Comprehensive Profile of Cardiopulmonary Exercise Testing in Ambulatory Persons with Multiple Sclerosis

Rationale and methodology for examining the combination of aerobic exercise and cognitive rehabilitation on new learning and memory in persons with multiple sclerosis and mobility disability: Protocol for a randomized controlled trial

BACKGROUND

This paper describes the protocol for a Phase I/II, parallel-group, single-blind randomized controlled trial (RCT). The RCT investigates the combined effects of 12-weeks of aerobic exercise training (AET) integrated with virtual reality (VR) and cognitive rehabilitation (CR) on new learning and memory in 78 persons with multiple sclerosis (MS) who have mobility disability and objective impairments in learning and memory.

METHODS

Participants will undergo baseline assessments consisting of neuropsychological testing, neuroimaging, self-report questionnaires, and cardiorespiratory fitness. Participants will then be randomized into one of two conditions using concealed allocation: aerobic cycling exercise that incorporates VR combined with CR or stretching and toning (i.e., active control; S/T) combined with CR. Participants will be masked regarding the intent of the conditions. After 7-weeks of exercise alone, the 5-week Kessler Foundation modified Story Memory Technique (KF-mSMT®) will be integrated into the training. After the 12-week training period, participants will complete the same measures as at baseline administered by treatment-blinded assessors. Primary study outcomes include new learning and memory (NLM) measured by a small battery of neuropsychological assessments that assess list learning (California Verbal Learning Test-II), prose memory (Memory Assessment Scale), visuospatial memory (Brief Visuospatial Memory Test-Revised), and everyday memory (Ecological Memory Simulations). Secondary study outcomes include neuroimaging outcomes of hippocampal structure, function, and connectivity.

CONCLUSION

If successful, this trial will provide the first Class I evidence supporting the unique combination of aerobic cycling exercise with VR and CR for treating MS-related learning and memory impairments in persons with mobility disability.

Study protocol: exercise training for treating major depressive disorder in multiple sclerosis

BACKGROUND

Major depressive disorder (MDD) is prevalent, yet sub-optimally treated among persons with multiple sclerosis (MS). We propose that exercise training may be a promising approach for treating depression in persons with MS who have MDD. Our primary hypothesis predicts a reduction in depression severity immediately after an exercise training intervention compared with minimal change in an attention control condition, and the reduction will be maintained during a follow-up period.

METHODS

This study involves a parallel-group, assessor-blinded RCT that examines the effect of a 4-month home-based exercise training intervention on depression severity in a sample of persons with MS who have MDD based on the MINI International Neuropsychiatric Interview. The primary outcomes of depression severity are the Patient Health Questionnaire-9 and Hamilton Depression Rating Scale. Participants (N = 146) will be recruited from within 200 miles of the University of Illinois at Chicago and randomized (1:1) into either a home-based exercise training condition or control condition with concealed allocation. The exercise training and social-contact, attention control (i.e., stretching) conditions will be delivered remotely over a 4-month period and supported through eight, 1:1 Zoom-based behavioral coaching sessions guided by social-cognitive theory and conducted by persons who are uninvolved in screening, recruitment, random assignment, and outcome assessment. We will collect outcome data at 0, 4 and 8 months using treatment-blinded assessors, and data analyses will involve intent-to-treat principles.

DISCUSSION

If successful, the proposed study will provide the first Class I evidence supporting a home-based exercise training program for treating MDD in persons with MS. This is critical as exercise training would likely have positive secondary effects on symptoms, cognition, and quality of life, and provide a powerful, behavioral approach for managing the many negative outcomes of MDD in MS. The program in the proposed research is accessible and scalable for broad treatment of depression in MS, and provides the potential for integration in the clinical management of MS.

TRIAL REGISTRATION

The trial was registered on September 10, 2021 at clinicaltrials.gov with the identifier NCT05051618. The registration occurred before we initiated recruitment on June 2, 2023.

Relative aerobic load of walking in people with multiple sclerosis

OBJECTIVE

To examine the energy demand of walking relative to aerobic capacity in people with multiple sclerosis.

DESIGN

Cross-sectional cohort study.

PATIENTS

A total of 45 people with multiple sclerosis (32 females), median disease duration 15 years (interquartile range (IQR) 9; 20), median Expanded Disability Status Scale 4 (min-max range: 2.0; 6.0).

METHODS

Aerobic capacity, derived from a cardiopulmonary exercise test and gas exchange measurements, assessed during a 6-min overground walk test at comfortable speed, were analysed. The relative aerobic load of walking was determined as the energy demand of walking relative to oxygen uptake at peak and at the first ventilatory threshold. Healthy reference data were used for clinical inference.

