Duchenne and Becker muscular dystrophy (DMD and BMD, respectively) are characterized by progressive loss of muscle function combined with an increase in fat tissue in muscle. In some muscles this... Show moreDuchenne and Becker muscular dystrophy (DMD and BMD, respectively) are characterized by progressive loss of muscle function combined with an increase in fat tissue in muscle. In some muscles this process of ‘fat replacement’ starts earlier or progresses faster than in others and this occurs in a consistent temporal pattern. In addition, even within muscles fat replacement seems to progress heterogeneously. Evidently there are factors that vary between and within muscles which cause differential fat replacement of muscle tissue, but these are currently unknown. The identification of factors that influence this process of muscle degeneration could support the selection of current, and the development of future, therapies.The aim of part 1 of this thesis was to identify differences between muscles that are related to muscle fat replacement over time. These can provide therapeutical targets for, and support the design of, future clinical trials in DMD and BMD. Part 2 aimed to develop new approaches to study intramuscular differences in muscle physiology and mechanics in healthy muscle. These can be applied in neuromuscular disease in the future, and can be related to intramuscular differences in disease progression. Show less
Physical activity (PA) is a key strategy for improving symptoms in people with rheumatic and musculoskeletal diseases (RMDs). The aim of this study was to investigate and rank the importance of... Show morePhysical activity (PA) is a key strategy for improving symptoms in people with rheumatic and musculoskeletal diseases (RMDs). The aim of this study was to investigate and rank the importance of known barriers and facilitators for engaging in PA, from the perspective of people living with RMD. Five hundred thirty-three people with RMD responded to a survey (nine questions) disseminated by the People with Arthritis and Rheumatism (PARE) network of the European Alliance of Associations for Rheumatology (EULAR). The survey required participants to rank - based on their perceived importance - known PA barriers and facilitators from the literature, and specifically RMD symptoms as well as healthcare and community factors that may affect PA participation. Of the participants, 58% reported rheumatoid arthritis as their primary diagnosis, 89% were female, and 59% were between 51 and 70 years of age. Overall, participants reported fatigue (61.4%), pain (53.6%) and painful/swollen joints (50.6%) as the highest ranked barriers for engaging in PA. Conversely, less fatigue (66.8%) and pain (63.6%), and being able to do daily activities more easy (56.3%) were identified as the most important facilitators to PA. Three literature identified PA barriers, i.e., general health (78.8%), fitness (75.3%) and mental health (68.1%), were also ranked as being the most important for PA engagement. Symptoms of RMDs, such as pain and fatigue, seem to be considered the predominant barriers to PA by people with RMD; the same barriers are also the ones that they want to improve through increasing PA, suggesting a bi-directional relationship between these factors. Show less
To increase clinical success rate of drugs, a better understanding of drug action mechanism and disease dynamics is required. Metabolomics, which studies small molecules involved in biochemical... Show moreTo increase clinical success rate of drugs, a better understanding of drug action mechanism and disease dynamics is required. Metabolomics, which studies small molecules involved in biochemical processes in organisms, has shown to be a useful tool for this better understanding. In this thesis, we focus on the endocannabinoid system (ECS) and profiling its related metabolic pathways using liquid chromatography - mass spectrometry (LC-MS) based metabolomics techniques. The endocannabinoid system (ECS) is a signaling system involved in multiple physiological and pathological processes. Due to its wide distribution and complex network of metabolic interactions, the development of drugs targeting the ECS has seen high failure rates. To get a better understanding of the behavior of the ECS and related pathways, LC-MS platforms with wide coverage of the major ECS-related metabolites, or with high sensitivity that reaches low levels of metabolites, were developed and optimized. Furthermore, these metabolomics platforms were applied in clinical studies looking into cardiometabolic health, and revealed correlations between endogenous metabolite signaling, cardiometabolic health and the benefits of exercise. Show less
