Muscle Strength and Muscle Endurance During the First Year of Treatment of Polymyositis and Dermatomyositis: A Prospective Study

High-intensity resistance training improves quality of life, muscle endurance and strength in patients with myositis: a randomised controlled trial

Myositis is associated with reduced quality of life, which is accompanied by significant impairments in muscle endurance and strength, altogether representing cardinal traits in patients with myositis. This randomised controlled trial aimed to investigate the effect of high-intensity resistance training on quality of life in patients with myositis. Thirty-two patients with established, stable myositis were randomised to 16 weeks of high-intensity resistance training (intervention group) or 16 weeks of usual care (control group). Primary outcome was quality of life assessed as the change in the physical component summary score (PCS) of the Short Form-36 health questionnaire from baseline to post-intervention. Secondary outcomes included functional capacity measures, such as functional index 3, and International Myositis Assessment and Clinical Studies Group (IMACS) disease activity and damage core set measures, including manual muscle testing 8 (MMT8). The primary outcome PCS showed an improvement in favour of high-intensity resistance training with a between-group difference of 5.33 (95% CI 0.61; 10.05) (p = 0.03). Additionally, functional index 3 showed a between-group difference indicating greater gains with high-intensity resistance training 11.49 (95% CI 3.37; 19.60) (p = 0.04), along with a between-group improvement in MMT8 1.30 (95% CI 0.09; 2.51) (p = 0.04). High-intensity resistance training for 16 weeks effectively improved quality of life in patients with myositis. Clinical measures of muscle endurance and muscle strength were also found to improve with high-intensity resistance training, while patients stayed in disease remission. Consequently, progressively adjusted high-intensity resistance training is feasible and causes no aggravation of the disease, while benefitting patients with myositis.Clinical trial registration: Clinicaltrials.gov ID: NCT04486261- https://clinicaltrials.gov/study/NCT04486261 .

The Role of Exercise to Improve Physiological, Physical and Psychological Health Outcome in Idiopathic Inflammatory Myopathies (IIM)

Idiopathic inflammatory myopathies (IIM) impact all aspects of health, physiological, physical, and psychological. Hallmark symptoms of IIM are muscle weakness, reduced muscle endurance and aerobic capacity. Recently, pain and fatigue as well as anxiety and depression have emerged as common and debilitating symptoms in patients with IIM. The aim of this scoping review is to, in a holistic way, describe how IIM impact patients' physiological, physical, and psychological health and how exercise has a role to treat as well as potentially counteract the effects of the disease. Inflammation induces non-immune response and organ damage. These changes with additional impact of physical inactivity lead to muscle impairment and reduced aerobic capacity. Pain, fatigue and low psychological well-being and overall quality of life are also common health aspects of IIM. Medical treatment can reduce inflammation but has in turn serious side effects such as muscle atrophy, type-II diabetes, and hypertension, which exercise has the potential to treat, and perhaps also counteract. In addition, exercise improves muscle function, aerobic capacity and might also reduce fatigue and pain. New evidence shows that reducing systemic inflammation may also improve patient-reported subjective health, quality of life and psychological well-being. Exercise in combination with medical treatment is becoming an important part of the treatment for patients with IIM as exercise has the potential to promote health aspects of various dimensions in patients with IIM.

Patient global assessment and inflammatory markers in patients with idiopathic inflammatory myopathies - A longitudinal study

AIM

To explore if patient global assessment (PGA) is associated with inflammation over time and if associations are explained by other measures of disease activity and function in patients with idiopathic inflammatory myopathies (IIM).

METHODS

PGA and systemic inflammatory markers prospectively collected over five years were retrieved from the International MyoNet registry for 1200 patients with IIM. Associations between PGA, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and creatine kinase (CK) were analyzed using mixed models. Mediation analysis was used to test if the association between PGA and inflammatory markers during the first year of observation could be explained by measures of disease activity and function.