RESULTS

People with multiple sclerosis walk at a mean relative aerobic load of 60.0% (standard deviation 12.8%) relative to peak aerobic capacity, and 89.1% (standard deviation 19.9%) relative to the first ventilatory threshold. Fourteen participants walked above the first ventilatory threshold (31%). Peak aerobic capacity was reduced in 45% of participants, and energy demands were increased in 52% of participants.

CONCLUSION

People with multiple sclerosis walk at a relative aerobic load close to their first ventilatory threshold. A high relative aerobic load can guide clinicians to improve aerobic capacity or reduce the energy demands of walking.

Decreased functional mobility in individuals with mild to moderate expanded disability status from relapsing multiple sclerosis: Analysis of the Glittre-ADL test

INTRODUCTION

Multiple sclerosis (MS) is a chronic inflammatory and autoimmune disease that significantly limits an individual's activities of daily living (ADLs) and negatively affects their social participation as it progresses. The impact of activities and participation must be continuously assessed, and the Glittre-ADL is a validated test for MS to assess functional capacity in tasks similar to ADLs.

OBJECTIVE

To evaluate whether the Glittre-ADL test is a valid method for assessing functional mobility in individuals with MS and moderate disability or those who use assistive devices.

METHODS

This cross-sectional study enrolled 30 individuals in two groups: 1) MS group (n = 15); and 2) healthy control group (n = 15). The MS group underwent three functional mobility tests: 1) Glittre-ADL; 2) Timed 25-Foot Walk (T25FWT); and 3) Timed Up and Go (TUG) while the healthy group underwent only the Glittre-ADL test.

RESULTS

An association was found between the Glittre-ADL time and T25FWT (r = 0.78, p < .001) and TUG (r = 0.56, p = .030) times. In the MS group, statistically significant differences were found in time (F = 2.88, p = .038) and speed (F = 5.17, p = .024) between laps. A statistically significant difference was observed between the total time in the MS and control groups (Area Under Curve - AUC: 0.982, p < .0001). A total time > 46.0s represents the reduction of functional performance during ADLs in individuals with MS (sensitivity: 93.3%; specificity: 92.2%).

CONCLUSION

The Glittre-ADL test is a valid tool for assessing functional mobility in individuals with MS and mild to moderate disability (EDSS score ≤ 6.5).

Arterial stiffness in persons with multiple sclerosis and controls: Does aerobic fitness account for group differences?

Vascular function is worse in multiple sclerosis (MS) than healthy controls perhaps based on differences in aerobic fitness. We compared carotid-femoral pulse wave velocity (cfPWV) and augmentation index (AIx75) between MS and controls while accounting for aerobic fitness. Aerobic fitness was measured as peak oxygen consumption on a recumbent stepper. cfPWV and AIx75 were measured using applanation tonometry. Persons with MS demonstrated lower aerobic fitness and higher cfPWV, but no difference in AIx75 compared with controls. The difference in cfPWV remained statistically significant after controlling for aerobic fitness, suggesting that arterial stiffness might reflect underlying pathophysiology processes of MS.

The effects of cognitive rehabilitation combined with aerobic exercise or stretching-and-toning on new learning and memory in persons with moderate-to-severe TBI: Protocol for a randomized controlled trial

This paper describes the protocol for a Phase I/II, parallel-group, blinded randomized controlled trial that compares the effects of 12-weeks of combined learning and memory rehabilitation with either aerobic cycling exercise or stretching on cognitive, neuroimaging, and everyday life outcomes in 60 persons with moderate-to-severe traumatic brain injury (TBI) who demonstrate impairments in new learning. Briefly, participants will undergo baseline testing consisting of neuropsychological testing, neuroimaging, daily life measures, and cardiorespiratory fitness. Following baseline testing, participants will be randomized to one of 2 conditions (30 participants per condition) using concealed allocation. Participants will be masked as to the intent of the conditions. The conditions will both involve supervised administration of an enhanced, 8-week version of the Kessler Foundation modified Story Memory Technique, embedded within either 12-weeks of supervised and progressive aerobic cycling exercise training (experimental condition) or 12-weeks of supervised stretching-and-toning (active control condition). Following the 12-week intervention period, participants will complete the same measures as at baseline that will be administered by treatment-blinded assessors. The primary study outcome is new learning and memory impairment based on California Verbal Learning Test (CVLT)-III slope, the secondary outcomes include neuroimaging measures of hippocampal volume, activation, and connectivity, and the tertiary outcomes involve measures of daily living along with other cognitive outcomes. We further will collect baseline sociodemographic data for examining predictors of response heterogeneity. If successful, this trial will provide the first Class I evidence supporting combined memory rehabilitation and aerobic cycling exercise training for treating TBI-related new learning and memory impairment.

