Effects of Six Months Training on Physical Capacity and Metaboreflex Activity in Patients with Multiple Sclerosis

Safety of exercise training in multiple sclerosis: An updated systematic review and meta-analysis

BACKGROUND

A review of the safety profile of exercise training in multiple sclerosis (MS) has not been conducted since 2013.

OBJECTIVE

We undertook a systematic review and meta-analysis of randomised controlled trials (RCTs) of exercise training published since 2013 and quantified estimated population risks of clinical relapse, adverse events (AE) and serious adverse event (SAE).

METHODS

Articles reporting safety outcomes from comparisons of exercise training with non-exercise among persons with MS were identified. The risk of bias was established from study's internal validity assessed using Physiotherapy Evidence Database (PEDro). Rates and estimated mean population relative risks (RRs; 95% confidence interval (CI)) of safety outcomes were calculated, and random-effects meta-analysis estimated the mean RR.

RESULTS

Forty-six interventions from 40 RCTs (N = 1780) yielded 46, 40 and 39 effects for relapse, AE, adverse effects and SAE, respectively. The mean population RRs ((95% CI), p-value) for relapse, AE and SAE were 0.95 ((0.61, 1.48), p = 0.82), 1.40 ((0.90, 2.19), p = 0.14) and 1.05 ((0.62, 1.80), p = 0.85), respectively. No significant heterogeneity is observed for any outcome.

CONCLUSION

In studies that reported safety outcomes, there was no higher risk of relapse, AE, adverse effects or SAE for exercise training than the comparator. Exercise training may be promoted as safe and beneficial to persons with MS.

Participant characteristics of existing exercise studies in persons with multiple sclerosis - A systematic review identifying literature gaps

BACKGROUND

Exercise is a cornerstone in rehabilitation of persons with multiple sclerosis (pwMS), which is known to elicit beneficial effects on various symptoms and to have a potential disease-modifying effect. However, it remains to be elucidated if the existing MS exercise literature covers the full age and disability span of pwMS.

OBJECTIVE

To systematically review MS exercise studies and provide a detailed mapping of the demographic and clinical characteristics of the included pwMS.

METHODS

A systematic review of MS exercise studies were performed using MEDLINE and EMBASE. From the resulting MS exercise studies, mean sample characteristics were extracted.

RESULTS

4576 records were identified, from which 202 studies were included. Of these, 166 studies (82.2%) enrolled pwMS aged 35-54 years, 10.9% enrolled pwMS <35 years, and 6.9% enrolled pwMS ≥55 years (only 1.5% enrolled pwMS ≥60 years). A total of 118 studies (58.4%) reported Expanded Disability Status Scale (EDSS), with 88.1% of included pwMS having an EDSS between 2.0 and 6.5, while only one study enrolled pwMS with an EDSS ≥7.0. Finally, 80% of the studies included pwMS having a disease duration of 5-14.5 years.

CONCLUSION

Exercise studies in pwMS included primarily middle-aged (35-54 years) pwMS having an EDSS of 2.0-6.5 and a disease duration of 5-14.5 years. Few exercise studies were identified in young and older pwMS, in pwMS with mild disability and severe disability, and in pwMS having shorter or longer disease durations. These findings highlight the need for further investigation of exercise in these specific subgroups of pwMS as benefits of exercise might not generalize across subpopulations.

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.

Systematic Review of Exercise Studies in Persons with Multiple Sclerosis: Exploring the Quality of Interventions According to the Principles of Exercise Training

INTRODUCTION

The objective of this systematic review is to explore the application and reporting of (i) the principles of exercise training in exercise trials, (ii) the components of exercise prescription, and (iii) the adherence towards the prescribed programmes in randomised controlled trials (RCTs) in persons with multiple sclerosis (pwMS).

METHODS

The MEDLINE, CINAHL, SPORTDiscus, PubMed and Embase electronic databases were searched from 1 January 2000 to 16 October 2020. RCTs comprising at least 3 weeks of aerobic and/or resistance exercise intervention in pwMS that reported at least one physiological outcome and were published in peer-reviewed journals were eligible for inclusion.

RESULTS

Out of 52 RCTs included in this review, 58 intervention arms were examined. None applied more than four principles of exercise training. Specificity was addressed by 85%, progression by 33%, overload by 59%, initial values by 26%, reversibility by 0% and diminishing returns by 2% of trials. Fifty-two percent of trials reported all components of exercise prescription, and 3% of trials reported the level of adherence to the prescribed exercise.

CONCLUSION

This systematic review reveals that exercise training principles were not respected in the majority of included RCTs. The weak quality of reported exercise interventions limits the interpretation of the studies' results and potentially leads to an underestimation of 'exercise as medicine' in pwMS. Also, the vague descriptions of exercise prescription and adherence impede the reproducibility of results. Future studies must attend to all principles of exercise training and provide transparent information on the prescribed and performed programmes to develop specific and valid exercise recommendations for pwMS.

SYSTEMATIC REVIEW REGISTRATION

CRD42020162671, 28/04/2020, PROSPERO.

