Muscle Of Individuals Research Articles

Analysis of the Differences in Muscle Nutrition among Individuals of Different Sexes in Redclaw Crayfish, Cherax quadricarinatus

Redclaw crayfish (Cherax quadricarinatus) was introduced to China many years ago. In recent years, a breeding boom for C. quadricarinatus has been set off in China due to a breakthrough in key technology of seedling breeding. The size and growth rate of C. quadricarinatus vary greatly between female and male individuals, usually the size and growth rate of male individuals are bigger than that of female individuals. There is usually a certain linkage relationship between the sex traits of crustaceans and their own nutrition. In order to explore the linkage relationship between the sex traits of C. quadricarinatus and its nutritional components, this study measured and analyzed the muscle nutritional components of female and male individuals. The results showed that the meat yield rate of male individuals was significantly higher than that of females (p < 0.05), and the crude fat content was significantly lower than that for females (p < 0.05). The ratios of essential amino acids to total amino acids for females and males were 39.61% and 38.49%, respectively. The ratios of essential amino acids to non-essential amino acids were 79.69% and 75.66%, respectively, which far exceed FAO/WHO standards and both belong to high-quality protein. The total amount of flavor amino acids of male individuals was significantly higher than that of female individuals (p < 0.05). The total amount of polyunsaturated fatty acids and the polyunsaturated fatty acid eicosapentaenoic acid of males are both significantly higher than that of females (p < 0.05). Studies have shown that there are certain differences in nutrition between male and female individuals. Compared with female individuals, the meat yield rate, crude protein content, and edible value of the muscles of male individuals is higher.

Modulation of spinal circuits following phase-dependent electrical stimulation of afferent pathways

Objective. Peripheral electrical stimulation (PES) of afferent pathways is a tool commonly used to induce neural adaptations in some neural disorders such as pathological tremor or stroke. However, the neuromodulatory effects of stimulation interventions synchronized with physiological activity (closed-loop strategies) have been scarcely researched in the upper-limb. Here, the short-term spinal effects of a 20-minute stimulation protocol where afferent pathways were stimulated with a closed-loop strategy named selective and adaptive timely stimulation (SATS) were explored in 11 healthy subjects. Approach. SATS was applied to the radial nerve in-phase (INP) or out-of-phase (OOP) with respect to the muscle activity of the extensor carpi radialis (ECR). The neural adaptations at the spinal cord level were assessed for the flexor carpi radialis (FCR) by measuring disynaptic Group I inhibition, Ia presynaptic inhibition, Ib facilitation from the H-reflex and estimation of the neural drive before, immediately after, and 30 minutes after the intervention. Main results. SATS strategy delivered electrical stimulation synchronized with the real-time muscle activity measured, with an average delay of 17 ± 8 ms. SATS-INP induced increased disynaptic Group I inhibition (77 ± 23% of baseline conditioned FCR H-reflex), while SATS-OOP elicited the opposite effect (125 ± 46% of baseline conditioned FCR H-reflex). Some of the subjects maintained the changes after 30 minutes. No other significant changes were found for the rest of measurements. Significance. These results suggest that the short-term modulatory effects of phase-dependent PES occur at specific targeted spinal pathways for the wrist muscles in healthy individuals. Importantly, timely recruitment of afferent pathways synchronized with specific muscle activity is a fundamental principle that shall be considered when tailoring PES protocols to modulate specific neural circuits. (NCT number 04501133).

Relative contribution of neuromuscular activation, muscle size, and muscle quality to maximum strength output of the thigh muscles in young individuals.

