02) gait speed (p = 0.02) and balance (p = 0.02). No significant differences between groups were observed in fatigue or general health perception. The results regarding the optimal dose are inconsistent.

CONCLUSIONS

RTP improves strength, functional capacity, balance, and fatigue in people with MS. Registration: (PROSPERO): CRD42020182781Implications for rehabilitationResistance training is a valid strategy to improve isometric strength and functional capacity in MS patients.RTP using long durations (more than 6 weeks), high intensity (more than 80% 1-RM) and two-day weekly training frequency may be a correct stimulus to improve strength, functional capacity, balance, and fatigue in people with MS.Trainers and rehabilitators should consider these indicators in order to maximize muscular and functional adaptations in this population.

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.

The Effects of Specific Omega-3 and Omega-6 Polyunsaturated Fatty Acids and Antioxidant Vitamins on Gait and Functional Capacity Parameters in Patients with Relapsing-Remitting Multiple Sclerosis

Patients with multiple sclerosis (MS) are characterized by, among other symptoms, impaired functional capacity and walking difficulties. Polyunsaturated fatty acids (PUFAs) have been found to improve MS patients' clinical outcomes; however, their effect on other parameters associated with daily living activities need further investigation. The current study aimed to examine the effect of a 24-month supplementation with a cocktail dietary supplement formula, the NeuroaspisTM PLP10, containing specific omega-3 and omega-6 PUFAs and specific antioxidant vitamins on gait and functional capacity parameters of patients with MS. Fifty-one relapsing-remitting MS (RRMS) patients with low disability scores (age: 38.4 ± 7.1 years; 30 female) were randomized 1:1 to receive either a 20 mL daily dose of the dietary formula containing a mixture of omega-3 and omega-6 PUFAs (12,150 mg), vitamin A (0.6 mg), vitamin E (22 mg), and γ-tocopherol (760 mg), the OMEGA group (n = 27; age: 39 ± 8.3 years), or 20 mL placebo containing virgin olive oil, the placebo group (n = 24; age: 37.8 ± 5.3 years). The mean ± SD (standard deviation) Expanded Disability Status Scale (EDSS) score for the placebo group was 2.36 and for the OMEGA group 2.22. All enrolled patients in the study were on Interferon-β treatment. Spatiotemporal gait parameters and gait deviation index (GDI) were assessed using a motion capture system. Functional capacity was examined using various functional tests such as the six-minute walk test (6MWT), two sit-to-stand tests (STS-5 and STS-60), and the Timed Up and Go test (TUG). Isometric handgrip strength was assessed by a dynamometer. Leg strength was assessed using an isokinetic dynamometer. All assessments were performed at baseline and at 12 and 24 months of supplementation. A total of 36 patients completed the study (18 from each group). Six patients from the placebo group and 9 patients from the OMEGA group dropped out from the study or were lost to follow-up. The dietary supplement significantly improved the single support time and the step and stride time (p < 0.05), both spatiotemporal gait parameters. In addition, while GDI of the placebo group decreased by about 10% at 24 months, it increased by about 4% in the OMEGA group (p < 0.05). Moreover, performance in the STS-60 test improved in the OMEGA group (p < 0.05) and there was a tendency for improvement in the 6MWT and TUG tests. Long-term supplementation with high dosages of omega-3 and omega-6 PUFAs (compared to previous published clinical studies using PUFAs) and specific antioxidant vitamins improved some functional capacity and gait parameters in RRMS patients.

Gait Pattern in People with Multiple Sclerosis: A Systematic Review

The aim of the present systematic review was to describe the gait pattern in people with multiple sclerosis (MS) by compiling the main findings obtained from studies using three-dimensional capture systems of human movement. The search was carried out in PubMed, Web of Science, Physiotherapy Evidence Database (PEDro), and the Cumulative Index to Nursing and Allied Health (CINAHL) databases. Studies that used three-dimensional gait analysis systems and that analyzed spatiotemporal, kinematic, kinetic, or electromyographic parameters, were included. The quality of the studies was assessed using the Critical Review Form-Quantitative Studies scale. 12 articles were included with 523 (342 women and 181 men) people with a diagnosis of MS. The present work suggests that people with MS have a decrease in speed and stride length, as well as an increase in double-stance intervals during gait. Likewise, it is common to observe a decrease in hip extension during the stance period, a decrease in knee flexion in the swing period, a decrease in ankle dorsiflexion in the initial contact and a decrease in ankle plantar flexion during the pre-swing phase. The subjects with MS decrease the hip extensor moment and the ankle power during the stance period of walking.

Blood-Flow Restriction Training for a Person With Primary Progressive Multiple Sclerosis: A Case Report

OBJECTIVE

Blood flow restriction (BFR) training, in which an inflatable cuff partially occludes blood flow around the proximal portion of a limb, coupled with low-intensity resistance training (LIRT) has resulted in gains comparable with traditional progressive resistive exercise in healthy populations. The use of BFR with LIRT may enable people with multiple sclerosis (MS) to improve strength without an increase in fatigue. The purpose of this case report is to describe the use of a BFR/LIRT program for a person with MS.

METHODS

The patient was a 54-year-old woman with a 13-year history of primary progressive MS with an Extended Disability Severity Score of 3.0 out of 10. She received a BFR/LIRT program for both lower extremities biweekly for 12 weeks. Outcomes measured at baseline and at 6 and 12 weeks included the 12-item Multiple Sclerosis Walking Scale (MSWS-12), Fatigue Severity Scale, Patient-Specific Functional Scale (PSFS) (goals: running for exercise and pleasure for 45 minutes, 100% confidence in negotiating a flight of stairs, confidently and safely drive without restriction), and 14 lower extremity strength tests.

