Intermedius Muscles Research Articles

Diagnostic test accuracy of ultrasound for sarcopenia diagnosis: A systematic review and meta-analysis.

Muscle ultrasound is an emerging tool for diagnosing sarcopenia. This review aims to summarize the current knowledge on the diagnostic test accuracy of ultrasound for the diagnosis of sarcopenia. We collected data from Ovid Medline, Embase and the Cochrane Central Register of Controlled Trials. Diagnostic test accuracy studies using muscle ultrasound to detect sarcopenia were included. Bivariate random-effects models based on sensitivity and specificity pairs were used to calculate the pooled estimates of sensitivity, specificity and the area under the curves (AUCs) of summary receiver operating characteristic (SROC), if possible. We screened 7332 publications and included 17 studies with 2143 participants (mean age range: 52.6-82.8years). All included studies had a high risk of bias. The study populations, reference standards and ultrasound measurement methods varied across the studies. Lower extremity muscles were commonly studied, whereas muscle thickness (MT) was the most widely measured parameter, followed by the cross-sectional area (CSA). The MTs of the gastrocnemius, rectus femoris, tibialis anterior, soleus, rectus abdominis and geniohyoid muscles showed a moderate diagnostic accuracy for sarcopenia (SROC-AUC 0.83, 8 studies; SROC-AUC 0.78, 5 studies; AUC 0.82, 1 study; AUC 0.76-0.78, 2 studies; AUC 0.76, 1 study; and AUC 0.79, 1 study, respectively), whereas the MTs of vastus intermedius, quadriceps femoris and transversus abdominis muscles showed a low diagnostic accuracy (AUC 0.67-0.71, 3 studies; SROC-AUC 0.64, 4 studies; and AUC 0.68, 1 study, respectively). The CSA of rectus femoris, biceps brachii muscles and gastrocnemius fascicle length also showed a moderate diagnostic accuracy (AUC 0.70-0.90, 3 studies; 0.81, 1 study; and 0.78-0.80, 1 study, respectively), whereas the echo intensity (EI) of rectus femoris, vastus intermedius, quadriceps femoris and biceps brachii muscles showed a low diagnostic accuracy (AUC 0.52-0.67, 2 studies; 0.48-0.50, 1 study; 0.43-0.49, 1 study; and 0.69, 1 study, respectively). The combination of CSA and EI of biceps brachii or rectus femoris muscles was better than either CSA or EI alone for diagnosing sarcopenia. Muscle ultrasound shows a low-to-moderate diagnostic test accuracy for sarcopenia diagnosis depending on different ultrasound parameters, measured muscles, reference standards and study populations. The combination of muscle quality indicators (e.g., EI) and muscle quantity indicators (e.g., MT) might provide better diagnostic test accuracy.

Anatomical variation of co-existing bilaminar tensor of the vastus intermedius muscle and new type of sixth head of the quadriceps femoris.

We present a case report of quadriceps femoris (QF) with co-existing bilaminar tensor of the vastus intermedius (TVI) muscle and new type of sixth head. Cadaveric dissection of left thigh of a 72-year-old man was performed for research and teaching purposes at the Department of Anatomical Dissection and Donation, Medical University of Lodz. The left lower limb was dissected using standard techniques according to a strictly specified protocol. Each head of the muscle was photographed and subjected to further measurement. During dissection, an unusual type of TVI muscle was observed. It consisted of two surfaces, superficial and deep. In addition, sixth head of QF muscle grew out from the vastus medialis muscle. The knowledge of the existence and possible variations of additional heads of QF muscle is necessary during diagnostic process of muscle strains. Moreover, according to course of tendons that heads may take part in patella stabilisation.

태권도 품새 선수들의 8주간 케틀벨 훈련이 하지 무산소성 파워와 근 두께에 미치는 영향

The purpose of this study is to suggest an appropriate training method by examining the effect on lower extremity anaerobic power and related muscle thickness through 8 weeks of kettlebell training in Taekwondo Poomsae athletes. Seven athletes who are currently registered as athletes were selected and kettlebell training was performed for 8 weeks, and the difference was confirmed by performing the Wilcoxon-test, a non-parametric test, through pre and postmeasurement measurements. For this study, the difference was measured using a wingate anaerobic power measuring instrument and an ultrasonic instrument. As a result of the study, significant improvements were found in average power per body weight and peak power of anaerobic power. The five representative muscles of the lower extremities, rectus femoris, vastus lateralis, vastus intermedius, vastus medialis, and biceps femoris long muscle, all showed significant improvement.

