Muscle Function In Patients Research Articles

Short-term effects of Theracurmin dose and exercise type on pain, walking ability, and muscle function in patients with knee osteoarthritis.

The purpose of this study was to investigate the short-term of Theracurmin dose and exercise type on pain, walking ability, and muscle function in patients with knee osteoarthritis. Twenty-five patients with knee osteoarthritis randomly selected to Theracurmin intake (T) group and Theracurmin in combined with exercise (T+E) group. T group (n= 13) was taken orally a capsule of 700 mg, 3 times per day, (total 2,100 mg, 35 mg/kg-body weight). T+E group (n= 12) performed aerobic training of 30-min walking and weight training for increasing leg muscular strength. After treatment, the number of steps, muscle mass, range of motion of knee, and the muscle strength in flexion and extension significantly increased. The percent body fat, visual analogue scale, The Western Ontario and McMaster score, centers of pressure with closed eye, 10-m walking ability, stair ascending speed were significantly decreased after treatment. Although no difference observed between the T and T+E groups, the 4-week intake of Theracurmin with and without exercise appeared to be effective in reducing the pain and enhancing muscular and balancing function. Therefore, Theracurmin intake for early symptoms and additional exercise as symptoms alleviate might be an effective way of delaying and managing osteoarthritis, and additional studies investigating the effects of Theracurmin and exercise on osteoarthritis could be beneficial.

Myasthenia gravis: the role of complement at the neuromuscular junction

Generalized myasthenia gravis (gMG) is a rare autoimmune disorder characterized by skeletal muscle weakness caused by disrupted neurotransmission at the neuromuscular junction (NMJ). Approximately 74-88% of patients with gMG have acetylcholine receptor (AChR) autoantibodies. Complement plays an important role in innate and antibody-mediated immunity, and activation and amplification of complement results in the formation of membrane attack complexes (MACs), lipophilic proteins that damage cell membranes. The role of complement in gMG has been demonstrated in animal models and patients. Studies in animals lacking specific complement proteins have confirmed that MAC formation is required to induce experimental autoimmune MG (EAMG) and NMJ damage. Complement inhibition in EAMG models can prevent disease induction and reverse its progression. Patients with anti-AChR+ MG have autoantibodies and MACs present at NMJs. Damaged NMJs are associated with more severe disease, fewer AChRs, and MACs in synaptic debris. Current MG therapies do not target complement directly. Eculizumab is a humanized monoclonal antibody that inhibits cleavage of complement protein C5, preventing MAC formation. Eculizumab treatment improved symptoms compared with placebo in a phase II study in patients with refractory gMG. Direct complement inhibition could preserve NMJ physiology and muscle function in patients with anti-AChR+ gMG.

Quadriceps muscle thickness changes in patients with aneurysmal subarachnoid hemorrhage during the acute phase

BackgroundAneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening condition that often leads to severe disability in relatively young and healthy people. This disability is physical in many aSAH survivors, so muscle dysfunction may be an important factor in the functional level of these patients. Thus, measuring muscle thickness represents a suitable method for determining muscle function in patients with acute aSAH, because the disordered consciousness often experienced during the acute phase causes active movement to be difficult for these patients.ObjectivesWe investigated changes in quadriceps muscle thickness in patients with aneurysmal subarachnoid hemorrhage to determine whether muscle dysfunction during the acute phase relates to (or predicts) the outcome of aSAH.MethodsSeventeen patients with aSAH (mean age = 66 ± 11, men/women = 4/13) were enrolled, and their quadriceps muscle thickness measured ultrasonographically upon admission and again 2 weeks later.ResultsQuadriceps muscle thickness significantly decreased from admission (mean = 3.00 ± 0.72 cm) to the second measurement (2.67 ± 0.74 cm, p = 0.001). The relative differences in quadriceps muscle thickness were correlated with the Hunt and Hess grade (r = −0.72, p = 0.001) and the modified Rankin Scale score at 90 days (r = −0.78, p = 0.0002).ConclusionsOur results indicate that quadriceps muscle thickness decreases in patients with acute aneurysmal subarachnoid hemorrhage, particularly in patients with poor Hunt and Hess grade or marked disability.