RESULTS

The intervention was well tolerated without adverse events. After 6 weeks, the MSWS-12 score improved; however, it did not exceed minimum detectable change (MDC). Fatigue Severity Scale was unchanged. All PSFS goals improved beyond MDC, and improvements in strength exceeded MDC in 2 out of 14 tests. After 12 weeks, MSWS-12 improvements persisted and the Fatigue Severity Scale score improved, but neither exceeded MDC. The PSFS improvements persisted. There were improvements exceeding MDC for 8 out of 14 strength tests. The remaining 6 strength tests improved but did not exceed MDC.

CONCLUSION

The patient had measurable improvements following the use of a BFR/LIRT program. BFR/LIRT may be an option for strength training in people with MS; however, research is needed to determine its safety and effectiveness across the population of people with MS.

IMPACT

Traditional physical therapist interventions for people with MS have been shown to be beneficial; however, their usefulness has been limited by fatigue. A growing body of literature has demonstrated the effects of a BFR/LIRT program on strength and other measures of physical function in healthy populations and those with chronic disease. This case report adds missing information to the existing literature and suggests directions for research on the effectiveness of BFR/LIRT in people with primary progressive MS.

LAY SUMMARY

Blood flow restriction, which has been used to help improve strength in healthy adults and in some people with chronic disease, applies pressure around the arm or leg to limit the flow of blood to that body part during exercise, helping to reduce fatigue. Blood flow restriction coupled with low-intensity strengthening exercises can be used for a person with MS.

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.

Functional relevance of resistance training-induced neuroplasticity in health and disease

Repetitive, monotonic, and effortful voluntary muscle contractions performed for just a few weeks, i.e., resistance training, can substantially increase maximal voluntary force in the practiced task and can also increase gross motor performance. The increase in motor performance is often accompanied by neuroplastic adaptations in the central nervous system. While historical data assigned functional relevance to such adaptations induced by resistance training, this claim has not yet been systematically and critically examined in the context of motor performance across the lifespan in health and disease. A review of muscle activation, brain and peripheral nerve stimulation, and imaging data revealed that increases in motor performance and neuroplasticity tend to be uncoupled, making a mechanistic link between neuroplasticity and motor performance inconclusive. We recommend new approaches, including causal mediation analytical and hypothesis-driven models to substantiate the functional relevance of resistance training-induced neuroplasticity in the improvements of gross motor function across the lifespan in health and disease.

[Efficacy and safety of Kinezia (fampridine) in the complex therapy of multiple sclerosis]

OBJECTIVE

To analyze the efficacy and safety of fampridine** (Valenta Pharm, Russia) in the complex therapy of multiple sclerosis (MS).

MATERIAL AND METHODS

One hundred and twenty-six patients with MS were double blind randomized to receive fampridine (n=60) or placebo (n=66). Fampridine was administered in prolonged-release form (film-coated tablets, 10 mg) at a dose of 10 mg (1 tablet) 2 times a day, for 24 weeks. The placebo group was treated in the same way. From the 12th week, all patients in the placebo group were transferred to therapy with fampridine, 10 mg 2 times a day, for another 12 weeks. Concomitant standard therapy for MS was allowed in both groups (concomitant disease-modifying medications and other treatment). The primary outcome in the study was the proportion of patients with reduced t25fw test time (determining walking speed on a 25-foot path) on at least two out of three visits compared to baseline. The mean change in Multiple Sclerosis Functional Composite (MSFC) scores from baseline was assessed at visits 4-7 (8-24 weeks).

RESULTS

The proportion of patients with reduced t25fw test time compared to the baseline level was 31.7% in the fampridine group, which is higher than in the placebo group - 3.0% (p<0.001). The overall result of the Multiple Sclerosis Functional Composite (MSFC) reflected a gradual improvement in the patient's condition during treatment period. The dynamics of MSFC result relative to the baseline level significantly differed (p<0.05) between the fampridine and placebo groups in favor of the fampridine group during all treatment periods. In the fampridine group, adverse events (AE) associated with disorders of the nervous system were more common: headache, dizziness, and coordination disorders.

CONCLUSIONS

Fampridine improves walking performance in MS patients. The Russian product fampridine has demonstrated a favorable safety profile.

Postural control quantification in minimally and moderately impaired persons with multiple sclerosis: The reliability of a posturographic test and its relationships with functional ability

BACKGROUND

Postural control has been associated with the functional impairment in persons with multiple sclerosis (pwMS). However, there is a need for reliable methods to assess postural control in early stages of the disease, when subtle changes can be difficult to detect. The aims of this study were to assess the absolute and relative reliability of a standing and a sitting posturographic protocol in minimally (Expanded Disability Status Scale ≤ 2) and moderately (2.5 ≤ Expanded Disability Status Scale ≤ 4) impaired pwMS, and to analyze relationships among postural control and functional mobility and gait performance.

