OBJECTIVE: To explore relationship between intramuscular fat content of quadriceps femoris and clinical severity of knee osteoarthritis (KOA). METHODS: Totally 30 KOA patients were selected from February 2021 to June 2021, including 6 males and 24 females, aged with an average of (64.20±9.19) years old, and body mass index (BMI) was (24.92±3.35) kg·m-2. Patients were divided into relative severe leg (RSL) and relative moderate leg (RML) according to severity of pain on visual analogue scale(VAS). Musculoskeletal ultrasound was used to collect muscle images of quadriceps muscles on both sides of the patient, and Image J was used to analyze echo intensity (EI) of each muscle. Both VAS and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were used to assess pain and function. Quadriceps muscle EI on both sides of patients was compared. Pearson correlation analysis was conducted to analyze correlation between quadriceps muscle EI value between RSL and RML, and linear regression was used to analyze relationship between each muscle EI and VAS and WOMA scores of patients. RESULTS: The EI of RSL lateral vastus lateralis (VL) was 123.78±36.25 and RSL vastus medialis (VM) was 109.46±30.36 which were significantly higher than those of 108.03±31.34 and 93.32±26.04 of RML (P<0.05), but there was no statistical significance in EI values of rectus femoris (RF) on both sides (P>0.05). EI values of VL and VM on both sides were significantly correlated (P<0.05). There was a significant positive correlation between VM EI value and VAS score in RSL and RML (P<0.05). VM EI values in RSL were positively correlated with total WOMAC (P<0.05), and VM VL EI values in RML were positively correlated with total WOMAC score (P<0.05). CONCLUSION Intramuscular fat content of quadriceps is closely related to severity of clinical symptoms in KOA patients, and the most obvious one is VM. Therefore, the intramuscular fat content of quadriceps may be an objective indicator to evaluate severity of KOA patients. At the same time, reducing intramuscular fat content of the quadriceps muscle of KOA patients may be a new direction for the prevention and treatment of KOA.
Male ; Female ; Humans ; Aged ; Middle Aged ; Quadriceps Muscle/physiology* ; Osteoarthritis, Knee/diagnosis* ; Pain ; Body Mass Index ; Muscle Strength/physiology* ; Knee Joint

BACKGROUNDSpontaneous potentials in electromyography (EMG) of paraspinal muscles are associated with diaphragm denervation and, therefore, poor respiratory function in amyotrophic lateral sclerosis (ALS) is understandable. EMG changes in the rectus abdominis (RA) display an effect similar to those in paraspinal muscles with respect to the function of lower motor neurons in the thoracic spinal cord. The RA denervation was examined to determine its association with ventilation dysfunction in ALS.

METHODSWe collected the clinical data of 128 patients with sporadic ALS in Department of Neurology of Peking University Third Hospital from 2009 to 2013. EMG, Revised ALS Functional Rating Scale (ALSFRS-R) and forced vital capacity (FVC) were performed in all patients and the differences in the EMG changes in RA between those with and without FVC ≥ 80% were analysed.

RESULTSThe mean FVC value was 83.4% ± 17.1% (range: 45%-131%) of the predicted value. A total of 79 patients displayed FVC ≥80%, and 49 patients displayed FVC <80%. Compared with the patients displaying a normal FVC (60/79, 75.9%), spontaneous activity in RA was significantly different among those patients displaying an FVC <80% (47/49, 95.9%). In addition, spontaneous potentials in RA were more frequently detected in patients exhibiting dyspnea (32/33, 97.0%) than in patients without dyspnea (75/95, 78.9%).

CONCLUSIONSpontaneous potentials in RA are associated with ventilation dysfunction and dyspnea in ALS patients.

Action Potentials ; physiology ; Adult ; Aged ; Aged, 80 and over ; Amyotrophic Lateral Sclerosis ; physiopathology ; Electromyography ; Electrophysiology ; Female ; Humans ; Male ; Middle Aged ; Motor Neurons ; physiology ; Paraspinal Muscles ; physiopathology ; Quadriceps Muscle ; innervation ; Rectus Abdominis ; innervation ; physiopathology ; Young Adult

BACKGROUNDLittle is known about the value of (31)P-magnetic resonance spectroscopy ((31)P-MRS) in in vivo assessment of exhaustive exercise-induced injury in skeletal muscle. We aimed to evaluate the value of a (31)P-MRS study using the quadriceps femoris after a single bout of acute exhaustive swimming in rats, and the correlation between (31)P-MRS and histological changes.

