Dose-dependent effect of individualized respiratory muscle training in children with Duchenne muscular dystrophy

Inspiratory muscle training in children with neuromuscular disorders

Background

Progressive respiratory muscle weakness and ineffective cough contribute to morbidity and mortality in children with neuromuscular disorders (NMD). Inspiratory muscle training (IMT) aims to preserve or improve respiratory muscle strength and reduce respiratory morbidity. This study aimed to determine the safety and efficacy of IMT in children with NMD.

Methods/design

A randomised cross-over study compared a 3-month intervention (IMT) with control periods (no IMT). Children diagnosed with NMD (5 years - 18 years) performed 30 breaths (at 30% of maximum inspiratory mouth pressure [Pimax]) with an electronic threshold device, twice daily. During the control period, participants did not perform any IMT.

Discussion

Twenty three children (median [interquartile range {IQR}] age of 12.33 [10.03-14.17] years), mostly male (n = 20) and non-ambulant (n = 14) participated. No adverse events related to IMT were reported. No difference in median patient hospitalisation and respiratory tract infection (RTI) rates between non-training and intervention periods (p = 0.60; p = 0.21) was found. During IMT, Pimax and peak cough flow improved with a mean ± standard deviation (s.d.) of 14.57 ± 15.67 cmH2O and 32.27 ± 36.60 L/min, compared to 3.04 ± 11.93 cmH2O (p = 0.01) and -16.59 ± 48.29 L/min (p = 0.0005) during the non-training period. Similar to other studies, spirometry did not show a significant change.

Conclusion

A 3-month IMT programme in children with NMD appears safe and well-tolerated, with significant improvement in respiratory muscle strength and cough efficacy.

Clinical implications

Inspiratory muscle training could be considered a cost-effective adjunct to respiratory management in children with NMD.

Trial Registration

Pan African Clinical Trial Registry, PACTR201506001171421, https://pactr.samrc.ac.za.

Future Directions for Respiratory Muscle Training in Neuromuscular Disorders: A Scoping Review

BACKGROUND

Respiratory muscle training (RMT) aims to improve inspiratory and/or expiratory muscle function in neuromuscular disorders (NMDs). A comprehensive overview of the available literature is lacking. This scoping review explores methodological characteristics, (adverse) effects, and adherence of RMT studies in NMDs. Moreover, it identifies limitations and research gaps in the literature and provides future research directions.

SUMMARY

Eligible studies were identified using MEDLINE, Embase, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials databases. Three reviewers independently selected articles. Inclusion criteria were English language, original research articles on RMT using a device, patients with an NMD, and pulmonary function tests or respiratory muscle strength as outcome measures. We included NMDs with slow, intermediate and fast progression. Exclusion criteria were critically ill patients, weaning from mechanical ventilation, other neurological disorders, and RMT combined with non-respiratory interventions. One reviewer extracted the data on patients' characteristics, methodological characteristics, results of outcome measures, adverse events, and patient adherence. Forty-five studies were identified. We found a large diversity in study designs and training protocols. The effects of RMT on respiratory muscle strength and/or endurance are variable. Patient adherence was high and no serious adverse events were reported.

KEY MESSAGES

The diversity in studies across the available literature precludes definitive conclusions regarding the effects of RMT on respiratory muscle function and clinically relevant outcomes in NMDs. Therefore, well-powered and -designed studies that focus on clinically relevant outcomes and assess whether RMT can improve or offset deterioration of respiratory muscle weakness in NMDs are needed.

Duchenne and Becker muscular dystrophy: Cellular mechanisms, image analysis, and computational models: A review

The muscle is the principal tissue that is capable to transform potential energy into kinetic energy. This process is due to the transformation of chemical energy into mechanical energy to enhance the movements and all the daily activities. However, muscular tissues can be affected by some pathologies associated with genetic alterations that affect the expression of proteins. As the muscle is a highly organized structure in which most of the signaling pathways and proteins are related to one another, pathologies may overlap. Duchenne muscular dystrophy (DMD) is one of the most severe muscle pathologies triggering degeneration and muscle necrosis. Several mathematical models have been developed to predict muscle response to different scenarios and pathologies. The aim of this review is to describe DMD and Becker muscular dystrophy in terms of cellular behavior and molecular disorders and to present an overview of the computational models implemented to understand muscle behavior with the aim of improving regenerative therapy.

A Virtual Reality Exergame: Clinician-Guided Breathing and Relaxation for Children with Muscular Dystrophy

This study introduces a VR-based breathing and relaxation exergame tailored for individuals with Duchenne muscular dystrophy (DMD). DMD is a rare neuromuscular disease that leads to respiratory muscle dysfunction with anxiety being a common comorbidity. Clinical management requires frequent visits to rare disease specialists to manage symptom progression. Limited availability and/or proximity of rare disease experts present challenges to care and can lead to missed care opportunities and reduced quality of life. We propose a breathing and relaxation exergame with remote telehealth applicability that incorporates shared patient-clinician VR interaction, and physiological sensors that provide both real-time feedback to the patient and health analytics for the clinician. The game focuses on two key aspects of DMD clinical care that can be mediated through control of breathing: relaxation/mindfulness training and respiratory muscle exercise. The system was evaluated among 13 individuals, including 4 participants with DMD. Feedback surveys, interviews, and focus group discussions with participants, accompanying family members, and clinicians demonstrated the feasibility of this VR tool for telehealth or as part of a home exercise program.

Inspiratory Muscle Training in Nemaline Myopathy

BACKGROUND

Respiratory muscle weakness is a common feature in nemaline myopathy. Inspiratory muscle training (IMT) is an intervention that aims to improve inspiratory muscle strength.

OBJECTIVE

The aim of this controlled before-and-after pilot study was to investigate if IMT improves respiratory muscle strength in patients with nemaline myopathy.

METHODS

Nine patients (7 females; 2 males, age 36.6±20.5 years) with respiratory muscle weakness and different clinical phenotypes and genotypes were included. Patients performed eight weeks of sham IMT followed by eight weeks of active threshold IMT. The patients trained twice a day five days a week for 15 minutes at home. The intensity was constant during the training after a gradual increase to 30% of maximal inspiratory pressure (MIP).

RESULTS

Active IMT significantly improved MIP from 43±15.9 to 47±16.6 cmH2O (p = 0.019). The effect size was 1.22. There was no significant effect of sham IMT. Sniff nasal inspiratory pressure, maximal expiratory pressure, spirometry, and diaphragm thickness and thickening showed no significant improvements.

CONCLUSIONS

This pilot study shows that threshold IMT is feasible in patients with nemaline myopathy and improves inspiratory muscle strength. Our findings provide valuable preliminary data for the design of a larger, more comprehensive trial.

Respiratory muscle training in neuromuscular disease: a systematic review and meta-analysis

Background

Neuromuscular disease causes a progressive decline in ventilatory function which respiratory muscle training may address. Previous systematic reviews have focussed on single diseases, whereas this study systematically reviewed the collective evidence for respiratory muscle training in children and adults with any neuromuscular disease.

Methods

Seven databases were searched for randomised controlled trials. Three reviewers independently reviewed eligibility, extracted characteristics, results, determined risk of bias and combined results using narrative synthesis and meta-analysis.