METHODS

To assess postural control in an upright stance, 14 minimally and 16 moderately impaired pwMS performed six 70 s trials in tandem stance, 3 with their weaker leg behind (TS_WL) and 3 with their stronger leg behind (TS_SL). Additionally, participants completed five 70 s trials using an unstable sitting protocol (US) to assess trunk stability. The mean radial errors of TS_WL, TS_SL, and US trials were calculated as postural control indexes. Furthermore, participants performed the Timed Up and Go test (TUG) and the Timed 25-foot Walk test (T25FW) to measure their functional mobility and gait speed, respectively. Reliability was evaluated using the intraclass correlation coefficient (ICC_3,1) and the standard error of measurement (SEM). Analyses of variances were carried out to assess between-group differences. Hedges' g index (d_g) was used to estimate the effect size of differences. Pearson correlation analyses (r) were performed to examine the relationships among the postural control and the functional tests.

RESULTS

Posturographic tests showed a high reliability in both minimally (0.87 ≤ ICC ≤ 0.92; 9.32% ≤ SEM ≤ 11.76%) and moderately (0.80 ≤ ICC ≤ 0.92; 10.33% ≤ SEM ≤ 15.33%) impaired pwMS. Similarly, T25FW and TUG displayed a high consistency in minimally (0.89 ≤ ICC ≤ 0.94; 3.43% ≤ SEM ≤ 5.17%) and moderately (0.85 ≤ ICC ≤ 0.93; 5.57% ≤ SEM ≤ 6.56%) impaired individuals. Minimally impaired pwMS showed a better performance on the TUG, T25FW, and TS_WL than moderately impaired individuals (p < 0.05; d_g ≥ 0.8). The TS_WL, TS_SL, and US variables correlated with TUG scores (0.419 ≤ r ≤ 0.604; p < 0.05), but TS_WL also correlated with T25FW scores (r = 0.53; p < 0.01). Furthermore, US scores correlated with both tandem stance parameters (TS_WL: r = 0.54, p < 0.01; TS_SL: r = 0.43, p < 0.05).

CONCLUSION

Tandem and sitting posturographic tests provide reliable measures of postural control in pwMS, even in individuals with a homogeneous disease profile. Gait speed, functional mobility, and weaker leg status seem decisive in assessing the degree of physical activity limitation in pwMS. Finally, although trunk stability does not seem to be so affected by the course of the disease, it remains relevant for postural control and functional capacity.

Effect of a Combined Program of Strength and Dual Cognitive-Motor Tasks in Multiple Sclerosis Subjects

This study investigated the effects of a 24-week combined training program (CTP) based on strength exercises and cognitive–motor tasks performed concurrently in participants with multiple sclerosis. A randomized, controlled intervention study was carried out. In total, 31 subjects with a confirmed diagnosis of multiple sclerosis (14 men and 17 women) were stratified and randomized into an intervention group (17 subjects) and a control group (14 subjects). The intervention group completed three weekly training sessions for 24 weeks, while the control group pursued their normal daily activities. In this program, cognitive–motor tasks were completed at once (dual tasking). A 3D photogrammetry connected to a selective attention system designed for dual tasking while walking was used. Ground reaction forces were measured using two force plates, one for sit-to-stand testing, while the other was used for static force measurement. Postural equilibrium was examined using a stabilometric plate based for Romberg test assessment. The 24-week training program for multiple sclerosis patients improved their static peak force by 11% (p < 0 .05), their rate of force development by 36% (p < 0.05), and their balance (p < 0.05). Performance in daily activities such as walking or sitting-to-standing improved significantly in multiple sclerosis participants. CTP training was effective in reducing the dual-task costs of step length (48%) and walking velocity (54%), as compared to a matched control group.

Force control during submaximal isometric contractions is associated with walking performance in persons with multiple sclerosis

Individuals with multiple sclerosis (MS) experience progressive declines in movement capabilities, especially walking performance. The purpose of our study was to compare the amount of variance in walking performance that could be explained by the functional capabilities of lower leg muscles in persons with MS and a sex- and age-matched control group. Participants performed two walking tests (6-min walk and 25-ft walk), strength tests for the plantar flexor and dorsiflexor muscles, and steady submaximal (10% and 20% maximum) isometric contractions. High-density electromyography (EMG) was recorded during the steady contractions, and the signals were decomposed to identify the discharge times of concurrently active motor units. There were significant differences between the two groups in the force fluctuations during the steady contractions (force steadiness), the strength of the plantar flexor and dorsiflexor muscles, and the discharge characteristics during the steady contractions. Performance on the two walking tests by the MS group was moderately associated with force steadiness of the plantar flexor and dorsiflexor muscles; worse force steadiness was associated with poorer walking performance. In contrast, the performance of the control group was associated with muscle strength (25-ft test) and force steadiness of the dorsiflexors and variance in common input of motor units to the plantar flexors (6-min test). These findings indicate that a reduction in the ability to maintain a steady force during submaximal isometric contractions is moderately associated with walking performance of persons with MS.NEW & NOTEWORTHY The variance in walking endurance and walking speed was associated with force control of the lower leg muscles during submaximal isometric contractions in individuals with multiple sclerosis (MS). In contrast, the fast walking speed of a sex- and age-matched control group was associated with the strength of lower leg muscles. These findings indicate that moderate declines in the walking performance of persons with MS are more associated with impairments in force control rather than decreases in muscle strength.

Does disability level impact the relationship of muscle strength to walking performance in people with multiple sclerosis? a cross-sectional analysis

BACKGROUND AND PURPOSE

Strength training can improve muscle weakness in people with multiple sclerosis (MS), but does not consistently improve walking. Disability level may impact the relationship of muscle weakness and walking performance in people with MS, but few studies have investigated the impact of disability on the relationship of strength and walking. The purpose of this study was to compare the relationships of strength in lower body and trunk muscles to walking performance between mild and moderate disability groups in people with MS.