Muscle metaboreflex adaptations to exercise training in health and disease

Abnormalities in the muscle metaboreflex concur to exercise intolerance and greater cardiovascular risk. Exercise training benefits neurocardiovascular function at rest and during exercise, but its role in favoring muscle metaboreflex in health and disease remains controversial. While some authors demonstrated that exercise training enhanced the sensitization of muscle metabolically afferents and improved neurocardiovascular responses to muscle metaboreflex activation, others reported unaltered responses. This narrative review aimed to: (a) highlight the current evidence on the effects of exercise training upon cardiovascular and autonomic responses to muscle metaboreflex activation; (b) analyze the role of training components and indicate potential mechanisms of metaboreflex adaptations; and (c) address key methodological features for future research. Though limited, accumulated evidence suggests that muscle metaboreflex adaptations depend on the individual clinical status, exercise modality, and training duration. In healthy populations, most trials negated the hypothesis of metaboreflex improvement due to chronic exercise, irrespective of the training duration. Favorable changes in patients with impaired metaboreflex, particularly chronic heart failure, mostly resulted from long-term interventions (> 16 weeks) including aerobic exercise of moderate to high intensity, performed in isolation or within multimodal training. Potential mechanisms of metaboreflex improvements include enhanced sensitivity of channels and receptors, greater antioxidant capacity, lower metabolite accumulation, increased functional sympatholysis, and muscle perfusion. Future research should investigate: (1) the dose-response relationship of training components within different exercise modalities to elicit improvements in individuals showing intact or impaired muscle metaboreflex; and (2) potential and specific underlying mechanisms of metaboreflex improvements in individuals with different medical conditions.

Fatigue, as measured using the Modified Fatigue Impact Scale, is a predictor of processing speed improvement induced by exercise in patients with multiple sclerosis: data from a randomized controlled trial

BACKGROUND

Few studies have evaluated the impact of physical activity (PA) on cognition and fatigue, and none have considered the effects of PA on the relationship between cognition and fatigue.

OBJECTIVES

We evaluated the effect of PA in people with multiple sclerosis (pwMS) in a 6-month-long single-blind randomized controlled trial. We focused on the impact of exercise on cognition, fatigue, and the relationship between cognition and fatigue.

METHODS

We recruited pwMS, who were then randomly assigned 1:1 to either a PA protocol group or a control group (CG). All patients underwent assessments using the Brief International Cognitive Assessment for Multiple Sclerosis including symbol digit modality test (SDMT), Berg Balance Scale (BBS), gait analysis, 6-Minute Walk Test, Timed Up and Go (TUG) test, and the Modified Fatigue Impact Scale (MFIS) at the beginning of the study (T0), at the end of the study (EOS) 24 weeks after T0, and at 24 weeks following the EOS (FU).

RESULTS

A Wilcoxon test revealed a significant effect of exercise in the PA group, but not in the CG. Significant differences between T0 and EOS were found in the spatiotemporal parameters of gait, and performance on the SDMT, TUG, BBS, and MFIS. These differences were also present during the FU period. A regression model revealed that the baseline MFIS score predicted processing speed improvement (R² = 0.65, p < 0.01), as the SDMT T score increased by 0.3 for each one-unit increase in the MFIS score at T0.

CONCLUSION

PA affects multiple aspects of the pathology in pwMS. Patients with greater fatigue must not be discouraged from exercise, as they may greatly benefit from PA. Specifically, PA was shown to improve information processing speed.

The Impact of Cardiovascular Diseases on Cardiovascular Regulation During Exercise in Humans: Studies on Metaboreflex Activation Elicited by the Post-exercise Muscle Ischemia Method

BACKGROUND

Hemodynamics during dynamic exercise is finely regulated by some neural mechanisms. One of these mechanisms is the metabolic part of the exercise pressor reflex, i.e. the muscle metaboreflex. Hemodynamic response during the metaboreflex is characterised by the recruitment of the reserves in cardiac inotropism, pre-load, after-load and chronotropism. If one of these reserves is exhausted, then the cardiovascular response is achieved by recruiting one of the other reserves, thereby indicating a remarkable plasticity of the control of circulation.

CONCLUSION

In this review, the effects of a number of cardiovascular diseases - such as heart failure, heart failure with preserved ejection fraction, hypertension, type 1 and type 2 diabetes mellitus, obesity and metabolic syndrome - on hemodynamics during the metaboreflex are reviewed.

Metaboreflex-mediated hemodynamic abnormalities in individuals with coronary artery disease without overt signs or symptoms of heart failure

This study was devised to investigate the effect of coronary artery disease (CAD) without overt signs of heart failure on the cardiovascular responses to muscle metaboreflex activation. We hypothesized that any CAD-induced preclinical systolic and/or diastolic dysfunction could impair hemodynamic response to the metaboreflex test. Twelve men diagnosed with CAD without any sign or symptoms of heart failure and 11 age-matched healthy control (CTL) subjects participated in the study. Subjects performed a postexercise muscle ischemia (PEMI) test to activate the metaboreflex. They also performed a control exercise recovery test to compare data from the PEMI test. The main results were that the CAD group reached a similar mean arterial blood pressure response as the CTL group during PEMI. However, the mechanism by which this response was achieved was different between groups. In particular, CAD achieved the target mean arterial blood pressure by increasing systemic vascular resistance (+383.8 ± 256.6 vs. +91.2 ± 293.5 dyn·s^-1·cm^-5 for the CAD and CTL groups, respectively), the CTL group by increasing cardiac preload (-0.92 ± 8.53 vs. 5.34 ± 4.29 ml in end-diastolic volume for the CAD and CTL groups, respectively), which led to an enhanced stroke volume and cardiac output. Furthermore, the ventricular filling rate response was higher in the CTL group than in the CAD group during PEMI ( P < 0.05 for all comparisons). This study confirms that diastolic function is pivotal for normal hemodynamics during the metaboreflex. Moreover, it provides evidence that early signs of diastolic impairment attributable to CAD can be detected by the metaboreflex test. NEW & NOTEWORTHY Individuals suffering from coronary artery disease without overt signs of heart failure may show early signs of diastolic dysfunction, which can be detected by the metaboreflex test. During the metaboreflex, these subjects show impaired preload and stroke volume responses and exaggerated vasoconstriction compared with controls.