Assessment of central aponeurosis curvature as an index of rectus femoris muscle overstrain in individuals with knee osteoarthritis.

In medial knee osteoarthritis (knee OA), compensatory overstrain of the rectus femoris (RF) muscle leads to its hypertrophy. We hypothesize that besides hypertrophy of the RF, a prominent flattening of the central aponeurosis (CA) curvature is also indicative of RF. This study aims to evaluate the structural changes in the CA and clarify the conditions associated with RF overstrain in knee OA. Twenty-three legs of 20 elderly without knee OA (elderly group) and 26 legs of 20 individuals with K-L grade II knee OA (knee OA group) with typical "comma"-shaped CA participated in this study. The knee extension torque (Nm/kg) in the sitting position, the thickness of the RF and vastus intermedius (VI) muscles (VI), and change in CA curvature (%Curvature) were measured at the mid-thigh by ultrasonography. The knee extension torque was not significantly different between the two groups. Compared to the elderly group, the knee OA group had significantly thicker RF at rest, while the VI thickness during contraction was significantly smaller. The %Curvature was significantly higher in the knee OA group than in the elderly group. In the knee OA group, the RF was hypertrophic with a more pronounced CA flattening during muscle contraction, although the other quadriceps muscles were atrophic, suggesting an overstrained RF. Assessing thickness and CA curvature of the RF is, therefore, useful and simple for evaluating overstrain caused by RF compensation.

Basic characteristics between mechanomyogram and muscle force during twitch and tetanic contractions in rat skeletal muscles

The mechanomyogram (MMG) is a signal measured by various vibration sensors for slight vibrations induced by muscle contraction, and it reflects the muscle force during electrically induced-contraction or until 60%–70% maximum voluntary contraction, so the MMG is considered an alternative and novel measurement tool for muscle strength. We simultaneously measured the MMG and muscle force in the gastrocnemius (GC), vastus intermedius (VI), and soleus (SOL) muscles of rats. The muscle force was measured by attaching a hook to the tendon using a load cell, and the MMG was measured using a charged-coupled device-type displacement sensor at the middle of the target muscle. The MMG-twitch waveform was very similar to that of the muscle force; however, the half relaxation time and relaxation time (10%), which are relaxation parameters, were prolonged compared to those of the muscle force. The MMG amplitude correlated with the muscle force. Since stimulation frequencies that are necessary to evoke tetanic progression have a significant correlation with the twitch parameter, there is a close relationship between twitch and tetanus in the MMG signal. Therefore, we suggest that the MMG, which is electrically induced and detected by a laser displacement sensor, may be an alternative tool for measuring muscle strength.

Diagnostic accuracy of muscle ultrasound and plasma monocyte chemoattractant protein-1 for ICU-acquired weakness in patients with sepsis