This study aimed to investigate the relationship between maximal muscle strength and neuromuscular activation, muscle size, and quality of quadriceps (QF) and hamstring muscles (HM). The study included 24 young men and women. The neuromuscular activation parameter was recorded using a single-channel surface electromyography (EMG) with the root mean square (RMS) during maximal isometric knee extension and flexion from four muscles: rectus femoris and vastus lateralis for QF; biceps femoris and semitendinosus for HM. In addition, the peak torque was measured during the same session. B-mode ultrasonographic transverse images were obtained from the anterior, lateral, and posterior thighs. Furthermore, we calculated the muscle thickness (MT) and echo intensity (EI) of the four muscles as indicators of muscle size and quality. The averaged MT, EI, and absolute RMS of QF were calculated by averaging the values of the rectus femoris and vastus lateralis, and that of HM was calculated by averaging the values of the biceps femoris and semitendinosus. The knee extension peak torque was correlated with EI (r=-0.61, P < 0.01) and RMS (r=0.53, P < 0.01) in the QF. In contrast, the knee flexion peak torque was correlated with RMS (r=0.53, P < 0.05) but not with MT and EI in HM. In addition, EI and RMS in QF, and RMS in HM were selected as the major determinants of muscle strength in the stepwise regression analysis. These results suggest that muscle strength is moderately associated with different factors related to the thigh muscles in young individuals.

Contralesional cortical representation of paretic leg muscles in individuals with abnormal co-excitation post-stroke: a TMS based motor mapping study

Contralesional cortical representation of paretic leg muscles in individuals with abnormal co-excitation post-stroke: a TMS based motor mapping study

Removable dentures and electrical activity of masticatory muscles in individuals with Parkinson’s disease

Removable dentures and electrical activity of masticatory muscles in individuals with Parkinson’s disease

Ultrasonographic evaluation of the masseter muscle in patients with temporomandibular joint degeneration.

Sonographic elastography can be used to evaluate the hardness of muscle tissue through the application of compression. Strain elastography gauges hardness through the comparison of echo sets before and after compression. This study utilized ultrasonography to measure the thickness and hardness of the masseter muscle in individuals with temporomandibular joint (TMJ) osteoarthritis. This study included 40 patients who presented with joint pain and were diagnosed with TMJ osteoarthritis via diagnostic cone-beam computed tomography, along with 40 healthy individuals. The thickness and hardness of each individual's masseter muscle were evaluated both at rest and at maximum bite using ultrasonography. The Mann-Whitney U test and the chi-square test were employed for statistical analysis, with the significance level set at P<0.05. The mean thickness of the resting masseter muscle was 0.91 cm in patients with osteoarthritis, versus 1.00 cm in healthy individuals. The mean thickness of the masseter muscle at maximum bite was 1.28 cm in osteoarthritis patients and 1.36 cm in healthy individuals. The mean masseter elasticity index ratio at maximum bite was 4.51 in patients with osteoarthritis and 3.16 in healthy controls. Significant differences were observed between patients with osteoarthritis and healthy controls in both the masseter muscle thickness and the masseter elasticity index ratio, at rest and at maximum bite (P<0.05). The thickness of the masseter muscle in patients with TMJ osteoarthritis was less than that in healthy controls. Additionally, the hardness of the masseter muscle was greater in patients with TMJ osteoarthritis.

