Skeletal Muscle Function in Young Patients With Cystic Fibrosis

Purpose:Defects in the gene encoding the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) cause CF. Absence of the CFTR may result in skeletal muscle dysfunction. Here, we tested skeletal muscle function in male adolescent patients with CF.Methods:Ten CF and 10 control participants (age: 16.8 ± 0.6 years) performed 7 repetitive sets of maximum voluntary contractions (MVCs) and underwent an isometric fatigue test of the knee extensors. Electromyography (EMG) activity was recorded from the m. vastus lateralis (VL) and m. vastus medialis (VM).Results:In CF, the MVC torque was lower and correlated with the predicted forced expiratory volume in one second (r = .73, p = .012, n = 10). The M-wave in the VL was shorter in CF than in controls (18.6 ± 0.5 vs. 20.3 ± 0.5 ms, p < .028). In the VM, both the M-wave (4.96 ± 0.61 vs. 7.97 ± 0.60 mV, p = .001) and the EMG (0.29 ± 0.04 vs. 0.47 ± 0.04 mV, p = .004) amplitudes were smaller in CF.Conclusion:The differences in the VL and VM EMG signals between the groups indicate that the lower MVC torque in CF did not result from the direct impact of a CFTR defect on the sarcolemmal excitability; the differences more likely resulted from the less developed musculature in the patients with CF.

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Lower limb skeletal muscle function after 6 wk of bed rest

Journal of Applied Physiology ◽

10.1152/jappl.1997.82.1.182 ◽

1997 ◽

Vol 82 (1) ◽

pp. 182-188 ◽

Cited By ~ 176

Author(s):

H. E. Berg ◽

L. Larsson ◽

P. A. Tesch

Keyword(s):

Skeletal Muscle ◽

Lower Limb ◽

Muscle Function ◽

Fiber Type ◽

Vastus Lateralis ◽

Knee Extensor ◽

Bed Rest ◽

Emg Activity ◽

Type I ◽

Skeletal Muscle Function

Berg, H. E., L. Larsson, and P. A. Tesch. Lower limb skeletal muscle function after 6 wk of bed rest. J. Appl. Physiol. 82(1): 182–188, 1997.—Force, electromyographic (EMG) activity, muscle mass, and fiber characteristics were studied in seven healthy men before and after 6 wk of bed rest. Maximum voluntary isometric and concentric knee extensor torque decreased ( P < 0.05) uniformly across angular velocities by 25–30% after bed rest. Maximum quadricep rectified EMG decreased by 19 ± 23%, whereas submaximum (100-Nm isometric action) EMG increased by 44 ± 28%. Knee extensor muscle cross-sectional area (CSA), assessed by using magnetic resonance imaging, decreased by 14 ± 4%. Maximum torque per knee extensor CSA decreased by 13 ± 9%. Vastus lateralis fiber CSA decreased 18 ± 14%. Neither type I, IIA, and IIB fiber percentages nor their relative proportions of myosin heavy chain (MHC) isoforms were altered after bed rest. Because the decline in strength could not be entirely accounted for by decreased muscle CSA, it is suggested that the strength loss is also due to factors resulting in decreased neural input to muscle and/or reduced specific tension of muscle, as evidenced by a decreased torque/EMG ratio. Additionally, it is concluded that muscle unloading in humans does not induce important changes in fiber type or MHC composition or in vivo muscle contractile properties.

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Corticosteroids and skeletal muscle function in cystic fibrosis

Journal of Applied Physiology ◽

10.1152/japplphysiol.00506.2002 ◽

2003 ◽

Vol 95 (4) ◽

pp. 1379-1384 ◽

Cited By ~ 49

Author(s):

Sinead C. Barry ◽

Charles G. Gallagher

Keyword(s):

Skeletal Muscle ◽

Cystic Fibrosis ◽

Muscle Strength ◽

Muscle Weakness ◽

Muscle Function ◽

Knee Extensor ◽

Skeletal Muscle Function ◽

Peripheral Muscle ◽

Causative Effect ◽

Concomitant Medications

Patients with cystic fibrosis (CF) have reduced peripheral muscle strength. We tested the hypothesis that steroid treatment contributes to muscle weakness in adults with CF. Twenty-three stable CF patients were studied. Measurements included knee extensor (KE), knee flexor (KF), elbow flexor (EF), handgrip (HG), expiratory (Pemax), and inspiratory (Pimax) muscle strengths. Spirometry, body mass index (BMI), and days spent in hospital over the preceding 12 mo (DH) were also measured. Average daily dose of prednisolone over the preceding 12 mo (ADD) was 5.1 mg/day. Pearson's correlation analysis revealed that ADD correlated significantly with skeletal muscle strengths (KF%, r = -0.63, P < 0.01) with the exception of HG%. These findings are independent of age, BMI, pulmonary function, and DH. Multiple-regression analysis revealed that ADD was the most significant predictor of all measures of skeletal muscle function except HG%. It was independently responsible for 54% of the variance in Pimax%, for 46% of the variance in Pemax%, for 45% of the variance in KE%, for 39% of the variance in KF%, and for 41% of the variance in EF%. Concomitant medications (e.g., theophylline) were shown to have no causative effect. Corticosteroids contribute to the skeletal muscle weakness seen in CF patients. The correlation of proximal muscle strength, but not HG strength, with steroid dosage further supports a cause-effect relationship.