Results

37 studies (40 publications from 1986–2021, n=951 participants) were included. Respiratory muscle training improved forced vital capacity (standardised mean difference (SMD) 0.40 (95% confidence interval 0.12–0.69)), maximal inspiratory (SMD 0.53 (0.21–0.85)) and maximal expiratory pressure (SMD 0.70 (0.35–1.04)) compared to control (usual care, sham or alternative treatment). No impact on cough, dyspnoea, voice, physical capacity or quality of life was detected. There was high degree of variability between studies.

Discussion

Study heterogeneity (children and adults, different diseases, interventions, dosage and comparators) suggests that the results should be interpreted with caution. Including all neuromuscular diseases increased the evidence pool and tested the intervention overall.

Conclusions

Respiratory muscle training improves lung volumes and respiratory muscle strength in neuromuscular disease, but confidence is tempered by limitations in the underlying research.

Inspiratory Muscle Rehabilitation Training in Pediatrics: What Is the Evidence?

Pulmonary rehabilitation is typically used for reducing respiratory symptoms and improving fitness and quality of life for patients with chronic lung disease. However, it is rarely prescribed and may be underused in pediatric conditions. Pulmonary rehabilitation can include inspiratory muscle training that improves the strength and endurance of the respiratory muscles. The purpose of this narrative review is to summarize the current literature related to inspiratory muscle rehabilitation training (IMRT) in healthy and diseased pediatric populations. This review highlights the different methods of IMRT and their effects on respiratory musculature in children. Available literature demonstrates that IMRT can improve respiratory muscle strength and endurance, perceived dyspnea and exertion, maximum voluntary ventilation, and exercise performance in the pediatric population. These mechanistic changes help explain improvements in symptomology and clinical outcomes with IMRT and highlight our evolving understanding of the role of IMRT in pediatric patients. There remains considerable heterogeneity in the literature related to the type of training utilized, training protocols, duration of the training, use of control versus placebo, and reported outcome measures. There is a need to test and refine different IMRT protocols, conduct larger randomized controlled trials, and include patient-centered clinical outcomes to help improve the evidence base and support the use of IMRT in patient care.

The new challenge of “exercise + X″ therapy for Duchenne muscular dystrophy—Individualized identification of exercise tolerance and precise implementation of exercise intervention

Duchenne muscular dystrophy (DMD) is an X-linked recessive fatal muscular disease. Gene therapy, cell therapy, and drug therapy are currently the most widely used treatments for DMD. However, many experiments on animals and humans suggested that appropriate exercise could improve the effectiveness of such precision medicine treatment, thereby improving patient’s muscle quality and function. Due to the striated muscle damage of DMD individuals, there are still many debates about whether DMD animals or patients can exercise, how to exercise, when to exercise best, and how to exercise effectively. The purpose of this review is to summarize and investigate the scientific basis and efficacy of exercise as an adjuvant therapy for DMD gene therapy, cell therapy and drug therapy, as well as to present the theoretical framework and optional strategies of “exercise + X″″ combination therapy.

The effects of inspiratory muscle training in adults with muscular dystrophy

Background/Aims Patients with muscular dystrophy usually have impaired lung function and respiratory muscle strength, leading to pneumonia and respiratory failure, which are significant causes of morbidity and mortality. Inspiratory muscle training might be a safe adjunct treatment to increase the strength and endurance of weakened respiratory muscles. The researchers have developed a new protocol for inspiratory muscle training and evaluated its effect on inspiratory muscle strength and coughing capacity.

Methods A total of 12 participants diagnosed with muscle dystrophy and decreased maximal inspiratory pressure (<60 cmH2O) participated in this prospective study. Training was individually tailored, starting with low resistance levels and progressing according to tolerance and symptoms. The primary outcome measure was maximal inspiratory pressure. Secondary outcomes were maximal expiratory pressure, peak cough flow and the feasibility of the intervention.

Results There were two participants who did not complete the study, and three were lost to follow-up; therefore, only seven patients finished the intervention. In these patients, the authors found a statistically significant improvement in the maximal inspiratory pressure (P=0.018) and peak cough flow (P=0.046) after 3 months of training. There was also an improvement in the maximal expiratory pressure, although this was not statistically significant (P=0.176). Median compliance to training was 99% (94.5–100).

Conclusions This intervention led to statistically significant improvements in inspiratory muscles strength and coughing capacity in patients with muscular dystrophy. The results were significantly positive and contribute to the evidence in support of this underused, yet possibly beneficial, treatment, although larger randomised controlled trials are required to verify this.

Benefits of Telemonitoring of Pulmonary Function—3-Month Follow-Up of Home Electronic Spirometry in Patients with Duchenne Muscular Dystrophy

Background: In patients with Duchenne Muscular Dystrophy (DMD), the respiratory system determines the quality and length of life; therefore, the search for easy and safe everyday monitoring of the pulmonary function is currently extremely important, particularly in the COVID-19 pandemic. The aim of the study was to evaluate the influence of a three-month home electronic spirometry (e-spirometry) monitoring of the pulmonary function and strength of respiratory muscles as well as the patients’ benefits from this telemetric program. Methods: Twenty-one boys with DMD (aged 7–22; non-ambulatory-11) received a remote electronic spirometer for home use with a special application dedicated for patients and connected with a doctor platform. Control of the hospital spirometry (forced vital capacity-FVC, forced expiratory volume in 1 second-FEV1, peak expiratory flow-PEF) and respiratory muscle strength (maximal inspiratory-MIP and expiratory pressures-MEP) before and after the three-month monitoring were performed as well telemonitoring benefit survey. Results: A total of 1403 measurements were performed; 15 of the participants were able to achieve correct attempts. There were no differences between the hospital and the home spirometry results as well as between respiratory muscle strength during v1 vs. v2 visits for the whole study group (all parameters p > 0.05); the six participants achieved increased value of FVC during the study period. There was a positive correlation between ΔFVC and the number of assessments during the home spirometry (r = 0.7, p < 0.001). Differences between FVC and MIP_cmH2O (r = 0.58; p = 0.01), MEP_cmH2O (r = 0.75; p < 0.001) was revealed. The mean general satisfaction rating of the telemonitoring was 4.46/5 (SD 0.66) after one month and 4.91/5 (SD 0.28) after three months. The most reported benefit of the home monitoring was the improvement in breathing (38% of participants after one month, 52% after three months of telemonitoring). Forgetting about the procedures was the most common reason for irregular measurements; the participants reported also increased motivation but less time to perform tests. Conclusions: The study indicates high compliance of the home telemonitoring results with the examination in the hospital. Benefits from home spirometry were visible for all participants; the most important benefit was breathing improvement. The remote home spirometry is usable for everyday monitoring of the pulmonary function in DMD patients as well can be also treated as respiratory muscle training.

Inspiratory muscle training in children and adolescents living with neuromuscular diseases: A pre-experimental study

Background

Children with neuromuscular diseases (NMD) are at risk of morbidity and mortality because of progressive respiratory muscle weakness and ineffective cough. Inspiratory muscle training (IMT) aims to preserve or improve respiratory muscle strength, thereby reducing morbidity and improving health-related quality of life (HRQoL).

Objectives

To describe the safety and feasibility of a 6-week IMT programme using an electronic threshold device (Powerbreathe®). Any adverse events and changes in functional ability, spirometry, peak expiratory cough flow (PECF), inspiratory muscle strength and HRQoL (Pediatric Quality of Life [PedsQL]) were recorded.