RESULTS

PGA improved, and inflammatory markers decreased during the first year of observation. In the mixed models, high levels of inflammatory markers were associated with worse PGA in both men and women across time points during five years of observation. In men, but not in women, the association between elevated ESR, CRP and poorer PGA was explained by measures of function and disease activity. With a few exceptions, the association between improved PGA and reduced inflammatory markers was partially mediated by improvements in all measures of function and disease activity.

CONCLUSION

Increased levels of systemic inflammation are associated with poorer PGA in patients with IIM. In addition to known benefits of lowered inflammation, these findings emphasize the need to reduce systemic inflammation to improve subjective health in patients with IIM. Furthermore, the results demonstrate the importance of incorporating PGA as an outcome measure in clinical practice and clinical trials.

Pain in autoimmune inflammatory myopathies: a scoping review

BACKGROUND

Pain is considered a priority for research by adult patients with autoimmune inflammatory myopathy (AIM) and their families. Our aim was to review the literature for studies reporting on pain in adult AIM and to summarise their findings.

METHODS

A scoping review was conducted searching for studies in PubMed and MEDLINE including more than five adult patients with AIM and assessing pain using a patient-reported outcome measure. Study population characteristics, pain measurement and clinical correlates of pain were extracted using a standardised protocol.

RESULTS

The search strategy identified 2831 studies with 33 meeting inclusion criteria. Most studies used visual analogue scales (n=14) and/or the Medical Outcomes Study 36-Item Short Form Bodily Pain Scale (n=17). Frequency of pain and/or myalgias ranged from 64% to 100%. Subjects with AIM had significantly more pain than the general population and comparable pain to other chronic rheumatic diseases. Insufficient results were available to identify significant clinical correlates of pain in AIM.

CONCLUSION

This review suggests that the burden of pain in AIM is considerable. Still, due to the heterogeneity and low quality of the evidence, significant knowledge gaps persist. Studies are needed to characterise pain trajectories of patients with AIM.

Performance of timed function tests as outcome measures in idiopathic inflammatory myopathy-results from a single-centre cohort

OBJECTIVE

To evaluate performance of timed function tests (TFTs) in assessing muscle strength and endurance as determined by Manual Muscle Testing 8 (MMT-8) and Functional Index 2 (FI-2), respectively, in idiopathic inflammatory myopathies (IIM).

METHODS

This cohort study included 42 IIM patients satisfying 2017 EULAR/ACR criteria. Patients were classified as active (n = 18) or inactive disease (n = 24) based on clinical status at baseline. MMT-8, FI-2, 30 s rise from chair test, 30 s 1 kg arm rise test and 2-min walking distance (2MWD) were administered at baseline, 3 months and 6 months. Pearson rank correlation analysis and receiver operating curves were performed to assess the performance of timed function tests.

RESULTS

All patients were followed up at 3 months and 39 completed 6 months' follow-up. All the three TFTs had excellent convergent (r > 0.7, P < 0.05) and divergent validity (P < 0.05). Only 2MWD had moderate to strong correlation with ΔMMT-8 at 3 and 6 months among those with active disease (P = 0.001). All the TFTs correlated with ΔFI-2 in active disease but only Δ2MWD correlated with ΔFI-2 in inactive disease at 6 months (r = 0.506, P = 0.036). At a cut-off of 5% improvement in MMT-8, 2MWD had an area under the curve (AUC) of 0.868 with 95% sensitivity with 2% improvement at 3 months. To detect a 10% ΔMMT-8, Δ2MWD at a cut of 8% and 7% had an AUC of 0.909 and 0.893 with a sensitivity of 92% at 3 and 6 months, respectively (P < 0.05).

CONCLUSION

2MWD is a reliable indicator of muscle strength, endurance and treatment response. The 2MWD can be self-administered by patients, making it a potential patient-reported outcome measure.

Branched chain amino acids in the treatment of polymyositis and dermatomyositis: a phase II/III, multi-center, randomized controlled trial

OBJECTIVES

To assess the efficacy and safety of branched chain amino acids (BCAAs) in the treatment of PM/DM prior to official approval of their use in Japan.

