The aerobic capacity - fatigue relationship in persons with Multiple Sclerosis is not reproducible in a pooled analysis of two randomized controlled trials

Is High-Intensity Interval Training More Effective Than Moderate Continuous Training in Rehabilitation of Multiple Sclerosis: A Comprehensive Systematic Review and Meta-analysis

OBJECTIVES

The present study aimed to conduct meta-analysis to determine whether the high intensity interval training (HIIT) protocol is more beneficial in improving outcome measures compared to moderate continuous training (MCT) in people with multiple sclerosis (PwMS). It also aimed to systematically review the exercise protocols differences.

DATA SOURCES

A search strategy, locating HIIT in PwMS, was executed in six databases, PubMed, EMBASE, Web of Science, Central Cochrane, Pedro, and Ovid MEDLine.

STUDY SELECTION

Randomized control trials of HIIT utilizing cycle ergometer or recumbent stepper as exercise modalities were included in analysis. Intervention arms should include at least two intervention arms, including HIIT in one arm, and MCT in the other group.

DATA EXTRACTION

Data extracted from each study includes the following items: basic details of the study (such as author, date of publication, location, and study design), participant characteristics (sample size, mean age, sex, mean disease duration, and extended disability status scale), specifications of the HITT protocol (exercise modality, session duration, number of intervals/session, interval intensity, recovery intensity, recovery interval, and adverse effect), as well as primary outcomes at baseline and post-intervention (cardiorespiratory fitness, fatigue, body composition, cognitive functions, and blood biomarkers).

DATA SYNTHESIS

22 studies included in the systematic review, 11 were included in random effects model pooled analysis. There was a significant effect in favor of HIIT for VO2max of cardiorespiratory functions compared to MCT (ES=0.45 95%, CI [0.14, 0.76], P=.004), and for memory domain of cognitive functions (ES=0.34 95% CI [0.05, 0.63], P=.02). Statistical significance was not achieved for the other variables.

CONCLUSION

HIIT and MCT yield similar results in terms of fatigue, body composition, cognitive functions, and blood biomarkers. However, VO2max of cardiorespiratory functions and memory domain of cognitive functions were in favor of HIIT protocol.

A Comprehensive Evaluation of Multiple Sclerosis-Related Fatigue with a Special Focus on Fatigability

INTRODUCTION

Fatigue is the most common and disabling symptom in multiple sclerosis (MS), being reported by 55% to 78% of patients with MS (PwMS). Etiology of MS-related fatigue remains poorly understood, but an increased neuromuscular fatigability (i.e., greater loss of torque during exercise) could contribute to this phenomenon. This study aimed to characterize the correlates of MS-related fatigue in PwMS using a comprehensive group of physiological and psychosocial measures, with a particular focus on fatigability.

METHODS

Forty-two relapsing-remitting PwMS and 20 healthy subjects were recruited. PwMS were assigned in two groups (high (HF) and low (LF) fatigue) based on two fatigue questionnaires (Fatigue Severity Scale and Modified Fatigue Impact Scale). The main outcomes of this study are derived from incremental cycling completed to task failure (i.e., inability to pedal around 60 rpm). Maximal voluntary contraction (MVC), rating of perceived exertion, and central and peripheral parameters measured using transcranial magnetic and peripheral nerve stimulation were assessed in the knee extensor muscles before, during, and after the fatiguing task. Other potential correlates of fatigue were also tested.

RESULTS

MVC torque decreased to a greater extent for the HF group than LF group after the third common stage of the incremental fatiguing exercise (-15.7% ± 6.6% vs -5.9% ± 13.0%, P < 0.05), and this occurred concurrently with a higher rating of perceived exertion for HF (11.8 ± 2.5 vs 9.3 ± 2.6, P < 0.05). Subjective parameters (depression, quality of life) were worse for HF compared with LF and healthy subjects ( P < 0.001). Moreover, MVC torque loss at the final common stage and maximal heart rate explained 29% of the variance of the Modified Fatigue Impact Scale.

CONCLUSIONS

These results provide novel insight into the relationship between MS-related fatigue and fatigability among PwMS. The HF group exhibited greater performance fatigability, likely contributing to a higher perceived exertion than the LF group when measured during a dynamic task.