Methods

A convenience sample of eight participants (n = 4 boys; median [interquartile range {IQR}] age: 12.21 [9.63–16.05] years) with various NMD were included in a pre-experimental, observational pre-test post-test feasibility study. Training consisted of 30 breaths, twice daily, 5 days a week, for 6 weeks.

Results

There were significant pre- to post-intervention improvements in upper limb function and coordination (p = 0.03) and inspiratory muscle strength: maximum inspiratory mouth pressure (Pimax) (p = 0.01); strength-index (p = 0.02); peak inspiratory flow (PIF) (p = 0.02), with no evidence of change in spirometry, PECF or HRQoL. No adverse events occurred and participant satisfaction and adherence levels were high.

Conclusion

Inspiratory muscle training (at an intensity of 30% Pimax) appears safe, feasible and acceptable, in a small sample of children and adolescents with NMD and was associated with improved inspiratory muscle strength, PIF and upper limb function and coordination.

Clinical implications

Larger, longer-term randomised controlled trials are warranted to confirm the safety and efficacy of IMT as an adjunct respiratory management strategy in children with NMD.

Development of clinical practice guidelines for allied health and nursing assessment and management of Duchenne muscular dystrophy

PURPOSE

To provide evidence-based guidance specific to allied health and nursing practice for the assessment and management of individuals with Duchenne muscular dystrophy (DMD).

MATERIALS AND METHODS

Thirteen key focus areas were identified in consultation with health professionals and consumer advocacy groups. A series of systematic literature reviews were conducted to identify assessment and management strategies for each key focus area. A consensus process using modified Delphi methodology, including an Australia-New Zealand expert consensus meeting, was conducted. Recommendations underwent consultative review with key groups before being finalised and prepared for dissemination.

RESULTS

This clinical practice guideline (CPG) generated 19 evidence-based recommendations, 117 consensus-based recommendations and five research recommendations across the 13 focus areas to inform allied health assessment and management of individuals with DMD.

CONCLUSIONS

The resulting recommendations can be used in conjunction with existing medical CPGs to improve, standardise and advocate for allied health and rehabilitation care in DMD. The process used here may be useful for the development of CPGs in other rare diseases.Implications for rehabilitationImplementation-ready evidence-based statements to guide clinical care of individuals with DMD are provided with the potential to improve participation, function in the community and quality of life.A model for developing best practice statements for other rare neurological diseases is described.Allied health and nursing health professionals should focus research efforts to generate quality evidence to support rehabilitation practice.

Respiratory Telerehabilitation of Boys and Young Men with Duchenne Muscular Dystrophy in the COVID-19 Pandemic

Background: The COVID-19 pandemic forced reorganization of the multidisciplinary healthcare system for Duchenne muscular dystrophy. Digital solutions seem to be optimal for providing rehabilitation at this time. The aim of this study was to investigate whether it is possible to conduct respiratory physical therapy with the use of telerehabilitation in Duchenne muscular dystrophy. Methods: The study was conducted during an online conference for families with DMD. During the physical therapy panel we showed the video with the instructions of respiratory exercises. All participants (n = 152) were asked to fill in the online survey evaluating the quality, acceptance, and understanding of the instructions. Results: The survey was filled in by 45 (29.6%) participants. The mean rating of satisfaction was 4.70/5, and for intelligibility was 4.78/5. Thirty-seven (82.2%) patients declared that they had performed the exercises, all caregivers declared that it was possible to perform the proposed exercises a few times a week or daily, and only two respondents replied to invitations to individual online sessions. Conclusions: Findings from the study show that respiratory telerehabilitation may be implemented for DMD patients; however, the interest in digital rehabilitation among caregivers of DMD boys in Poland is low. The reasons for this situation require further research.

Effect of Yoga and Physiotherapy on Pulmonary Functions in Children with Duchenne Muscular Dystrophy - A Comparative Study

Context:

Abnormal respiratory function is known to be detectable almost as soon as it can be measured reliably. Studies have identified the effect of respiratory muscle training as well as breathing exercises in improving pulmonary functions in children with Duchenne muscular dystrophy (DMD).

Aims:

This study aims to identify the add-on effect of yoga over physiotherapy on pulmonary functions in children with DMD.

Settings and Design:

One hundred and twenty-four patients with DMD were randomized to two groups. Group I received home-based physiotherapy and Group II received physiotherapy along with yoga intervention.

Materials and Methods:

Pulmonary function test (PFT) was assessed before the intervention (baseline data) and at regular intervals of 3 months for a period of 1 year.

Statistical Analysis Used:

Normality was assessed using Shapiro–Wilk normality test. The baseline data were analyzed using Mann–Whitney U-test to identify the homogeneity. Repeated measures analysis of variance was used to assess significant changes in study parameters during the assessment of every 3 months, both within and between the two groups of patients.

Results:

A total of 88 participants completed all the 5 assessments, with a mean age of 7.9 ± 1.5 years. PFT parameters such as forced vital capacity (FVC), peak expiratory flow rate, maximum voluntary ventilation (MVV), and tidal volume during maximum voluntary ventilation (MVt) demonstrated significant improvements in Group I. In Group II, FVC and MVt significantly improved from baseline up to 1 year, whereas MVV improved from baseline up to 9 months. Tidal volume did not show any changes in both the groups.

Conclusions:

The findings suggest that introduction of yoga with physiotherapy intervention at an early age can be considered as one of the therapeutic strategies in improving pulmonary functions in patients with DMD.

Establishing a telerehabilitation program for patients with Duchenne muscular dystrophy in the COVID-19 pandemic

Background

Duchenne muscular dystrophy is a genetic disease characterized by gradual loss of motor function, respiratory failure and cardiomyopathy. During the time of the global coronavirus pandemic, maintenance of social distancing and self-isolation might complicate regular multidisciplinary care of patients with Duchenne muscular dystrophy but on the other hand may lead to new medical care telehealth solutions. The aim of the study was to investigate patients’ situation regarding rehabilitation in the pandemic, to establish an online rehabilitation program and motor assessment and to determine the needs of telerehabilitation in this group.

Methods

The project involved 69 boys with Duchenne muscular dystrophy. The rehabilitation program was presented during online workshops for patients and caregivers. The same program was recorded on video and published in the internet. The online motor assessment tool consisted of six motor tests, caregivers were asked to perform the tasks and share a photograph of the patient’s posture using a designed app.

Results

In the nonambulant group the emphasis was placed on chest physiotherapy, stretching of upper extremities, positioning and wheelchair ergonomics. The program for the ambulant group focused on lower extremities stretching and full body exercises. Response rate for the workshops for ambulant patients was 29.7%, and only 9.0% for nonambulant patients. Videos showing exercises were displayed 132 times within a month.

Conclusion

With the physiotherapist guidance (online communication or video) patients with caregivers’ help can continue home based rehabilitation. Online videos/instructions/video guidelines are more acceptable by parents/caregivers of patients with Duchenne muscular dystrophy than live workshops.

The Effect of Inspiratory Muscle Training on Duchenne Muscular Dystrophy: A Meta-analysis

PURPOSE

This study reports the respiratory muscle training effect on strength and endurance in individuals with Duchenne muscular dystrophy.