METHODS

Treatment naïve adults with PM/DM were enrolled in a randomized, double-blind trial to receive either TK-98 (drug name of BCAAs) or placebo in addition to conventional treatment. After 12 weeks, patients with an average manual muscle test (MMT) score <9.5 were enrolled in an open label extension study for a further 12 weeks. The primary end point was the change of the MMT score at 12 weeks. The secondary end points were the clinical response and the change of functional index (FI).

RESULTS

Forty-seven patients were randomized either to the TK-98 (n = 24) or placebo (n = 23) groups. The changes of MMT scores at 12 weeks were 0.70±0.19 (mean±SEM) and 0.69±0.18, respectively (P = 0.98). Thirteen patients from the TK-98 group and 12 from the placebo group were enrolled in the extension study. The MMT scores in both groups improved similarly. The increase of the FI scores of the shoulder flexion at 12 weeks was significantly greater in the TK-98 group (27.9±5.67 vs. 12.8±5.67 for the right shoulder flexion, and 27.0±5.44 vs. 13.4±5.95 for the left shoulder [P < 0.05]). Frequencies of adverse events upto 12 weeks were similar.

CONCLUSION

BCAAs showed no effect on the improvement of the muscle strength evaluated by MMT and the clinical response. However, they were partly effective for improving dynamic repetitive muscle functions.

TRIAL REGISTRATION

UMIN-CTR Clinical Trial, https://center6.umin.ac.jp/, UMIN000016233.

Consumer-based activity trackers in evaluation of physical activity in myositis patients

OBJECTIVES

Inflammatory myopathies are characterized by muscle weakness that limit activities of daily living. Daily step count is an accepted metric of physical activity. Wearable technologies such as Fitbit® enable tracking of daily step counts. We assessed psychometric properties of Fitbit® and compared the accuracy of Fitbit® step counts to ActiGraph®.

METHODS

This was a pilot, proof of concept, prospective observational study with 4 visits at 0, 1-, 3-, and 6-months in polymyositis (PM), dermatomyositis (DM), necrotizing myopathy (NM) or anti-synthetase syndrome (AS) subjects. Six core set measures [manual muscle testing, physician (MD-GDA), patient (PT-GDA), and extra-muscular disease activity, HAQ-DI and creatine kinase], 3 functional tests [six-minute walk, timed up-and-go, sit-to-stand tests] and SF-36 physical function-10 (PF10) were collected at each visit. Patients wore waist-worn Fitbit® One and ActiGraph® T3X-BT concurrently for 7 days/month for 6-months.

RESULTS

Twenty-four (10 DM, 8 PM/NM, 6 AS) patients (17 females/7 males; 91% Caucasian) were enrolled. Test-retest reliability of daily steps was strong in 1-month follow-up (ICC 0.89). Daily steps and peak 1-min cadence showed moderate-strong correlations with MD-GDA, PT-GDA, HAQ-DI, SF-36 PF10 and all three functional tests. Fitbit® and ActiGraph® step counts demonstrated good agreement and strong correlation (ICC 0.96).

CONCLUSION

Fitbit® daily steps and peak 1-min cadence are reliable and valid measures of physical activity in a cohort of myositis patients. This pilot data suggests that Fitbit® has a potential for use in clinical practice and trials to monitor physical activity in myositis patients, but larger studies are needed for further validation.

Exercise as a multi-modal disease-modifying medicine in systemic sclerosis: An introduction by The Global Fellowship on Rehabilitation and Exercise in Systemic Sclerosis (G-FoRSS)