The reason for a high Ca2+-sensitivity associated with Arg91Gly substitution in TPM2 gene is the abnormal behavior and high flexibility of tropomyosin during the ATPase cycle

Substitution of Arg for Gly residue in 91th position in β-tropomyosin caused by a point mutation in TPM2 gene is associated with distal arthrogryposis, characterized by a high Ca2+-sensitivity of myofilament and contracture syndrome. To understand the mechanisms of this defect, we studied multistep changes in mobility and spatial arrangement of tropomyosin, actin and myosin heads during the ATPase cycle in reconstituted ghost fibres, using the polarized fluorescence microscopy. The mutation was shown to markedly decrease the bending stiffness of β-tropomyosin in the thin filaments. In the absence of the myosin heads the mutation did not alter the ability of troponin to shift tropomyosin to the blocked position and to switch actin monomers off at low Ca2+. During the ATPase cycle the movement of the mutant tropomyosin is restrained, it is located near the open position, which allows strong binding of the myosin heads to actin even at low Ca2+. This may be the reason for both high Ca2+-sensitivity and contractures associated with the Arg91Gly mutation. The use of reagents that decrease the Ca2+sensitivity of the troponin complex may not be appropriate to restore muscle function in patients with this mutation.

Long term longitudinal study of muscle function in patients with glycogen storage disease type IIIa.

Glycogen storage disease type III (GSDIII) is an autosomal recessive disorder caused by mutations in the AGL gene coding for the glycogen debranching enzyme. Current therapy is based on dietary adaptations but new preclinical therapies are emerging. The identification of outcome measures which are sensitive to disease progression becomes critical to assess the efficacy of new treatments in upcoming clinical trials. In order to prepare future longitudinal studies or therapeutic trials with large cohorts, information about disease progression is required. In this study we present preliminary longitudinal data of Motor Function Measure (MFM), timed tests, Purdue pegboard test, and handgrip strength collected over 5 to 9years of follow-up in 13 patients with GSDIII aged between 13 and 56years old. Follow-up for nine of the 13 patients was up to 9years. Similarly to our previous cross-sectional retrospective study, handgrip strength significantly decreased with age in patients older than 37years. MFM scores started to decline after the age of 35. The Purdue pegboard score also significantly reduced with increasing age (from 13years of age) but with large inter-visit variations. The time to stand up from a chair or to climb 4 stairs increased dramatically in some but not all patients older than 30years old. In conclusion, this preliminary longitudinal study suggests that MFM and handgrip strength are the most sensitive muscle function outcome measures in GSDIII patients from the end of their third decade. Sensitive muscle outcome measures remain to be identified in younger GSDIII patients but is challenging as muscle symptoms remain discrete and often present as accumulated fatigue.

Muscle metabolism.

To review the recent findings on metabolic derangements leading to loss of muscle mass and function. Several recent studies investigated methods to assess muscle mass and function and its clinical relevance. These are also included. A few studies confirm that a low muscle mass is related to a worse outcome but also a compromised muscle function at discharge is related to long-term survival. A low quality of muscle assessed by the density of muscle from a computed tomography scan is related to mortality. For the metabolic derangements, a compromised handling of calcium is present in muscle of animal models and might be causing a decreased muscle function in patients. Transcriptomics analyses of muscle post-ICU indicated an upregulation of regenerative pathways, but still muscle mass is not recovering in most patients. This could be due to an impairment regenerative capacity due to satellite cells dysfunction. Muscle mass and function are related to outcome. New finding show that not only muscle mass but also muscle quality is important, that a compromised handling of calcium might be involved in muscle weakness and that regaining muscle could be compromised due to a defective regenerative capacity of satellite cells.

Gait deficiencies associated with peripheral artery disease are different than chronic obstructive pulmonary disease

ObjectivePrevious studies have indicated that patients with peripheral artery disease (PAD), display significant differences in their kinetic and kinematic gait characteristics when compared to healthy, aged-matched controls. The ability of patients with chronic obstructive pulmonary disease (COPD) to ambulate is also limited. These limitations are likely due to pathology-driven muscle morphology and physiology alterations establish in PAD and COP, respectively. Gait changes in PAD were compared to gait changes due to COPD to further understand how altered limb muscle due to disease can alter walking patterns. Both groups were independently compared to healthy controls. It was hypothesized that both patients with PAD and COPD would demonstrate similar differences in gait when compared to healthy controls. MethodsPatients with PAD (n=25), patients with COPD (n=16), and healthy older control subjects (n=25) performed five walking trials at self-selected speeds. Sagittal plane joint kinematic and kinetic group means were compared. ResultsPeak values for hip flexion angle, braking impulse, and propulsive impulse were significantly reduced in patients with symptomatic PAD compared to patients with COPD. After adjusting for walking velocity, significant reductions (p<0.05) in the peak values for hip flexion angle, dorsiflexor moment, ankle power generation, propulsion force, braking impulse, and propulsive impulse were found in patients with PAD compared to healthy controls. No significant differences were observed between patients with COPD and controls. ConclusionsThe results of this study demonstrate that while gait patterns are impaired for patients with PAD, this is not apparent for patients with COPD (without PAD). PAD (without COPD) causes changes to the muscle function of the lower limbs that affects gait even when subjects walk from a fully rested state. Altered muscle function in patients with COPD does not have a similar effect.