METHODSSixty male Sprague-Dawley rats were randomly assigned to control, half-exhaustive, and exhaustive exercise groups. (31)P-MRS of the quadriceps femoris of the right lower limb was performed immediately after swimming exercise to detect Pi, PCr, and β-ATP. The Pi/PCr, Pi/β-ATP, PCr/β-ATP, and PCr/(PCr+Pi) were calculated and pH measured. Areas under the receiver operating characteristic curve (AUCs) were calculated to evaluate the diagnostic potential of (31)P-MRS in identifying and distinguishing the three groups. HE staining, electron microscopy and desmin immunostaining after imaging of the muscle were used as a reference standard. The correlation between (31)P-MRS and the mean absorbance (A value) of desmin staining were analyzed with the Pearson correlation test.

RESULTSPi, PCr, Pi/PCr, and PCr/(PCr+Pi) showed statistically significant intergroup differences (P < 0.05). AUCs of Pi, PCr, Pi/PCr, and PCr/(PCr+Pi) were 0.905, 0.848, 0.930, and 0.930 for the control and half-exhaustive groups, while sensitivity and specificity were 90%/85%, 95%/55%, 95%/80%, and 90%/85%, respectively. The AUCs of Pi, PCr, Pi/PCr and PCr/(PCr+Pi) were 0.995, 0.980, 1.000, and 1.000 for the control and exhaustive groups, while sensitivity and specificity were 95%/90%, 100%/90%, 100%/95%, and 100%/95%, respectively. The AUCs of Pi, PCr, Pi/PCr, and PCr/(PCr+Pi) were 0.735, 0.865, 0.903, and 0.903 for the half-exhaustive and exhaustive groups, while sensitivity and specificity were 80%/60%, 90%/75%, 95%/65%, and 95%/70%, respectively. In the half-exhaustive group, some muscle fibers exhibited edema in HE staining, and the unclear Z-discs and the mitochondria with vacuolar degeneration under electron microscopy. Compared with the half-exhaustive group, muscle fiber edema was increased in the exhaustive group, and the Z-discs were broken and the mitochondria exhibited marked vacuolar degeneration under electron microscopy. There were significant difference in A values of desmin staining in the right vastus lateralis among the control, half-exhaustive, and exhaustive groups with 0.58 ± 0.06, 0.30 ± 0.04, and 0.21 ± 0.02, respectively (P < 0.05). Histological examination also showed injury-induced changes in the vastus lateralis among the different intensities groups. Statistically a moderate correlation between (31)P-MRS and desmin was observed, the correlation coefficients of Pi, PCr, Pi/PCr, and PCr/(PCr+Pi) were -0.706, 0.709, -0.726, and 0.791, respectively (P < 0.01).

CONCLUSIONS(31)P-MRS can effectively reflect the changes in energy metabolism in the skeletal muscle after a single bout of acute exhaustive swimming in rats. Based on the significant correlation between (31)P-MRS parameters and histological changes, the changes of Pi, PCr, Pi/PCr, and PCr/(PCr+Pi) can indirectly reflect the degree of exercise-induced injury.

Animals ; Energy Metabolism ; physiology ; Magnetic Resonance Spectroscopy ; methods ; Male ; Physical Conditioning, Animal ; physiology ; Quadriceps Muscle ; metabolism ; Rats ; Rats, Sprague-Dawley

BACKGROUNDSuppression of myostatin (MSTN) has been associated with skeletal muscle atrophy and insulin resistance (IR). However, few studies link MSTN suppression by ladder-climbing training (LCT) and IR. Therefore, we intended to identify the correlation with IR between LCT and to analyze the signaling pathways through which MSTN suppression by LCT regulates IR.

METHODSThe rats were randomly assigned to two types of diet: normal pellet diet (NPD, n = 8) and high-fat diet (HFD, n = 16). After 8 weeks, the HFD rats were randomly re-assigned to two groups (n = 8 for each group): HFD sedentary (HFD-S) and high-fat diet ladder-climbing training (HFD-LCT). HFD-LCT rats were assigned to LCT for 8 weeks. Western blotting, immunohistochemistry and enzyme assays were used to measure expression levels and activities of MSTN, GLUT4, PI3K, Akt and Akt-activated targets (mTOR, FoxO1 and GSK-3β).

RESULTSThe LCT significantly improved IR and whole-body insulin sensitivity in HDF-fed rats. MSTN protein levels decreased in matching serum (42%, P = 0.007) and muscle samples (25%, P = 0.035) and its receptor mRNA expression also decreased (16%, P = 0.041) from obese rats after LCT. But the mRNA expression of insulin receptor had no obvious changes in LCT group compared with NPD and HFD-S groups (P = 0.074). The ladder-climbing training significantly enhanced PI3K activity (1.7-fold, P = 0.024) and Akt phosphorylation (83.3%, P = 0.022) in HFD-fed rats, significantly increased GLUT4 protein expression (84.5%, P = 0.036), enhanced phosphorylation of mTOR (4.8-fold, P < 0.001) and inhibited phosphorylation of FoxO1 (57.7%, P = 0.020), but did not affect the phosphorylation of GSK-3β.