Cardiopulmonary exercise testing in people with minimally impaired multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is a chronic demyelinating inflammatory disorder of the central nervous system that may affect respiratory system at the later stages of the disease. The aim of our study was to evaluate respiratory function and cardiopulmonary exercise testing in ambulatory without aid people with MS (pwMS), and to investigate quality of life parameters and fatigue in this population.

METHODS

25 pwMS and 16 healthy controls were included in this study. Pulmonary function tests were performed and were followed by proper cardiopulmonary exercise testing with the use of treadmill. Quality of life assessment was done with SF-36 questionnaire.

RESULTS

The mean age of the patient group was 38.4 ± 8.2 years. Spirometric values were within normal limits, and so did lung diffusion capacity, while maximal voluntary ventilation was reduced. In cardiopulmonary exercise testing the patient group showed impairment compared to control group. The statistically significant lower parameters were V'O2 peak, V'CO2 peak, RER, V'O2/kg peak, V'CO2/kg peak, oxygen pulse peak and V'E/V'CO2 slope. Moreover, there was a negative and statistically significant correlation between CPET values and BMI and MFIS, while there was a positive and statistically significant correlation with quality of life, evaluated by SF-36.

CONCLUSION

Our study showed that the main cardiopulmonary exercise testing parameters were affected in ambulatory pwMS, even without evidence of respiratory symptoms. Therefore, these people should be evaluated for pulmonary function compromise.

Home-based exercise improves subclinical atherosclerosis marker in multiple sclerosis

PURPOSE

Using a 12-week, randomized controlled trial coupled with social cognitive theory behavioral coaching, we aimed to assess the effect of a home-based aerobic training intervention versus an attention-control on aerobic fitness, subclinical atherosclerosis, and mobility in persons with MS.

METHODS

Persons with MS with an expanded disability status scale score between 0 and 4 were randomized to a 12-week aerobic exercise (EX) (n = 26; 19 females; 49 yrs; 28.8 kg/m2) or attention-control (CON) condition (stretching; n = 22; 16 females; 44 yrs; 29.2 kg/m2). Aerobic capacity was assessed via a graded cycle ergometry test with indirect calorimetry. The co-primary measures of subclinical atherosclerosis assessed included carotid intima media thickness, a test of vasodilatory reactivity, and arterial stiffness. Mobility was assessed via a timed 25-foot walk test (T25FW) and a 6 min walk test. The EX group engaged in cycle ergometry 3d/wk with gradual increases in the intensity and duration of the exercise sessions. CON participated in standardized stretching designed to provide the same contact time as EX 3d/wk. Behavioral coaching took place via weekly phone/video chats to track adherence.

RESULTS

Aerobic capacity, vasodilatory reactivity, and T25FW speed increased only in the EX group, 7%, 16%, and 13% (p<0.05), respectively; whereas the CON group did not change.

CONCLUSION

The EX group had modest, yet significant, increases in aerobic capacity over the 12-week period, coupled with improvements in T25FW speed and vasodilatory reactivity. A home-based exercise intervention can improve outcomes of a subclinical marker of atherosclerosis, which provides a basis for examining these outcomes in persons prescreened for CVD-related comorbidities and/or mobility issues.

The pathophysiology of motor fatigue and fatigability in multiple sclerosis

Multiple Sclerosis (MS) is a heterogeneous immune mediated disease of the central nervous system (CNS). Fatigue is one of the most common and disabling symptom of MS. It interferes with daily activities on the level of cognition and motor endurance. Motor fatigue can either result from lesions in cortical networks or motor pathways (“primary fatigue”) or it may be a consequence of detraining with subsequent adaptions of muscle and autonomic function. Programmed exercise interventions are used frequently to increase physical fitness in MS-patients. Studies investigating the effects of training on aerobic capacity, objective endurance and perceived fatigability have yielded heterogenous results, most likely due to the heterogeneity of interventions and patients, but probably also due to the non-uniform pathophysiology of fatigability among MS-patients. The aim of this review is to summarize the current knowledge on the pathophysiology of motor fatigability with special reference to the basic exercise physiology that underlies our understanding of both pathogenesis and treatment interventions.

Cardiorespiratory fitness and moderate-to-vigorous physical activity in older adults with multiple sclerosis

Background

Cardiorespiratory fitness (VO_2peak) may be a modifiable indicator of health status and well-being in older adults with multiple sclerosis.

Purpose

We examined differences in VO_2peak and moderate-to-vigorous physical activity between older adults with multiple sclerosis and healthy controls, and whether moderate-to-vigorous physical activity accounted for group differences in VO_2peak.

Methods

Older adults with multiple sclerosis (n = 31) and healthy controls (n = 29) completed a cardiopulmonary exercise test and wore an accelerometer for measuring moderate-to-vigorous physical activity. The data were analyzed using the Baron and Kenny approach for examining moderate-to-vigorous physical activity as a mediator of group differences in VO_2peak.