Systemic sclerosis (SSc) is a heterogeneous multisystem autoimmune disease whereby its main pathological drivers of disability and damage are vascular injury, inflammatory cell infiltration, and fibrosis. These mechanisms result in diffuse and diverse impairments arising from ischemic circulatory dysfunction leading to painful skin ulceration and calcinosis, neurovascular aberrations hindering gastrointestinal (GI) motility, progressive painful, incapacitating or immobilizing effects of inflammatory and fibrotic effects on the lungs, skin, articular and periarticular structures, and muscle. SSc-related impairments impede routine activities of daily living (ADLs) and disrupt three critical life areas: work, family, social/leisure, and also impact on psychological well-being. Physical activity and exercise are globally recommended; however, for connective tissue diseases, this guidance carries greater impact on inflammatory disease manifestations, recovery, and cardiovascular health. Exercise, through myogenic and vascular phenomena, naturally targets key pathogenic drivers by downregulating multiple inflammatory and fibrotic pathways in serum and tissue, while increasing circulation and vascular repair. G-FoRSS, The Global Fellowship on Rehabilitation and Exercise in Systemic Sclerosis recognizes the scientific basis of and advocates for education and research of exercise as a systemic and targeted SSc disease-modifying treatment. An overview of biophysiological mechanisms of physical activity and exercise are herein imparted for patients, clinicians, and researchers, and applied to SSc disease mechanisms, manifestations, and impairment. A preliminary guidance on exercise in SSc, a research agenda, and the current state of research and outcome measures are set forth.

Therapeutic management of immune-mediated necrotizing myositis

Purpose of Review

The idiopathic inflammatory myopathies are a heterogeneous group of autoimmune disorders characterized by skeletal muscle inflammation leading to chronic muscle weakness. Immune-mediated necrotizing myopathy (IMNM) is a distinct subgroup of inflammatory myopathy typically characterized by myofiber necrosis with minimal inflammatory infiltrates on muscle biopsy, highly elevated creatine kinase levels, and infrequent extra-muscular involvement. This review provides an overview of currently recommended treatment strategies for IMNM, including discussion of disease activity monitoring and recommended first-line immunomodulatory agents depending on clinical phenotype and autoantibody status.

Recent Findings

IMNM can be divided into three subtypes based on autoantibody positivity: anti-3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) IMNM, anti-signal recognition particle (SRP) IMNM, and antibody negative IMNM. Autoantibody status in IMNM has considerable correlation with clinical phenotype, prognosis, and recommended choice of immunosuppressive agent. Patients with anti-HMGCR IMNM tend to respond well to intravenous immunoglobulin (IVIG), and IVIG monotherapy may be sufficient treatment for certain patients. In anti-SRP IMNM, early rituximab is commonly favored. More generally, prompt initiation of aggressive immunosuppression is often indicated, as both anti-SRP and anti-HMGCR IMNM can potentially cause debilitating weakness, and muscle atrophy and irreversible fatty replacement happen early in the disease course. Patients with IMNM frequently require combination therapy to achieve disease control, and have a high rate of relapse when tapering immunosuppression. Young age of onset is a poor prognostic factor.

Summary

IMNM can be severely disabling and often requires aggressive immunosuppression. For any given patient, the treatment strategy should be informed by the severity of their presenting features and autoantibody status. While our ability to treat IMNM has certainly improved, there remains a need for more prospective trials to inform optimal treatment strategies.

Expert Perspective: Management of Refractory Inflammatory Myopathy

The idiopathic inflammatory myopathies (IIMs) are chronic disorders characterized by inflammation in skeletal muscle but also in other organs such as the skin, lungs, joints, gastrointestinal tract, and heart. The effect of immunosuppressive treatment varies between individual patients and between organ manifestations within the same individual. Many patients respond poorly to first-line treatment with glucocorticoids and other immunosuppressive agents such as methotrexate or azathioprine, with symptoms persisting in the muscles, skin, and lungs, leading to refractory disease. Management of refractory IIM is a clinical challenge, and a systematic approach is proposed to better understand the lack of treatment response, in order to guide disease management. The first step in the management of refractory IIM is to recognize whether remaining symptoms are caused by persistent inflammation in the affected tissue or whether the symptoms may be attributable to damage preceding inflammation. Thus, a second diagnostic examination is recommended. Second, in particular for patients with remaining muscle weakness, it is important to ascertain whether the diagnosis of myositis is correct or whether another underlying muscle disorder could explain the symptoms. Third, with confirmation of remaining inflammation in the tissues, a strategy to change treatment needs to be undertaken. Few controlled trials are available to guide our treatment strategies. Furthermore, different subgroups of patients may benefit from different therapies, and different organ manifestations may respond to different therapies. In this context, subgrouping of patients with IIM based on autoantibody profile may be helpful, as there are emerging data from open studies and case series to support the notion of a varying treatment response in different autoantibody-defined subgroups of IIM patients.