Multimodal agility-based exercise training (MAT) versus strength and endurance training (SET) to improve multiple sclerosis-related fatigue and fatigability during inpatient rehabilitation: a randomized controlled pilot and feasibility study [ReFEx]

BACKGROUND

Multimodal agility-based exercise training (MAT) is a group-based exercise training framework for persons with multiple sclerosis (pwMS) with a potential to impact fatigue and fatigability. In a mixed-methods design, this study evaluated the feasibility of implementing MAT in an inpatient rehabilitation setting and the feasibility of a randomized controlled trial (RCT) study protocol with 'traditional' strength and endurance training (SET) as an active control condition. Secondarily, preliminary outcome data was acquired.

METHODS

PwMS with low to moderate disability and self-reported fatigue were randomly allocated to either MAT or SET when starting inpatient rehabilitation (4-6 weeks). The MAT-participants exercised in a group following a MAT-manual (sessions were gym- (5x/week) and pool-based (3x/week)). SET-participants exercised individually 5x/week on a cycle ergometer, and 3x/week on strength training machines. Feasibility assessments focused on processes, resources, management, time, and scientific domains. Assessed clinical outcomes at admission and discharge included perceived fatigue, motor and cognitive fatigability, cognitive performance, motor function, and balance confidence. Perceived fatigue was reassessed 1, 4, and 12 weeks after discharge. Feasibility was determined regarding predetermined progression criteria.

RESULTS

Twenty-two participants were randomized. Both groups performed the minimum number of sessions (> 18), and retention was adequate (73-91%). SET-participants performed more sessions than MAT-participants (30.8 vs. 22.7) and stayed longer in the facility (34.2 vs. 31.6 days). Non-eligibility of admitted pwMS was high (74% non-eligible), mainly due to high EDSS and inability to attend pool-based sessions. Consequently, recruitment (1.8/month) was slower than the predetermined progression criterium. Baseline assessments took longer than required (only 50% completed within 3 days). Short-term fatigue reduction was similar for both groups. Motor fatigability also improved in both groups, whereas cognitive fatigability deteriorated. In MAT, average improvement in walking endurance (43.9 m) exceeded minimal important change values for individuals (> 26.9 m).

CONCLUSIONS

Progressing to a definitive RCT necessitates adaptation of eligibility criteria. In the present design it will also be difficult to attain similar dosing of interventions. A multicenter RCT focused only on gym-based MAT might be another option to assess the effect of MAT. The primary outcome measure should be able to measure change in perceived fatigue more robustly.

TRIAL REGISTRATION

German Clinical Trials Register: DRKS00023943, date of registration: 23 September 2021.

Randomised controlled pilot and feasibility study of multimodal agility-based exercise training (MAT) versus strength and endurance training (SET) to improve multiple sclerosis-related fatigue and fatigability during inpatient rehabilitation (ReFEx): study protocol

INTRODUCTION

Subjective fatigue and objectively assessed fatigability are common symptoms in persons with multiple sclerosis (pwMS). Recent work has suggested a positive effect of balance and motor control training (BMCT) in reducing fatigue. It is unclear whether this effect can also be attained during inpatient rehabilitation. Multimodal agility-based exercise training (MAT) has been developed as a framework that incorporates BMCT with added agility components but has not been applied to pwMS. Therefore, this study will evaluate the feasibility of a randomised controlled trial comparing MAT against strength and endurance training (SET) for the improvement of MS-related fatigue and fatigability in a German neurological rehabilitation centre.

METHODS AND ANALYSIS

A total of 24 pwMS (Expanded Disability Status Scale ≤5.0, Fatigue Scale for Motor and Cognitive Functions ≥53) will be randomly assigned to either SET or land and water-based MAT for 4-6 weeks during inpatient rehabilitation. Assessments of subjective fatigue, motor and cognitive fatigability, cognitive and cardiorespiratory performance, and balance confidence will be performed at admission and discharge. Subjective fatigue will also be assessed at 1, 4 and 12 weeks after discharge. Feasibility outcomes will include patients' acceptance of study procedures and interventions, recruitment rate, retention rate, time needed to complete baseline assessments, intervention adherence and fidelity. All quantitative outcomes will be reported descriptively. A total of 12 pwMS (6 per group) will be interviewed to gain insights into participants' experiences during study participation.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Ethics Committee of the University of Bonn (reference number: 543/20). Dissemination of findings is planned via peer-reviewed journals, conferences and media releases.

TRIAL REGISTRATION NUMBER

DRKS00023943.

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.