The prevalence of low muscle mass associated with obesity in the USA

BackgroundSarcopenia is defined as age-related low muscle mass and function, and can also describe the loss of muscle mass in certain medical conditions, such as sarcopenic obesity. Sarcopenic obesity describes loss of muscle and function in obese individuals; however, as sarcopenia is an age-related condition and obesity can occur in any age group, a more accurate term is obesity with low lean muscle mass (OLLMM). Given limited data on OLLMM (particularly in those aged < 65 years), the purpose of this study was to estimate the prevalence of OLLMM in adults aged ≥ 20 years in the USA.MethodsData from the National Health and Nutrition Examination Survey (NHANES) 2017–2018 and 1999–2006 were used. OLLMM was defined as an appendicular lean mass, adjusted for body mass index (BMI), cut-off point < 0.789 for males and < 0.512 for females, measured by dual-energy X-ray absorptiometry (DXA). DXA was only measured in individuals 20–59 years old in NHANES 2017–2018; we therefore utilized logistic regression models to predict OLLMM from NHANES 1999–2006 for those aged ≥ 60 years. The prevalence of OLLMM was estimated overall, and by sex, age, race/ethnicity, and clinical subgroup (high BMI, prediabetes, type 2 diabetes mellitus [T2DM], non-alcoholic fatty liver disease [NAFLD] with fibrosis, or post-bariatric surgery). Prevalence estimates were extrapolated to the USA population using NHANES sampling weights.ResultsWe estimated that, during 2017–2018, 28.7 million or 15.9% of the USA population had OLLMM. The prevalence of OLLMM was greater in older individuals (8.1%, aged 20–59 years vs 28.3%, aged ≥ 60 years), highest (66.6%) in Mexican-American females aged ≥ 60 years, and lowest (2.6%) in non-Hispanic Black males aged 20–59 years. There was a higher prevalence of OLLMM in adults with prediabetes (19.7%), T2DM (34.5%), NAFLD with fibrosis (25.4%), or post-bariatric surgery (21.8%), compared with those without each condition.ConclusionsOverall, the burden of OLLMM in the USA is substantial, affecting almost 30 million adults. The prevalence of OLLMM increased with age, and among those with prediabetes, T2DM, NAFLD with fibrosis, or post-bariatric surgery. A unified definition of OLLMM will aid diagnosis and treatment strategies.

MUSCLE GROUP SPECIFIC SKELETAL MUSCLE AGING: A FIVE YEAR LONGITUDINAL STUDY IN SEPTUAGENARIANS

Abstract Most of the scientific literature on human skeletal muscle aging has focused on the quadriceps femoris, with the remaining few hundred skeletal muscles receiving limited specific investigation. This longitudinal investigation compared changes in skeletal muscle size via computed tomography of the quadriceps (rectus femoris, vastus lateralis, vastus medialis, vastus intermedius), hamstrings (biceps femoris short and long heads, semitendinosus, semimembranosus), psoas, rectus abdominis, lateral abdominals (obliques and transversus abdominus), and paraspinal muscles (erector spinae and multifidi) of older individuals from the Health ABC study at baseline and 5.0±0.1 years later (n=469, 73±3y &amp; 78±3y, 49% women, 33% black). Skeletal muscle size decreased (p &amp;lt; 0.05) in quadriceps (-3.3%), hamstrings (-5.9%), psoas (-0.4%), and rectus abdominus (-7.0%). The hamstrings and rectus abdominus atrophied approximately twice as much as the quadriceps (p &amp;lt; 0.05), while the quadriceps atrophied substantially more than the psoas (p &amp;lt; 0.05). The paraspinals (+4.3%) and lateral abdominals (+5.9%) hypertrophied (p &amp;lt; 0.05) to a similar degree (p&amp;gt;0.05) over the 5 years. These data suggest that skeletal muscle mass in older individuals changes in a muscle group specific fashion in the eighth decade, a critical time period in the aging process. A broader understanding of muscle group specific skeletal muscle aging is needed to better guide exercise programs and other interventions that mitigate decrements in physical function with aging.

Preservation of shortening velocity and power output in single muscle fibres from patients with idiopathic inflammatory myopathies.

Idiopathic inflammatory myopathies (IIMs) are autoimmune disorders of skeletal muscle causing weakness and disability. Utilizing single fibre contractility studies, we have previously shown that contractility is affected in muscle fibres from individuals with IIMs. For the current study, we hypothesized that a compensatory increase in shortening velocity occurs in muscle fibres from individuals with IIMs in an effort to maintain power output. We performed in vitro single fibre contractility studies to assess force-velocity relationships and maximum shortening velocity (Vmax) of muscle fibres from individuals with IIMs (25 type I and 58 type IIA) and healthy controls (66 type I and 27 type IIA) and calculated maximum power output (Wmax) for each fibre. We found significantly higher Vmax (mean ± SEM) of fibres from individuals with IIMs, for both type I (1.40 ± 0.31 fibre lengths/s, n = vs. 0.63 ± 0.13 fibre lengths/s; p = 0.0019) and type IIA fibres (2.00 ± 0.17 fibre lengths/s vs 0.77 ± 0.10 fibre lengths/s; p < 0.0001). Furthermore, Wmax (mean ± SEM) was maintained compared to fibres from healthy controls, again for both type I and type IIA fibres (4.10 ± 1.00 kN/m2·fibre lengths/s vs. 2.00 ± 0.16 kN/m2·fibre lengths/s; p = ns and 9.00 ± 0.64 kN/m2·fibre lengths/s vs. 6.00 ± 0.67 kN/m2·fibre lengths/s; p = ns respectively). In addition, type I muscle fibres from individuals with IIMs was able to develop maximum power output at lower relative force. The findings of this study suggest that compensatory responses to maintain power output, including increased maximum shortening velocity and improved efficiency, may occur in muscle of individuals with IIMs. The mechanism underlying this response is unclear, and different hypotheses are discussed.