The Role of Immune Cells in the Pathogenesis of Idiopathic Inflammatory Myopathies

Idiopathic inflammatory myopathies (IIMs) are chronic autoimmune disorders involving multiple organs, such as the muscle, skin, lungs and joints. Although the detailed pathogenesis of IIMs remains unclear, immune mechanisms have long been recognised as of key importance. Immune cells contribute to many inflammatory processes via intercellular interactions and secretion of inflammatory factors, and many studies have demonstrated the participation of a variety of immune cells, such as T cells and B cells, in the development of IIMs. Here, we summarise the current knowledge regarding immune cells in IIM patients and discuss their potential roles in IIM pathogenesis.

Ability of the COPD Assessment Test to evaluate the lung‐specific quality of life in systemic sclerosis‐associated interstitial lung disease

Introduction

The COPD Assessment Test (CAT) is utilised to evaluate the treatment outcome regarding the health status in idiopathic interstitial pneumonia (IIP). However, the ability of the CAT to evaluate the lung‐specific quality of life in systemic sclerosis‐associated interstitial lung disease (SSc‐ILD) is not established. Therefore, we investigated whether CAT scores can be used to evaluate SSc‐ILD as they are for IIP.

Methods

A total of 150 patients with IIP or SSc‐ILD who were evaluated by the CAT were retrospectively assigned to this study. Clinical data at the visit for the CAT were analysed.

Results

The forced vital capacity and distance walked during the 6‐minute walk test (6MWD) were significantly correlated with the CAT score for SSc‐ILD and IIP, and the CAT scores were similarly distributed in SSc‐ILD and IIP. The CAT score of SSc‐ILD patients was negatively affected by pulmonary arterial hypertension, but not by corticosteroids, which affected it in IIP patients. CAT scores of patients with either disease receiving home oxygen therapy were poor. In multiple regression analysis, pulmonary arterial hypertension and 6MWD were independent predictors for the CAT score in patients with SSc‐ILD, while corticosteroid administration was selected as an independent factor in patients with IIP.

Conclusions

Our study suggests that the CAT can be applied to evaluate the lung‐specific quality of life in SSc‐ILD similar to IIP regarding the pulmonary function, but it should be noted that pulmonary arterial hypertension in SSc‐ILD influences the CAT score.

Functional Index-3: A Valid and Reliable Functional Outcome Assessment Measure in Patients With Dermatomyositis and Polymyositis

OBJECTIVE

Patients with dermatomyositis (DM) and polymyositis (PM) have reduced muscle endurance.The aim of this study was to streamline the Functional Index-2 (FI-2) by developing the Functional Index-3 (FI-3) and to evaluate its measurement properties, content and construct validity, and intra- and interrater reliability.

METHODS

A dataset of the previously performed and validated FI-2 (n = 63) was analyzed for internal redundancy, floor, and ceiling effects. The content of the FI-2 was revised into the FI-3. Construct validity and intrarater reliability of FI-3 were tested on 43 DM and PM patients at 2 rheumatology centers. Interrater reliability was tested in 25 patients. The construct validity was compared with the Myositis Activities Profile (MAP), Health Assessment Questionnaire (HAQ), and Borg CR-10 using Spearman correlation coefficient.

RESULTS

Spearman correlation coefficients of 63 patients performing FI-3 revealed moderate to high correlations between shoulder flexion and hip flexion tasks and similar correlations with MAP and HAQ scores; there were lower correlations for neck flexion task. All FI-3 tasks had very low to moderate correlations with the Borg scale. Intraclass correlation coefficients (ICC) of FI-3 tasks for intrarater reliability (n = 25) were moderate to good (0.88-0.98). ICC of FI-3 tasks for interrater reliability (n = 17) were fair to good (range 0.83-0.96).

