Sex differences in quantitative ultrasonographic measurements of the rectus femoris in children.

The distribution and amount of intramuscular fat and fibrous tissue can be influenced by biological sex and impact muscle quality in both the functional (force-generating capacity) and morphological (muscle composition) domains. While ultrasonography (US) has proven effective in assessing age- or sex-related differences in muscle quality, limited information is available on sex differences in children. Quantitative ultrasonographic measurements, such as echo intensity (EI), EI bands (number of pixels across 50-unit intervals) and texture, may offer a comprehensive framework for identifying sex differences in muscle composition. The aim of our study was to examine the effect of sex on the rectus femoris (RF) muscle quality in children. We used EI (mean and bands) and texture as muscle quality estimates derived from B-mode US. We hypothesised that RF muscle quality differs significantly between girls and boys. Additionally, we also hypothesised that there is a significant correlation between EI bands and texture. Forty-four non-active healthy children were recruited (n = 22 girls, 12.8 ± 1.5 years; and n = 22 boys, 13.5 ± 1.2 years). RF was assessed using EI mean, EI bands, and texture analysis (homogeneity and correlation) using the Gray-Level Co-Occurrence Matrix. The results revealed significant (p < 0.05) sex differences in RF EI bands and texture. Boys displayed higher values in the 0-50 EI band and had more homogeneous muscle texture than girls. Conversely, girls displayed greater values in the 51-100 EI band and had less homogenous texture compared to boys (p < 0.05). A positive correlation was observed between the 0-50 EI band and muscle homogeneity. However, the 51-100 EI band correlated negatively with homogeneity (p < 0.05), particularly for girls. In conclusion, our study revealed sex-specific differences in mean EI, EI bands, and texture of the RF muscle in children. The variations in the correlations between the first and second EI bands and texture reveal different levels of homogeneity in each band. This indicates that distinct muscle tissue constituents, such as intramuscular fat and/or connective tissue, may be reflected in EI bands. Overall, the methods used in this study may be useful for examining muscle quality in healthy children and those with medical conditions.

Association between heart failure in asymptomatic stages and skeletal muscle function assessed by ultrasonography in community-dwelling older adults.

BACKGROUND: Symptomatic heart failure (HF) negatively affects the quantity and quality of skeletal muscles. However, the association between asymptomatic HF and skeletal muscle function remains unclear. We aimed to use ultrasonography to elucidate the association between asymptomatic HF and skeletal muscle function in community-dwelling older adults. METHODS: This cross-sectional study comprised community-dwelling older adults aged ≥ 60 years who could perform activities of daily living independently and had never had symptomatic HF (n = 52, 76.3 ± 6.1 years). The participants were classified into three groups namely, non-HF (n = 26), stage A (n = 19), and stage B (n = 7) according to the HF stage criteria of the American Heart Association /American College of Cardiology /Heart Failure Society of America guideline. Skeletal muscle quantity and quality were assessed using ultrasonography (thickness and echo intensity) of the rectus femoris (RF) and vastus intermedius (VI) muscles. The group effects on muscle thickness and echo intensity in each group were assessed using a multivariate analysis. RESULTS: Both muscles consistently demonstrated significant group effects on the thickness and echo intensity. Thicknesses of the RF (p = 0.020) and VI (p = 0.035) were lower in the stage B group than that in the non-HF group. The echo intensities in the RF (p = 0.006) and VI (p = 0.009) were higher in the stage B group than that in the non-HF group. CONCLUSION: Asymptomatic HF negatively associated with the characteristics of skeletal muscle function, as assessed by ultrasonography in community-dwelling older adults. The stage B HF contributes to reduced skeletal muscle function as well as symptomatic HF.

Resistance training effects on pubertal children with a risk of developing pediatric dynapenia.