Physical Activity (PA) is one of the most important lifestyle factors influencing human health. The general and disease-specific health benefits of PA are well known to the general population and... Show morePhysical Activity (PA) is one of the most important lifestyle factors influencing human health. The general and disease-specific health benefits of PA are well known to the general population and to those people living with rheumatic musculoskeletal diseases (RMDs). The importance of PA as an intervention for the management of RMDs has been endorsed by various stakeholders, e.g. the World Health Organisation and the European Alliance of Associations for Rheumatology/EULAR. The early translation of research evidence into clinical care benefits patients with RMDs greatly.This thesis is focused on the effects and promotion of PA and exercise on people with RMDs, and particularly those with axial Spondyloarthritis (axSpA).The overall aim of this thesis was to document the journey from the development of the EULAR PA recommendations for people with RMDs (including axSpA) to the practical implementation of a concept for group exercise therapy for people with axSpA living in Switzerland that conforms to these recommendations. Show less
Mitropoulos, A.; Bostrom, C.; Mattsson, M.; Kouidi, E.; Dimitroulas, T.; Liem, S.I.E.; ... ; Klonizakis, M. 2022
Background: Pain, related to Raynaud's phenomenon or digital ulceration, has been identified as very prevalent and debilitating symptoms of systemic sclerosis (SSc), both significantly affecting... Show moreBackground: Pain, related to Raynaud's phenomenon or digital ulceration, has been identified as very prevalent and debilitating symptoms of systemic sclerosis (SSc), both significantly affecting patients' quality of life (QoL). Pharmacological therapeutic strategies were found not to be sufficiently effective in the management of SSc-induced pain and fatigue, and evidence for exercise is scarce. As yet, the effects of a long-term, tailored exercise programme on pain and fatigue in patients with SSc have not been explored. In addition to pain and fatigue, this study aims to evaluate the effects of exercise on QoL, physical fitness, functional capacity, and vascular structure in people with SSc (PwSSc). Methods: This will be a multicentre (n = 6) randomised controlled clinical trial to assess the effect of a previously established, supervised 12-week combined exercise programme on pain and fatigue as compared to no exercise in PwSSc. The study will recruit 180 patients with SSc that will be allocated randomly to two groups. Group A will perform the exercise programme parallel to standard usual care and group B will receive usual care alone. Patients in the exercise group will undertake two, 45-min sessions each week consisting of 30-min high-intensity interval training (HIIT) (30-s 100% peak power output/30-s passive recovery) on an arm crank ergometer and 15 min of upper body circuit resistance training. Patients will be assessed before as well as at 3 and 6 months following randomisation. Primary outcomes of the study will be pain and fatigue assessed via questionnaires. Secondary outcomes include quality of life, structure of digital microvasculature, body composition, physical fitness, and functional capacity. Discussion: Data from this multi-centre research clinical trial will primarily be used to establish the effectiveness of a combined exercise protocol to improve pain and fatigue in SSc. In parallel, this study will be the first to explore the effects of long-term exercise on potential microvascular alterations assessed via NVC. Overall, this study will provide sufficient data to inform current clinical practice guidelines and may lead to an improvement of QoL for patients with SSc. Show less
This thesis showed that there appears much room for improvement in optimizing physical activity and exercise of people with axial spondyloarthritis (axSpA), both in patients using and not using... Show moreThis thesis showed that there appears much room for improvement in optimizing physical activity and exercise of people with axial spondyloarthritis (axSpA), both in patients using and not using individual physical therapy and axSpA-specific group exercise. Although recommended, only a minority engages in high-intensity aerobic physical activity and in strengthening and mobility exercise with the recommended frequency. This is also the case in people with axSpA using physical therapy. Furthermore, certain evidence-based enhancements in axSpA-specific exercise groups seem warranted. A pilot implementation of these enhancements was found to be partially successful and a number of barriers remain to be overcome in a larger-scale implementation. Because only a small minority of people with axSpA participate in such exercise groups, it is also desired to implement modifications to individual physical therapy as well as interventions in which people with axSpA can participate independently (without supervision). A number of components of such interventions were identified in this thesis. Show less