METHODS

Articles published from 1984 to 2017 were reviewed. Six articles met the inclusion criteria that included within-subject control or between-subject control group, participants with a diagnosis of only Duchenne muscular dystrophy, participation in respiratory muscle training intervention, and outcome measures of endurance and strength. Effect sizes were calculated for each study and overall, weighted mean effect sizes for strength and endurance outcome measures.

RESULTS

There was a large effect for improving respiratory endurance and a moderate effect for muscle strength. However, these effects were not significant.

CONCLUSION

Findings justify further exploration of the potential benefits of respiratory muscle training for individuals with Duchenne muscular dystrophy.

Respiratory muscle training in children and adults with neuromuscular disease

BACKGROUND

Neuromuscular diseases (NMDs) are a heterogeneous group of diseases affecting the anterior horn cell of spinal cord, neuromuscular junction, peripheral nerves and muscles. NMDs cause physical disability usually due to progressive loss of strength in limb muscles, and some NMDs also cause respiratory muscle weakness. Respiratory muscle training (RMT) might be expected to improve respiratory muscle weakness; however, the effects of RMT are still uncertain. This systematic review will synthesize the available trial evidence on the effectiveness and safety of RMT in people with NMD, to inform clinical practice.

OBJECTIVES

To assess the effects of respiratory muscle training (RMT) for neuromuscular disease (NMD) in adults and children, in comparison to sham training, no training, standard treatment, breathing exercises, or other intensities or types of RMT.

SEARCH METHODS

On 19 November 2018, we searched the Cochrane Neuromuscular Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase. On 23 December 2018, we searched the US National Institutes for Health Clinical Trials Registry (ClinicalTrials.gov), the World Health Organization International Clinical Trials Registry Platform, and reference lists of the included studies.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and quasi-RCTs, including cross-over trials, of RMT in adults and children with a diagnosis of NMD of any degree of severity, who were living in the community, and who did not need mechanical ventilation. We compared trials of RMT (inspiratory muscle training (IMT) or expiratory muscle training (EMT), or both), with sham training, no training, standard treatment, different intensities of RMT, different types of RMT, or breathing exercises.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodological procedures.

MAIN RESULTS

We included 11 studies involving 250 randomized participants with NMDs: three trials (N = 88) in people with amyotrophic lateral sclerosis (ALS; motor neuron disease), six trials (N = 112) in Duchenne muscular dystrophy (DMD), one trial (N = 23) in people with Becker muscular dystrophy (BMD) or limb-girdle muscular dystrophy, and one trial (N = 27) in people with myasthenia gravis.Nine of the trials were at high risk of bias in at least one domain and many reported insufficient information for accurate assessment of the risk of bias. Populations, interventions, control interventions, and outcome measures were often different, which largely ruled out meta-analysis. All included studies assessed lung capacity, our primary outcome, but four did not provide data for analysis (1 in people with ALS and three cross-over studies in DMD). None provided long-term data (over a year) and only one trial, in ALS, provided information on adverse events. Unscheduled hospitalisations for chest infection or acute exacerbation of chronic respiratory failure were not reported and physical function and quality of life were reported in one (ALS) trial.Amyotrophic lateral sclerosis (ALS)Three trials compared RMT versus sham training in ALS. Short-term (8 weeks) effects of RMT on lung capacity in ALS showed no clear difference in the change of the per cent predicted forced vital capacity (FVC%) between EMT and sham EMT groups (mean difference (MD) 0.70, 95% confidence interval (CI) -8.48 to 9.88; N = 46; low-certainty evidence). The mean difference (MD) in FVC% after four months' treatment was 10.86% in favour of IMT (95% CI -4.25 to 25.97; 1 trial, N = 24; low-certainty evidence), which is larger than the minimal clinically important difference (MCID, as estimated in people with idiopathic pulmonary fibrosis). There was no clear difference between IMT and sham IMT groups, measured on the Amyotrophic Lateral Sclerosis Functional Rating Scale (ALFRS; range of possible scores 0 = best to 40 = worst) (MD 0.85, 95% CI -2.16 to 3.85; 1 trial, N = 24; low-certainty evidence) or quality of life, measured on the EuroQol-5D (0 = worst to 100 = best) (MD 0.77, 95% CI -17.09 to 18.62; 1 trial, N = 24; low-certainty evidence) over the medium term (4 months). One trial report stated that the IMT protocol had no adverse effect (very low-certainty evidence).Duchenne muscular dystrophy (DMD)Two DMD trials compared RMT versus sham training in young males with DMD. In one study, the mean post-intervention (6-week) total lung capacity (TLC) favoured RMT (MD 0.45 L, 95% CI -0.24 to 1.14; 1 trial, N = 16; low-certainty evidence). In the other trial there was no clear difference in post-intervention (18 days) FVC between RMT and sham RMT (MD 0.16 L, 95% CI -0.31 to 0.63; 1 trial, N = 20; low-certainty evidence). One RCT and three cross-over trials compared a form of RMT with no training in males with DMD; the cross-over trials did not provide suitable data. Post-intervention (6-month) values showed no clear difference between the RMT and no training groups in per cent predicted vital capacity (VC%) (MD 3.50, 95% CI -14.35 to 21.35; 1 trial, N = 30; low-certainty evidence).Becker or limb-girdle muscular dystrophyOne RCT (N = 21) compared 12 weeks of IMT with breathing exercises in people with Becker or limb-girdle muscular dystrophy. The evidence was of very low certainty and conclusions could not be drawn.Myasthenia gravisIn myasthenia gravis, there may be no clear difference between RMT and breathing exercises on measures of lung capacity, in the short term (TLC MD -0.20 L, 95% CI -1.07 to 0.67; 1 trial, N = 27; low-certainty evidence). Effects of RMT on quality of life are uncertain (1 trial; N = 27).Some trials reported effects of RMT on inspiratory and/or expiratory muscle strength; this evidence was also of low or very low certainty.

AUTHORS' CONCLUSIONS

RMT may improve lung capacity and respiratory muscle strength in some NMDs. In ALS there may not be any clinically meaningful effect of RMT on physical functioning or quality of life and it is uncertain whether it causes adverse effects. Due to clinical heterogeneity between the trials and the small number of participants included in the analysis, together with the risk of bias, these results must be interpreted very cautiously.

Is Exercise the Right Medicine for Dystrophic Muscle?

INTRODUCTION

Duchenne muscular dystrophy (DMD) is a neuromuscular disease caused by a dystrophin protein deficiency. Dystrophin functions to stabilize and protect the muscle fiber during muscle contraction; thus, the absence of functional dystrophin protein leads to muscle injury. DMD patients experience progressive muscle necrosis, loss of function, and ultimately succumb to respiratory failure or cardiomyopathy. Exercise is known to improve muscle health and strength in healthy individuals as well as positively affect other systems. Because of this, exercise has been investigated as a potential therapeutic approach for DMD.

METHODS

This review aims to provide a concise presentation of the exercise literature with a focus on dystrophin-deficient muscle. Our intent was to identify trends and gaps in knowledge with an appreciation of exercise modality.

RESULTS

After compiling data from mouse and human studies, it became apparent that endurance exercises such as a swimming and voluntary wheel running have therapeutic potential in limb muscles of mice and respiratory training was beneficial in humans. However, in the comparatively few long-term investigations, the effect of low-intensity training on cardiac and respiratory muscles was contradictory. In addition, the effect of exercise on other systems is largely unknown.