Approches thérapeutiques communes de la sarcopénie du sujet âgé et de la myopathie urémique

The gradual loss of weight and function of muscle in patients with chronic kidney disease as in the elderly impacts the quality of life. Early management should help slow the functional limitation. Physical activity is the first therapy to propose that ensures stability of muscle mass and improved function. Resistance training programs have proven effective but are not yet widely available in nephrology units. The nutritional management should not be forgotten because there is a resistance to anabolism and protein intake should be involved in physical activity program. Associated treatments should not be neglected: vitamin D, anti-inflammatory, androgens. Some are still under evaluation. Therapeutic option, tomorrow, could be anti-myostatin antibodies and glitazones.

Muscle Function in Osteogenesis Imperfecta Type IV.

Results of previous studies suggest that children and adolescents with osteogenesis imperfecta (OI) type IV have muscle force deficits. However, muscle function remains to be objectively quantified in this population. This study aimed to assess upper and lower extremity muscle function in patients with OI type IV. It was carried out in the outpatient department of a pediatric orthopedic hospital; 27 individuals with OI type IV (7-21years; 13 males), 27 age- and sex-matched individuals with OI type I, and 27 age- and sex-matched controls. Upper extremity muscle force was assessed with hydraulic hand dynamometry, and lower extremity muscle function (peak force per body weight and peak power per body mass) was measured by mechanography through five tests: multiple two-legged hopping, multiple one-legged hopping, single two-legged jump, chair-rise test, and heel-rise test. Upper-limb grip force was normal for patients with OI type IV when compared to height and sex reference data (average z-score=0.17±1.30; P=0.88). Compared to age- and sex-matched controls, patients with OI type IV had approximately 30% lower-limb peak force and 50% peak power deficits (P values<0.05). At the lower-limb level, they had a 50% lower peak power than age- and sex-matched patients with OI type I (P<0.05). Patients with OI type IV have normal upper-limb muscle force but a muscle function deficit at the lower-limb level. These results suggest that lower-limb muscle weakness may contribute to functional deficits in these individuals.

Lower-limb muscle function is a determinant of exercise tolerance after lung resection surgery in patients with lung cancer.

This study aims to investigate the association between exercise tolerance, pulmonary function and lower-limb muscle function in patients with lung cancer who underwent lung resection surgery in the previous year. Sixty-four patients (age: 67 ± 11 years, 66% males) performed a symptom-limited incremental cycle test to define peak oxygen consumption (VO2 peak) and peak workload (Wpeak). The best of two 6-min walking distance (6MWD) tests was also included. Isometric quadriceps strength and isokinetic quadriceps endurance were measured. Post-bronchodilator spirometry, lung volumes and diffusing capacity of the lung for carbon monoxide (DLCO ) measurements were assessed. Univariate correlation analysis and multiple regression analyses were performed. VO2 peak, W peak and 6MWD showed moderate to strong correlations with quadriceps strength/endurance and DLCO while weak to moderate correlations were found with forced expiratory volume in 1 s (FEV1) , functional residual capacity (FRC) and body weight. Multiple regression showed that peak isometric quadriceps strength (P < 0.001) and DLCO (P < 0.001) were significant predictors of VO2 peak (explained variance R2 = 0.67), while quadriceps endurance (P = 0.0015) and DLCO (P < 0.0001) were significant predictors of W peak (R2 = 0.61). Quadriceps endurance capacity (P = 0.013), but not DLCO , significantly contributed to the 6MWD model (R2 = 0.29). We identified a strong significant relationship between peak aerobic capacity and quadriceps muscle function and lung diffusing capacity. 6MWD was significantly related to quadriceps muscle function but not to pulmonary function. These findings suggest that accurate assessment of lower-limb muscle strength has a role in the accurate interpretation of exercise tests and in selecting optimal candidates for resistance training interventions targeting the lower-limb muscles after resection surgery.