METHODS

Data from 36 participants with MS who had mild disability (Expanded Disability Status Scale - EDSS 0 to 3.5) and 36 participants who had moderate disability (EDSS 4.0 to 5.5) were analyzed. Hand-held dynamometry measured strength in eight muscle groups from the ankle, knee, hip, and trunk. Timed 25-Foot Walk (T25FW) and 6-Minute Walk Test (6MWT) measured walking speed and endurance, respectively. Pearson correlations and beta coefficients (ß) were reported for each bivariate relationship of muscle strength to T25FW and 6MWT from both mild and moderate disability groups. Linear regression was then used to compare differences in beta coefficients (Δß) between disability groups for the relationship of each muscle variable to T25FW and 6MWT. A positive Δß indicated a stronger relationship of strength to walking performance in the mild disability group, while a negative Δß favored the moderate disability group.

RESULTS

Overall, there were stronger Pearson correlations between muscle strength variables to T25FW and 6MWT in the mild (r = 0.57 to 0.77) compared to moderate disability group (r = 0.10 to 0.54). The mild disability group had significantly greater beta coefficients for T25FW with ankle dorsiflexion (Δß = 0.67, 95%CI: 0.27-1.07), knee extension (Δß = 0.68, 95%CI: 0.28-1.08), and hip abduction (Δß = 0.77, 95%CI: 0.01-1.52); and for 6MWT with knee extension (Δß = 0.47, 95%CI: 0.06 to 0.88).

DISCUSSION AND CONCLUSION

For people with MS, muscle strength in the lower extremity and trunk may be a more important contributor to T25FW in mild versus moderate disability, but not for 6MWT. While more studies are needed, these results may help to inform rehabilitation intervention when prioritizing strength training to improve walking.

The Tolerability and Efficacy of 4 mA Transcranial Direct Current Stimulation on Leg Muscle Fatigability

Transcranial direct current stimulation (tDCS) modulates cortical excitability and affects a variety of outcomes. tDCS at intensities ≤2 mA is well-tolerated, but the tolerability and efficacy of tDCS at intensities >2 mA merits systematic investigation. The study objective was to determine the tolerability and effects of 4 mA tDCS on leg muscle fatigability. Thirty-one young, healthy adults underwent two randomly ordered tDCS conditions (sham, 4 mA) applied before and during an isokinetic fatigue test of the knee extensors and flexors. Subjects reported the severity of the sensations felt from tDCS. Primary outcomes were sensation tolerability and the fatigue index of the knee extensors and flexors. A repeated-measures ANOVA determined statistical significance (p < 0.05). Sensation severity at 4 mA tDCS was not substantially different than sham. However, two subjects reported a moderate–severe headache, which dissipated soon after the stimulation ended. The left knee flexors had significantly greater fatigability with 4 mA tDCS compared with sham (p = 0.018). tDCS at 4 mA was well-tolerated by young, healthy subjects and increased left knee flexor fatigability. Exploration of higher intensity tDCS (>2 mA) to determine the potential benefits of increasing intensity, especially in clinical populations with decreased brain activity/excitability, is warranted.

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

BACKGROUND

Lower-limb functional capacity is impaired in most people with multiple sclerosis (PwMS). Reductions in lower-extremity muscle mechanical function (e.g., muscle strength) appear to have critical implications for lower-limb functional capacity. However, no review has summarized the current knowledge about the importance of muscle strength for functional tasks in PwMS. Expanding the current knowledge would advance the design of both clinical and research interventions aiming to improve functional capacity in PwMS.

OBJECTIVES

(1) To identify studies that measured lower-extremity muscle mechanical function and lower-limb functional capacity outcomes in PwMS, and (2) to map associations between muscle strength and functional capacity.

METHODS

This review was based on a literature search (databases: PubMed, Embase). Included studies had to report data on lower-extremity muscle mechanical function and lower-limb functional capacity outcomes in PwMS. The associations between muscle strength and functional capacity were analyzed by using the reported correlation coefficients (R) recalculated to the determination coefficient R². Randomized trials and observational studies were included.

RESULTS

A total of 59 articles were reviewed; 17 (773 participants) reported associations between muscle strength and functional capacity. Lower-extremity muscle mechanical function explained a significant part of the variance in most lower-limb functional capacity tests (approximately 20-30%). This was particularly evident in muscle strength from the weakest leg. Muscle strength was predominantly tested on knee extensors and knee flexors by using isokinetic dynamometry during maximal isometric (0°/s) and dynamic (30-60°/s) contractions. Walking tests such as the timed 25-Foot Walk Test and 10-Min, 2-Min and 6-Min Walk Test were the most frequently performed functional capacity tests.

CONCLUSIONS

In PwMS, muscle strength of particularly the weakest limb explains 20% to 30% of the variance across a number of lower-limb functional capacity tests. Thus, exercise programs should focus on increasing lower-extremity muscle mechanical function in PwMS and minimizing strength asymmetry between limbs.