CONCLUSIONSThe LCT significantly reduced IR in diet-induced obese rats. MSTN may play an important role in regulating IR and fat accumulation by LCT via PI3K/Akt/mTOR and PI3K/Akt/FoxO1 signaling pathway in HFD-fed rats.

Animals ; Blotting, Western ; Diet, High-Fat ; adverse effects ; Glucose Tolerance Test ; Glucose Transporter Type 4 ; metabolism ; Immunohistochemistry ; Insulin Resistance ; physiology ; Male ; Myostatin ; metabolism ; Obesity ; etiology ; metabolism ; Phosphatidylinositol 3-Kinases ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Quadriceps Muscle ; metabolism ; Rats ; Rats, Sprague-Dawley

Animals ; HSP70 Heat-Shock Proteins ; metabolism ; Male ; Physical Conditioning, Animal ; Physical Endurance ; physiology ; Quadriceps Muscle ; metabolism ; physiology ; Rats ; Rats, Sprague-Dawley ; Vascular Endothelial Growth Factor A ; metabolism

BACKGROUNDSkeletal muscle dysfunction is one of important systemic manifestations of chronic obstructive pulmonary disease (COPD) and is associated with mortality in patients with COPD, thus quantifying its strength is of great clinical interest and of particular value. Quadriceps maximal volitional contraction (MVC) is often used for the routine measurements of this muscle's strength; while twitch tension (TwQ) evoked by magnetic stimulation of the femoral nerve has been employed for measurement of quadriceps strength non-volitionally. We aimed to investigate the prevalence and severity of skeletal muscle dysfunction in COPD patients by measurement of quadriceps strength with volitional and non-volitional techniques, and to probe into some methodological issues.

METHODSWe recruited 71 COPD patients and 60 control subjects. Quadriceps strength was measured with both maximality of TwQ and MVC force. The reproducibility for TwQ and MVC was investigated using within-occasion variability from three repeated maneuvers.

RESULTSMaximal TwQ was achieved in 121 participants at a mean of 90% of the stimulator's maximum output. The mean maximality of TwQ was decrease by about 44% - 47% in COPD patients as compared with controls (P < 0.05), so was MVC. There was a significant correlation between quadriceps TwQ and MVC, and the mean ratio of TwQ/MVC was 0.29 in controls and 0.33 in patients. The coefficient of variation showed that TwQ yielded lower within-occasion variability than MVC in both groups.

CONCLUSIONSQuadriceps strength is commonly and substantially impaired in patients with COPD, in terms of MVC as well as TwQ. The magnetic stimulation of the femoral nerve presents a higher reproducibility and is a better technique for measurement of quadriceps strength for the general population, especially for those who are too unwell to perform a full MVC; while it may not be applied to subjects who are over-weighted.

Aged ; Female ; Femoral Nerve ; physiology ; Humans ; Male ; Middle Aged ; Muscle Strength ; physiology ; Pulmonary Disease, Chronic Obstructive ; physiopathology ; Quadriceps Muscle ; physiology

Strength training is one of the most common exercises practiced in the field of physical therapy or sports training. However, limited methodology is available to evaluate its effect on the target muscle. This study aimed to test the hypothesis that surface electromyographic (EMG) data from both isometric and isotonic exercise can express changes within the muscle during a 12-week strength training program. Ten healthy male volunteer students (5 for training, 5 for controls) from Yonsei University were recruited for evaluation in this study. DeLorme's axiom was practiced for 12 weeks in the dominant elbow flexors and knee extensors of the training group. Tension for 1 repetition maximum and maximal voluntary isometric contraction, and surface EMG information such as the integrated EMG and three variables from the regression line of median frequency (MDF) data were measured at weeks 0, 3, 6, 9, and 12. The limb circumference was measured at weeks 0 and 12. During the strength training, which was enough for the increment of muscle strength and limb circumference, the rectified-integrated EMG and initial MDF increased with a significant linear pattern in both types of contraction. The two surface EMG variables were able to monitor the physiologic muscle changes during the training. Based on these results, we propose that these two surface EMG variables can be used for monitoring electrophysiological changes in the specific muscle that is undergoing the training program, under conditions where the contraction mode for EMG data collection is either static or dynamic.
Quadriceps Muscle/anatomy & histology/physiology ; Muscle, Skeletal/anatomy & histology/physiology ; Male ; Isotonic Contraction/physiology ; Isometric Contraction/physiology ; Humans ; Fourier Analysis ; Exercise Therapy/*methods ; Electromyography/*methods ; Body Weights and Measures ; Adult