To explore the diagnostic accuracy of muscle ultrasound and plasma monocyte chemoattractant protein-1 (MCP-1) for ICU-acquired weakness (ICU-AW) in patients with sepsis. A prospective observational study was conducted. Patients with sepsis admitted to the intensive care unit (ICU) of Henan Provincial People's Hospital from April 2021 to October 2021 were enrolled. The demographic data were collected. The enrolled patients were evaluated with Medical Research Council (MRC) score every day until discharged from ICU. During this period, patients with total MRC score < 48 (for two consecutive times and a time interval of 24 hours) were divided into ICU-AW group, those with total MRC score ≥ 48 were served as non-ICU-AW group. On the 1st, 4th and 7th day following admission into ICU, ultrasound was used to measure the muscle linear thickness of the rectus femoris (RF-MLT), the cross sectional area of the rectus femoris (RF-CSA) and the muscle linear thickness of the vastus intermedius muscle (VI-MLT). And meanwhile, the plasmas samples of patients were collected to measure MCP-1 concentration by enzyme-linked immunosorbent assay (ELISA). The difference of each index was compared between the ICU-AW group and the non-ICU-AW group. The risk factors of ICU-AW in patients with sepsis were analyzed by binary Logistic regression. Besides, receiver operator characteristic curve (ROC curve) was plotted, the diagnostic value of ultrasound parameters and plasma MCP-1 level for ICU-AW in patients with sepsis was analyzed. A total of 99 septic patients were enrolled, with 68 patients in the ICU-AW group and 31 patients in the non-ICU-AW group. Compared with the patients in the ICU-AW group, the patients in the non-ICU-AW group tended to be older, and had higher sequential organ failure assessment (SOFA) score, higher acute physiology and chronic health evaluation II (APACHE II) score, higher rates of septic shock, higher blood lactic acid and lower Glasgow coma score (GCS). Binary Logistic regression analysis showed that APACHE II score and septic shock were the risk factors of ICU-AW for septic patients [odds ratio (OR) and 95% confidence interval (95%CI) were 1.310 (1.138-1.509) and 0.232 (0.072-0.746), respectively, both P < 0.05]. The RF-MLT, RF-CSA and VI-MLT on the 1st, 4th and 7th ICU day was falling over time. Compared with the patients in the ICU-AW group, the patients in the non-ICU-AW group had smaller RF-MLT on the 7th day [cm: 0.32 (0.22, 0.47) vs. 0.45 (0.34, 0.63), P < 0.05] and higher 7-day RF-CSA atrophy rate [25.85% (10.37%, 34.28%) vs. 11.65% (2.28%, 22.41%), P < 0.05]. According to ROC curve analysis, 7-day RF-MLT had diagnostic value for ICU-AW of septic patients. Area under ROC curve (AUC) was 0.688 (95%CI was 0.526-0.849); when the cut-off value was 0.41 cm, the sensitivity and the specificity were 66.7% and 68.4%. The levels of plasma MCP-1 in the ICU-AW group were significantly higher than those in the non-ICU-AW group on the 1st, 4th and 7th day. ROC curve analysis showed that the plasma MCP-1 levels on the 1st, 4th and 7th day played a significant role to diagnose ICU-AW for septic patients, the AUC and 95%CI were 0.732 (0.629-0.836), 0.865 (0.777-0.953), 0.891 (0.795-0.986), respectively. When the cut-off values were 206.3, 410.9, 239.5 ng/L, the sensitivity was 87.1%, 64.0%, 82.4%, and the specificity was 54.4%, 96.1%, 86.2%, respectively. The muscle mass parameters on the 7th day of bedside ultrasound and plasma MCP-1 levels had certain diagnostic values for ICU-AW in patients with sepsis.

Protective effect by low-intensity downhill running training against muscle damage and oxidative stress after high-intensity downhill running in rats.

This study examined the effects of low-intensity eccentric exercise training performed before high-intensity eccentric exercise on muscle damage markers, oxidative stress and antioxidant defense. Twenty-two rats were divided into 3 groups; control (CON; n = 6), high-intensity eccentric exercise (HE; n = 8) and low-intensity eccentric exercise training plus high-intensity eccentric exercise (LET + HE; n = 8). Rats in the HE group performed HE at once. Rats in the LET + HE group performed LET and then HE protocol was applied. Blood and vastus intermedius muscle samples were taken 24 hours after the last exercise session for analyses of muscle damage, oxidative stress, and antioxidant defense markers. Muscle damage markers were higher in the HE group than the CON (137%-488%) and the LET + HE groups (82%-110%) (P < 0.05). Oxidative stress marker was higher in the HE group than the CON (65%) and the LET + HE (50%) groups (P < 0.05). Antioxidant defense markers were higher in the LTE + HE group than the HE group (39%-51%) (P < 0.05). In conclusion, low-intensity eccentric exercise training performed before high-intensity eccentric exercise conferred a protective effect against muscle damage by reducing oxidative stress and increasing antioxidant defense.