Transcranial Direct Current Stimulation (tDCS) to Improve Gait in Multiple Sclerosis: A Timing Window Comparison

Unilateral weakness of the lower limb is a hallmark of multiple sclerosis (MS) and a significant contributor to the progressive worsening of walking ability. There are currently no effective rehabilitation strategies targeting strength asymmetries and/or gait impairments in people with MS (PwMS). Transcranial direct current stimulation (tDCS) has improved motor outcomes in various populations, but the effect of tDCS on gait in PwMS and the ideal timing window of tDCS application are still unknown. This study investigated the effects of tDCS, either before or during a 6 min walk test (6MWT), on the distance walked and gait characteristics in PwMS. Twelve participants were recruited and randomly assigned into BEFORE or DURING groups (both n = 6). The BEFORE group received stimulation before performing a 6MWT (sham/2 mA, 13 min). The DURING group received stimulation only during a 6MWT (sham/2 mA, 6 min). Stimulation was over the more MS-affected primary motor cortex (M1). Distance walked and gait characteristics of the walk were the primary and secondary outcomes. The results indicated a significant decrease in distance walked in the DURING group (p = 0.026) and a significant increase in gait velocity in the BEFORE group (p = 0.04). These changes were accompanied by trends (p < 0.1) in distance walked, gait velocity, and stride length. Overall, the results of this study suggest that tDCS performed before a 6MWT might be more effective than tDCS during a 6MWT and that a single session of tDCS may not be sufficient to influence gait. Clinical Trial Registration: www.ClinicalTrials.gov, identifier #NCT03757819.

Muscle Dysfunction and Walking Impairment in Women with Multiple Sclerosis

Background

Recent evidence suggests that skeletal muscle dysfunction is involved in disability progression in people with multiple sclerosis (MS). However, the relationship between muscle dysfunction and walking impairments in MS remains unclear. Thus, the cross-sectional relationships between muscle-specific oxidative capacity and walking endurance in women with MS were evaluated.

Methods

Twenty women with MS (11 African American, 9 white) were tested. Muscle oxidative capacity of the medial gastrocnemius was measured using near-infrared spectroscopy after electrical stimulation. Muscle endurance was evaluated using accelerometer-based mechanomyography during electrical stimulation. Muscle strength was measured during maximal voluntary plantarflexion using handheld dynamometry. Walking function was measured using the Timed 25-Foot Walk test and the 6-Minute Walk Test (6MWT).

Results

Reduced muscle oxidative capacity (R ² = 0.68-0.71, P < .01) and muscle endurance (R ² = 0.59-0.78, P < .01) were associated with lower Timed 25-Foot Walk time and 6MWT distance. Muscle strength was weakly correlated to 6MWT distance (R ² = 0.21, P = .02). No differences in muscle function or clinical outcome measures were found between African American and white subgroups. Women with moderate-to-severe disability (Expanded Disability Status Scale [EDSS] score, 5.0-6.5) had significantly reduced muscle oxidative capacity, muscle endurance, and walking ability compared with women with mild disability (EDSS score, 2.5-4.5).

Conclusions

Reductions in muscle function in people with MS are related to declines in walking function across all levels of disability. Muscle dysfunction is not differentially related to walking impairment in African American and white women with MS.

Quantitative Synthesis of Timed 25-Foot Walk Performance in Multiple Sclerosis

OBJECTIVE

To provide a meta-analysis of articles that have included the timed 25-foot walk (T25FW) in persons with multiple sclerosis (MS), quantify differences in T25FW scores between those with MS and controls without MS, and quantify differences between categories of disability status and clinical disease courses within MS.

DATA SOURCES

The literature search was conducted using 4 databases (Google Scholar, PubMed, Cumulative Index to Nursing and Allied Health, EBSCO Host). We searched reference lists of published articles to identify additional articles.

STUDY SELECTION

A systematic literature search identified articles reporting average T25FW performance in seconds between those with MS and controls without MS, between those with MS who had mild and moderate and/or severe disability status, and between relapsing-remitting and progressive clinical courses of MS.

DATA EXTRACTION

Information was extracted and categorized based on reported data: comparisons of controls without MS and MS, comparisons of mild and moderate and/or severe MS based on study-defined Expanded Disability Status Scale groups, and comparisons of relapsing-remitting and progressive MS clinical courses.

DATA SYNTHESIS

We performed a random effects meta-analysis to quantify differences between groups as estimated by effect sizes (ESs). We expressed the differences in Cohen d as well as the original units of the T25FW (ie, seconds).

CONCLUSIONS

There was a large difference in T25FW performance in MS compared with controls without MS (ES=-0.93, mean difference=2.4s, P<.01). Persons with moderate and/or severe disability walked substantially slower compared with mild disability (ES=-1.02, mean difference=5.4s, P<.01), and persons with progressive courses of MS walked substantially slower than relapsing-remitting MS (ES=-1.4, mean difference=13.4s, P<.01).

Physical activity is associated with neuromuscular and physical function in patients with multiple sclerosis independent of disease severity

PURPOSE

Examine the association between physical activity and neuromuscular and physical function in patients with multiple sclerosis when also considering disease severity.

METHODS

91 patients with multiple sclerosis were enrolled. Assessments included physical activity by 7-day thigh-worn accelerometry, knee extensor neuromuscular function by dynamometry (maximal isometric muscle strength, rate of force development (0-50 ms)), and physical function by 5× sit-to-stand, 2-min walk test, and timed 25 ft walk test. Physical activity tertile comparisons along with simple and multiple regressions (adjusting for age, gender, EDSS, time since diagnosis) were performed.

RESULTS

Physical activity tertiles revealed differences (p < 0.05) in maximal muscle strength (1.77 ≈ 1.97 < 2.28 Nm/kg), rate of force development (4.66 < 8.03 ≈ 10.55 Nm/kg/s), 5× sit-to-stand (11.4 ≈ 9.7 > 8.5 s), 2-min walk test (153 < 183 < 207 m), and timed 25 ft walk test (6.3 > 4.4 > 4.3 s). Moreover, physical activity was associated (p < 0.05) with maximal muscle strength and rate of force development (r²  =  0.13-0.15) along with 5× sit-to-stand, 2-min walk test, and timed 25 ft walk test (r² = 0.18-0.24), also after adjusting for age + gender + EDSS + time since diagnosis (r² = 0.25-0.37 and 0.24-0.52), with physical activity consistently being a strong predictor.