PURPOSE: Many modern-day children are at risk of pediatric dynapenia (muscle weakness). We examined the effects of a 12-week resistance training (RT) program on neuromuscular function and body composition parameters in pubertal children with a risk of dynapenia. METHODS: Twelve children (13.4 ± 0.9 y) with dynapenia performed a progressive RT program consisting of knee extension and flexion, bench press, abdominal crunch, back extension, lateral pull-down, elbow flexion, and upright row (1-2 sets of 10-15 repetitions/exercise) twice/week for 12 weeks. Outcome measures included one-repetition maximum (1-RM) strength, maximal voluntary isometric contraction (MVIC) torque, rate of torque development (RTD), electromyographic (EMG) activity, muscle thickness (MT), muscle quality (MQ) assessed by echo intensity (MQEI) of the knee extensors and specific tension of MVIC torque to thigh fat-free mass (MQST), and total and regional body and bone composition assessed by dual-energy X-ray absorptiometry. Changes in the measures before and after the 12-week RT and associations among the measures were analyzed by linear mixed models. RESULTS: Significant (p < 0.05) increases in 1-RM (63.9 ± 4.5%), MVIC torque (16.3 ± 17.8%), MT (18.8 ± 5.5%) and MQ (MQEI: -25.9 ± 15.2%; MQST: 15.1 ± 18.8%;) were evident from pre- to post-training. Total fat-free mass (FFM) increased by 2.3 ± 3.2% from baseline (p = 0.01), but no changes (p > 0.05) in the other measures were observed. Significant (p < 0.05) associations between the changes in 1-RM and/or MVIC torque and the changes in quadriceps MT, MQEI, MQST and total body FFM were evident. CONCLUSIONS: The 12-week RT was effective for improving neuromuscular and body composition parameters, and thereby reversed the risk of pediatric dynapenia.

Association between physical fitness tests and neuromuscular properties.

PURPOSE: While various fitness tests have been developed to assess physical performances, it is unclear how these tests are affected by differences, such as, in morphological and neural factors. This study was aimed to investigate associations between individual differences in physical fitness tests and neuromuscular properties. METHODS: One hundred and thirty-three young adults participated in various general physical fitness tests and neuromuscular measurements. The appendicular skeletal muscle mass (ASM) was estimated by bioelectrical impedance analysis. Echo intensity (EI) was evaluated from the vastus lateralis. During submaximal knee extension force, high-density surface electromyography of the vastus lateralis was recorded and individual motor unit firings were detected. Y-intercept (i-MU) and slope (s-MU) from the regression line between the recruitment threshold and motor unit firing rate were calculated. RESULTS: Stepwise multiple regression analyses revealed that knee extension strength could be explained (adjusted R2 = 0.712) by ASM (ß = 0.723), i-MU (0.317), EI (- 0.177), and s-MU (0.210). Five-sec stepping could be explained by ASM (adjusted R2 = 0.212). Grip strength, side-stepping, and standing broad jump could be explained by ASM and echo intensity (adjusted R2 = 0.686, 0.354, and 0.627, respectively). Squat jump could be explained by EI (adjusted R2 = 0.640). Counter-movement jump could be explained by EI and s-MU (adjusted R2 = 0.631). On the other hand, i-MU and s-MU could be explained by five-sec stepping and counter-movement jump, respectively, but the coefficients of determination were low (adjusted R2 = 0.100 and 0.045). CONCLUSION: Generally developed physical fitness tests were mainly explained by morphological factors, but were weakly affected by neural factors involved in performance.

Skeletal Muscle Texture Assessment Using Ultrasonography: Comparison with Magnetic Resonance Imaging in Chronic Kidney Disease.

Skeletal muscle dysfunction is common in chronic kidney disease (CKD). Of interest is the concept of "muscle quality," of which measures include ultrasound-derived echo intensity (EI). Alternative parameters of muscle texture, for example, gray level of co-occurrence matrix (GCLM), are available and may circumvent limitations in EI. The validity of EI is limited in humans, particularly in chronic diseases. This study aimed to investigate the associations between ultrasound-derived parameters of muscle texture with MRI. Images of the thigh were acquired using a 3 Tesla MRI scanner. Quantification of muscle (contractile), fat (non-contractile), and miscellaneous (connective tissue, fascia) components were estimated. Anatomical rectus femoris cross-sectional area was measured using B-mode 2D ultrasonography. To assess muscle texture, first (i.e., EI)- and second (i.e., GLCM)-order statistical analyses were performed. Fourteen participants with CKD were included (age: 58.0 ± 11.9 years, 50% male, eGFR: 27.0 ± 7.4 ml/min/1.73m2, 55% Stage 4). Higher EI was associated with lower muscle % (quadriceps: ß = -.568, p = .034; hamstrings: ß = -.644, p = .010). Higher EI was associated with a higher fat % in the hamstrings (ß = -.626, p = .017). A higher angular second moment from GLCM analysis was associated with greater muscle % (ß = .570, p = .033) and lower fat % (ß = -.534, p = .049). A higher inverse difference moment was associated with greater muscle % (ß = .610, p = .021 and lower fat % (ß = -.599, p = .024). This is the first study to investigate the associations between ultrasound-derived parameters of muscle texture with MRI. Our preliminary findings suggest ultrasound-derived texture analysis provides a novel indicator of reduced skeletal muscle % and thus increased intramuscular fat.