CONCLUSIONS

To safely prescribe exercise as a therapy to DMD patients, multisystemic investigations are needed including the evaluation of respiratory and cardiac muscle.

Respiratory Management of the Patient With Duchenne Muscular Dystrophy

In 2010, Care Considerations for Duchenne Muscular Dystrophy, sponsored by the Centers for Disease Control and Prevention, was published in Lancet Neurology, and in 2018, these guidelines were updated. Since the publication of the first set of guidelines, survival of individuals with Duchenne muscular dystrophy has increased. With contemporary medical management, survival often extends into the fourth decade of life and beyond. Effective transition of respiratory care from pediatric to adult medicine is vital to optimize patient safety, prognosis, and quality of life. With genetic and other emerging drug therapies in development, standardization of care is necessary to accurately assess treatment effects in clinical trials. This revision of respiratory recommendations preserves a fundamental strength of the original guidelines: namely, reliance on a limited number of respiratory tests to guide patient assessment and management. A progressive therapeutic strategy is presented that includes lung volume recruitment, assisted coughing, and assisted ventilation (initially nocturnally, with the subsequent addition of daytime ventilation for progressive respiratory failure). This revision also stresses the need for serial monitoring of respiratory muscle strength to characterize an individual's respiratory phenotype of severity as well as provide baseline assessments for clinical trials. Clinical controversies and emerging areas are included.

The assessment of sniff nasal inspiratory pressure in patients with Duchenne muscular dystrophy in China

OBJECTIVE

Progressive weakness of respiratory muscles remains one of the leading causes of death among patients with Duchenne muscular dystrophy (DMD). Currently, there are few pulmonary function data among Chinese DMD patients. This study was carried out to evaluate the sniff nasal inspiratory pressure (SNIP) change among a group of Chinese DMD patients, and compare it with the SNIP value of patients with neuromuscular disorders in other countries.

METHODS

SNIP data were collected in three research groups that consists of 581 subjects: 125 DMD boys who have taken steroid (Age 5.0-13.3, DMD-steroid group), 145 DMD steroid-naive boys (Age 5.0-13.9, DMD-nonsteroid group), and 311 healthy controls (Age 5.0-14.0, Control group).

RESULTS

The SNIP for DMD-nonsteroid group, DMD-steroid group and Control group were: 56.5 (±14.3) cm H₂O,66.4 (±15.5) cm H₂O and 78.9 (±21.5) respectively. The SNIP in the DMD-nonsteroid group became significantly different from that of the healthy controls since age 7.0-8.9. The significant difference of SNIP between DMD-steroid group and DMD-nonsteroid group at age 7.0-10.9. The peak value of SNIP in the DMD-nonsteroid group appeared at age 8.7, and decreased dramatically thereafter, while in DMD-steroid group and the Control group peaked at 10.2 years and 12.2 years respectively. There was a bit difference between SNIP in this group and that in previous researches which may be due to geographical distribution and ethnic backgrounds.

CONCLUSION

This study strengthens the previous findings that SNIP can be used to evaluate respiratory dysfunction during the early stage of young patients with neuromuscular disorders, and demonstrates that steroid is effective in slowing the decrease of SNIP in this group of Chinese DMD boys.

Inspiratory muscle training for children and adolescents with neuromuscular diseases: A systematic review

Patients with neuromuscular diseases are at risk of morbidity and mortality due to respiratory compromise caused by respiratory muscle weakness. A systematic review was performed using pre-specified search strategies to determine the safety of inspiratory muscle training (IMT) and whether it has an impact on inspiratory muscle strength and endurance, exercise capacity, pulmonary function, dyspnoea and health-related quality of life. Randomised, quasi-randomised, cross-over and clinical controlled trials were included if they assessed the use of an external IMT device compared to no, sham/placebo, or alternative IMT treatment in children aged 5-18 years with neuromuscular diseases. Seven full-text articles and two on-going trials (n = 168) were included. Most studies used threshold IMT devices over a medium to long-term period, and none reported any adverse events. Studies differed regarding intensity, repetitions, frequency, rest intervals and duration of IMT. Six studies reported no significant improvement in pulmonary function tests following IMT. Two comparable studies reported significant improvement in inspiratory muscle endurance and four studies reported significantly greater improvement in inspiratory muscle strength in experimental groups. The latter was confirmed in a meta-analysis of two comparable studies (overall effect p < 0.00001). Other outcome measures could not be pooled. There is currently insufficient evidence to guide clinical IMT practice, owing to the limited number of included studies; small sample sizes; data heterogeneity; and risk of bias amongst included studies. Large sample randomised controlled trials are needed to determine safety and efficacy of IMT in paediatric and adolescent patients with neuromuscular diseases.

Inspiratory muscle training in pediatrics: main indications and technical characteristics of the protocols

Abstract Introduction: Inspiratory muscle training (IMT) is a resource widely used in pediatrics. However, there is great variability in relation to the characteristics of the protocols used. Objective: To identify the main clinical conditions and IMT protocols used in the pediatric age group. Methods: Integrative review of the literature by searching on Pubmed, Scielo, PEDro and EMBASE databases using the following strategy: threshold OR inspiratory muscle training OR muscle endurance OR muscle resistance OR endurance training OR maximal inspiratory pressure AND respiratory muscle. We have selected clinical trials that performed IMT in children and adolescents (0 to 18 years old), with a clinical diagnosis, and published in English, Portuguese and Spanish. Results: 17 studies were included. From these, 11 underwent IMT in patients with some neuromuscular disorder, being Duchenne Muscular Dystrophy the most common. The selected articles included a total sample of 327 participants. As for the characteristics of the protocols, 7 performed strength training, 5 endurance and 5 strength and endurance. The training load ranged from 30 to 80% of maximal inspiratory pressure. Moreover, 8 studies performed IMT twice daily and the session duration and the training period varied between 10 and 30 minutes, and from 3 weeks to 24 months, respectively. Conclusion: The IMT was used more frequently in patients with some neuromuscular disorder. Although there is no consensus as to the characteristics of the protocols, the choice of the load should take into account the purpose of IMT and the disease severity.

Inspiratory Muscle Training in Late-Onset Pompe Disease: The Effects on Pulmonary Function Tests, Quality of Life, and Sleep Quality

INTRODUCTION

Late-onset Pompe disease (LOPD) is characterized by progressive skeletal and respiratory muscle weakness. Little is known about the effect of inspiratory muscle training (IMT) on pulmonary function in subjects with LOPD. The aim of the present study was to investigate the effect of an 8-week IMT program on pulmonary function tests, quality of life, and sleep quality in eight patients with LOPD who were receiving enzyme replacement therapy (ERT).

METHODS

Before and after the IMT program, spirometric measurements in sitting and supine positions, and measurements of maximum inspiratory and expiratory pressures, peak cough flow, quality of life (assessed using the Nottingham Health Profile), and sleep quality (assessed using the Pittsburgh sleep quality index) were performed.

RESULTS

A significant increase in maximum inspiratory pressure (cmH2O and % predicted) (median [interquartile range]: 30.0 cmH2O [21.5-48] versus 39 cmH2O [31.2-56.5] and 38.3 % [28.1-48.4] versus 50.5 % [37.7-54.9]) was observed after training (p = 0.01). There were no significant changes in the other pulmonary function measurements. With the exception of the social isolation subscore (p = 0.02), quality of life subscores did not change after IMT (p > 0.05). Sleep quality subscores and total scores were similar before and after IMT.