CONCLUSIONS

Higher levels of physical activity are associated with greater neuromuscular and physical function in ambulatory patients with multiple sclerosis independent of disease severity. These findings emphasize the importance of performing regular physical activity at all stages of multiple sclerosis.IMPLICATIONS FOR REHABILITATIONPhysical activity is associated with neuromuscular and physical function, independent of disease severity.Physical activity may be important in improving or preserving neuromuscular and physical function at all stages of ambulatory multiple sclerosis patients, yet longitudinal studies are warranted.Clinicians and rehabilitation professionals should encourage ambulatory patients at all stages of their disease to be as physically active as possible.

Effects of Treadmill Training on Muscle Oxidative Capacity and Endurance in People with Multiple Sclerosis with Significant Walking Limitations

Background

Exercise can improve muscle function and mobility in people with multiple sclerosis (MS). However, the effects of exercise training on skeletal muscle oxidative capacity and endurance in people with MS remain unclear, and few studies have evaluated muscle plasticity in people with MS who have moderate-to-severe disability. The present study evaluated the effects of treadmill training on muscle oxidative capacity and muscle endurance and examined the relationship to walking function in people with MS who have moderate-to-severe disability.

Methods

Six adults (mean ± SD age, 50 ± 4.9 years) with MS (Expanded Disability Status Scale score, 6.0-6.5) performed treadmill training for 24 minutes approximately twice per week for approximately 8 weeks (16 sessions total) using an antigravity treadmill system. The following measures were taken before and after the intervention phase: muscle oxidative capacity in the medial gastrocnemius using near-infrared spectroscopy after 15 to 20 seconds of electrical stimulation; muscle endurance in the medial gastrocnemius using accelerometer-based mechanomyography during 9 minutes of twitch electrical stimulation in three stages (3 minutes per stage) of increasing frequency (2, 4, and 6 Hz); and walking function using the 2-Minute Walk Test.

Results

Mean ± SD muscle oxidative capacity increased from 0.64 ± 0.19 min^-1 to 1.08 ± 0.52 min^-1 (68.2%). Mean ± SD muscle endurance increased from 80.9% ± 15.2% to 91.5% ± 4.8% at 2 Hz, from 56.3% ± 20.1% to 76.6% ± 15.8% at 4 Hz, and from 29.2% ± 13.1% to 53.9% ± 19.4% at 6 Hz of stimulation in the gastrocnemius. There were no significant improvements in walking function.

Conclusions

Treadmill training can improve muscle oxidative capacity and endurance in people with MS who have moderate-to-severe levels of disability.

Evaluation of 18-Week Whole-Body Vibration Training in Normobaric Hypoxia on Lower Extremity Muscle Strength in an Elderly Population

Therapeutic benefits of hypoxic training have been suggested for clinical populations, such as elderly who could suffer loss of lower limb muscle strength and higher risk of falling. This study investigated the effects of 18 weeks of whole-body vibration (WBV) training in normobaric hypoxia on the strength parameters of an elderly population. Thirty-one healthy elderly participants were randomly assigned to a hypoxic whole-body vibration group (HWBV; n = 10), normoxic whole-body vibration group (NWBV; n = 11), or control group (n = 10). The experimental groups received the same vibration treatment in a hypoxia chamber (HWBV: 16.1% fraction of inspired oxygen [FiO₂]; NWBV: 21.0% FiO₂). Isokinetic leg muscle strength was evaluated using a Biodex System-3 isokinetic dynamometer. Body composition was obtained with dual-energy X-ray absorptiometry. There were no significant differences between groups in either strength or body composition parameters. The NWBV group showed statistically significant improvements in the maximal strength of knee extensors, with a small effect size (p = 0.004; d = 0.54). No significant differences were found in any variable of the HWBV group. The combination of WBV training and exposure to normobaric cyclic hypoxia carried out in the present study did not have an effect on strength parameters in healthy elderly subjects.

Strength Training to Improve Gait in People with Multiple Sclerosis: A Critical Review of Exercise Parameters and Intervention Approaches

Background

There are mixed reports on the effectiveness of strength training to improve gait performance in people with multiple sclerosis (MS), yet the reasons for these inconsistent results are not clear. Therefore, a critical review was conducted to explore dosage, frequency, mode, position, and muscle targets of studies that have included strength training in people with MS.

Methods

An electronic search was conducted through July 2017. Randomized controlled trials involving people with MS were included that implemented strength training with or without other interventions and assessed 1) strength in the lower extremities and/or trunk and 2) gait speed and/or endurance. Strength and gait results were extracted, along with exercise frequency, intensity, duration, mode, position, and muscle targets.

Results

Thirteen trials met the inclusion criteria; nine used dosing consistent with recommended guidelines. Overall, six studies reported significant between-group strength improvements, and four reported within-group changes. Four studies reported significant between-group gait improvements for gait speed and/or endurance, and two reported within-group changes. Most exercises were performed on exercise machines while sitting, supine, or prone. The most common intervention target was knee extension.