Measurement Position Influences Sex Comparisons of Distal Femoral Cartilage Thickness With Ultrasound Imaging.

The purpose was to examine (1) the effect of measurement position and sex on femoral cartilage outcomes, and (2) the association between gait biomechanics and cartilage outcomes. Fifty individuals participated (25 males and 25 females; age = 20.62 [1.80] y). Ultrasound measured femoral cartilage thickness and echo-intensity at 90°, 115°, and 140° of knee flexion. Gait outcomes included the external knee adduction and knee flexion moments. Cartilage outcomes were compared using 2 (sex) × 3 (position) repeated-measures analysis of variance. Gait and cartilage associations were assessed using stepwise regression. Medial cartilage was thicker when measured at 90° compared with 115° (P = .02) and 140° (P < .01), and 115° compared with 140°, (P < .01) in males but not in females. Cartilage was thicker at 90° compared with 140° across both sexes within all regions (P < .01). Males had thicker cartilage than females in all positions (P < .01). Echo-intensity was lower at 90° than 115° (P < .01) and 140° (P = .01) in the central and lower at 90° than at 115° (P < .01) and 140° (P = .03) in lateral regions. No association was found between gait and cartilage outcomes. Ultrasound imaging position effects cartilage features more in males compared with females. Imaging position and sex influence cartilage outcomes and should be considered in study designs and clinical evaluation.

Reliability of Ultrasound Assessment of Hamstring Morphology, Quality, and Stiffness Among Healthy Adults and Athletes: A Systematic Review.

CONTEXT: The incidence and recurrence rate of hamstring strain injuries remain persistently high, with recurrent injuries leading to increased time lost during play and extended recovery periods compared with initial injury. Ultrasound imaging assesses important factors such as hamstring fascicle length (FL), pennation angle (PA), cross-sectional area (CSA), muscle thickness (MT), echo intensity (EI), and shear wave elastography (SWE), all impacting athletic performance. However, its reliability must be established before employing any measurement tool in research or clinical settings. OBJECTIVES: To determine the reliability and measurement error of ultrasound for assessing hamstring FL, PA, CSA, MT, EI, and SWE among healthy adults and athletes; to synthesize the information regarding the operationalization of ultrasound. EVIDENCE ACQUISITION: A systematic literature search was done from January 1990 to February 5, 2023, to identify reliability and validity studies of hamstring ultrasound assessment published in peer-reviewed journals with identifiable methodology of outcome measures. EVIDENCE SYNTHESIS: Intraclass correlation coefficient measurement of 14 included studies reported moderate to excellent intrarater, interrater, and test-retest reliabilities of FL, PA, and MT regardless of the site of muscle testing, probe size, and setting, state of muscle, and use of different techniques in the extrapolation of FL. Good to excellent test-retest reliability rates for all hamstring anatomic CSA along midmuscle and different percentages of thigh length using panoramic imaging. Good intrarater reliability of EI regardless of gender and orientation of the probe but with excellent intrarater reliability in transverse scan using maximum region of interest. Good intrarater, interrater, and interday repeatability on SWE with the muscle in a stretched position. CONCLUSION: Evidence from studies with a predominantly low risk of bias shows that ultrasound is a reliable tool to measure hamstring FL, PA, CSA, MT, EI, and SWE in healthy adults and athletes under various experimental conditions.

Reliability of 3D freehand ultrasound to assess lower limb muscles in children with spastic cerebral palsy and typical development.

