Muscle Size Research Articles

Efficacy of tocilizumab in patients with moderate-to-severe corticosteroid-resistant thyroid eye disease: a prospective study.

To evaluate the clinical outcomes of intravenous tocilizumab (TCZ) injection in patients with moderate-to-severe active thyroid eye disease (TED). Patients with active and moderate-to-severe TED who did not respond to conventional therapies were treated with TCZ from June 2019 to January 2021. The medical records of the patients were evaluated before the treatment. We analyzed patient demographics, including the duration of Graves' disease and TED, and assessed subjective symptoms, such as diplopia and ocular movement, clinical activity score (CAS), modified NOSPECS score, and exophthalmos before treatment and at 4, 8, 12, and 16weeks after the first drug injection. Blood tests, including TSH Rc Ab and TS Ab, were performed before treatment and 24weeks after the first injection. And orbital computed tomography (CT) was performed and Barrett's Index was calculated at baseline and after completion of all injections. Nineteen completed the scheduled treatment. There were no significant side effects, other than herpes zoster in one case and headache and dermatitis in another. Clinical symptoms before and 16 weeks after the treatment showed mean CAS decreased by 2.4 points, mean modified NOSPECS score decreased by 3.7 points, and mean exophthalmos decreased by 0.4 mm. Diplopia and extraocular muscle limitation improved in ten and remained stationary in five of the 15 patients, who presented with extraocular motility abnormalities. Six of 11 patients who underwent orbit CT showed improvement in muscle size. The mean TSH Rc Ab decreased by 7.5 IU/L and TS-Ab decreased by 162.9%. TCZ can treat active moderate-to-severe TED, showing high drug compliance and reasonable response to inflammation and extraocular motility abnormality.

A modified rehabilitation paradigm bilaterally increased rat extensor digitorum communis muscle size but did not improve forelimb function after stroke.

Malnutrition after stroke may lessen the beneficial effects of rehabilitation on motor recovery through influences on both brain and skeletal muscle. Enriched rehabilitation (ER), a combination of environmental enrichment and forelimb reaching practice, is used preclinically to study recovery of skilled reaching after stroke. However, the chronic food restriction typically used to motivate engagement in reaching practice is a barrier to using ER to investigate interactions between nutritional status and rehabilitation. Thus, our objectives were to determine if a modified ER program comprised of environmental enrichment and skilled reaching practice motivated by a short fast would enhance post-stroke forelimb motor recovery and preserve forelimb muscle size and metabolic fiber type, relative to a group exposed to stroke without ER. At one week after photothrombotic cortical stroke, male, Sprague-Dawley rats were assigned to modified ER or standard care for 2 weeks. Forelimb recovery was assessed in the Montoya staircase and cylinder task before stroke and on days 5-6, 22-23, and 33-34 after stroke. ER failed to improve forelimb function in either task (p > 0.05). Atrophy of extensor digitorum communis (EDC) and triceps brachii long head (TBL) muscles was not evident in the stroke-targeted forelimb on day 35, but the area occupied by hybrid fibers was increased in the EDC muscle (p = 0.038). ER bilaterally increased EDC (p = 0.046), but not TBL, muscle size; EDC muscle fiber type was unchanged by ER. While the modified ER did not promote forelimb motor recovery, it does appear to have utility for studying the role of skeletal muscle plasticity in post-stroke recovery.

Radiographic Thigh Muscle Measurements Are a Reliable Predictor of Psoas Area and Sarcopenia.

Sarcopenia is associated with falls, fractures, postoperative complications such as periprosthetic joint infections and dislocations, and early mortality. Although cross-sectional imaging is currently used to diagnose sarcopenia, inexpensive and widely available screening tests are needed. The goal of this study was to investigate whether measurements of thigh muscles made on radiographs can predict psoas muscle area and the presence of sarcopenia as determined on computed tomography (CT) scans. A retrospective radiographic review was performed to measure thigh muscle area in the coronal and sagittal planes using the differential in soft-tissue attenuation. Psoas muscle area on CT at L3 and L4 served as the gold standard for the diagnosis of sarcopenia. The correlation between thigh muscle and psoas muscle areas was determined, and multivariable models were developed to identify predictors of psoas muscle area and sarcopenia. Four hundred and fourteen patients (252 male, 162 female) were identified. Seventy-six (18.4%) of the patients had an L4 psoas muscle area below the sex-specific cutoff value for sarcopenia. Patients with sarcopenia on abdominal CT had significantly smaller thigh muscle measurements on all radiographic views. The mean and standard deviation of the thigh muscle measurements were determined for the entire cohort and for patients with sarcopenia, as well as for adults aged 18 to 40 years without sarcopenia to provide normative reference values. The intraclass correlation coefficients were >0.8 for all radiographic measurements. The anteroposterior-view measurement of thigh muscle width and lateral-view measurement of quadriceps height were identified as independent predictors of both psoas muscle area and sarcopenia. Measurements of thigh muscle size made on radiographs can predict both psoas muscle area and sarcopenia. These measurements are a reliable and readily available screening tool to aid in the diagnosis and treatment of sarcopenia in the orthopaedic population. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Comparison of Blood Flow Restriction Interventions to Standard Rehabilitation After an Anterior Cruciate Ligament Injury: A Systematic Review.