Conclusions

Studies generally improved strength, yet only two studies reported potentially meaningful between-group changes in gait. Future strength intervention studies designed to improve gait might consider dosing beyond that of the minimum intensity to improve strength and explore muscles targets, positions, and modes that are task-specific to walking.

The relationship between corticospinal tract integrity and lower-extremity strength is attenuated when controlling for age and sex in multiple sclerosis

Muscle weakness, particularly in the lower-extremities, is common in multiple sclerosis (MS) and seemingly results from damage along white matter pathways in the central nervous system including the corticospinal tract (CST). This study examined CST structural integrity indicated by diffusion tensor imaging (DTI) related metrics (fractional anisotropy [FA], mean diffusivity [MD], radial diffusivity [RD], and axial diffusivity [AD]) as correlates of knee flexor (KF) and knee extensor (KE) muscle strength in MS. We included 36 persons with MS who underwent MRI and measurements of peak KE and KF strength using an isokinetic dynamometer. We examined associations using bivariate Spearman (rs) and partial Spearman correlation (prs) analyses controlling for age and sex. Peak KF strength was significantly associated with FA (rs = 0.42) and RD (rs = -0.36) and peak KE strength was significantly associated with MD (rs = -0.47) and RD (rs = -0.36). The correlations were attenuated after controlling for age and sex, but the relationship between KF strength and FA demonstrated a trend towards significance (prs = 0.33, p = 0.056). We provide evidence that the anatomical integrity of the CST may be associated with lower-extremity strength in MS. The attenuated correlations when controlling for age and sex suggest these factors, rather than MS per se, may be important contributors toward an association between CST DTI-metrics and KF and KE strength. Future rehabilitation trials of resistance training should consider including CST integrity as an outcome and/or predictor of strength adaptations.

No association of leg strength asymmetry with walking ability, fatigability, and fatigue in multiple sclerosis

This cross-sectional study aims to determine whether leg strength asymmetries are associated with walking ability, objective measures of fatigability, or subjective perceptions of fatigue. Maximal knee extensor strength was assessed in 19 patients with multiple sclerosis (PwMS), and a symmetry index was calculated. Walking ability was determined through the total distance covered during a 6-min walk test (6MWT) and fatigability by calculating the change in distance covered between minutes 6 and 1. Perceptions of fatigue were assessed using the Fatigue Severity Scale and by obtaining ratings of perceived exertion during the first and final minute of the 6MWT. PwMS covered less distance (P=0.01) and perceived greater exertion (P<0.01) during minute 6 compared with minute 1. Knee extensor strength was asymmetric (P<0.01). The magnitude of asymmetry did not correlate with walking ability, fatigability, or measures of fatigue. Knee extensor strength asymmetry may not play an important role in prolonged walking performance in PwMS.

Contributions of Ankle, Knee, Hip, and Trunk Muscle Function to Gait Performance in People With Multiple Sclerosis: A Cross-Sectional Analysis

BACKGROUND

The relative importance of lower extremity and trunk muscle function to gait in people with multiple sclerosis (MS) is unknown.

OBJECTIVE

This study aimed to investigate the association of lower extremity and trunk muscle function with gait performance in people who have MS and mild-to-moderate disability.

DESIGN

This was a cross-sectional, observational study.

METHODS

Participants were people who had an Expanded Disability Status Scale score of ≤ 5.5. Eleven lower extremity and trunk muscles were assessed using handheld dynamometry or endurance tests. Gait performance was assessed with the Timed 25-Foot (7.62 m) Walk (T25FW) and 6-Minute Walk Test (6MWT). Regression analysis was used to quantify the association between gait outcomes and muscle variables.

RESULTS

Seventy-two participants with MS and a mean Expanded Disability Status Scale score of 3.5 (SD = 1.14) were enrolled. Adjusted for age and sex, the multivariate model including hip abduction, ankle plantar flexion, trunk flexion, and knee flexion explained 57% of the adjusted variance in the T25FW; hip abduction, ankle plantar flexion, and trunk flexion explained 61% of the adjusted variance in the 6MWT. The strongest predictors were ankle plantar flexion endurance for the T25FW and hip abduction strength for the 6MWT: a 1-SD increase in ankle plantar flexion (15.2 heel-raise repetitions) was associated with a 0.33-second reduction in the T25WT (95% CI = - 0.71 to - 0.14 seconds); a 1-SD increase in normalized hip abduction strength (0.14 kg/body mass index) was associated with a 54.4-m increase in the 6MWT (28.99 to 79.81 m).

LIMITATIONS

Different measurement scales for independent variables were included because the muscle function assessment used either force or endurance.

CONCLUSIONS

For the major muscles in the lower extremity and trunk, hip abduction, ankle plantar flexion, trunk flexion, and knee flexion were the strongest predictors of gait performance.

Case Report: Effect of Antigravity Treadmill Training on Muscle Oxidative Capacity, Muscle Endurance, and Walking Function in a Person with Multiple Sclerosis

Background

Exercise training can improve skeletal muscle metabolism in persons with multiple sclerosis (MS). However, quantification of exercise-mediated improvements in muscle metabolism has been limited, particularly in people with high levels of disability. We evaluated the effect of 9 weeks of antigravity treadmill training on muscle oxidative capacity and muscle endurance and assessed the relationship to walking function in a person with MS.