This study investigated the reliability of 3-dimensional freehand ultrasound (3DfUS) to quantify the size (muscle volume [MV] and anatomical cross-sectional area [aCSA]), length (muscle length [ML], tendon length [TL], and muscle tendon unit length [MTUL]), and echo-intensity (EI, whole muscle and 50% aCSA), of lower limb muscles in children with spastic cerebral palsy (SCP) and typical development (TD). In total, 13 children with SCP (median age 14.3 (7.3) years) and 13 TD children (median age 11.1 (1.7) years) participated. 3DfUS scans of rectus femoris, semitendinosus, medial gastrocnemius, and tibialis anterior were performed by two raters in two sessions. The intra- and inter-rater and intra- and inter-session reliability were defined with relative and absolute reliability measures, that is, intra-class correlation coefficients (ICCs) and absolute and relative standard error of measurement (SEM and SEM%), respectively. Over all conditions, ICCs for muscle size measures ranged from 0.818 to 0.999 with SEM%s of 12.6%-1.6%. For EI measures, ICCs varied from 0.233 to 0.967 with SEM%s of 15.6%-1.7%. Length measure ICCs ranged from 0.642 to 0.999 with SEM%s of 16.0%-0.5%. In general, reliability did not differ between the TD and SCP cohort but the influence of different muscles, raters, and sessions was not constant for all 3DfUS parameters. Muscle length and muscle tendon unit length were the most reliable length parameters in all conditions. MV and aCSA showed comparable SEM%s over all muscles, where tibialis anterior MV was most reliable. EI had low-relative reliability, but absolute reliability was better, with better reliability for the distal muscles in comparison to the proximal muscles. Combining these results with earlier studies describing muscle morphology assessed in children with SCP, 3DfUS seems sufficiently reliable to determine differences between cohorts and functional levels. The applicability on an individual level, for longitudinal follow-up and after interventions is dependent on the investigated muscle and parameter. Moreover, the semitendinosus, the acquisition, and processing of multiple sweeps, and the definition of EI and TL require further investigation. In general, it is recommended, especially for longitudinal follow-up studies, to keep the rater the same, while standardizing acquisition settings and positioning of the subject.

Short-term Effects of Static Stretching on Hamstring Passive Stiffness in Young and Older Women.

OBJECTIVES: The objectives of this study were to assess the acute effects of static stretching on hamstring passive stiffness in young and older women. A secondary objective was to compare hamstring muscle size and quality measurements (cross-sectional area and echo intensity) between the two groups and to determine if these characteristics are related to passive stiffness at baseline. METHODS: Fifteen young (23±4 years) and 15 older (73±5 years) women underwent two randomized conditions that included a control treatment and an experimental treatment of four, 15-s static stretches of the hamstrings. Passive stiffness was calculated before (pre-test) and after (post-test) each treatment using a passive knee extension test. Ultrasound imaging was used to measure hamstring muscle cross-sectional area and echo intensity. RESULTS: Passive stiffness collapsed across group decreased from pre- to post-test for the stretching treatment (P=0.001) but not for the control (P=0.467). The older women had lower cross-sectional area (P=0.033) and greater baseline (pre-test) passive stiffness (P=0.042-0.049) and echo intensity (P=0.022) than the young women. Moreover, baseline passive stiffness was significantly related to echo intensity (r=0.430, P=0.018) but not cross-sectional area (r=-0.014, P=0.943). CONCLUSION: An acute bout of static stretching decreased passive stiffness in both young and older women.

Enhanced echo intensity in vastus medialis is associated with worsening of functional disabilities and symptoms in patients with knee osteoarthritis: a 3 years longitudinal study.

Patients with knee osteoarthritis (OA) experience muscle quality loss, and is characterized by the enhanced echo intensity (EI) of the vastus medialis (VM) muscles and a high extracellular water-to-intracellular water (ECW/ICW) ratio of the thigh. This study aimed to elucidate the association between muscle degeneration and the worsening of functional disabilities and symptoms in patients with KOA over 3 years duration. Thirty-three patients with KOA who completed follow-up over 3 years were included in the analysis. The knee scoring system (KSS) was used to evaluate the functional abilities and symptoms. Based on the 3 years change in KSS scores, patients were classified into progressive or non-progressive groups. Muscle thickness (MT) and EI of the VM were determined using ultrasonography. The ECW/ICW ratio was measured using segmental-bioelectrical impedance spectroscopy. Multivariable logistic regression analyses were conducted with the groups as the dependent variables and VM-MT, VM-EI, and ECW/ICW ratio at baseline as independent variables, including potential confounders. Thirteen (39.4%) patients showed progressive features. VM-EI at baseline was significantly associated with the progression of functional disabilities (adjusted odds ratio [OR] 1.24; 95% confidence interval [CI] 1.03 - 1.50) and symptoms (adjusted OR 1.13; 95% CI 1.01 - 1.25). Enhanced VM-EI was associated with the worsening of functional disabilities and symptoms in patients with KOA over a period of 3 years. Therefore, the assessment of VM-EI using ultrasonography is a useful indicator for predicting the future worsening of KOA.