Deficits in muscle cross-sectional area and maximal isometric force following a shark bite injury are not reflected in jumping performance

Introduction: Environmental changes and growing surfing populations have led to increases in the number of shark sightings and unprovoked shark attacks on surfers. We present a case study of a 26-year-old male (height 178.4cm, mass 67.3kg) who was bitten by a shark on his left lateral thigh whilst surfing. The surfer lost most of the muscle and skin of the distal 2/3 of his anterolateral thigh, including all of vastus lateralis and most of vastus intermedius and rectus femoris muscles. After 3 years of intensive physiotherapy and rehabilitation, the surfer returned to a high-level of competitive surfing and has remarkable physical function. We investigated the anatomical structure and function of his affected (A) and unaffected (UA) thigh muscles relative to his dynamic functional strength to understand the potential physical function that can be achieved despite substantial muscle loss. Methods: Muscle group cross-sectional area (CSA) for the quadriceps and hamstrings were measured using magnetic resonance imaging, with axial slices taken from ~50% of the distance between the lesser trochanter and the medial femoral condyle. A handheld dynamometer was used to assess the maximal isometric strength of the quadriceps muscles through resisted knee extension while the surfer was seated and the hamstring muscles through resisted knee flexion in a prone position. Dynamic strength and jumping performance were assessed by the surfer performing countermovement jumps (CMJ) on two force platforms. Data are reported as means ± standard deviations. Results: The surfer’s quadriceps CSA was substantially larger in the UA (8304.8mm2) compared to the A (2857.2mm2) limb, although there was little between-limb difference in hamstring CSA (UA: 3499.1mm2, A: 3273.6mm2). The surfer produced more maximal isometric quadriceps strength in the UA compared to the A limb (406.1±45.0N vs 205.9±12.6N). The surfer’s peak CMJ height was 34±1.0cm, with relative peak forces of 1.28±0.10N/BW and 0.82±0.03N/BW generated for the UA and A, respectively. Discussion: Differences in quadriceps muscle function between the limbs were consistent with the differences in anatomical structure, whereby lower quadriceps CSA resulted in lower maximal isometric quadriceps strength. This quadriceps strength deficit, however, was not reflected in the functional dynamic strength achieved in the CMJ because the surfer’s peak jump height was comparable to that of international-level competitive surfers. Differences in the between-limb peak forces were much less than differences in maximal isometric strength, suggesting that neuromuscular adaptations developed during rehabilitation might have contributed to the high-level of physical function the surfer achieved. Conflict of interest statement: The authors have no conflicts of interest to declare.

Effects of magnetic stimulation compared to electrical stimulation on muscle contraction in quadriceps femoris muscle of healthy subjects: A pilot study

Background/Aims: This study investigated whether pulsed magnetic stimulation contracts superficial and/or deep muscles compared with those induced by electrical stimulations, i.e., low- and kilohertzfrequency currents. Methods: Eight healthy subjects were recruited and measured the quadriceps femoris muscle thickness using ultrasound imaging, and Visual Analog Scale (VAS) for stimulation-induced pain during the same stimulation intensity. Results: Pulsed magnetic stimulation increased the thickness of rectus femoris muscle similar to other electrical stimulations, but not the vastus intermedius muscle. Meanwhile, the pain score of VAS caused by pulsed magnetic stimulation was lower than that by those electrical stimulations. Conclusions: These results suggest that pulsed magnetic stimulation is effective for the contraction of superficial layer muscles without stimulation-induced pain but not for contraction of deep layer muscles. Keywords: pulsed magnetic stimulation; electrical stimulation; stimulation-induced pain; muscle contraction.

Different changes of muscle hardness between the rectus femoris and vastus intermedius muscle after maximal knee extension exercise

Different changes of muscle hardness between the rectus femoris and vastus intermedius muscle after maximal knee extension exercise

Changes in muscle ultrasound for the diagnosis of intensive care unit acquired weakness in critically ill patients

To test diagnostic accuracy of changes in thickness (TH) and cross-sectional area (CSA) of muscle ultrasound for diagnosis of intensive care unit acquired weakness (ICU-AW). Fully conscious patients were subjected to muscle ultrasonography including measuring the changes in TH and CSA of biceps brachii (BB) muscle, vastus intermedius (VI) muscle, and rectus femoris (RF) muscles over time. 37 patients underwent muscle ultrasonography on admission day, day 4, day 7, and day 10 after ICU admission, Among them, 24 were found to have ICW-AW. Changes in muscle TH and CSA of RF muscle on the right side showed remarkably higher ROC-AUC and the range was from 0.734 to 0.888. Changes in the TH of VI muscle had fair ROC-AUC values which were 0.785 on the left side and 0.779 on the right side on the 10th day after ICU admission. Additionally, Sequential Organ Failure Assessment (SOFA), Acute Physiology, and Chronic Health Evaluation II (APACHE II) scores also showed good discriminative power on the day of admission (ROC-AUC 0.886 and 0.767, respectively). Ultrasonography of changes in muscles, especially in the TH of VI muscle on both sides and CSA of RF muscle on the right side, presented good diagnostic accuracy. However, SOFA and APACHE II scores are better options for early ICU-AW prediction due to their simplicity and time efficiency.