Background People living with axial Spondyloarthrtis (axSpA) have an increased risk of cardiovascular diseases, which can be reduced by regular physical activity (PA) and its subset of... Show moreBackground People living with axial Spondyloarthrtis (axSpA) have an increased risk of cardiovascular diseases, which can be reduced by regular physical activity (PA) and its subset of cardiorespiratory training (CRT). To fulfil their crucial role in PA promotion, physiotherapists and other health professionals need to understand the beliefs that people living with axSpA possess concerning general PA and CRT. The aim of this study is to explore these behavioural, normative and control beliefs. Methods A qualitative descriptive design approach was chosen. Five semi-structured focus group interviews with 24 individuals living with axSpA were performed. Data was analysed using structured thematic qualitative content analysis. Results People with axSpA possessed multifaceted behavioural, normative and control beliefs concerning general PA and CRT. Behavioural beliefs revealed a positive attitude towards general PA, with participants mentioning numerous physical, psychological, and social benefits and only few risks. However, the conceptual difference between general PA and CRT, and the relevance of CRT, was unclear to some participants. Normative beliefs were expressed as the beliefs of significant others that influenced their motivation to comply with such beliefs, e.g. spouses, other people living with axSpA, rheumatologists. Regarding control beliefs, general PA and CRT were both mentioned as effective self-management strategies to control the disease. From experience, a high level of self-discipline, as well as technology, were shown to be useful. Conclusions General PA is understood to be an important self-management strategy for people with axSpA and most participants build general PA into their daily routines. They believe that general PA beneficially impacts personal health and wellbeing. However, some participants are unaware of the difference between general PA and CRT and the important impact that this difference could have on their health. The consequences of CRT promotion for people living with axSpA should be the subject of further research. Show less
Noorduyn, J.C.A.; Graaf, V.A. van de; Willigenburg, N.W.; Scholten-Peeters, G.G.M.; Mol, B.W.; Heymans, M.W.; ... ; ESCAPE Res Grp 2022
Purpose Marker-by-treatment analyses are promising new methods in internal medicine, but have not yet been implemented in orthopaedics. With this analysis, specific cut-off points may be obtained,... Show morePurpose Marker-by-treatment analyses are promising new methods in internal medicine, but have not yet been implemented in orthopaedics. With this analysis, specific cut-off points may be obtained, that can potentially identify whether meniscal surgery or physical therapy is the superior intervention for an individual patient. This study aimed to introduce a novel approach in orthopaedic research to identify relevant treatment selection markers that affect treatment outcome following meniscal surgery or physical therapy in patients with degenerative meniscal tears. Methods Data were analysed from the ESCAPE trial, which assessed the treatment of patients over 45 years old with a degenerative meniscal tear. The treatment outcome of interest was a clinically relevant improvement on the International Knee Documentation Committee Subjective Knee Form at 3, 12, and 24 months follow-up. Logistic regression models were developed to predict the outcome using baseline characteristics (markers), the treatment (meniscal surgery or physical therapy), and a marker-by-treatment interaction term. Interactions with p < 0.10 were considered as potential treatment selection markers and used these to develop predictiveness curves which provide thresholds to identify marker-based differences in clinical outcomes between the two treatments. Results Potential treatment selection markers included general physical health, pain during activities, knee function, BMI, and age. While some marker-based thresholds could be identified at 3, 12, and 24 months follow-up, none of the baseline characteristics were consistent markers at all three follow-up times. Conclusion This novel in-depth analysis did not result in clear clinical subgroups of patients who are substantially more likely to benefit from either surgery or physical therapy. However, this study may serve as an exemplar for other orthopaedic trials to investigate the heterogeneity in treatment effect. It will help clinicians to quantify the additional benefit of one treatment over another at an individual level, based on the patient's baseline characteristics. Show less
Hall, M.; Esch, M. van der; Hinman, R.S.; Peat, G.; Zwart, A. de; Quicke, J.G.; ... ; Bennell, K.L. 2022
Hip and knee osteoarthritis (OA) are leading causes of global disability. Most research to date has focused on the knee, with results often extrapolated to the hip, and this extends to treatment... Show moreHip and knee osteoarthritis (OA) are leading causes of global disability. Most research to date has focused on the knee, with results often extrapolated to the hip, and this extends to treatment recommendations in clinical guidelines. Extrapolating results from research on knee OA may limit our understanding of disease characteristics specific to hip OA, thereby constraining development and implementation of effective treatments. This review highlights differences between hip and knee OA with respect to prevalence, prognosis, epigenetics, pathophysiology, anatomical and biomechanical factors, clinical presentation, pain and non-surgical treatment recommendations and management. (c) 2021 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved. Show less