Results

The multiple sclerosis group had significantly lower VO_2peak and moderate-to-vigorous physical activity than healthy controls. VO_2peak had a large correlation with moderate-to-vigorous physical activity (r = .59). Group initially explained 8% of the variance in VO_2peak (β  =  -0.29). The inclusion of moderate-to-vigorous physical activity accounted for an additional 27% of the variance in VO_2peak, but only moderate-to-vigorous physical activity (β  =  0.57) was a statistically significant correlate of VO_2peak. The effect of Group was attenuated and non-significant with the addition of moderate-to-vigorous physical activity in Step 2 (Group β Step 1  =  -0.29, Group β Step 2  =  -0.05).

Conclusions

Our results provide initial support for targeting moderate-to-vigorous physical activity as an approach for improving VO_2peak in older adults with multiple sclerosis.

Blood lactate concentrations during rest and exercise in people with Multiple Sclerosis: A systematic review and meta-analysis

BACKGROUND

Multiple Sclerosis (MS) is a chronic disorder which irreversibly damages axons within brain matter. Blood lactate concentration could be a biomarker of MS onset and progression, but no systematic review has yet sought to confirm or dispute the elevation and biomarker potential of blood lactate in people with MS (PwMS) or to consolidate understanding of lactate production during exercise in PwMS.

OBJECTIVE

To perform a systematic review and meta-analysis on blood lactate in PwMS during rest and exertion compared to Healthy Controls (HC) and following chronic exercise intervention.

METHODS

A systematic search of six electronic databases (PubMed, CINAHL, Science Direct, Cochrane Library, SPORTDiscus and PEDro) was performed on 10th April 2020. Mean, standard deviation and sample size for lactate measures at rest and during exercise were pooled to determine overall effect size using a random effects model.  The 20-point Appraisal tool for Cross-Sectional Studies was utilised to assess study quality and inherent risk of bias. To qualify for inclusion, studies had to include human adults (>18 years) with a confirmed clinical diagnosis of MS, be published in English, have undergone peer review, report absolute blood lactate values for data extraction, and if involving testing during/after exercise, to do so during bilateral exercise methods.

RESULTS

18 studies were qualitatively analysed and 15 studies quantitatively analysed. Outcome data was available for 1986 participants (n_MS = 1129). A total of 7 papers tested blood lactate during rest (Lactate_REST), 7 papers tested during sub-maximal intensity exercise (Lactate_SUB-MAX), and 8 papers tested during maximal intensity exercise (Lactate_MAX). Meta analyses showed elevated Lactate_REST and reduced Lactate_MAX in PwMS compared to HC, higher Lactate_MAX in lower EDSS-scoring PwMS compared to higher EDSS-scoring PwMS, and that Lactate_SUB-MAX decreases and Lactate_MAX increases in PwMS following a chronic exercise intervention. Qualitative analysis reported Lactate_REST to be reduced in PwMS following a chronic exercise intervention.

CONCLUSIONS

Lactate_REST is elevated in PwMS compared to HC. Lactate_MAX is lower in PwMS compared to HC and lower still in higher compared to lower EDSS-scoring groups of PwMS. Chronic exercise interventions have the potential to reduce Lacatate_SUB-MAX for a given power output and increase Lactate_MAX in PwMS compared to baseline values. Lactate_REST may be reduced in PwMS following a chronic exercise intervention but more research is required for confirmation. The results of this review were limited by small sample sizes and number of studies available for each testing condition, limited data available for potentially confounding/correlating factors (eg. VO₂ and power output) as well as heterogeneity of methodology adopted across studies, often due to lactate testing being a secondary outcome measure. PLS: Lactate levels in the blood are different during rest and at intense exercise levels in people with Multiple Sclerosis (MS) compared to healthy counterparts, with people with MS showing a smaller jump in lactate during intense exercise from a higher resting level. After exercising for at least 3 months, blood lactate levels during exercise may become more similar to the levels seen in people without Multiple Sclerosis, but more research is required to give a clearer picture of this. We can hopefully use blood lactate in future to measure the progression of MS in an individual as well as the effectiveness of their exercise programme.

Cardiorespiratory fitness and free-living physical activity are not associated with cognition in persons with progressive multiple sclerosis: Baseline analyses from the CogEx study

BACKGROUND

Aerobic exercise training (physical activity for improving cardiorespiratory fitness) represents a promising approach for managing cognitive impairment in multiple sclerosis (MS). However, there is limited evidence that levels of physical activity and fitness are associated with cognition in progressive MS.

OBJECTIVE

We examined associations among cardiorespiratory fitness, moderate-to-vigorous physical activity (MVPA), and cognitive performance in a large, international progressive MS sample.