Spontaneous Muscle Hematoma in Patients with COVID-19: A Systematic Literature Review with Description of an Additional Case Series

Coagulation abnormalities, thrombosis, and endothelial dysfunction have been described in COVID-19 patients. Spontaneous muscle hematoma (SMH) is a rare complication in COVID-19. The aims of this study are to: (1) perform a systematic review of the literature to better define the clinical SMH characteristics, (2) describe the prevalence and the clinical characteristics of SMH in COVID-19 patients referring to a Department of Internal Medicine (IM) (Federico II University of Naples), a Department of Sub-Intensive Care Medicine (SIM) (Ospedale Del Mare), and a Department of Intensive Care Unit (ICU) (Federico II University). The systematic review was performed according to PRISMA criteria. The local prevalence of SMH in COVID-19 was evaluated retrospectively. The medical records of all COVID-19 patients referring to IM and ICU from March 11th, 2020, to February 28th, 2021 were examined for SMH occurrence. In our retrospective analysis, we describe 10 cases of COVID-19 patients with SMH not previously reported in literature, with a prevalence of 2.1%. The literature review, inclusive of our case series, describes a total of 50 SMHs in COVID-19 patients (57.4% males; mean age 68.8 ± 10.0 years). The SMH sites were ileo-psoas, vastus intermedius, gluteus, sternocleidomastoid, and pectoralis major muscles. Males developed SMH earlier than females (9.5 ± 7.8 vs. 17.1 ± 9.7 days). Ileo-psoas hematoma was more frequent in males (69.2 vs. 30.8%), while pectoralis major hematoma occurred only in females. The in-hospital mortality rate of SMH in COVID-19 patients was 32.4%. SMH is a rare but severe complication in COVID-19 hospitalized patients, associated with high mortality. A gender difference seems to be present in the clinical presentation of the disorder.

Effects Of Acute Exercise And Acupuncture Treatment On Collagen Of Skeletal Muscle Extracellular Matrix

PURPOSE: Skeletal muscle ultrastructure and content changes of different collagen types in the rat skeletal muscle extracellular matrix after acute eccentric exercise was measured to elucidate the effects of acupuncture on exercise-induced skeletal muscle damage and remodeling of the skeletal muscle extracellular matrix. METHODS: Eight-week-old Sprague-Dawley rats (n = 96, body wt 220 ± 6.9 g) were randomly assigned to four groups: sedentary control (C), acupuncture control (CA), exercise (E) and acupunctured exercise (EA). Animals were adapted to the environment for 3 days and made to run on a motor-driven treadmill with −16° downhill tracks at a speed of 16 m/min for 90 min. CA and EA rats underwent intervention after exercise. Tissues were collected from the vastus intermedius muscle of the experimental rats immediately, and at 24 hours, 48 hours, 72 hours, and 120 hours after exercise. A transmission electron microscope was used to observe the skeletal muscle ultrastructure, a scanning electron microscope was used to analyze the morphological changes of collagen fibers, and western blotting were used to detect gene and protein expression of type I, II, and IV collagen. All animal experiments were approved by the Animal Welfare and Ethics Committee of Zhengzhou University. RESULTS: Acute eccentric exercise increased collagen fiber expression, whereas acupuncture inhibited it. Scanning electron microscope results revealed that collagen hyperplasia was increased in the skeletal muscle of E rats but not EA rats 120 hours post exercise. mRNA levels of type I and III collagen of E rats were upregulated to a maximal level 24 hours after exercise compared with immediately killed rats (Type I: 3.865 ± 1.181 to 11.651 ± 3.526, p = 0.28; Type III: 1.032 ± 0.270 to 2.657 ± 0.883, p = 0.17). The mRNA levels of type I and III collagen in EA rats significantly increased 48 hours after exercise compared with immediately killed rats (Type I: 1.024 ± 0.359 to 4.537 ± 1.621, p = 0.56; Type III: 0.680 ± 0.251 to 2.334 ± 0.945, p = 0.32). CONCLUSION: Acute eccentric exercise may stimulate increase collagen levels in rat skeletal muscle. Acupuncture altered collagen expression to facilitate the recovery and regeneration of injured skeletal muscle.