Correlation of Percentage Body Fat, Waist Circumference and Waist-to-Hip Ratio with Abdominal Muscle Strength.

Sedentary lifestyle and consumption of high-fat foods have become widespread, especially in the urban population. This leads to a reduction in lean body mass and increased body fat. The correlation between body fat indices and low back pain has been less explored and documented. The aim of this study was to identify the correlation between the percentage of body fat, waist circumference and waist-to-hip ratio and abdominal muscle strength. Percentage of body fat was estimated by using the body composition analyzer method using Tanita BC-545 Innerscan Segmental Body Composition. Waist-to-hip ratio was calculated by dividing the waist circumference by hip circumference. Abdominal muscle (rectus abdominis and external oblique) strength was measured by maximum voluntary isometric contraction as measured by surface electromyography. A positive correlation was observed between waist circumference and the percentage of body fat, while a negative correlation was observed between the average maximum voluntary isometric contraction of rectus abdominis and external oblique muscles and the percentage of body fat. Individuals with a high percentage of body fat tend to have higher fat distribution over the abdominal region and decreased abdominal muscle strength. Therapists should emphasize the use of abdominal muscles in individuals with high body fat in order to reduce the associated risk of the development of poor posture and low back pain.

Macroscopic Analysis of the Insertion Points of the Lateral Pterygoid Muscle in Adult Individuals

The lateral pterygoid muscle (LPM) is intimately related with the temporomandibular joint (TMJ), playing an important role in its physiology. This makes it of interest to researchers who investigate temporomandibular disorders. The literature indicates that anatomical variations exist in the insertion of the superior fascicle of the LPM. Imaging and cadaver studies have revealed that the LPM may present an accessory fascicle. The study object was to carry out macroscopic analysis of the LPM, examining the origin and insertion of its superior and inferior fascicles. The study used 38 half-heads of adult individuals fixed in formaldehyde 10 %. To carry out macroscopic analysis of the LPM, an initial incision was made along the lower margin of the zygomatic arch; the origin of the masseter muscle was then dissected, separating its insertion on the lateral face of the mandibular ramus and retracting the muscle to posteroinferior. Two incisions were made on the zygomatic arch and the insertion of the temporal muscle on the coronoid process was identified with dissection pincers; it was dissected to gain access to the infratemporal fossa and the two fascicles of the LPM. The superior fascicle (SF) originated on the infratemporal face of the greater wing of the sphenoid, and on the superior third of the lateral face of the lateral lamina of the pterygoid process of the sphenoid in 26 samples. In 12 samples, it originated on the greater wing of the sphenoid and the infratemporal crest of the sphenoid. Type I insertion was found in 20 samples, Type II in 6 samples and Type III in 12 samples. In all the samples analysed, the inferior fascicle (IF) originated on the inferior two thirds of the lateral face of the lateral lamina of the pterygoid process and on the lateral face of the pyramidal process of the palatine, with insertion on the pterygoid fovea. The accessory fascicle (AF) of the LPM was present in 6 samples. The AF originated on the greater wing of the sphenoid in 2 cases and inferior to the superior fascicle in 4 cases; its insertion was on the capsular disc complex in all cases. The results obtained in our study contribute anatomical data on the LPM in Brazilian adult individuals, with evaluation of its insertion points.