METHODS

Two hundred forty European and North American persons with progressive MS underwent cardiorespiratory fitness measurement on a recumbent stepper, wore an ActiGraph GT3X + accelerometer for 7 days for measuring MVPA, and underwent the Brief International Cognitive Assessment in MS.

RESULTS

Cardiorespiratory fitness was not significantly correlated with Symbol Digit Modalities Test (SDMT; r = -0.01; r = -0.04), California Verbal Learning Test-II (CVLT-II; r = 0.05; r = 0.05), or Brief Visuospatial Memory Test-Revised (BVMT-R; r = -0.14; r = -0.14) z-scores controlling for age, sex, and education. MVPA and SDMT (r = 0.05), CVLT-II (r = -0.07), and BVMT-R (r = 0.01) z-scores were not significantly correlated.

CONCLUSION

Cardiorespiratory fitness and MVPA were not associated with cognition in this large progressive MS sample, yet these outcomes represent critical manipulation checks for documenting the success of the CogEx trial. This highlights the importance of examining other exercise-related mechanisms-of-action for improving cognition in progressive MS.

Effects of walking exercise training on learning and memory and hippocampal neuroimaging outcomes in MS: A targeted, pilot randomized controlled trial

PURPOSE

The current pilot study involved a single-blind, randomized controlled trial (RCT) on the effects of treadmill walking exercise training compared with an active control condition on learning and memory (L/M) and hippocampal neuroimaging outcomes in 11 fully-ambulatory persons with multiple sclerosis (MS) who demonstrated impairments in new learning.

METHODS

The study protocol is registered at clinicaltrials.gov: NCT03319771 (February 2018). Eleven fully-ambulatory persons with MS-related impairments in new learning were randomly assigned into either 12-weeks of supervised, treadmill walking exercise training or 12-weeks of low-intensity resistive exercise (active control condition). Participants underwent neuropsychological tests of L/M and hippocampal neuroimaging before and after the 12-week study period; outcomes were administered by treatment-blinded assessors.

RESULTS

There were moderate-to-large intervention effects on measures of verbal L/M (η_p² = 0.11, d = 0.63, 95% CI: -0.61, 1.83), whereby those in the intervention condition demonstrated improvement in California Verbal Learning Test-II (CVLT-II) scores compared with the control condition. There were smaller effects on a composite L/M measure (η_p² = 0.02, d = 0.28, 95% CI: -0.93, 1.46). There were large intervention effects on normalized hippocampal volume (η_p² = 0.36, d = 1.13, 95% CI: 0.09, 2.82), whereby hippocampal volume was preserved in the intervention condition, compared with hippocampal atrophy in the control condition. By comparison, there were no intervention effects on hippocampal resting-state functional connectivity.

CONCLUSIONS

Collectively, this study provides initial proof-of-concept data for further examining treadmill walking exercise training as a possible behavioral approach for managing L/M impairment and preserving hippocampal volume as common and debilitating manifestations of MS.

Aerobic reserve capacity in multiple sclerosis-Preliminary evidence

OBJECTIVES

Aerobic reserve capacity reflects the available energy for performing everyday life tasks, and it has been studied in older adult populations. This preliminary study examined proof of concept and measurement of aerobic reserve capacity in multiple sclerosis (MS).

MATERIALS & METHODS

Twenty-one fully ambulatory people with MS performed a maximal, cardiopulmonary exercise test (CPET). We calculated aerobic reserve capacity based on the difference between peak aerobic power (VO_2peak ) and first stage oxygen consumption (VO₂ ). Participants completed assessments for disability (Expanded Disability Status Scale, EDSS), cognition (Symbol Digit Modalities Test, SDMT), mood (Beck Depression Inventory, BDI), walking endurance (six-minute walk distance, 6MWD), walking speed (Timed Twenty-Foot Walk, T25FW), impact of MS (Multiple Sclerosis Impact Scale, MSIS-29), and anthropometric measurements (height and weight).

RESULTS

Aerobic reserve capacity was 9.3 ± 3.7 ml/kg/min. Aerobic reserve capacity was positively associated with VO_2peak (ρ = .67, p < .01), time to exhaustion (ρ = .63, p < .01), and SDMT (ρ = .51, p < .05). Aerobic reserve capacity was negatively associated with BMI (ρ = -.62, p < .01) and RHR (ρ = -0.47, p < .05).

CONCLUSION

We provide preliminary evidence that aerobic reserve capacity is a feasible outcome derived from maximal CPET (eg, modified Balke protocol) in MS. Aerobic reserve capacity was associated with clinically relevant outcomes and could become an important outcome for rehabilitation in future research.