CONCLUSION

The FI-3 is an efficient and valid method for clinically assessing muscle endurance in DM and PM patients. FI-3 construct validity is supported by the significant correlations between functional tasks and the MAP, HAQ, and Borg CR-10 scores.

Patient and physician discordance of global disease assessment in juvenile dermatomyositis: findings from the Childhood Arthritis & Rheumatology Research Alliance Legacy Registry

BACKGROUND

Global disease activity scores (gVAS) capture patient or family (PF) and physician (MD) assessments of disease. This study sought to measure discordance between PF and MD global activity scores in juvenile dermatomyositis (JDM), and determine factors associated with discordance.

METHODS

Patients with JDM were included from the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Legacy Registry (N = 563). PF and MD gVAS were assessed for discordance, defined as a ≥ 2-point difference. Factors associated with discordant gVAS were compared in univariate analysis. Multivariable regression analysis was used to identify predictors of discordance.

RESULTS

Almost 40% (N = 219) of PF and MD gVAS were discordant. Among discordant scores, 68% of PF rated gVAS ≥2-points above MD, which was associated with calcinosis and lower quality of life and functional scores (p < 0.01). MD gVAS rated ≥2-points above PF in 32%, which was associated with abnormal laboratory results, weakness, arthritis, rash and other skin changes, and current intravenous steroid treatment (p < 0.01). In multivariate analysis, predictors for higher PF rating included calcinosis, lower quality of life and functional scores, while predictors for higher MD rating included rash, calcinosis, nailfold capillaroscopy changes, and current intravenous steroid treatment.

CONCLUSIONS

Discordance between PF and MD gVAS was common in this JDM cohort. Overall, higher PF rating was associated with poorer patient reported outcome (PRO) scores, while higher MD rating was associated with poorer objective measures. This suggests PF and MD assessments of gVAS may be measuring different aspects of disease, highlighting the importance of integrating PROs into clinical practice and research.

A review of accelerometer-derived physical activity in the idiopathic inflammatory myopathies

Background

The idiopathic inflammatory myopathies (IIMs) are a group of rare conditions characterised by muscle inflammation (myositis). Accurate disease activity assessment is vital in both clinical and research settings, however, current available methods lack ability to quantify associated variation of physical activity, an important consequence of myositis.

This study aims to review studies that have collected accelerometer-derived physical activity data in IIM populations, and to investigate if these studies identified associations between physical and myositis disease activity.

Methods

A narrative review was conducted to identify original articles that have collected accelerometer-derived physical activity data in IIM populations. The following databases were searched from February 2000 until February 2019: Medline via PubMed, Embase via OVID and Scopus.

Results

Of the 297 publications screened, eight studies describing accelerometer use in 181 IIM cases were identified. Seven out of the eight studies investigated juvenile dermatomyositis (JDM) populations and only one reported on an adult-onset population. Population sizes, disease duration, accelerometer devices used, body placement sites, and study duration varied between each study.

Accelerometer-derived physical activity levels were reduced in IIM cohorts, compared to healthy controls, and studies reported improvement of physical activity levels following exercise programme interventions, thus demonstrating efficacy.

Higher levels of accelerometer-derived physical activity measurements were associated with shorter JDM disease duration, current glucocorticoid use and lower serum creatine kinase. However, no clear association between muscle strength and accelerometer-derived physical activity measures was identified.

Conclusions

The use of accelerometer-derived physical activity in IIM research is in its infancy. Whilst knowledge is currently limited to small studies, the opportunities are promising and future research in this area has the potential to improve disease activity assessment for clinical and research applications.

OMERACT 2018 Modified Patient-reported Outcome Domain Core Set in the Life Impact Area for Adult Idiopathic Inflammatory Myopathies

OBJECTIVE

To present and vote on a myositis modified patient-reported outcome core domain set in the life impact area at the Outcome Measures in Rheumatology (OMERACT) 2018.

METHODS

Based on results from international focus groups and Delphi surveys, a draft core set was developed.

RESULTS

Domains muscle symptoms, fatigue, level of physical activity, and pain reached ≥ 70% consensus and were mandatory to assess in all trials. Domains lung, joint, and skin symptoms were mandatory in specific circumstances. This core set was endorsed by > 85% at OMERACT 2018.