Acetate circumvents impaired metabolic switch in skeletal muscle of letrozole-induced PCOS rat model by suppression of PDK4/NLRP3

ObjectivesEndocrine disorders in women of childbearing age, including polycystic ovarian syndrome (PCOS), have been linked to skeletal muscle insulin resistance with multiple post-receptor intracellular defects, disrupting metabolic flexibility. Short-chain fatty acids, such as acetate have been suggested as a metabolic modulator. However, the effects of acetate on aberrant metabolic switch in skeletal muscle of individuals with PCOS are unknown. This study therefore hypothesized that acetate would circumvent impaired metabolic switch in the skeletal muscle of a letrozole-induced PCOS rat model, probably by suppression of PDK4/NLRP3. Methods: Eight-wk-old female Wistar rats were assigned into three groups (n = 6), which received vehicle, letrozole (1 mg/kg), and letrozole plus acetate (200 mg/kg), respectively. The administrations were done by oral gavage for 21 d. . ResultsAnimals with PCOS had insulin resistance, increased testosterone, and leptin, as well as decreased adiponectin level. Additionally, the skeletal muscle was also characterized with increased lipid deposition, malondialdehyde, inflammatory mediators (nuclear factor-κB and tumor necrosis factor-α), lactate dehydrogenase, lactate/pyruvate ratio, HDAC and PDK 4 with corresponding decrease in glycogen synthesis, glutathione and NrF2. Besides, immunohistochemical evaluation showed severe expression of inflammasome and apoptosis in PCOS animals. Nonetheless, supplementation with acetate significantly attenuated these perturbations. ConclusionsThe present results demonstrate aberrant metabolic switch in the skeletal muscle of PCOS animals, which is accompanied by excessive inflammation, oxidative stress and elevated levels of histone deacetylase and PDK4. The results suggested that histone deacetylase inhibitor, acetate circumvents impaired metabolic switch in the skeletal muscle of PCOS rats by suppression of PDK4/NLRP3 inflammasome.

Greater muscle volume and muscle fat infiltrate in the deep cervical spine extensor muscles (multifidus with semispinalis cervicis) in individuals with chronic idiopathic neck pain compared to age and sex-matched asymptomatic controls: a cross-sectional study

Muscle size and composition (muscle volume and muscle fat infiltrate [MFI]) may provide insight into possible mechanisms underpinning chronic idiopathic neck pain, a common condition with no definitive underlying pathology. In individuals with chronic idiopathic neck pain > 3 months and age- and sex-matched asymptomatic controls, muscle volumes of levator scapulae, multifidus including semispinalis cervicis (MFSS), semispinalis capitis, splenius capitis including splenius cervicis (SCSC), sternocleidomastoid and longus colli from C3 through T1 were quantified from magnetic resonance imaging. Between-group differences were determined using linear mixed models, accounting for side (left or right), muscle, spinal level, sex, age, and body mass index (BMI). Individuals with pain had greater muscle volume (mean difference 76.8mm3; 95% CI 26.6–127.0; p = .003) and MFI (2.3%; 0.2–4.5; p = .034) of the MFSS compared to matched controls with no differences in relative volume, accounting for factors associated with the outcomes: muscle, spinal level, side (left had smaller volume, relative volume and MFI than right), sex (females had less volume and relative volume than males), age (older age associated with less relative volume and greater MFI), and BMI (higher BMI associated with greater muscle volume and MFI). Greater MFI in individuals with chronic idiopathic neck pain suggests a possible underlying mechanism contributing to neck pain. Perspective: These findings suggest MFI in the MFSS may be radiologic sign, potentially identifying patients with a less favourable prognosis. Future studies are needed to confirm this finding and determine if MFI is a contributor to the development or persistence of neck pain, or consequence of neck pain.

Identification of underexplored mesenchymal and vascular-related cell populations in human skeletal muscle.