Effect of age on shear modulus, muscle thickness, echo intensity of the upper limb, lower limb, and trunk muscles in healthy women.

PURPOSE: This study aimed to examine the effect of age on the mechanical properties, muscle size, and muscle quality in the upper and lower limb and trunk muscles. METHODS: We evaluated the shear modulus (G), muscle thickness (MT), and echo intensity (EI) of the upper and lower limb and trunk muscles of 83 healthy women (21-83-year-old). The G values of some limb muscles were measured in relaxed and stretched positions. RESULTS: Regarding the effect of age on G at the distinct positions, the G of the upper limb muscles were not significantly correlated with age in the relaxed and stretched positions. In contrast, the G of the iliacus showed a significant negative correlation in both positions. Additionally, the G of the rectus femoris had a significant negative correlation only in the relaxed position. Regarding differences among body parts, the G of the lower limb and oblique abdominal muscles showed a significant negative correlation, but no correlation in the upper limb, rectus abdominis, and back muscles. Moreover, MT showed a significant negative correlation with age in the lower limb, abdominal, and erector spinae muscles, but no correlation was detected in the upper limb and lumbar multifidus muscles. EI had a significant positive correlation in all the muscles. CONCLUSION: The effect of age on G depended on body parts, and the G of the lower limb and oblique abdominal muscles negatively associated with age. Additionally, G in the relaxed position may be more susceptible to aging than G in the stretched position.

Eight-week neuromuscular electrical stimulation training produces muscle strength gains and hypertrophy, and partial muscle quality improvement in the knee extensors.

This study investigated the effect of an 8-week neuromuscular electrical stimulation (NMES) training programme (3 days/week) on muscle quantity and quality and single-joint performance in the knee extensors. Thirty-nine untrained young male participants were randomly assigned to NMES training (n = 21) and control (n = 18) groups. The 8-week NMES training induced significant increase in the isometric maximal voluntary contraction (MVC) torque of the knee extensors (≈9.3%), muscle volume of the individual and entire quadriceps muscles determined by magnetic resonance imaging (≈3.3%-6.4%), and a significant decrease in the ultrasound echo intensity of the vastus lateralis (≈-4.0%); however, hypertrophy of the vastus intermedius (i.e., the deep muscle) was limited (≈3.3%). In the NMES training group, the repeated measures correlations of the isometric MVC torque with the muscle volume of the entire quadriceps muscle and each quadriceps muscle were significant (rrm (20) = 0.551-0.776), whereas that of the isometric MVC torque with the ultrasound echo intensity of the vastus lateralis was not significant. These findings suggest that NMES training produces muscle strength gains, muscle hypertrophy, and partial muscle quality improvement and that the NMES training-induced muscle strength gains is caused by muscle hypertrophy in the knee extensors.

Ultrasonographic echo intensity in the medial femoral cartilage is enhanced prior to cartilage thinning in women with early mild knee osteoarthritis.