CONCLUSION

We propose a life impact core set for patients with idiopathic inflammatory myopathies and will proceed with instrument selections.

Considerations and Practical Options for Measuring Muscle Strength: A Narrative Review

Muscle strength impairments are related to mobility limitations and other untoward outcomes. This narrative review, therefore, describes considerations relative to the definition and measurement of muscle strength. Thereafter, practical options for measuring muscle strength are described and their clinimetric properties are delineated. Information provided herein may help students, clinicians, and researchers select the strength tests best suited to their research needs and limitations.

Muscle endurance deficits in myositis patients despite normal manual muscle testing scores

INTRODUCTION

It is unclear whether quantitating muscle endurance adds nonredundant information useful for the care of patients with muscular disease.

METHODS

Records were retrospectively reviewed for all Johns Hopkins Myositis Center patients with a muscle endurance assessment (n = 128, 226 patient-visits). Muscle endurance and strength were quantitated with the Myositis Functional Index-2 (FI2) and manual muscle testing (MMT), respectively.

RESULTS

Composite FI2 muscle endurance scores were comparable in inclusion body myositis (n = 58), dermatomyositis (n = 31), and polymyositis (n = 39). Overall, muscle endurance correlated with and evolved similarly to strength, inversely to serum creatine kinase. However, in patients with normal or near-normal strength (mean MMT > 9.75/10), muscle endurance was typically abnormal and highly variable (mean FI2, 5.6/10; interquartile range, 3.3-7.8/10).

DISCUSSION

Muscle endurance testing may identify muscle impairment inadequately described by MMT, particularly in patients with high MMT scores. Muscle Nerve 59:70-75, 2019.

Exercise in Myositis

Purpose of the review

A growing body of evidence supports exercise as a very important part of the treatment for adult patients with idiopathic inflammatory myopathies (IIM). This review mainly focuses on exercise studies published during the last 2 years in adult myositis.

Recent findings

During the last couple of years, new publications present further evidence for intensive endurance exercise as an anti-inflammatory treatment inducing muscle growth and improving mitochondrial function compared a non-exercising control group. Further, blood-flow restricted resistance training was effective to maintain muscle strength compared to a non-exercising control group which lost a mean of 9.2% in quadriceps strength over 3 months in inclusion body myositis. Another study evaluates the effects of intra-muscular injections of an isoform of follistatin (FS344) by AAV1 in combination with exercise in a small group of patients with inclusion body myositis. An improvement in physical capacity was associated to higher exercise levels. Less is known about exercise effects in patients with recent onset, active polymyositis, and dermatomyositis.

Summary

All studies report safety of exercise in all types and stages of myositis and exercise could now be considered as medicine. It is recommended to initiate exercise on a low intensity under supervision of a physical therapist with regular follow-up and progression of intensity over time.

Current Treatment for Myositis

PURPOSE OF REVIEW

The purpose of this review was to give an update on treatment modalities for patients with idiopathic inflammatory myopathies, or shortly myositis, excluding the subgroup inclusion body myositis, based on a literature survey on therapies used in myositis. Few controlled trials have been performed in patients with myositis; therefore, we also included a summary of open-label trials, case series, and case reports.

RECENT FINDINGS

Glucocorticoid (GC) in high doses is still the first-line treatment of patients with myositis. There is a general recommendation to combine GCs with another immunosuppressive agent in the early phase of disease to better control disease activity and possibly to reduce the risk for GC-related side effects. Furthermore, combining pharmacological treatment with individualized and supervised exercise can be recommended based on evidence. There is some evidence for the effect of rituximab in patients with certain myositis-specific autoantibodies, whereas other biologic agents are currently being tested in clinical trials.

SUMMARY

Immunosuppressive treatment in combination with exercise is recommended for patients with myositis to reduce disease activity and improve muscle performance. Subgrouping of patients into clinical and serological subtypes may be a way to identify biomarkers for response to specific immunosuppressive and biological agents and should be considered in future trials.