Skeletal muscle repair and maintenance are directly and indirectly supported by interstitial cell populations such as vascular cells and fibro-adipogenic progenitors (FAPs), a subset of which express Twist2 and possess direct myogenic potential. Furthermore, work in rodents has highlighted the potential of pericytes to act as progenitor cells, giving rise to muscle cells and transdifferentiating into endothelial cells. However, less is understood about these populations in human skeletal muscle. Here, we performed single-cell RNA sequencing (scRNAseq) on ∼2,000 cells isolated from the human semitendinosus muscle of young individuals. This demonstrated the presence of a vascular-related cell type that expressed pericyte and pan-endothelial genes that we localized to large blood vessels within skeletal muscle cross sections and termed endothelial-like pericytes (ELPCs). RNA velocity analysis indicated that ELPCs may represent a "transition state" between endothelial cells and pericytes. Analysis of published scRNAseq data sets revealed evidence for ELPCs in trunk and heart musculature, which showed transcriptional similarity. In addition, we identified a subset of FAPs expressing TWIST2 mRNA and protein. Human TWIST2-expressing cells were anatomically and transcriptionally comparable to mouse Twist2 cells as they were restricted to the myofiber interstitium, expressed fibrogenic genes but lacked satellite cell markers, and colocalized with the FAPs marker PDGFRα in human muscle cross sections. Taken together, these results highlight the complexity of stromal cells residing in human skeletal muscle and support the utility of scRNAseq for discovery and characterization of poorly described cell populations.

CircRNA Identification and CircRNA–miRNA–mRNA Network in Cynoglossus semilaevis Sexual Size Dimorphism

Simple SummaryChinese tongue sole (Cynoglossus semilaevis) typically displays female-biased sexual size dimorphism (SSD), but its epigenetic regulatory mechanisms are poorly understood, especially the role of circRNAs. To explore the function of circRNAs in Chinese tongue sole SSD, we firstly identified differentially expressed circular RNAs (DE circRNAs) in female, male, and pseudo-male C. semilaevis. Secondly, the ceRNA network containing DE circRNAs, miRNAs, and mRNAs in the three genders was constructed. Among the ceRNA network, several circRNAs such as novel_circ_004374 and novel_circ_014597 may regulate hipk2 expression by sponging miR-130-x. It is also worth exploring whether or how novel_circ_008696 regulates setd2 by binding to novel-m0387-3p. The present study provided the cirRNA and its ceRNA network that potentially regulate C. semileavis female-biased SSD for the first time. Sexual size dimorphism (SSD), which is the sexual differences in body size, has been widely reported in various species including fishes. For Chinese tongue sole (Cynoglossus semilaevis), a flatfish exhibiting typically female-biased SSD, little is known for its epigenetic regulation mechanism, especially the role of circRNAs. Here, we identified the differently expressed abundances of circRNAs in females, males, and pseudo-males to explore the potential functions of circRNAs in Chinese tongue sole SSD. In total, 14,745 novel circRNAs were screened, among which 1461 DE circRNAs were identified from the brain, gonad, liver, and muscle in female, male, and pseudo-male individuals. The ceRNA network was subsequently constructed, including 10 circRNAs, 26 mRNAs, and 11 miRNAs. These DE mRNAs were mainly related to the mRNA surveillance pathway, metabolic pathways, and cellular senescence. Importantly, the ceRNA network has revealed that several circRNAs such as novel_circ_004374 and novel_circ_014597 may regulate homeodomain interacting protein kinase 2 (hipk2) expression by sponging miR-130-x. It is also worth exploring whether or how novel_circ_008696 regulates SET Domain Containing 2, histone lysine methyltransferase (setd2), which in turn affects the epigenetic patterns of different sexual individuals. The present study not only enriches the knowledge on the potential roles of circRNA in the physiological process, but also provides new clues for the explanation of fish SSD. In future studies, the precise function and involvement of circRNAs in female-biased SSD will require more efforts.