Feasibility and initial efficacy of a high-intensity interval training program using adaptive equipment in persons with multiple sclerosis who have walking disability: study protocol for a single-group, feasibility trial

Background

There is considerable evidence for the efficacy of moderate-intensity continuous exercise benefitting clinically relevant outcomes in persons with multiple sclerosis (MS). However, persons with MS who have walking disability (pwMS-wd) are severely deconditioned and may achieve superior benefits by engaging in high-intensity interval training (HIIT), especially while utilizing adaptive equipment, such as recumbent arm/leg stepping (RSTEP). The proposed study will assess the feasibility of a 12-week, RSTEP HIIT program in pwMS-wd. The secondary aim will examine changes in aerobic fitness, physical activity, ambulation, upper arm function, cognition, fatigue, and depression as clinically relevant efficacy outcomes following the 12-week, RSTEP HIIT intervention.

Methods

The study will recruit 15 pwMS-wd. Feasibility will be measured via process, resource, management, and scientific outcomes throughout the entirety of the research study. The secondary, clinically relevant outcomes will consist of a neurological exam, aerobic capacity, physical activity, ambulation, cognition, upper arm function, fatigue, and depression. Outcomes will be assessed at baseline (T1), midpoint (T2, following 6 weeks), and post-intervention (T3, following 12 weeks). The intervention will involve 12 weeks of supervised, individualized HIIT sessions two to three times per week. The individual HIIT sessions will each involve 10 cycles of 60-s intervals at the wattage associated with 90% VO_2peak followed by 60 s of active recovery intervals at 15 W, totaling 20 min in length plus 5-min warm-up and cool-down periods.

Discussion

The feasibility design of the proposed study will provide experience and preliminary data for advancing towards a proof-of-concept study comparing HIIT to moderate-intensity continuous RSTEP for improving clinically relevant outcomes in a randomized control trial design. The results will be disseminated via manuscripts for publication and a report for distribution among the National Multiple Sclerosis Society.

Trial registration

ClinicalTrials.gov NCT04416243. Retrospectively registered on June 4, 2020

Do subcortical gray matter volumes and aerobic capacity account for cognitive-motor coupling in multiple sclerosis?

BACKGROUND

There is evidence of cognitive-motor coupling in multiple sclerosis (MS) such that the slowing of cognitive processing speed correlates with the worsening of walking speed and endurance.

OBJECTIVE

The current study first established the presence of cognitive-motor coupling and second examined the possibility that volumes of subcortical gray matter (SGM) structures and aerobic capacity might explain the coupling of cognitive and motor functions in persons with MS.

METHODS

We included data from 62 persons with clinically definite MS who underwent assessments of cognitive processing speed, walking performance, and aerobic capacity, and completed magnetic resonance imaging (MRI) within 7 days of the aforementioned assessments.

RESULTS

The strong correlations between cognitive processing speed and walking performance were attenuated in magnitude and not statistically significant when controlling for aerobic capacity alone and aerobic capacity and SGM volumes together. The associations between cognitive processing speed and walking performance remained statistically significant when controlling for SGM volumes alone.

CONCLUSION

Aerobic capacity may be an important target for neurorehabilitation-based approaches for managing co-occurring cognitive and motor dysfunction in MS.

Safety and Feasibility of Various Functional Electrical Stimulation Cycling Protocols in Individuals With Multiple Sclerosis Who Are Nonambulatory

Objective

To examine the safety, feasibility, and response to functional electrical stimulation (FES) cycling protocols requiring differing levels of effort in people with multiple sclerosis (MS) who are nonambulatory.

Design

Pilot study with pre-post intervention testing.

Setting

Outpatient clinic setting of a long-term acute care hospital.

Participants

Individuals (N=10) with MS (6 men; mean age 58.6±9.86y) who use a wheelchair for community mobility. Participants’ Expanded Disability Status Scale score ranged from 6.5 to 8.5 (median 7.5).

Intervention

Participants performed 3 or 4 FES cycling protocols requiring different levels of volitional effort during 6-8 testing sessions.

Main Outcome Measures

The primary outcome was safety, measured by adverse events and increase in MS symptoms, all assessed throughout, immediately post- and 1 day postsession. FES cycling performance for each protocol was also recorded. Exploratory outcome measures collected before and after all testing sessions included functional assessment of MS, MS Impact Scale, Exercise Self Efficacy Scale, Patient Health Questionnaire-9 item, and the Zarit Caregiver Burden Scale.

Results

All participants (4 women, 6 men) completed all testing sessions. There were no serious adverse events or differences in vitals or symptoms between protocols. Two participants had an isolated episode of mild hypotension. Changes in pain, spasticity, and fatigue were minimal. Five participants were able to cycle for 30 minutes and completed interval training protocols requiring increasing difficulty. The remainder cycled for <3 minutes and completed a rest interval protocol. There was modest improvement on the exploratory outcome measures.

Conclusions

People with MS who use a wheelchair for community mobility can safely perform FES cycling requiring more effort than previously reported research. Therefore, the individuals may experience greater benefits than previously reported. Further study is required to better understand the potential benefits for optimizing function and improving health in people with MS.