Background Blockade of cardiac sympathetic fibers by thoracic epidural anesthesia (TEA) was previously shown to reduce right and left ventricular systolic function and effective pulmonary arterial... Show moreBackground Blockade of cardiac sympathetic fibers by thoracic epidural anesthesia (TEA) was previously shown to reduce right and left ventricular systolic function and effective pulmonary arterial elastance. At conditions of constant paced heart rate, cardiac output and systemic hemodynamics were unchanged. In this study, we further investigated the effect of cardiac sympathicolysis during physical stress and increased oxygen demand.Methods In a cross-over design, 12 patients scheduled to undergo thoracic surgery performed dynamic ergometric exercise tests with and without TEA. Hemodynamics were monitored and biventricular function was measured by transthoracic two-dimensional and M-mode echocardiography, pulsed wave Doppler and tissue Doppler imaging.Results TEA attenuated systolic RV function (TV SMODIFIER LETTER PRIME: - 21%, P < 0.001) and LV function (MV SMODIFIER LETTER PRIME: - 14%, P = 0.025), but biventricular diastolic function was not affected. HR (- 11%, P < 0.001), SVI (- 15%, P = 0.006), CI (- 21%, P < 0.001) and MAP (- 12%, P < 0.001) were decreased during TEA, but SVR was not affected. Exercise resulted in significant augmentation of systolic and diastolic biventricular function. During exercise HR, SVI, CI and MAP increased (respectively, + 86%, + 19%, + 124% and + 17%, all P < 0.001), whereas SVR decreased (- 49%, P < 0.001). No significant interactions between exercise and TEA were found, except for RPP (P = 0.024) and MV E DT (P = 0.035).Conclusion Cardiac sympathetic blockade by TEA reduced LV and RV systolic function but did not significantly blunt exercise-induced increases in LV and RV function. These data indicate that additional mechanisms besides those controlled by the cardiac sympathetic nervous system are involved in the regulation of cardiac function during dynamic exercise. Show less
Bongers-Karmaoui, M.N.; Jaddoe, V.W.V.; Roest, A.A.W.; Gaillard, R. 2020
Stress inducement by physical exercise requires major cardiovascular adaptations in both adults and children to maintain an adequate perfusion of the body. As physical exercise causes a stress... Show moreStress inducement by physical exercise requires major cardiovascular adaptations in both adults and children to maintain an adequate perfusion of the body. As physical exercise causes a stress situation for the cardiovascular system, cardiovascular exercise stress tests are widely used in clinical practice to reveal subtle cardiovascular pathology in adult and childhood populations with cardiac and cardiovascular diseases. Recently, evidence from small studies suggests that the cardiovascular stress response can also be used within research settings to provide novel insights on subtle differences in cardiovascular health in non-diseased adults and children, as even among healthy populations an abnormal response to physical exercise is associated with an increased risk of cardiovascular diseases. This narrative review is specifically focused on the possibilities of using the cardiovascular stress response to exercise combined with advanced imaging techniques in pediatric population-based studies focused on the early origins of cardiovascular diseases. We discuss the physiology of the cardiovascular stress response to exercise, the type of physical exercise used to induce the cardiovascular stress response in combination with advanced imaging techniques, the obtained measurements with advanced imaging techniques during the cardiovascular exercise stress test and their associations with cardiovascular health outcomes. Finally, we discuss the potential for cardiovascular exercise stress tests to use in pediatric population-based studies focused on the early origins of cardiovascular diseases. Show less
Hilberdink, B.; Vlieland, T.V.; Giesen, F. van der; Gaalen, F. van; Goekoop, R.; Peeters, A.; ... ; Weely, S. van 2020
Introduction This study aimed to compare the engagement in moderate- and vigorous-intensity PA in axSpA patients with and without current physical therapy (PT). Methods In this cross-sectional... Show moreIntroduction This study aimed to compare the engagement in moderate- and vigorous-intensity PA in axSpA patients with and without current physical therapy (PT). Methods In this cross-sectional study, a survey, including current PT treatment (yes/no) and PA, using the 'Short QUestionnaire to ASsess Health-enhancing PA' (SQUASH), was sent to 458 axSpA patients from three Dutch hospitals. From the SQUASH, the proportions meeting aerobic PA recommendations (>= 150 min/week moderate-, >= 75 min/week vigorous-intensity PA or equivalent combination; yes/no) were calculated. To investigate the association between PT treatment and meeting the PA recommendations, odds ratios (OR) with 95% confidence intervals (95% CI) were estimated using logistic regression models, adjusting for