Effect Of Transcutaneous Electrical Spinal Cord Stimulation On The Functional Activity Of Reciprocal And Presynaptic Inhibition In Healthy Subjects

The objective of our research was to examine an effect of 20-minute electrical stimulation session of the spinal cord (tESCS) on the manifestation of reciprocal and presynaptic inhibition in the system of shin antagonist muscles in healthy individuals in a state of a relative muscle rest and weak muscle effort, along with possible physiological mechanisms of these manifestations. Material and Methods — The study involved 10 healthy men 27 to 35 years of age. Reciprocal and presynaptic inhibition was evaluated by suppressing the amplitude of testing H-reflex of m. soleus under conditions of conditioning stimulation of n. peroneus profundus and testing stimulation of n. tibialis with interstimulus intervals of 3 ms and 100 ms, respectively. Reciprocal inhibition and presynaptic inhibition were recorded during a 20-minute tESCS in the area of T11-T12 thoracic vertebrae at rest, in combination with voluntary muscular effort (5% of the maximum voluntary contraction), and after the stimulation. Results — During 20-minute electrical stimulation of the spinal cord at rest, the severity of reciprocal inhibition decreased, inverting to reciprocal facilitation, while presynaptic inhibition weakened only at the twentieth minute of stimulation; and in the postactivation period, the activity of spinal inhibition processes in the antagonist muscle system corresponded to background values. The most pronounced effect of prolonged tESCS was observed when performing a weak isometric contraction, which was accompanied by an increase in reciprocal inhibition activity during 10 minutes of exposure and 10 minutes after the end of stimulation. The severity of presynaptic inhibition during and after the spinal cord stimulation remained unchanged and complied with background values. The presynaptic inhibition activity was expressed to a greater extent during prolonged stimulation of the spinal cord at rest, and when performing a weak voluntary effort, as well as during the postactivation period. Conclusion — Changes in the spinal inhibitory interactions in the system of antagonist muscles on the basis of tESCS effects during arbitrary muscle tension could probably be explained by the fact that in this case, the inhibitory interneuron circuits of spinal cord were exposed to a wider range supraspinally descending and ascending peripheral effects, compared with spinal cord stimulation in a state of a relative muscle rest.

Morphology and composition of the ventral neck muscles in individuals with chronic whiplash related disorders compared to matched healthy controls: a cross-sectional case–control study

BackgroundObjectiveStudies of cross-sectional area (CSA) (morphology) and muscle fat infiltration (MFI) (composition) in ventral neck muscles is scarce in patients with chronic whiplash associated disorders (WAD), especially for men and those with severe WAD compared with matched healthy controls. The aim was to compare CSA and MFI of sternocleidomastoid (SCM), longus capitis (LCA) and longus colli (LCO) in patients with chronic right-sided dominant moderate (Neck Disability Index: NDI < 40) or severe WAD (NDI ≥ 40), compared to age- and sex-matched healthy controls.MethodsCross-sectional case–control study with blinded investigators. Thirty-one patients with chronic WAD (17 women and 14 men, mean age 40 years) (SD 12.6, range 20–62)) and 31 age- and sex-matched healthy controls underwent magnetic resonance imaging of ventral neck muscles segmental level C4.ResultsUnique to the severe group was a larger magnitude of MFI in right SCM (p = 0.02) compared with healthy controls. There was no significant difference between the groups with regards to the other muscles and measures.ConclusionsIndividuals with severe right-sided dominant WAD have a higher MFI in the right SCM compared to healthy controls. No other differences were found between the groups. The present study indicates that there are changes in the composition of muscles on the side of greatest pain.

Differential Sensitization of Muscle versus Fascia in Individuals with Low Back Pain.