Effects Of Acute Exercise And Acupuncture Treatment On Regulation MMPs/TIMPs Balance Of Skeletal Muscle

PURPOSE: This study investigated MMPs/TIMPs balance in the rat skeletal muscle extracellular matrix after acute eccentric exercise to elucidate the effects of acupuncture on exercise-induced skeletal muscle damage and remodeling of the skeletal muscle extracellular matrix. METHODS: Eight-week-old Sprague-Dawley rats (n = 96, body wt 220 ± 6.9 g) were randomly assigned to four groups: sedentary control (C), acupuncture control (CA), exercise (E) and acupunctured exercise (EA). Animals were made to run on a motor-driven treadmill with −16° downhill tracks at a speed of 16 m/min for 90 minutes. Tissues were collected from the vastus intermedius muscle immediately, and at 24 hours, 48 hours, 72 hours and 120 hours after exercise. Western blotting was used to detect protein expression of matrix metalloproteinases-2 (MMP2), MMP9, tissue inhibitor of metalloproteinases-1 (TIMP1) and TIMP2. All animal experiments were approved by the Animal Welfare and Ethics Committee of Zhengzhou University. RESULTS: The protein expression of MMP2 (EA: 1.330 ± 0.065, E: 1.341 ± 0.120, C: 1.000 ± 0.060) reached the maximal level 24 hours and MMP9 of EA rats (EA: 3.776 ± 1.253, C: 1.000 ± 0.357, P < 0.05) and E rats (E: 5.828 ± 2.151, C: 1.000 ± 0.357, P = 0.016) reached the maximal level at 48 hours and 24 hours respectively. The protein expression of TIMP1 of EA rats (EA: 2.938 ± 0.437, C: 1.000 ± 0.251, P = 0.032) and E rats (E: 1.984 ± 0.077, C: 1.000 ± 0.251, p = 0.059) reached the maximal level at 72 hours and 48 hours respectively. The protein expression of TIMP2 of EA rats (EA: 1.477 ± 0.199, C: 1.000 ± 0.063, p = 0.067) and E rats (E: 1.371 ± 0.081, C: 1.000 ± 0.063, p = 0.074) reached the maximal level immediately after exercise. CONCLUSION: Acupuncture facilitated the recovery and regeneration of injured skeletal muscle by increasing the expression of MM2 and MMP9. TIMP1 and TIMP2 played different roles in inflammation of injured skeletal muscle.

Augmented muscle glycogen utilization following a single session of sprint training in hypoxia.

This study determined the effect of a single session of sprint interval training in hypoxia on muscle glycogen content among athletes. Ten male college track and field sprinters (mean ± standard error of the mean: age, 21.1 ± 0.2years; height, 177 ± 2cm; body weight, 67 ± 2kg) performed two exercise trials under either hypoxia [HYPO; fraction of inspired oxygen (FiO2), 14.5%] or normoxia (NOR: FiO2, 20.9%). The exercise consisted of 3 × 30s maximal cycle sprints with 8-min rest periods between sets. Before and immediately after the exercise, the muscle glycogen content was measured using carbon magnetic resonance spectroscopy in vastus lateralis and vastus intermedius muscles. Moreover, power output, blood lactate concentrations, metabolic responses (respiratory oxygen uptake and carbon dioxide output), and muscle oxygenation were evaluated. Exercise significantly decreased muscle glycogen content in both trials (interaction, P = 0.03; main effect for time, P < 0.01). Relative changes in muscle glycogen content following exercise were significantly higher in the HYPO trial (- 43.5 ± 0.4%) than in the NOR trial (- 34.0 ± 0.3%; P < 0.01). The mean power output did not significantly differ between the two trials (P = 0.80). The blood lactate concentration after exercise was not significantly different between trials (P = 0.31). A single session of sprint interval training (3 × 30s sprints) in hypoxia caused a greater decrease in muscle glycogen content compared with the same exercise under normoxia without interfering with the power output.