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Skeletal muscle function and structure in patients with non-cystic fibrosis bronchiectasis

10.1183/13993003.congress-2016.oa265 ◽

2016 ◽

Author(s):

Ana Balañá ◽

Juana Martínez-Llorens ◽

Diego Agustin Rodríguez ◽

Mireia Admetlló ◽

Anna Salazar ◽

...

Keyword(s):

Skeletal Muscle ◽

Cystic Fibrosis ◽

Muscle Function ◽

Skeletal Muscle Function

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Corticosteroids and Skeletal Muscle Function in Cystic Fibrosis.

Cardiopulmonary Physical Therapy Journal ◽

10.1097/01823246-200415010-00014 ◽

2004 ◽

Vol 15 (1) ◽

pp. 30

Author(s):

S C Barry ◽

C G Gallagher

Keyword(s):

Skeletal Muscle ◽

Cystic Fibrosis ◽

Muscle Function ◽

Skeletal Muscle Function

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Faculty Opinions recommendation of TNF-alpha-mediated reduction in PGC-1alpha may impair skeletal muscle function after cigarette smoke exposure.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1556023.1047131 ◽

2010 ◽

Author(s):

Annemie Schols ◽

Harry Gosker

Keyword(s):

Skeletal Muscle ◽

Cigarette Smoke ◽

Muscle Function ◽

Smoke Exposure ◽

Tnf Alpha ◽

Cigarette Smoke Exposure ◽

Skeletal Muscle Function ◽

Mediated Reduction

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Gait disturbances and muscle dysfunction in fibroblast growth factor 2 knockout mice

Scientific Reports ◽

10.1038/s41598-021-90565-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

C. Homer-Bouthiette ◽

L. Xiao ◽

Marja M. Hurley

Keyword(s):

Skeletal Muscle ◽

Growth Factor ◽

Muscle Strength ◽

Fibroblast Growth Factor ◽

Muscle Function ◽

Fibroblast Growth Factor 2 ◽

Fibroblast Growth ◽

Skeletal Muscle Function ◽

Age Related ◽

Gait Disturbances

AbstractFibroblast growth factor 2 (FGF2) is important in musculoskeletal homeostasis, therefore the impact of reduction or Fgf2 knockout on skeletal muscle function and phenotype was determined. Gait analysis as well as muscle strength testing in young and old WT and Fgf2KO demonstrated age-related gait disturbances and reduction in muscle strength that were exacerbated in the KO condition. Fgf2 mRNA and protein were significantly decreased in skeletal muscle of old WT compared with young WT. Muscle fiber cross-sectional area was significantly reduced with increased fibrosis and inflammatory infiltrates in old WT and Fgf2KO vs. young WT. Inflammatory cells were further significantly increased in old Fgf2KO compared with old WT. Lipid-related genes and intramuscular fat was increased in old WT and old Fgf2KO with a further increase in fibro-adipocytes in old Fgf2KO compared with old WT. Impaired FGF signaling including Increased β-Klotho, Fgf21 mRNA, FGF21 protein, phosphorylated FGF receptors 1 and 3, was observed in old WT and old Fgf2KO. MAPK/ ERK1/2 was significantly increased in young and old Fgf2KO. We conclude that Fgf2KO, age-related decreased FGF2 in WT mice, and increased FGF21 in the setting of impaired Fgf2 expression likely contribute to impaired skeletal muscle function and sarcopenia in mice.

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Fourteen days of smoking cessation improves muscle fatigue resistance and reverses markers of systemic inflammation

Scientific Reports ◽

10.1038/s41598-021-91510-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mohammad Z. Darabseh ◽

Thomas M. Maden-Wilkinson ◽

George Welbourne ◽

Rob C. I. Wüst ◽

Nessar Ahmed ◽

...

Keyword(s):

Oxidative Stress ◽

Skeletal Muscle ◽

Smoking Cessation ◽

Muscle Fatigue ◽

Fatigue Resistance ◽

Systemic Inflammation ◽

Muscle Function ◽

Low Grade ◽

Skeletal Muscle Function ◽

Tnf Α

AbstractCigarette smoking has a negative effect on respiratory and skeletal muscle function and is a risk factor for various chronic diseases. To assess the effects of 14 days of smoking cessation on respiratory and skeletal muscle function, markers of inflammation and oxidative stress in humans. Spirometry, skeletal muscle function, circulating carboxyhaemoglobin levels, advanced glycation end products (AGEs), markers of oxidative stress and serum cytokines were measured in 38 non-smokers, and in 48 cigarette smokers at baseline and after 14 days of smoking cessation. Peak expiratory flow (p = 0.004) and forced expiratory volume in 1 s/forced vital capacity (p = 0.037) were lower in smokers compared to non-smokers but did not change significantly after smoking cessation. Smoking cessation increased skeletal muscle fatigue resistance (p < 0.001). Haemoglobin content, haematocrit, carboxyhaemoglobin, total AGEs, malondialdehyde, TNF-α, IL-2, IL-4, IL-6 and IL-10 (p < 0.05) levels were higher, and total antioxidant status (TAS), IL-12p70 and eosinophil numbers were lower (p < 0.05) in smokers. IL-4, IL-6, IL-10 and IL-12p70 had returned towards levels seen in non-smokers after 14 days smoking cessation (p < 0.05), and IL-2 and TNF-α showed a similar pattern but had not yet fully returned to levels seen in non-smokers. Haemoglobin, haematocrit, eosinophil count, AGEs, MDA and TAS did not significantly change with smoking cessation. Two weeks of smoking cessation was accompanied with an improved muscle fatigue resistance and a reduction in low-grade systemic inflammation in smokers.

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