CONCLUSION

These results suggest that IMT has a positive effect on maximum inspiratory pressure in subjects with LOPD who are under ERT.

Comparison of Experimental Protocols of Physical Exercise for mdx Mice and Duchenne Muscular Dystrophy Patients

Duchenne Muscular Dystrophy (DMD) is caused by mutations in the gene coding for dystrophin and leads to muscle degeneration, wheelchair dependence and death by cardiac or respiratory failure. Physical exercise has been proposed as a palliative therapy for DMD to maintain muscle strength and prevent contractures for as long as possible. However, its practice remains controversial because the benefits of training may be counteracted by muscle overuse and damage.

The effects of physical exercise have been investigated in muscles of dystrophin-deficient mdx mice and in patients with DMD. However, a lack of uniformity among protocols limits comparability between studies and translatability of results from animals to humans. In the present review, we summarize and discuss published protocols used to investigate the effects of physical exercise on mdx mice and DMD patients, with the objectives of improving comparability between studies and identifying future research directions.

Assessment and management of respiratory function in patients with Duchenne muscular dystrophy: current and emerging options

Duchenne muscular dystrophy (DMD) is an X-linked myopathy resulting in progressive weakness and wasting of all the striated muscles including the respiratory muscles. The consequences are loss of ambulation before teen ages, cardiac involvement and breathing difficulties, the main cause of death. A cure for DMD is not currently available. In the last decades the survival of patients with DMD has improved because the natural history of the disease can be changed thanks to a more comprehensive therapeutic approach. This comprises interventions targeted to the manifestations and complications of the disease, particularly in the respiratory care. These include: 1) pharmacological intervention, namely corticosteroids and idebenone that significantly reduce the decline of spirometric parameters; 2) rehabilitative intervention, namely lung volume recruitment techniques that help prevent atelectasis and slows the rate of decline of pulmonary function; 3) scoliosis treatment, namely steroid therapy that is used to reduce muscle inflammation/degeneration and prolong ambulation in order to delay the onset of scoliosis, being an additional contribution to the restrictive lung pattern; 4) cough assisted devices that improve airway clearance thus reducing the risk of pulmonary infections; and 5) non-invasive mechanical ventilation that is essential to treat nocturnal hypoventilation, sleep disordered breathing, and ultimately respiratory failure. Without any intervention death occurs within the first 2 decades, however, thanks to this multidisciplinary therapeutic approach life expectancy of a newborn with DMD nowadays can be significantly prolonged up to his fourth decade. This review is aimed at providing state-of-the-art methods and techniques for the assessment and management of respiratory function in DMD patients.

Effects of yoga breathing exercises on pulmonary function in patients with Duchenne muscular dystrophy: an exploratory analysis

OBJECTIVE:

Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy in children, and children with DMD die prematurely because of respiratory failure. We sought to determine the efficacy and safety of yoga breathing exercises, as well as the effects of those exercises on respiratory function, in such children.

METHODS:

This was a prospective open-label study of patients with a confirmed diagnosis of DMD, recruited from among those followed at the neurology outpatient clinic of a university hospital in the city of São Paulo, Brazil. Participants were taught how to perform hatha yoga breathing exercises and were instructed to perform the exercises three times a day for 10 months.

RESULTS:

Of the 76 patients who entered the study, 35 dropped out and 15 were unable to perform the breathing exercises, 26 having therefore completed the study (mean age, 9.5 ± 2.3 years; body mass index, 18.2 ± 3.8 kg/m²⁾. The yoga breathing exercises resulted in a significant increase in FVC (% of predicted: 82.3 ± 18.6% at baseline vs. 90.3 ± 22.5% at 10 months later; p = 0.02) and FEV₁ (% of predicted: 83.8 ± 16.6% at baseline vs. 90.1 ± 17.4% at 10 months later; p = 0.04).

CONCLUSIONS:

Yoga breathing exercises can improve pulmonary function in patients with DMD.

Current treatment and management of dystrophinopathies

OPINION STATEMENT

• Duchenne muscular dystrophy (DMD), the most common and severe type of dystrophinopathy, is a progressive disease affecting primordially skeletal and cardiac muscle. A coordinated multidisciplinary approach is required to address its multisystemic manifestations and secondary problems.• Treatment with glucocorticosteroids (GCS) is accepted as standard of care in ambulant DMD. Daily and intermittent administrations are both in common use with different efficacy and different side effect profile.• There are no established guidelines for age/stage at initiation and treatment duration of GCS. Common practice is initiation of GCS before the child is starting to decline (between age 3 and 6 years) and continuation of monitored treatment after loss of ambulation, aiming at delaying cardiac and respiratory manifestations and preventing the development of scoliosis.• Prevention, monitoring, and treatment of the side effects of long-term chronic GCS use, such as excessive weight gain, hypertension, osteoporosis, impairment of glucose metabolism, delayed puberty, and cataract, should be integrated in the standards of care.• Noninvasive ventilatory support associated with cough assisting techniques has significantly improved the longevity in DMD.• Pharmacologic treatment for cardiac manifestations includes the standard treatments of dilated cardiomyopathy and arrhythmia such as the use of angiotensin converting enzyme (ACE) inhibitors, beta-blockers and diuretics. The lack of robust controlled data hampers clear recommendations about preventive treatment with ACE inhibitors.• DMD is associated with low bone mineral content, which is aggravated by the use of corticosteroids. The use of biphosphonates can be considered in the treatment of painful vertebral fractures. The use of biphosphonates as a preventive treatment should be investigated in randomized controlled studies.• DMD has evolved from a pediatric disease to an adult condition. This underscores the need to prepare adult neurologists for the optimal surveillance and management of patients with a severe chronic disease that have outgrown the pediatric care and that may develop new disease manifestations with improved longevity.

Effects of inspiratory muscle training on lung volumes, respiratory muscle strength, and quality of life in patients with ataxia telangiectasia

BACKGROUND

Ataxia telangiectasia (AT) is a genetic syndrome caused by a mutation of chromosome 11. The clinical features are cerebellar ataxia, telangiectasia, and progressive loss of muscular coordination, including an inefficient cough secondary to progression of neurological disease.

OBJECTIVE

To evaluate the effects of inspiratory muscle training (IMT) on ventilation, lung volume, dyspnoea, respiratory muscle strength, and quality of life in patients with AT.

METHODS

A longitudinal study was conducted with 11 AT patients and nine healthy volunteers. Ventilometry, subjective sensation of dyspnoea, maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and quality of life were assessed before and after a 24-week IMT program. The IMT load used was set at 60% of the MIP, and the training was performed for 20 min daily.

RESULTS

Patients with AT had lower height and weight and also had lower respiratory muscle strength and lung volume compared with healthy volunteers. Furthermore, patients with AT showed a significant improvement when pre- and post-IMT were compared for ventilatory pattern: Vt (476.5 ± 135 ml vs. 583.3 ± 66 ml, P = 0.015) and f (23.3 ± 6 rpm vs. 20.4 ± 4 rpm, P = 0.018), and VC (1,664 ± 463 ml/kg vs. 2,145 ± 750 ml/kg, P = 0.002). IMT also significantly improved the sensation of dyspnoea (median 0.5; minimum 0; maximum 1.0; P = 0.022) and respiratory muscle strength: MIP (-22.2 ± 2 cmH2O vs. -38 ± 9 cmH2O, P < 0.001) and MEP (29 ± 7 cmH2O vs. 40 ± 8 cmH2O, P = 0.001). The health and vitality domains of the SF-36 also showed significant improvement (P = 0.009 and P = 0.014, respectively) post-IMT.