Contractility of permeabilized rat vastus intermedius muscle fibres following high-fat, high-sucrose diet consumption.

Obesity is a worldwide health concern associated with impaired physical function. It is not clear if contractile protein dysfunction contributes to the impairment of muscle function observed with obesity. The purpose of this study was to examine if diet-induced obesity affects contractile function of chemically permeabilized vastus intermedius fibres of male Sprague-Dawley rats expressing fast myosin heavy chain (MHC) IIa or slow MHC I. Rats consumed either a high-fat, high sucrose (HFHS) diet or a standard (CHOW) diet beginning as either weanlings (7-week duration: WEAN7 cohort, or 14-week duration: WEAN14 cohort) or young adults (12-week duration: ADULT12 cohort, 24-week duration: ADULT24 cohort). HFHS-fed rats had higher (P < 0.05) whole-body adiposity (derived from dual-energy X-ray absorptiometry) than CHOW-fed rats in all cohorts. Relative to CHOW diet groups, the HFHS diet was associated with impaired force production in (a) MHC I fibres in the ADULT24 cohort; and (b) MHC IIa fibres in the ADULT12 and ADULT24 cohorts combined. However, the HFHS diet did not significantly affect the Ca2+-sensitivity of force production, unloaded shortening velocity, or ratio of active force to active stiffness in any cohort. We conclude that diet-induced obesity can impair force output of permeabilized muscle fibres of adult rats. Novelty: We assessed contractile function of permeabilized skeletal muscle fibres in a rat model of diet-induced obesity. The high-fat, high-sucrose diet was associated with impaired force output of fibres expressing MHC I or MHC IIa in some cohorts of rats. Other measures of contractile function were not significantly affected by diet.

Association of baseline diaphragm, rectus femoris and vastus intermedius muscle thickness with weaning from mechanical ventilation

BackgroundTo determine whether baseline diaphragm (Tdi), rectus femoris (RF) and vastus intermedius (VI) muscle thickness (TRF and TRF + VI) are associated with weaning success. Material and methodsRight Tdi, TRF and TRF + VI were measured by ultrasonography within 36 h of intubation and diaphragmatic excursion (DE) was evaluated at the first spontaneous breathing trial in adult critically-ill patients. Reintubation or death within 7 days after extubation was defined as weaning failure. Weaning failure and success groups were compared in terms of ultrasonographic measurements and clinical features. ResultsThirty-eight patients were assessed for weaning, 15 (39.4%) being in the weaning failure group. The median body mass index (BMI) was lower while the median clinical frailty scale (CFS), vasopressor use, duration of mechanical ventilation, intensive care and hospital mortality rate were higher in the weaning failure group, and the median TRF + VI (14.0 [12.3–26.2] vs 23.6 [21.3–27.1] mm, p = 0.03) and median DE (19.4 [14.6–24.0] vs 25.9 [19.3–38.5] mm, p = 0.045) were lower. The median Tdi was similar in two groups (1.9 [1.5–2.3] vs 2.0 [1.7–2.4] mm, p = 0.26). In ROC analysis, area under the curve for TRF + VI was 0.71 (95% CI: 0.51–0.90; p = 0.035), with 21 mm cut-off having sensitivity of 82% and specificity of 57%. Binary logistic regression analysis revealed TRF + VI < 21 mm as the only predictor of weaning failure with an odds ratio of 10.5 (95% CI: 1.1–97.8, p = 0.038) after adjusting for age, sex, BMI and CFS. ConclusionsTRF + VI lower than 21 mm, measured by ultrasonography within 36 h of intubation, was associated with weaning failure among critically-ill patients.

Cut-off Values for Lower Limb Muscle Thickness to Detect Low Muscle Mass for Sarcopenia in Older Adults.