ACTA1-Related Nemaline Myopathy Mutations Engender a Range of Structural and Functional Phenotypes in Drosophila Indirect Flight Muscles

Nemaline myopathy is a congenital disorder characterized by muscle weakness. Dominant-negative disease-causing mutations have been identified in various genes that encode sarcomeric thin filament proteins. of these, mutations in skeletal muscle α-actin (ACTA1) account for ∼25% of all reported cases. To investigate the myopathic phenotypes from the level of whole muscle down through the level of single molecules, we generated multiple transgenic Drosophila fly lines expressing three different mutations - V37L, D288G and F352S - in Act88F, the indirect flight muscle (IFM) actin gene. A gradation in flight behavior was observed (V37L>D288G>F352S), which correlated with the observed differences in muscle fiber morphology. While most of these mutations depress muscle function in patients, the F352S lesion elevates myosin cross-bridge strain and steady-state isometric force production and, thereby, apparently increases contractile function. Confocal and electron microscopy revealed breaks in mutant F352S IFM fibers and extensive myofibrillar and myofilamentous disarray. Z-lines showed streaming and formed “zebra bodies”. The microscopic alterations are consistent with excessive acto-myosin interactions, unevenly distributed force, and destructive hypercontraction. Interestingly, in vitro sliding velocities of purified IFM F-actin from wild-type (3.17±0.12 μm/s) vs. F352S mutant heterozygous (2.88±0.09 μm/s, mean±SEM) flies did not significantly differ. Similarly, no differences in maximum calcium-activated velocity (3.88±0.11 vs. 3.77±0.10 μm/s) or in cooperativity (nH = 2.13±0.27 vs. 2.62±0.46) were observed for F-actin in the presence of vertebrate tropomyosin and troponin. However, relative to control, F352S heterozygous filaments showed a significant (p<0.01) increase in calcium sensitivity (pCa50 = 5.99±0.03 vs. 6.11±0.03), consistent with a mutation-induced gain in molecular function. Going forward, our novel Drosophila models will be used to screen for in vivo modifiers of mutant muscle performance. Supported by NIH R01HL124091 to AC.

Relationship Between Mandibular Ramus Height and Masticatory Muscle Function in Patients With Unilateral Hemifacial Microsomia.

To clarify the relationship between mandibular ramus height and function of masticatory muscles in patients with hemifacial microsomia. Retrospective study of imaging and physiological data. Images and physiological data were obtained from the records of Sapporo Medical University Hospital. A total of 29 patients with hemifacial microsomia who showed Pruzansky grades I, II deformity. Mandibular ramus height and masticatory muscle volume were evaluated with multi-detector row computed tomography. The electromyographic value was measured by the K7 Evaluation System. The hemifacial microsomia patients were classified into three groups based on the mandibular ramus height ratio of the affected and unaffected sides: group 0, >1.00; group 1, 1.00 to 0.85; group 2, <0.85. The Tukey-Kramer method and Games-Howell method were used to determine correlations between parameters. Decreased mandibular ramus height was significantly correlated with both reduced electromyographic values of the masseter muscle (P < .05) and the amount of mandibular lateral deviation at the time of maximum opening (P < .05) on the affected side. These differences were prominent in unilateral hemifacial microsomia patients classified as group 2. Decreased mandibular ramus height may cause dysfunction of the masseter muscles but not the temporal muscle on the affected side in patients with hemifacial microsomia.

Association between severe asthma and changes in the stomatognathic system.

ABSTRACTObjective:To describe orofacial muscle function in patients with severe asthma. Methods:This was a descriptive study comparing patients with severe controlled asthma (SCA) and severe uncontrolled asthma (SUA). We selected 160 patients, who completed a sociodemographic questionnaire and the 6-item Asthma Control Questionnaire (ACQ-6), as well as undergoing evaluation of orofacial muscle function. Results:Of the 160 patients evaluated, 126 (78.8%) and 34 (21.2%) presented with SCA and SUA, respectively, as defined by the Global Initiative for Asthma criteria. Regardless of the level of asthma control, the most frequent changes found after evaluation of muscle function were difficulty in chewing, oronasal breathing pattern, below-average or poor dental arch condition, and difficulty in swallowing. When the sample was stratified by FEV1 (% of predicted), was significantly higher proportions of SUA group patients, compared with SCA group patients, showed habitual open-mouth chewing (24.8% vs. 7.7%; p < 0.02), difficulty in swallowing water (33.7% vs. 17.3%; p < 0.04), and voice problems (81.2% vs. 51.9%; p < 0.01). When the sample was stratified by ACQ-6 score, the proportion of patients showing difficulty in swallowing bread was significantly higher in the SUA group than in the SCA group (66.6% vs. 26.6%; p < 0.01). Conclusions:The prevalence of changes in the stomatognathic system appears to be high among adults with severe asthma, regardless of the level of asthma control. We found that some such changes were significantly more common in patients with SUA than in those with SCA.