•

People with multiple sclerosis who are nonambulatory can safely perform functional electrical stimulation (FES) cycling using parameters requiring more effort.

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FES cycling may offer an opportunity for increased exercise stimulus or neuromuscular training if individuals are adequately challenged using an appropriate cycling protocol.

Physical activity and peak oxygen consumption are associated with walking in multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system with a prevalence of nearly 1 million adults in the United States. MS results in declines in physical activity and peak oxygen consumption that might be independently associated with declines in walking performance. Therefore our purpose was to evaluate the association between physical activity and peak oxygen consumption with walking performance in individuals with MS.

METHODS

Fifty individuals with MS between the ages of 18-70 yrs. (Female: 38; 46  ±  12 yrs.; BMI: 28.5  ±  6.4; EDSS: 3.3 [IQR: 2.5-4]) performed a maximal incremental cycle test to assess peak oxygen consumption (VO_2peak), and wore an accelerometer for one week to measure moderate-to-vigorous physical activity (MVPA). Subjects further completed a timed 25-foot walk test (T25FW) and 6-minute walk (6MW) to measure walking performance.

RESULTS

MVPA and VO₂peak were correlated with 6MW and T25FW (p < 0.05). When combined in multivariate regression analyses, VO_2peak and MVPA were both significant contributors of T25FW speed and 6MW, but after controlling for sex and age, MVPA was the only significant contributor (β = 0.32 and β = 0.44, respectively).

CONCLUSION

Both higher MVPA and VO_2peak were associated with better walking performance and in a combined model physical activity, but not peak oxygen consumption, remained an independent contributor to walking performance in individuals with MS. These results suggest that improving MVPA is a potential target for interventions to improve walking performance in persons with MS.

Exercise and Multiple Sclerosis

Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system (CNS) with an estimated prevalence approaching 1 million adults in the United States. The disease pathogenesis and resulting damage express as dysfunction (e.g., walking and cognitive impairment) and symptoms (e.g., fatigue and depression) that compromise quality of life (QOL) and full participation. There has been a steadily increasing body of research on the outcomes of exercise among persons with MS, and this has accelerated sharply over the past decade. The current chapter provides a review of exercise and its outcomes, safety, and prescription in MS. This chapter initially reviews the evidence for benefits of exercise based principally on meta-analyses and literature reviews. The chapter then reviews evidence on the safety of exercise in MS and lastly provides guidelines for exercise prescription in MS. Collectively, this chapter serves as an overview and reference for researchers and clinicians interested in the benefits, safety, and prescription of exercise in MS.

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.

Evaluation of Power Production Asymmetry during Cycling in Persons with Multiple Sclerosis

Lower limb asymmetries have been observed in persons with multiple sclerosis (PwMS), and have been associated with mobility impairment. An incremental cycling test was performed on a cycle ergometer to determine peak power output (PPO) and peak oxygen consumption (VO₂peak). Then, participants cycled at 50%, 60%, and 70% of their PPO to assess the contribution of each lower limb to power production. Two-way repeated measures ANOVA was used to detect group × intensity differences in power production asymmetry. Eight PwMS and six healthy individuals (Non-MS) completed the study. No statistically significant (p > 0.05) group × intensity interactions or main effects were present when examining between-limb differences in power production. The current data do not indicate a statistically significant difference in power production asymmetry between groups and exercise intensities. Previous research has established a 10% difference between contralateral limbs as a threshold for asymmetry. The average asymmetry in power production in PwMS exceeded the 10% threshold at all measured outputs, suggesting the presence of asymmetry in power production.

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.

Aerobic Fitness and Instrumental Activities of Daily Living in People with Multiple Sclerosis: A Cross-sectional Study

Background

There is ample evidence that aerobic fitness is reduced in people with multiple sclerosis (MS), and this may yield a reduction in independence in instrumental activities of daily living (IADLs). This study examined the association between aerobic fitness and self-reported IADLs in persons with MS.

Methods

Sixty-two adults with MS completed an incremental exercise test as a measure of aerobic fitness (peak oxygen consumption), a demographic questionnaire, and an IADL scale and underwent a neurologic examination for characterization of disability level (ie, Expanded Disability Status Scale) in a single session.

Results

The analysis revealed a weak but significant association between aerobic fitness and total IADL score (r = 0.28 [95% CI, 0.03-0.49], P = .033). Those reporting dependence in different IADL categories (eg, shopping, food preparation, housekeeping, laundry, and responsibility for own medication) presented with lower aerobic fitness compared with those reporting independence, although the difference was not statistically significant.

Conclusions

These findings extend previous studies on activities of daily living in people with MS and underscore the need for studies examining the potential effect of aerobic exercise interventions on independence regarding IADLs in this population.