Methods

One person with MS (Expanded Disability Status Scale score, 6.5) performed treadmill training for 24 minutes approximately twice weekly for 9 weeks (16 sessions) using an antigravity treadmill system. Before and after the intervention phase, we measured muscle oxidative capacity in the medial gastrocnemius using near-infrared spectroscopy after 15 to 20 seconds of electrical stimulation; muscle endurance in the medial gastrocnemius using accelerometer-based mechanomyography during 9 minutes of twitch electrical stimulation in three stages (3 minutes per stage) of increasing frequency (2, 4, and 6 Hz); muscle strength (plantarflexion) using a maximal voluntary contraction; and walking function using the Timed 25-Foot Walk test and the 2-Minute Walk Test.

Results

Muscle oxidative capacity increased from 0.73 min^-1 to 1.08 min^-1 (48%). Muscle endurance increased from 75.9% to 84.0% at 2 Hz, from 67.8% to 76.2% at 4 Hz, and from 13.5% to 44.7% at 6 Hz. Maximal voluntary contraction decreased by 0.68 kg (15%), Timed 25-Foot Walk test speed decreased by 0.19 ft/s (20%), and 2-Minute Walk Test distance increased by 65 m (212%).

Conclusions

Muscle oxidative capacity and muscle endurance, as well as walking function, improved in a person with MS after training on an antigravity treadmill.

Effects of Muscle Function and Limb Loading Asymmetries on Gait and Balance in People With Multiple Sclerosis

People with MS (PwMS) often have a more- and less-affected side of the body which results in a variety of asymmetries, including measures of power, strength, muscle activity, and limb loading. Though many studies have identified asymmetries, their impact on gait and balance in PwMS is currently unclear. In this mini-review we first summarize previous findings of asymmetries in muscle function and limb loading and their impact on gait and balance in PwMS. We then provide potential explanations for this lack of consistency in the current literature, and propose study guidelines to improve future lower limb asymmetry studies. Making use of a unified approach to study lower limb asymmetry may then provide more clarity regarding their impact on mobility, specifically gait and balance, in PwMS.

Impaired postural balance correlates with complex walking performance in mildly disabled persons with multiple sclerosis

BACKGROUND

It is relevant to understand the possible influence of impaired postural balance on walking performance in multiple sclerosis (MS) gait rehabilitation.

OBJECTIVE

We expected associations between impaired postural balance and complex walking performance in mildly disabled persons with MS, but not in healthy controls.

METHODS

Thirteen persons with MS (Expanded Disability Status Scale = 2.5) and 13 healthy controls' walking performance were measured at fast walking speed, Timed Up & Go and Timed 25 Feet Walking. Postural balance was measured by stabilometry, 95% confidence ellipse sway area and sway velocity.

RESULTS

Except from sway velocity (p = 0.07), significant differences were found between persons with MS and healthy controls in postural balance and walking. Significant correlations were observed between sway area and Timed Up & Go (r = 0.67) and fastest safe walking speed (r = -0.63) in persons with MS but not in healthy controls (r = 0.52 and r = 0.24, respectively). No other significant correlations were observed between postural balance and walking performance in neither persons with MS nor healthy controls.

CONCLUSION

Findings add to the understanding of postural balance and walking in persons with MS, as impaired postural balance was related to complex walking performance. Exercises addressing impaired postural balance are encouraged in early MS gait rehabilitation.

Profiling walking dysfunction in multiple sclerosis: characterisation, classification and progression over time

Gait dysfunction is a common and relevant symptom in multiple sclerosis (MS). This study aimed to profile gait pathology in gait-impaired patients with MS using comprehensive 3D gait analysis and clinical walking tests. Thirty-seven patients with MS walked on the treadmill at their individual, sustainable speed while 20 healthy control subjects walked at all the different patient's paces, allowing for comparisons independent of walking velocity. Kinematic analysis revealed pronounced restrictions in knee and ankle joint excursion, increased gait variability and asymmetry along with impaired dynamic stability in patients. The most discriminative single gait parameter, differentiating patients from controls with an accuracy of 83.3% (χ2 test; p = 0.0001), was reduced knee range of motion. Based on hierarchical cluster and principal component analysis, three principal pathological gait patterns were identified: a spastic-paretic, an ataxia-like, and an unstable gait. Follow-up assessments after 1 year indicated deterioration of walking function, particularly in patients with spastic-paretic gait patterns. Our findings suggest that impaired knee/ankle control is common in patients with MS. Personalised gait profiles and clustering algorithms may be promising tools for stratifying patients and to inform patient-tailored exercise programs. Responsive, objective outcome measures are important for monitoring disease progression and treatment effects in MS trials.

Knee flexor strength and balance control impairment may explain declines during prolonged walking in women with mild multiple sclerosis

BACKGROUND

Physiological factors such as muscle weakness and balance could explain declines in walking distance by multiple sclerosis (MS) patients. The purpose of this study was to characterize levels and examine associations among decline in walking distance, balance and muscular strength in women with mild MS.

METHODS

Participants included 28 women with mild relapsing-remitting MS and 21 women without MS. We executed the 6-min walk test (6MWT) to verify declines in walking distance. Isokinetic knee flexion (KF) and extension (KE) muscle strength was measured using a dynamometer. Balance was quantified using a force platform, with eyes open and closed, on a rigid and foam surface.

RESULTS

The MS patients presented declines in walking, lower KF muscle strength, and worse balance than controls. KF strength and balance correlated with walking in the MS group. The KF strength explained differences between groups in walking. The KF strength and balance presented as predictors of walking slowing down in the 6MWT, in mild MS.

CONCLUSION

Women with mild MS have strength impairment of knee flexor muscles and balance control impairment that may explain walking related motor fatigability during prolonged walking.