PURPOSE: We aimed to determine whether altered cartilage echo intensity is associated with knee osteoarthritis (OA) severity and whether the alteration occurs before thinning of the femoral cartilage in knee OA. METHODS: The medial femoral cartilage thickness and echo intensity of 118 women aged ≥ 50 years were assessed using an ultrasound imaging device. Based on the Kellgren-Lawrence (KL) grade and knee symptoms, participants were classified into five groups: control (asymptomatic grades 0-1), early OA (symptomatic grade 1), grade 2, grade 3, and grade 4. Analysis of covariance, with adjusted age and height, and the Sidak post hoc test were used to assess the differences in cartilage thickness and echo intensity in knees with varying OA severity. RESULTS: The echo intensity on longitudinal images, equivalent to the tibiofemoral weight-bearing surface, was significantly higher in the grade 2 group than that in the control group (p = 0.049). However, no significant difference was noted in cartilage thickness (n.s.). In the grades 3 and 4 groups, cartilage thickness became thinner as OA progressed (p < 0.001 and p < 0.001, respectively). However, the cartilage echo intensity was not significantly enhanced compared with that of the grade 2 group (n.s.). There were no significant differences in the cartilage thickness and echo intensity between the early OA and control groups on the longitudinal images (n.s.). CONCLUSIONS: The echo intensity of the medial femoral cartilage was high in patients with KL grade 2, without decreased thickness. Our findings suggested that higher echo intensity is a feature of early cartilage degeneration in mild knee OA. Further studies are needed to establish this feature as a useful screening parameter of early cartilage degeneration in knee OA. LEVEL OF EVIDENCE: Level III.

Backscattering Echo Intensity Characteristics of Laser in Soil Explosion Dust.

Soil dust generated by explosions can lead to the absorption and scattering of lasers, resulting in low detection and recognition accuracy for laser-based devices. Field tests to assess laser transmission characteristics in soil explosion dust are dangerous and involve uncontrollable environmental conditions. Instead, we propose using high-speed cameras and an indoor explosion chamber to assess the backscattering echo intensity characteristics of lasers in dust generated by small-scale explosive blasts in soil. We analyzed the influence of the mass of the explosive, depth of burial, and soil moisture content on crater features and temporal and spatial distributions of soil explosion dust. We also measured the backscattering echo intensity of a 905 nm laser at different heights. The results showed that the concentration of soil explosion dust was highest in the first 500 ms. The minimum normalized peak echo voltage ranged from 0.318 to 0.658. The backscattering echo intensity of the laser was found to be strongly correlated with the mean gray value of the monochrome image of soil explosion dust. This study provides experimental data and a theoretical basis for the accurate detection and recognition of lasers in soil explosion dust environments.

Echo Intensity of Gastrocnemius Is Independently Associated with 6-Minute Walking Distance in Male Patients with Peripheral Arterial Disease.

Background and Objectives: This study aimed to examine the differences in the thickness and echo intensity (EI) of the gastrocnemius muscle measured via ultrasonography between healthy adults and patients with peripheral arterial disease (PAD) and to determine the associations of gastrocnemius thickness (GT) and EI within a 6 min walking distance (6MD) in patients with PAD. Materials and Methods: This cross-sectional study targeted 35 male patients with PAD (mean age, 73.7 years; mean body mass index [BMI], 23.5 kg/m2) and age- and gender-matched 73 male healthy adults (mean age, 73.2 years; mean BMI, 23.3 kg/m2). The gastrocnemius thickness (GT) and EI were measured using ultrasound. Both legs of patients with PAD were classified based on higher and lower ankle brachial pressure index (ABI), and the GTs and EIs with higher and lower ABI were compared with those of healthy adults. Multiple regression analysis incorporated 6MD as a dependent variable and each GT and EI with higher and lower ABI, age, and BMI as independent variables. Results: This study showed that GT was considerably greater in healthy adults than in both legs with higher and lower ABI (median values, 13.3 vs. 11.3 vs. 10.7, p < 0.01), whereas EI was lower in healthy adults than in the lower ABI leg (72.0 vs. 80.8 vs. 83.6, p < 0.05). The 6MD was shown to be substantially related to EI in both legs with higher and lower ABIs (p < 0.01) but not in the GT. Conclusions: In patients with PAD, the GT was lower, and EI was higher than in healthy adults. In addition, EIs in both legs with higher and lower ABIs were independently associated with 6MD in male PAD patients. This study showed that the EI measured via ultrasonography could become an important indicator for treatments for patients with PAD.

Association of Hand Grip Strength with Ultrasound-derived Forearm Muscle Thickness and Echo Intensity in Young Indian Adults.