Impact of Non-Invasive Ventilation on Sympathetic Nerve Activity in Chronic Obstructive Pulmonary Disease.

Chronic obstructive pulmonary disease (COPD) is associated with elevated sympathetic nerve activity, which is probably linked to an increased cardiovascular risk, and may contribute to muscle dysfunction by heightened muscle vasoconstrictor drive. We hypothesized that resistive unloading of respiratory muscles by intermittent non-invasive ventilation (NIV) reduces sympathetic tone at rest and during subsequent handgrip exercise in patients with COPD. Muscle sympathetic nerve activity (MSNA) in the peroneal nerve, heart rate, blood pressure, CO2, and SpO2 were continuously recorded in 5 COPD patients with intermittent NIV and 11 control COPD patients without NIV. Static and dynamic handgrip exercises were performed before and after NIV. At baseline, heart rate-adjusted MSNA (bursts/100 heart beats) did not differ between groups. NIV did not significantly affect MSNA levels at rest. However, during handgrip exercises directly following NIV, MSNA was lower than before, which was significant for dynamic handgrip (67.00±3.70 vs. 62.13±4.50 bursts/100 heart beats; p=0.035 in paired t test). In contrast, MSNA (non-significantly) increased in the control group during repeated dynamic or static handgrip. During dynamic handgrip, tCO2 was lower after NIV than before (change by -5.04±0.68mmHg vs. -0.53±0.64 in the control group; p=0.021), while systolic and diastolic blood pressure did not change significantly. NIV reduces sympathetic activation during subsequent dynamic handgrip exercise and thereby may elicit positive effects on the cardiovascular system as well as on muscle function in patients with COPD.

Muscle MRI Findings in Childhood/Adult Onset Pompe Disease Correlate with Muscle Function.

ObjectivesEnzyme replacement therapy has shown to be effective for childhood/adult onset Pompe disease (AOPD). The discovery of biomarkers useful for monitoring disease progression is one of the priority research topics in Pompe disease. Muscle MRI could be one possible test but the correlation between muscle MRI and muscle strength and function has been only partially addressed so far.MethodsWe studied 34 AOPD patients using functional scales (Manual Research Council scale, hand held myometry, 6 minutes walking test, timed to up and go test, time to climb up and down 4 steps, time to walk 10 meters and Motor Function Measure 20 Scale), respiratory tests (Forced Vital Capacity seated and lying, Maximun Inspiratory Pressure and Maximum Expiratory Pressure), daily live activities scales (Activlim) and quality of life scales (Short Form-36 and Individualized Neuromuscular Quality of Life questionnaire). We performed a whole body muscle MRI using T1w and 3-point Dixon imaging centered on thighs and lower trunk region.ResultsT1w whole body muscle MRI showed a homogeneous pattern of muscle involvement that could also be found in pre-symptomatic individuals. We found a strong correlation between muscle strength, muscle functional scales and the degree of muscle fatty replacement in muscle MRI analyzed using T1w and 3-point Dixon imaging studies. Moreover, muscle MRI detected mild degree of fatty replacement in paraspinal muscles in pre-symptomatic patients.ConclusionBased on our findings, we consider that muscle MRI correlates with muscle function in patients with AOPD and could be useful for diagnosis and follow-up in pre-symptomatic and symptomatic patients under treatment.Take home messageMuscle MRI correlates with muscle function in patients with AOPD and could be useful to follow-up patients in daily clinic.

Effects of Exercise Training on Delaying Disease Progression in Patients with Chronic Kidney Disease: a Review of the Literature.