sex, age, health status and hospital. Results The questionnaire was completed by 200 patients, of whom 68%, 50% and 82% met the moderate-, vigorous- or combined-intensity PA recommendations, respectively. Ninety-nine patients (50%) had PT treatment, and those patients were more likely to meet the moderate- (OR 2.09 [95% CI 1.09-3.99]) or combined-intensity (OR 3.35 [95% CI 1.38-8.13]) PA recommendations, but not the vigorous-intensity PA recommendation (OR 1.53 [95% CI 0.80-2.93]). Aerobic exercise was executed in 19% of individual PT programs. Conclusion AxSpA patients with PT were more likely to meet the moderate- and combined-intensity PA recommendations, whereas there was no difference in meeting the vigorous-intensity PA recommendation. Irrespective of having PT treatment, recommendations for vigorous-intensity PA are met by only half of the patients. Implementation should thus focus on aerobic PA in patients without PT and on vigorous-intensity PA in PT programs. Show less
Purpose Recombinant human erythropoietin (rHuEPO) is known to increase thrombotic risk in patients and might have similar effects in athletes abusing the drug. rHuEPO is prohibited by anti-doping... Show morePurpose Recombinant human erythropoietin (rHuEPO) is known to increase thrombotic risk in patients and might have similar effects in athletes abusing the drug. rHuEPO is prohibited by anti-doping legislation, but this risk has not been investigated thoroughly. This analysis was designed to evaluate whether rHuEPO impacts hemostatic profile and endothelial and platelet activation markers in trained subjects, and whether the combination with exercise affects exercise induced alterations. Methods This double-blind, randomized, placebo-controlled trial enrolled healthy, trained male cyclists aged 18-50 years. Participants were randomly allocated (1:1) to receive subcutaneous injections of rHuEPO (epoetin-beta; mean dose 6000 IU per week) or placebo (0.9% NaCl) for 8 weeks. Subjects performed five maximal exercise tests and a road race, coagulation and endothelial/platelet markers were measured at rest and directly after each exercise effort. Results rHuEPO increased P-selectin (+ 7.8% (1.5-14.5),p = 0.02) and E-selectin (+ 8.6% (2.0-15.7),p = 0.01) levels at rest. Maximal exercise tests significantly influenced all measured coagulation and endothelial/platelet markers, and in the rHuEPO group maximal exercise tests led to 15.3% ((7.0-24.3%),p = 0.0004) higher E-selectin and 32.1% ((4.6-66.8%),p = 0.0207) higher Platelet factor 4 (PF4) levels compared to the placebo group. Conclusion In conclusion, rHuEPO treatment resulted in elevated E- and P-selectin levels in trained cyclists, indicating enhanced endothelial activation and/or platelet reactivity. Exercise itself induces hypercoagulability, and the combination of rHuEPO and exercise increased E-selectin and PF4 levels more than either intervention alone. Based on this, exercise potentially increases thrombotic risk, a risk that might be enhanced in combination with rHuEPO use. Show less
Moseng, T.; Dagfinrud, H.; Bodegom-Vos, L. van; Dziedzic, K.; Hagen, K.B.; Natvig, B.; ... ; Osteras, N. 2020
BackgroundTo address the well-documented gap between hip and knee osteoarthritis (OA) treatment recommendations and current clinical practice, a structured model for integrated OA care was... Show moreBackgroundTo address the well-documented gap between hip and knee osteoarthritis (OA) treatment recommendations and current clinical practice, a structured model for integrated OA care was developed and evaluated in a stepped-wedge cluster-randomised controlled trial. The current study used secondary outcomes to evaluate clinically important response to treatment through the Outcome Measures in Rheumatology Clinical Trials clinical responder criteria (OMERACT-OARSI responder criteria) after 3 and 6months between patients receiving the structured OA care model vs. usual care. Secondly, the study aimed to investigate if the proportion of responders in the intervention group was influenced by adherence to the exercise program inherent in the model.MethodsThe study was conducted in primary healthcare in six Norwegian municipalities. General practitioners and physiotherapists received training in OA treatment recommendations and use of the structured model. The intervention group attended a physiotherapist-led OA education program and performed individually tailored exercises for 8-12weeks. The control group received usual care. Patient-reported pain, function and global assessment of disease activity during the last week were evaluated using 11-point numeric rating scales (NRS 0-10). These scores were used to calculate the proportion of OMERACT-OARSI responders. Two-level mixed logistic regression models were fitted to investigate differences in responders between the intervention and control group.ResultsTwo hundred eighty-four intervention and 109 control group participants with hip and knee OA recruited from primary care in six Norwegian municipalities. In total 47% of the intervention and 35% of the control group participants were responders at 3 or 6months combined; showing an uncertain between-group difference (ORadjusted 1.38 (95% CI 0.41, 4.67). In the intervention group, 184 participants completed the exercise programme (exercised >= 2 times/week for >= 8weeks) and 55% of these were classified as responders. In contrast, 28% of the 86 non-completers were classified as responders.ConclusionsThe difference in proportion of OMERACT-OARSI responders at 3 and 6months between the intervention and control group was uncertain. In the intervention group, a larger proportion of responders were seen among the exercise completers compared to the non-completers.Clinical trial registrationClinicaltrials.gov identifier: NCT02333656. Registered 7. January 2015. Show less