Body mass index and cardiorespiratory fitness in persons with multiple sclerosis

OBJECTIVE

This study examined body fatness and its association with cardiorespiratory fitness (CRF) in persons with multiple sclerosis (pwMS) accounting for disability status.

MATERIALS AND METHODS

This study involved a secondary data analysis from a previous study of 62 pwMS. Body fatness was indirect measured as body mass index (BMI), and CRF was measured as peak oxygen consumption from an incremental exercise test with spirometry. Participants were allocated into 3 different groups based on established BMI categories (ie, normal, overweight, and obese), and data were analyzed using SPSS.

RESULTS

The average BMI was 27.0 (6.7) kg/m² , and CRF was 19.5 (7.2) mL/kg/min. There was an inverse correlation (pr = -.38 [-.57; -.14]; P = .003) between BMI and CRF controlling for age, sex, disease duration, and disability level. ANCOVA with linear contrast analysis revealed a statistical significant reduction in CRF between groups of different BMI categories; normal weight 20.8 (0.85); overweight 19.8 (1.13); and obese 16.9 (1.73) mL/kg/min; F (2, 55) = 3.33, P = .043; η²  = .11.

CONCLUSIONS

The findings suggest that BMI has a negative impact on CRF in pwMS, with a marked reduction in CRF for those classified as obese compared to those in the normal and overweight category.

Ventilatory efficiency and aerobic capacity in people with multiple sclerosis: A randomized study

Objectives:

To assess ventilatory efficiency and aerobic capacity in people with multiple sclerosis and whether treadmill walking or progressive strength training has an effect on these parameters in this population.

Methods:

In all, 24 adults with multiple sclerosis with an Expanded Disability Status Scale score of ≤6 completed a cardiopulmonary exercise test before and after 8 weeks of exercise. They were randomized to treadmill walking of low-to-moderate intensity (50%–70% of peak heart rate) or progressive strength training (six repetitions × two at 80% of one repetition maximum). Both groups exercised for 30 min three times per week. Primary outcome measure was ventilatory efficiency measured as the minute ventilation/carbon dioxide production (VE/VCO₂) ratio and oxygen uptake efficiency slope. Secondary outcome was aerobic capacity, measured as peak oxygen uptake (VO_2peak).

Results:

Despite low aerobic capacity, ventilatory efficiency was found to be within normal range. After 8 weeks of exercise, no significant between-group differences emerged in (1) VE/VCO₂ ratio (26 ± 2.2 to 26 ± 2.0, 29 ± 2.0 to 28 ± 2.3, p = 0.66), (2) oxygen uptake efficiency slope (2697 ± 442 to 2701 ± 577, 2473 ± 800 to 2481 ± 896, p = 0.71), or (3) VO_2peak in mL/kg/min (28 ± 4.4 to 30 ± 4.3, 29 ± 6.7 to 29 ± 6.4, p = 0.38) in treadmill walking and progressive strength training, respectively. There were no significant within-group differences either. No adverse events occurred during cardiopulmonary exercise test or exercise training.

Conclusion:

In people with mild-to-moderate multiple sclerosis, 8 weeks of treadmill walking of low-to-moderate intensity or progressive strength training did not have any effect on ventilatory efficiency or aerobic capacity. Although aerobic capacity was lower than reference values, ventilatory efficiency was not reduced.

Fitness and its association with fatigue in persons with multiple sclerosis

This study compared physical fitness components between fatigued and non-fatigued persons with MS and examined those components as correlates of fatigue. Sixty-two ambulatory persons with MS completed the Modified Fatigue Impact Scale (MFIS) and underwent assessments of cardiorespiratory capacity, lower extremity muscle strength (i.e., peak torque and asymmetry), body composition, and static balance over two different sessions 7 days apart. Participants were allocated into fatigue groups based on MFIS scores (non-fatigued group (i.e., MFIS ≤38), n = 26; and fatigued group (MFIS >38), n = 36). The fatigued group had significantly (P < 0.05) lower cardiorespiratory capacity (VO_2peak ) and muscular strength (i.e., knee flexion peak torque) than the non-fatigued group. VO_2peak and knee extension peak torque were the two physical fitness components significantly correlated with fatigue scores in the fatigued group (P < 0.05), and follow-up stepwise linear regression revealed that VO_2peak was a significant predictor of fatigue scores (R²  = 0.13). Discriminant function analysis further identified VO_2peak as a significant (P < 0.05) correlate of fatigue status. This model explained 21% of variance in group status (i.e., fatigued vs non-fatigued) and correctly classified approximately 76% of cases into fatigue status groups. The improvement of cardiorespiratory capacity should be considered in rehabilitation programs for persons with MS, especially those presenting with elevated fatigue.