CONCLUSION

IMT was effective in improving ventilatory pattern, lung volume, respiratory muscle strength, and the health and vitality domains for quality of life in patients with AT. IMT may be an effective adjunct therapy to drug treatment for patients with AT.

Exercise in neuromuscular disease

In this review, we present an overview of the role of exercise in neuromuscular disease (NMD). We demonstrate that despite the different pathologies in NMDs, exercise is beneficial, whether aerobic/endurance or strength/resistive training, and we explore whether this benefit has a similar mechanism to that of healthy subjects. We discuss further areas for study, incorporating imaginative and novel approaches to training and its assessment in NMD. We conclude by suggesting ways to improve future trials by avoiding previous methodological flaws and drawbacks in this field.

Exercise and Duchenne muscular dystrophy: toward evidence-based exercise prescription

To develop a rational framework for answering questions about the role of exercise in Duchenne muscular dystrophy (DMD), we focused on five pathophysiological mechanisms and offer brief hypotheses regarding how exercise may beneficially modulate pertinent cellular and molecular pathways. We aimed to provide an integrative overview of mechanisms of DMD pathology that may improve or worsen as a result of exercise. We also sought to stimulate discussion of what outcomes/dependent variables most appropriately measure these mechanisms, with the purpose of defining criteria for well-designed, controlled studies of exercise in DMD. The five mechanisms include pathways that are both intrinsic and extrinsic to the diseased muscle cells.

Lifestyle and the Respiratory Health of Children

This article offers a review of the potential influences of personal lifestyle on respiratory health in children, looking at both healthy individuals and those with respiratory disorders. As with many aspects of health, regular physical activity, an appropriate diet, and avoidance of obesity and cigarette smoke all contribute to optimal development of the healthy child. An active lifestyle is associated with greater static and dynamic lung volumes, greater efficiency of the ventilatory process, and an optimization of breathing patterns. The risk of upper respiratory infections is also reduced in those maintaining a moderate level of physical activity. Maternal smoking during pregnancy, as well as active and passive smoking, all have an adverse influence on lung function in the child, the largest effects being on dynamic lung volumes. The risk of developing asthma seems reduced in children who maintain a normal body mass and are physically active. A program of graded physical activity is of therapeutic value in a number of established respiratory conditions, including asthma, cystic fibrosis, and ventilatory impairment from neuromuscular disorders. Exercise carries a slight risk of fatalities from asthma and anaphylactic reactions. In designing an optimal physical activity program, it is also important to guard against the hazards of deep oronasal breathing, including the precipitation of bronchospasm by the inhalation of cold, dry air and pollens; an increased exposure to atmospheric pollutants (reducing and oxidant smog, fine and ultra-fine particulates, and carbon monoxide); and possible long-term dangers from chlorine derivatives in the atmosphere of indoor swimming pools.

Aging with muscular dystrophy: pathophysiology and clinical management

Major advances in the fields of medical science and physiology, molecular genetics, biomedical engineering, and computer science have provided individuals with muscular dystrophy (MD) with more functional equipment, allowing better strategies for improvement of quality of life. These advances have also allowed a significant number of these patients to live much longer. As progress continues to change management, it also changes patients' expectations. A comprehensive medical and rehabilitative approach to management of aging MD patients can often fulfill expectations and help them enjoy an enhanced quality of life.

Aquatic therapy: scientific foundations and clinical rehabilitation applications

The aquatic environment has broad rehabilitative potential, extending from the treatment of acute injuries through health maintenance in the face of chronic diseases, yet it remains an underused modality. There is an extensive research base supporting aquatic therapy, both within the basic science literature and clinical literature. This article describes the many physiologic changes that occur during immersion as applied to a range of common rehabilitative issues and problems. Because of its wide margin of therapeutic safety and clinical adaptability, aquatic therapy is a very useful tool in the rehabilitative toolbox. Through a better understanding of the applied physiology, the practitioner may structure appropriate therapeutic programs for a diverse patient population.

Surgical management of severe scoliosis with high-risk pulmonary dysfunction in Duchenne muscular dystrophy

Between 2005 and 2007, 14 patients who had severe scoliosis in Duchenne muscular dystrophy (DMD) and a poor forced vital capacity (FVC) of <30% at admission underwent scoliosis surgery. FVC on admission was 21.6% (range, 16-27%). The patients were given respiratory muscle training using a pulmonary trainer (Threshold IMT, Philips Respironics, Inc.) for six weeks before operation. FVC increased to 26.2% (range, 22-31%) the day before operation. The mean preoperative scoliosis was 98 degrees (range, 81 degrees-130 degrees). All patients underwent posterior fusion and all-screw construction and were extubated on the operative day. No patients developed any respiratory complications. The postoperative scoliosis was 34 degrees (range, 20 degrees-40 degrees) (65%). FVC remained stable at six weeks after operation. FVC decreased to 19.8% (range, 16-25%) and the mean scoliosis was 35 degrees (range, 23 degrees-40 degrees) (64%) at two years after operation. DMD patients with severe scoliosis and FVC considered too low to permit reasonable surgical risk could undergo surgery and could benefit from surgery.

Comparison study of chest physiotherapy home training programmes on respiratory functions in patients with muscular dystrophy

Objective: To compare the effects of home training programmes, threshold inspiratory muscle training and breathing exercise on spirometry and maximal pressures in patients with muscular dystrophy.

Design: Prospective blinded 12-week study.

Settings: Cardiopulmonary department of university hospital.

Subjects: Twenty-three patients with muscular dystrophy (17 patients with limb girdle muscular dystrophy and 6 patients with Becker muscular dystrophy) assigned to the threshold inspiratory muscle training and breathing exercise groups with alternate allocation.

Methods: Spirometry, maximal inspiratory pressure (PImax) and maximal expiratory pressure (PEmax) were measured before and after training. In the threshold inspiratory muscle training group threshold pressure load was determined as equal to 30% of weekly PImaxmeasurement. In the breathing exercise group, patients performed deep and forceful diaphragmatic and segmental exercises. All patients performed exercises at home and once a week at hospital under supervision.

Results: The improvement of PImaxin the threshold inspiratory muscle training group was more significant than the improvement observed in the breathing exercise group (P= 0.05). PEmaxincreased significantly only in the breathing exercise group (P= 0.01). Spirometry results did not change significantly in both groups after the training.

Conclusions: We conclude that respiratory muscle strength is enhanced by training in the patients with muscular dystrophy who are ambulatory, but inspiratory and/or expiratory training effect is specific to the trained muscles. The techniques that improve the strength of respiratory muscles should be included in the physiotherapy management of patients with muscular dystrophy.