Background: Muscle thickness (MT) quantification, which reflects the muscle function, can be measured using ultrasonography. Echo intensity (EI) quantified from the ultrasonography-derived skeletal muscle images reflects muscle quality. This study aimed to analyze the associations between handgrip strength, ultrasound-measured forearm MT, and EI in healthy young adults. Methods: Sixty healthy volunteers between the ages of 18 and 25 years participated in the study. Brightness mode ultrasonography (USG) was done to measure forearm radial and ulna MT. The EI was measured from an ultrasound image as a mean pixel value using a histogram in Adobe Photoshop. Individuals were tested for forearm handgrip strength using hand dynamometry. Results: Males had higher forearm MT and handgrip strength compared to females. Handgrip strength had a significant positive correlation with forearm radius, ulna MT (r = 0.726, 0.757 and P < 0.01), and forearm circumference (r = 0.529 and P < 0.01) and a negatively correlation with subcutaneous fat thickness (r = -0.496 and P < 0.01) and EI (r = -0.618 and P < 0.01). Linear regression showed a significant correlation between MT, circumference, and EI with handgrip strength (r = 0.825 and P < 0.001). After adjustment for the other two parameters, the forearm MT correlated positively and EI negatively with handgrip strength. Conclusion: USG can be more easily used than other imaging methods in research and clinical setting as it is nonhazardous, less expensive, versatile, and provides results faster. Thus, USG measurements in skeletal muscle are useful for measuring MT and subcutaneous fat thickness. EI measurement can be a convenient and noninvasive method for assessing muscle quality.

Age- and muscle-specific reliability of muscle architecture measurements assessed by two-dimensional panoramic ultrasound.

BACKGROUND: Age-related changes in muscle properties affect daily functioning, therefore a reliable assessment of such properties is required. We examined the effects of age on reliability, muscle quality and interrelation among muscle architecture (MA) parameters of the gastrocnemius medialis (GM), tibialis anterior (TA), and vastus lateralis (VL) muscles. METHODS: Three raters scored ultrasound (US) scans of 12 healthy younger and older adults, on fascicle length (FL), pennation angle (PA) and muscle thickness (MT). Intra- and inter-rater reliability of MA measures in rest and contraction was assessed by intraclass correlation coefficients (ICC) and standard error of measurements (SEM, SEM%). The relationship between MA parameters was examined using Pearson correlation coefficients. Muscle quality (MQ) was examined using mean pixel intensity. RESULTS: Reliability was moderate to excellent for TA in both groups (ICCs: 0.64-0.99, SEM% = 1.6-14.8%), and for VL in the younger group (ICCs: 0.67-0.98, SEM% = 2.0-18.3%). VL reliability was poor to excellent in older adults (ICCs: 0.22-0.99, SEM% = 2.7-36.0%). For GM, ICCs were good to excellent (ICCs: 0.76-0.99) in both groups, but GM SEM% were higher in older adults (SEM%Younger = 1.5-10.7%, SEM%Older = 1.6-28.1%). Muscle quality was on average 19.0% lower in older vs. younger adults. In both groups, moderate to strong correlations were found for VL FL and MT (r ≥ 0.54), and TA PA and MT (r ≥ 0.72), while TA FL correlated with MT (r ≥ 0.67) in younger adults only. CONCLUSIONS: In conclusion, age- and muscle-specificities were present in the relationships between MT and PA, and MT and FL at rest. Furthermore, the reliability of MA parameters assessed with 2D panoramic US is acceptable. However, the level of reliability varies with age, muscle and MA measure. In older adults notably, the lowest reliability was observed in the VL muscle. Among the MA parameters, MT appears to be the simplest and most easily reproducible parameter in all muscles and age groups.

Cervical Multifidus Morphology and Quality Are Not Associated with Clinical Variables in Women with Fibromyalgia: An Observational Study.