Metsios, G.S.; Moe, R.H.; Esch, M. van der; Zanten, J.J.C.S.V. van; Fenton, S.A.M.; Koutedakis, Y.; ... ; IMPACT-RMD Consortium 2019
Cardiovascular disease (CVD) morbidity and mortality is highly prevalent in patients with rheumatoid arthritis (RA) with debilitating effects for the individual as well as significant healthcare... Show moreCardiovascular disease (CVD) morbidity and mortality is highly prevalent in patients with rheumatoid arthritis (RA) with debilitating effects for the individual as well as significant healthcare impact. Current evidence demonstrates that engaging in aerobic and resistance exercise (i.e. structured physical activity) can significantly improve patient-reported and clinical index-assessed outcomes in RA. In addition to this, engagement in exercise programmes improves, in a dose-dependent manner, the risk of developing CVD as well as CVD symptoms and outcomes. The present narrative review uses evidence from systematic reviews and meta-analyses as well as controlled trials, to synthesize the current state-of-the-art on the potential effects of aerobic and resistance exercise on CVD risk factors as well as on cardiac and vascular function and structure in people with RA. Where there is a lack of evidence in RA to explain potential mechanisms, relevant studies from the general population are also discussed and linked to RA. Show less
Some athletes use prohibited substances, a relevant problem given the coverage on doping in the media. In addition not all these athletes are being caught and clean athletes are sometimes falsely... Show moreSome athletes use prohibited substances, a relevant problem given the coverage on doping in the media. In addition not all these athletes are being caught and clean athletes are sometimes falsely accused. In short, doping is a problem in sports and society. The goal of this thesis is to contribute to a solution to this problem by applying knowledge of (clinical) pharmacology to handling the use and detection of doping. First, our research shows that there is no convincing evidence for performance enhancement for 18 out of 23 substance classes on the Prohibit List. This is problematic and is mainly due to a lack of knowledge. For this reason we evaluated one of the substances, erythropoietin (EPO), in a study that could serve as a model study for evaluating potential doping substances. This study showed that although EPO did have effects, EPO-treated cyclists did not perform any better than placebo-treated cyclists in a time trial or an uphill road race. Additionally, the doping detection methods we evaluated, for EPO and salbutamol, proved to have shortcomings in detecting cheating and protecting innocent athletes. Concluding, anti-doping efforts will need to become more evidence-based to effectively tackle the doping problem. Show less
Bos, M.M.; Noordam, R.; Blauw, G.J.; Slagboom, P.E.; Rensen, P.C.N.; Heemst, D. van 2019
Duchenne muscular dystrophy is a severe muscle wasting disease, characterized by a severely reduced lifespan in which cardiomyopathy is one of the leading causes of death. Multiple therapies aiming... Show moreDuchenne muscular dystrophy is a severe muscle wasting disease, characterized by a severely reduced lifespan in which cardiomyopathy is one of the leading causes of death. Multiple therapies aiming at dystrophin restoration have been approved. It is anticipated that these therapies will maintain muscle function for longer and extend the ambulatory period, which in turn will increase the cardiac workload which could be detrimental for cardiac function. We investigated the effects of voluntary running exercise in combination with low dystrophin levels on function and pathology of skeletal muscle and heart. We divided 15.5-month old female mdx (no dystrophin), mdx-Xist(Delta hs) (varying low dystrophin levels) and wild type mice (BL10-WT and Xist(Delta hs)-WT) to either a sedentary or voluntary wheel running regime and assessed muscle function at 17.5 months of age. Thereafter, a cardiac MRI was obtained, and muscle and heart histopathology were assessed. We show that voluntary exercise is beneficial to skeletal muscle and heart function in dystrophic mice while not affecting muscle pathology. Low amounts of dystrophin further improve skeletal muscle and cardiac function. These findings suggest that voluntary exercise may be beneficial for skeletal muscle and heart in DMD patients, especially in conjunction with low amounts of dystrophin. Show less