Cardiopulmonary support in duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked, rapidly progressive myopathy affecting the limb muscles, the respiratory muscles, the heart, the intestines, and the brain. Since about 90% of DMD patients die from muscular respiratory failure or cardiomyopathy, early and adequate therapy is essential. Ventilatory failure from muscle weakness requires mechanical support for ventilation and coughing as soon as there is symptomatic nocturnal hypoventilation. Today noninvasive positive-pressure ventilation (NIPPV) is the method of choice for supportive long-term mechanical ventilation in DMD. For assisted coughing, various methods are available, among which the mechanical in-exsufflator is the most widely used device. There is large nonrandomized clinical trial evidence that NIPPV improves quality of life and prolongs the lives of DMD patients if medical, social, economic, and ethical issues, raised by the availability of long-term NIPPV, are adequately addressed. Cardiac involvement in DMD manifests as impulse generation or impulse conduction abnormalities or cardiomyopathy. Cardiac abnormalities in DMD respond well to adequate therapy. Though DMD is ultimately a fatal disease, quality of life and life expectancy can be markedly improved if cardiopulmonary manifestations are adequately treated.

Changes in respiratory muscle endurance during puberty

The evaluation of respiratory muscle endurance provides clinically useful information on muscle function, especially in children with respiratory and neuromuscular diseases. However, endurance may be lower in young children than in older children because of the major physical changes of puberty. We thus compared respiratory muscle endurance in 15 healthy pre- and peripubertal children (S1-S2/P1 group) and 14 healthy children near the end of the pubertal process (S4P4 group). All performed a respiratory muscle endurance test threshold load fixed at 50% of the individual maximal inspiratory pressure; (Pi(max)), using a standardized method with a controlled breathing pattern. No significant difference was found between groups for Pi(max). The mean endurance time limit for the S1-S2/P1 group was 138 +/- 20 sec. The S4P4 group was able to breathe with the threshold valve for more than 20 min (1,200 sec) without task failure, except for one girl (385 sec). This study shows that inspiratory muscle endurance is significantly lower in children in early puberty compared to children at the end of the pubertal process. If the underlying mechanisms are not well-known, the present study revealed that if we use the same inspiratory load in prepubertal children as in adults during clinical testing, we are likely to underestimate the susceptibility to task failure of their respiratory muscles. To define a fatigue threshold for the respiratory muscles, as a function of age, thus appears clinically important in further studies, particularly for the management of children with respiratory diseases.

The effect of respiratory muscle training with CO2 breathing on cellular adaptation of mdx mouse diaphragm

The aim of our study was to investigate the cellular mechanisms induced by hypercapnic stimulation of ventilation, during 6 weeks/30 min per day, in 10 mdx and 8 C57BL10 mice (10+/-0.2 months old). Ten mdx and eight C57BL10 mice served as control group. This respiratory training increases in vitro maximal tetanic tension of the diaphragm only in mdx mice. Western blot analysis of diaphragm showed: (1) an over-expression of alpha-dystrobrevin in mdx and C57BL10 training group compared to control group (8100+/-710 versus 6100+/-520 and 2800+/-400 versus 2200+/-250 arbitrary units); (2) a decrease in utrophin expression only in mdx training group compared to control group (2100+/-320 versus 3100+/-125 arbitrary units). Daily respiratory muscle training in mdx mice, induces a beneficial effect on diaphragm strength, with an over-expression of alpha-dystrobrevin. Further studies are needed to determine if, in absence of dystrophin, the over-expression of alpha-dystrobrevin could be interpreted as a possible pathway to improve function of dystrophic muscle.

Regenerative capacity of the dystrophic (mdx) diaphragm after induced injury

Duchenne muscular dystrophy is characterized by myofiber necrosis, muscle replacement by connective tissue, and crippling weakness. Although the mdx mouse also lacks dystrophin, most muscles show little myofiber loss or functional impairment. An exception is the mdx diaphragm, which is phenotypically similar to the human disease. Here we tested the hypothesis that the mdx diaphragm has a defective regenerative response to necrotic injury, which could account for its severe phenotype. Massive necrosis was induced in mdx and wild-type (C57BL10) mouse diaphragms in vivo by topical application of notexin, which destroys mature myofibers while leaving myogenic precursor satellite cells intact. At 4 h after acute exposure to notexin, >90% of diaphragm myofibers in both wild-type and mdx mice demonstrated pathological sarcolemmal leakiness, and there was a complete loss of isometric force-generating capacity. Both groups of mice showed strong expression of embryonic myosin within the diaphragm at 5 days, which was largely extinguished by 20 days after injury. At 60 days postinjury, wild-type diaphragms exhibited a persistent loss ( approximately 25%) of isometric force-generating capacity, associated with a trend toward increased connective tissue infiltration. In contrast, mdx diaphragms achieved complete functional recovery of force generation to noninjured values, and there was no increase in muscle connective tissue over baseline. These data argue against any loss of intrinsic regenerative capacity within the mdx diaphragm, despite characteristic features of major dystrophic pathology being present. Our findings support the concept that significant latent regenerative capacity resides within dystrophic muscles, which could potentially be exploited for therapeutic purposes.

Muscular dystrophy overview: genetics and diagnosis

A specific genetic diagnosis can be reached for most children with muscular dystrophy. Advanced diagnostics, including genetic testing and analysis of nonmuscle tissues, such as skin and blood, often allow the diagnosis to be reached using minimally invasive procedures. These diagnostic advances accompany improved understanding of pathophysiology and pave the way for specific and curative treatments.

Muscular dystrophies: influence of physical conditioning on the disease evolution

PURPOSE OF REVIEW

To summarize the current knowledge of the effects of physical activity on muscular dystrophies.

RECENT FINDINGS

Although the usefulness of exercise training in muscular dystrophy patients has been debated for many years, only a limited number of articles addressing this issue have been published to date. Existing studies on the effects of strength training in patients with muscular dystrophies have shown promising results, but interpretations are hampered by several methodological shortcomings.

SUMMARY

The scientific basis for solid recommendations of different exercise regimens in muscular dystrophies is poor, but existing data suggest beneficial effects of adopting an active lifestyle. Low- to moderate-intensity resistance and aerobic training may be recommended in slowly progressive myopathic disorders. To date, there is no evidence to support the recommendation of high-resistance exercise regimens over low-moderate intensity exercise. In rapidly progressive myopathies, which are due to aberrant structural proteins such as Duchenne muscular dystrophy, the use of high-resistance and eccentric training should be avoided. There is still, however, no evidence that physical training can influence the evolution of muscular dystrophies in the long term.

Pulmonary complications of chronic neuromuscular diseases and their management

Chronic neuromuscular diseases may affect all major respiratory muscles groups including inspiratory, expiratory, and bulbar, and respiratory complications are the major cause of morbidity and mortality. Untreated, many of these diseases lead inexorably to hypercapnic respiratory failure, precipitated in some cases by chronic aspiration and secretion retention or pneumonia, related to impairment of cough and swallowing mechanisms. Many measures are helpful including inhibition of salivation, cough-assist techniques, devices to enhance communication, and physical therapy. In addition, ventilatory assistance is an important part of disease management for patients with advanced neuromuscular disease. Because of its comfort, convenience, and portability advantages, noninvasive positive pressure ventilation (NPPV) has become the modality of first choice for most patients. Patients to receive NPPV should be selected using consensus guidelines, and initiation should be gradual to maximize the chances for success. Attention should be paid to individual preferences for interfaces and early identification of cough impairment that necessitates the use of cough-assist devices. For patients considered unsuitable for noninvasive ventilation, invasive mechanical ventilation should be considered, but only after a frank but compassionate discussion between the patient, family, physician, and other caregivers.