Muscles and the deep fascia surrounding them have been suggested to play an important role in various musculoskeletal pain conditions including low back pain. Both have been shown to host rich nociceptive innervation and to undergo changes in individuals with chronic pain. However, evidence for the respective contribution of muscle and fascia sensitization in humans with myofascial pain syndrome is lacking. Here, we studied the sensitization of muscle and fascia in individuals with myofascial low back pain. Twenty individuals with acute (5) and chronic (15) myofascial low back pain of the quadratus lumborum muscle and a matched control group of twenty healthy individuals were recruited and clinically evaluated. All participants underwent ultrasound-guided needling of their subcutaneous tissue, deep fascia and quadratus lumborum muscle. Reported pain intensity and episodes of muscle twitching were recorded and analyzed. Among pain patients, both muscles and deep fascia demonstrated pain hypersensitivity, but muscles were significantly more sensitized than the deep fascia. No difference between acute- or chronic-pain patients was observed. Results of this study suggest that while both deep fascia and muscle show pain sensitization in both early and chronic stages of low back pain, muscles are more sensitized than fascia.

ABDOMINAL BRACING MANEVRASININ FARKLI DİZ FLEKSİYON AÇILARINDA, KUADRİSEPS ZİRVE TORKU, ZİRVE TORKA ULAŞMA SÜRESİ VE KAS AKTİVASYONU ÜZERİNE ETKİSİ

Purpose: The aim of the present study was to investigate the effects of abdominal bracing maneuver (ABM) on quadriceps peak torque (PT), time to peak torque (TTPT) and muscle activation levels during maximal strength testing of the quadriceps muscle in healthy individuals.&#x0D; Methods: Sixteen healthy individuals (Age: 24.63±1.67 years) participated in the present study. Each participant was taught ABM technique by a physical therapist’s guidance. Surface electromyography was used to measure internal oblique/transversus abdominis, vastus medialis, vastus lateralis, and rectus femoris activation levels. Isokinetic dynamometry was used to measure quadriceps PT and TTPT during maximum isometric muscle testing at 60° and 90° of knee flexion angles with and without ABM. Repeated measures of ANOVA was performed for statistical analysis.&#x0D; Results: There was a significant angle by condition interaction for quadriceps PT (F(1,15)=5.30, p=0.04). PT decreased when ABM was performed, but the decrease was greater at 600 compared to 900 of knee flexion (60°: p=0.001, ES=0.68; 90°: p=0.008, ES=0.33). Quadriceps activation levels also decreased during ABM (p=0.04) regardless of knee flexion angle.&#x0D; Conclusion: The present study revealed that ABM may decrease muscle activation levels and peak torque during maximal quadriceps strength testing. Researchers should evaluate compensatory movements of the lumbopelvic region in order to prevent the error of force transfer in test results.

Evaluation of the abdominal transverse muscle in individuals with low back pain: a literature review

Introduction: Low back pain is the leading cause of years lived with disability in the world. Despite the relevance of the subject in the literature, some authors have criticized and conducted studies without methodological criteria for the evaluation of the transverse abdominis muscle, creating a gap in knowledge and divergences in evidence-based practice. Objective: The aim of the study was to carry out a literature review, looking for studies that observed changes in the Transverse Abdominal muscle in individuals with low back pain. Methods: The following keywords were used as methodology: Low back Pain, Lumbago, Transverse Abdominal, Transversus Abdominis, Transverse Abdominals, In the following databases: Pubmed 137 studies, Web of Science 625 studies, Scopus 228 studies. Inclusion criteria: Studies that evaluated the Transverse Abdominal muscle in individuals with pain were selected for analysis of the results. Exclusion criteria: Studies that evaluated only healthy individuals, studies that addressed treatment or therapeutic intervention, studies conducted before 2016, duplications by authors, or those that did not use evaluation as methodology were excluded. Results: Finding a total of 990 studies, after elimination for duplication, 725 articles After being analyzed and selected by the inclusion and exclusion criteria, 18 studies were selected. Conclusion: The Transverse Abdominal muscle showed changes in its muscle thickness, neuromuscular activation, motor control, between healthy individuals and individuals with low back pain, being evaluated in different postures and populations. It is suggested that the evaluation of the transverse abdominal muscle should be performed in patients with low back pain, as an important dysfunctional diagnostic tool for these patients.