PurposeUltrasound-based prediction methods for the detection of low muscle mass for sarcopenia in older adults have been explored previously; however, the muscle that most accurately predicts it is unclear. This study aimed to clarify prediction accuracy and cut-off values for ultrasound-derived thigh and lower leg muscle thickness (MT) to detect low skeletal muscle mass index (SMI) in older adults and to estimate cut-off values based on two standard deviations (SD) below younger adult means for the corresponding muscles as an early detection tool for site-specific low muscle mass.MethodsThis study included 204 community-dwelling older (64 males, 140 females, mean age: 75.4 years) and 59 younger (31 males, 28 females, mean age: 22.3 years) adults. The MT of the rectus femoris, vastus intermedius, gastrocnemius, and soleus muscles was measured using ultrasound; SMI was measured using bioelectrical impedance analysis.ResultsThe prevalence of a low SMI among older adults was 20.3% (n=13) for males and 21.4% (n=30) for females. The receiver operating characteristic analysis revealed that the total MT for the four muscles measured presented the highest area under the curve (AUC) value to predict low SMI for males (0.849) and females (0.776). The AUC value was the highest for the total MT of the gastrocnemius and soleus muscles for males and the gastrocnemius for females (0.836, 0.748; cut-off value: 5.67 cm, 1.42 cm, respectively). Muscle-specific differences between the low SMI-predicting and SD-based cut-off values were observed. The SD-based value for the rectus femoris (1.85 cm) was substantially higher than the low SMI-predicting value (1.51 cm) in males.ConclusionUltrasound measurement of lower leg muscles may be a simple, robust measure to detect low muscle mass for sarcopenia. Additionally, cut-off values for site-specific muscle mass loss may not always agree with those for whole-limb muscle mass loss.

The development of the tensor vastus intermedius during the human embryonic period and its clinical implications.

The tensor vastus intermedius (TVI) is a newly discovered muscle located in the anterolateral thigh area and is considered the fifth component of the quadriceps femoris muscle. There have been several papers describing its anatomical and morphological features in detail; however, many features of this muscle, such as its ontology or kinetic functions, remain unknown. The purpose of this study was to determine the initial appearance of the TVI muscle in human embryonic development and to investigate its growth and development. Histological observations were performed on 30 lower limbs of 15 human embryos from Carnegie stage (CS) 21, 22, and 23 (with crown-rump length ranging from 18.7 to 28.7mm). Myocyte clusters of the TVI were observed between the vastus lateralis and intermedius muscles in 7 out of 10 limbs in CS 22, indicating that the TVI arises during this stage. In CS 23, the TVI was clearly present in all specimens except one. However, neither the aponeurosis nor the tendonous structure of the TVI were observed in these embryonic stages. Formation of the conventional four components of the quadriceps muscle is completed within CS 21; therefore, our results suggest that the TVI is the last element to develop in the quadriceps femoris complex. It is posited that after the embryonic period, the TVI continues to grow, while forming the tendinous structure toward the patella and receiving vascular supply from certain vascular branches. The clinical significance of these findings is that orthopedists and plastic surgeons who perform surgical procedures within the anterolateral thigh (ALT) area should be aware of the anatomy and development of the TVI in order to reduce surgical complications. Our present research aims to contribute to a deeper understanding of the morphogenesis of the TVI and the other femoral extensor muscles.

Quantifiable Contrast-Enhanced Ultrasound Explores the Role of Protection, Rest, Ice (Cryotherapy), Compression and Elevation (PRICE) Therapy on Microvascular Blood Flow

The aim of this randomized controlled laboratory study was to evaluate the role of standardized protection, rest, ice (cryotherapy), compression and elevation (PRICE) therapy on microvascular blood flow in human skeletal muscle. Quantifiable contrast-enhanced ultrasound was used to analyze intramuscular tissue perfusion (ITP) of the rectus femoris (RF) and vastus intermedius (VI) muscles in 20 healthy athletes who were randomly assigned to PRICE or control groups. Baseline perfusion measurements (resting conditions, T0) were compared with cycling exercise (T1), intervention (PRICE or control, T2) and follow-up at 60 min post-intervention (T3). The 20 min PRICE intervention included rest, cryotherapy (3°C), compression (35 mm Hg) and elevation. After intervention, PRICE demonstrated a decrease of ITP in VI (–47%, p = 0.01) and RF (–50%, p = 0.037) muscles. At T3, an ongoing decreased ITP for the RF (p = 0.003) and no significant changes for the VI were observed. In contrast, the control group showed an increased ITP at T2 and no significant differences at T3. PRICE applied after exercise led to a down-regulation of ITP, and the termination of PRICE does not appear to be associated with a reactive hyperemia for at least 60 min after treatment.