Chronic Kidney Disease (CKD) is an important public health problem throughout the world. The effects of exercise training are unclear in patients with CKD. This review aimed to evaluate the effects of exercise training to delay the progression of CKD and which training style is most effective. We developed individualized search strategies for the National Library of Medicine including the PubMed MeSH database to June 2015. We searched articles related to exercise training and kidney disease using the terms "CKD", "renal disease", "renal insufficiency", "renal failure", "end-stage renal disease (ESRD)" and "physical therapy". We searched only for reports in English and for full free papers. We also chose papers based on the references in the papers obtained by the search. Our search identified 6 different trials including 131 participants. Our review of these 6 studies suggests that aerobic exercise training may improve exercise capacity, and resistance training may also improve muscle function in patients with CKD. No cardiac events were reported in any of the published exercise training studies reviewed, suggesting the safety of exercise in patients with CKD.

Paper of note in Science Translational Medicine

This week’s article describes how the mechanical stress response could be exploited to maintain diaphragm muscle function in patients needing ventilation support.

Physical Fatigue, Fitness, and Muscle Function in Patients With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

This study investigated differences in cardiorespiratory fitness, muscular function, perceived exertion, and anxiety/depression between patients and healthy controls (HCs) and assessed which of these variables may account for the fatigue experienced by patients. Fatigue was measured in 48 antineutrophil cytoplasmic antibody-associated vasculitis patients and 41 healthy controls using the Multidimensional Fatigue Inventory (MFI-20), focusing on the physical component. Quality of life, anxiety/depression, and sleep quality were assessed by validated questionnaires. Muscle mass was measured by dual-energy x-ray absorptiometry scan, strength as the maximal voluntary contraction (MVC) force, and endurance as sustained isometric contraction at 50% MVC of the quadriceps. Voluntary activation was assessed by superimposed electrical stimulation. Cardiorespiratory fitness ( ˙Vo2 max and oxygen pulse [O2 pulse]) and perceived exertion (Borg scale) were measured during progressive submaximal exercise. Patients reported elevated physical fatigue scores compared to HCs (patients MFI-20 physical 13 [interquartile range (IQR) 8-16], HCs MFI-20 physical 5.5 [IQR 4-8]; P < 0.001). Muscle mass was the same in both groups, but MVC and time to failure in the endurance test were lower due to reduced voluntary activation in patients. Estimated ˙Vo2 max and O2 pulse were the same in both groups. For the same relative workload, patients reported higher ratings of perceived exertion, which correlated with reports of MFI-20 physical fatigue (R(2) = 0.2). Depression (R(2) = 0.6), anxiety (R(2) = 0.3), and sleep disturbance (R(2) = 0.3) were all correlated with MFI-20 physical fatigue. These observations suggest that fatigue in patients is of a central rather than peripheral origin, supported by associations of fatigue with heightened perception of exertion, depression, anxiety, and sleep disturbance but normal muscle and cardiorespiratory function.

Smooth Muscle Progenitor Cells Derived From Human Pluripotent Stem Cells Induce Histologic Changes in Injured Urethral Sphincter

The present study provides evidence that a pure population of human smooth muscle progenitor cells (pSMCs) derived from human pluripotent stem cells (hPSCs) (human embryonic stem cells and patient induced pluripotent stem cells) restores urethral sphincter function by two mechanisms: modulation of extracellular matrix protein metabolism in vivo and pSMC proliferation and differentiation into smooth muscle cells to regenerate the muscle layer in the lower urinary tract. These findings on the in vivo effects of human pSMCs should aid in optimizing regenerative therapies using human myoblasts.

Cross-sectional retrospective study of muscle function in patients with glycogen storage disease type III

Glycogen storage disease type III is an inherited metabolic disorder characterized by liver and muscle impairment. This study aimed to identify promising muscle function measures for future studies on natural disease progression and therapeutic trials. The age-effect on the manual muscle testing (MMT), the hand-held dynamometry (HHD), the motor function measure (MFM) and the Purdue pegboard test was evaluated by regression analysis in a cross-sectional retrospective single site study. In patients aged between 13 and 56 years old, the Purdue pegboard test and dynamometry of key pinch and knee extension strength were age-sensitive with annual losses of 1.49, 1.10 and 0.70% of the predicted values (%pred), respectively. The MFM score and handgrip strength were also age-sensitive but only in patients older than 29 and 37 years old with annual losses of 1.42 and 1.84%pred, respectively. Muscle strength assessed by MMT and elbow extension measured by HHD demonstrated an annual loss of less than 0.50%pred and are thus unlikely to be promising outcome measures for future clinical trials. In conclusion, our results identified age-sensitive outcomes from retrospective data and may serve for future longitudinal studies in which an estimation of the minimal number of subjects is provided.