OBJECTIVE: Some studies have reported the presence of histological alterations, such as myofiber disorganization and abnormalities in the number and shape of mitochondria, in patients with fibromyalgia syndrome (FMS). Although Ultrasound imaging (US) is used to quantitatively characterize muscle tissues, US studies in patients with FMS are lacking. Therefore, we aimed to describe morphological and qualitative cervical multifidus (CM) muscle US features in women with FMS and to assess their correlation with clinical indicators. DESIGN: Observational study. SETTING: AFINSYFACRO Fibromyalgia Association (Madrid, Spain). SUBJECTS: Forty-five women with FMS participated. METHODS: Sociodemographic variables (e.g., age, height, weight, body mass index) and clinical outcomes (e.g., pain as assessed on a numerical pain rating scale, evolution time, pain-related disability as assessed by the Fibromyalgia Impact Questionnaire) were collected. Images were acquired bilaterally at the cervical spine (C4-C5 level) and measured by an experienced examiner for assessment of muscle morphology (e.g., cross-sectional area, perimeter, and shape) and quality (mean echo intensity and intramuscular fatty infiltration). Side-to-side comparisons and a correlational analysis were conducted. RESULTS: No significant side-to-side differences were found for morphology or quality features (P > 0.05). None of the clinical indicators were associated with US characteristics (all, P > 0.05). CONCLUSION: Our results showed no side-to-side differences for CM morphology and quality as assessed with US. No associations between CM muscle morphology or quality and Fibromyalgia Impact Questionnaire, pressure pain threshold, numerical pain rating scale score, or evolution time were observed. Our preliminary data suggest that muscle morphology is not directly related to pain and pain-related disability in women with FMS.

Comparison of the mass and amount of intramuscular non-contractile tissue of the trunk and lower extremity muscles between patients with Parkinson's disease and community-dwelling older adults.

OBJECTIVE: This study compared the masses and amounts of intramuscular non-contractile tissue of the trunk and lower extremity muscles, sagittal spinal alignment, and mobility and balance ability between patients with Parkinson's disease (PD) and older adults. METHODS: This study included 26 older adults (control [CTR] group) and eight patients with PD (PD group). Muscle thicknesses and echo intensities of the trunk and lower extremity muscles were measured using an ultrasound imaging device. Sagittal spinal alignments in the standing and prone positions were assessed using a Spinal Mouse. Mobility capacity was assessed based on the measurements of usual and maximal walking speeds, timed up-and-go (TUG) time, and five-chair-stand time, while balance ability was assessed based on the measurement of one-legged stance (OLS) time. RESULTS: Our results showed significantly lower gluteus maximus and tibialis anterior muscle thicknesses, higher thickness of the short head of the biceps femoris muscle, and higher echo intensity of the gluteus maximus muscle in the PD group than in the CTR group. Lumbar lordosis angle in the standing position, usual and maximal walking speeds, and OLS time were significantly lower, while the TUG and five-chair-stand times were significantly higher in the PD group than in the CTR group. The other factors did not differ significantly between groups. CONCLUSIONS: Our results revealed lower masses of the gluteus maximus and tibialis anterior muscles, higher mass of the short head of the biceps femoris muscle, and higher amounts of intramuscular non-contractile tissue of the gluteus maximus muscle in patients with PD.

Muscle quality indices separately associate with joint-level power-related measures of the knee extensors in older males.

PURPOSE: The purpose of this study was to investigate associations of muscle quality indices with joint-level power-related measures in the knee extensors of thirty-two older males (65-88 years). METHODS: Muscle quality indices included: echo intensity, ratio of intracellular- to total water content (ICW/TW), and specific muscle strength. Echo intensity was acquired from the rectus femoris (EIRF) and vastus lateralis (EIVL) by ultrasonography. ICW/TW was computed from electrical resistance of the right thigh obtained by bioelectrical impedance spectroscopy. Specific muscle strength was determined as the normalized maximal voluntary isometric knee extension (MVIC) torque to estimated knee extensor volume. Isotonic maximal effort knee extensions with a load set to 20% MVIC torque were performed to obtain the knee extension power-related measures (peak power, rate of power development [RPD], and rate of velocity development [RVD]). Power and RPD were normalized to MVIC. RESULTS: There were no significant correlations between muscle quality indices except between EIRF and EIVL (|r|≤ 0.253, P ≥ 0.162). EIRF was negatively correlated with normalized RPD and RVD (r ≤ - 0.361, P ≤ 0.050). ICW/TW was positively correlated with normalized peak power (r = 0.421, P = 0.020). Specific muscle strength was positively correlated with absolute peak power and RPD (r ≥ 0.452, P ≤ 0.012). CONCLUSION: Knee extension power-related measures were lower in participants with higher EI, lower ICW/TW, and lower specific muscle strength, but the muscle quality indices may be determined by independent physiological characteristics.