Blood flow restriction training (BFR-t) data are heterogeneous. It is unclear whether rehabilitation with BFR-t after an anterior cruciate ligament (ACL) injury is more effective in improving muscle strength and muscle size than standard rehabilitation. To review outcomes after an ACL injury and subsequent reconstruction in studies comparing rehabilitation with and without BFR-t. Systematic review. Level of evidence, 3. A search of English-language human clinical studies published in the past 20 years (2002-2022) was carried out in 5 health sciences databases, involving participants aged 18-65 undergoing rehabilitation for an ACL injury. Outcomes associated with muscle strength, muscle size, and knee-specific patient-reported outcome measures (PROMs) were extracted from studies meeting inclusion criteria and compared. The literature search identified 279 studies, of which 5 met the selection criteria. Two studies suggested that BFR-t rehabilitation after an ACL injury improved knee or thigh muscle strength and muscle size compared with rehabilitation consisting of comparable and higher load resistance training, with two studies suggesting the opposite. The single study measuring PROMs showed improvement compared to traditional rehabilitation, with no difference in muscle strength or size. BFR-t after an ACL injury seems to benefit muscle strength, muscle size, and PROM scores compared with standard rehabilitation alone. However, only 1 large study included all these outcomes, which has yet to be replicated in other settings. Further studies utilizing similar methods with a common set of outcome measures are required to confirm the effects of BFR-t on ACL rehabilitation.

Effects of Ashwagandha (Withania somnifera) standardized root extract on physical endurance and VO2max in healthy adults performing resistance training: An eight-week, prospective, randomized, double-blind, placebo-controlled study

Background Ashwagandha is a well-known Ayurvedic herb used for youthful vigor and wellbeing. This study investigated the effects of 600 mg standardized root extract (>5% withanolides) of Ashwagandha (Withania somnifera) on muscle size, strength and cardiorespiratory endurance following resistance training. Methods In this eight-week, parallel-group, multicenter, randomized, double-blind, placebo-controlled clinical study, 80 healthy male and female participants aged 18-45 years, who engaged in regular physical activity were randomly allocated in a 1:1 ratio to receive Ashwagandha (AG, n=40) 300 mg capsules twice daily for eight weeks, or identical placebo (PB, n=40). Seven (3 AG, 4 PB) participants were excluded due to poor compliance. All participants conducted eight-week resistance training. Study outcomes included muscle strength (1RM bench press and leg extension), muscle size (circumference of arm, chest and upper thigh) and cardio-respiratory endurance (VO2max) assessed at baseline and at eight weeks. Analysis of covariance (ANCOVA) was used to estimate adjusted differences based on sex, BMI and chest circumference at baseline. Results AG caused greater improvement in bench press (males: p = 0.0084; females: p = 0.0005), leg press (males: p = 0.0049; females: p = 0.018) and endurance (males: p <0.0001; females: p <0.0001) as compared to PB. Also, greater improvements in muscle girth for arm, chest and thigh were seen in both male and female participants with AG. No adverse events were reported in the study. Conclusions Eight weeks of AG root extract supplementation along with resistance training is effective in improving muscle strength, growth and endurance in both male and female participants. AG root extract could be a safer, effective and low-cost alternative for athletes to improve muscle endurance.

Exploring the Relationship between Ultrasonographic Measures of the Quadriceps and Knee Extensor Muscle Fitness in Endurance-Trained Individuals

Background. B-mode ultrasonography is an accessible and cost-effective method to assess muscle size and quality through muscle thickness (MT) and echo intensity (EI), respectively. Muscle thickness and EI have demonstrated relationships with maximal strength and local muscle endurance, providing a noninvasive and efficient modality to examine muscle fitness. However, these relationships have not been quantified in the individual quadriceps muscles of habitually endurance-trained populations, which may provide information to practitioners regarding rehabilitation and performance. Methods. Twenty-three participants (males: N = 10; females: N = 13) underwent B-mode ultrasonography to assess MT, EI, and adipose tissue thickness-corrected echo intensity (cEI) in the vastus intermedius (VI), vastus lateralis (VL), and rectus femoris (RF). Muscle fitness was evaluated through maximal strength (1RM) and local muscle endurance (4 sets to failure at 50% 1RM) during dynamic knee extension. Relationships between ultrasonography outcomes and muscle fitness were examined through stepwise multiple linear regression. Results. The results indicate that VI cEI is the strongest predictor of 1RM strength (r = −0.643), while no ultrasonography-derived measures significantly predicted local muscle endurance. Conclusion. The study demonstrates that ultrasonography, specifically measures of cEI in the VI, has the greatest association with maximal strength in endurance-trained individuals. These findings suggest monitoring VI muscle size and quality may benefit practitioners who aim to improve knee extension strength for performance or following injury. In addition, the findings support the use of EI examinations in trained populations.

Ultrasound Morphometry of the Pelvic Floor Muscles in Women of Reproductive Age

Biometric studies in nulliparous women conducted to date are limited by small sample sizes. The pelvic floor muscles perform an important function throughout a woman’s life. They provide fixation and maintenance of the pelvic organs, stretches during childbirth, ensuring the formation of the birth canal, and are a potential site for the formation of a hernia in the female body. Impaired function of this muscle group can lead to either excessive muscle contraction (chronic pelvic pain syndrome) or excessive stretching (pelvic organ prolapse). The purpose of the study is to assess the morphometric properties of the pelvic floor muscles in nulliparous women using 3D ultrasound scanning (sonography). Material and methods. The observation group consisted of 60 women of middle reproductive age who applied for an appointment with an obstetriciangynecologist with complaints of pain of various types localized in the perineum and pelvis, decreased desire and quality of sexual life, clinically confirmed by a diagnosis of incompetence of the pelvic floor muscles. The control group consisted of 30 women without dysfunction of the pelvic floor muscles according to clinical examination. The main criterion for inclusion of patients in the study was reproductive age - 18–45 years and natural childbirth in obstetric and gynecological history. Results. We found that the absence of visible sonographic markers of changes in the myofascial structures of the pelvis is not a prognostically significant criterion for muscle dysfunction, since predominantly changes in morphometric parameters are a reliable sign of the formation of pelvic floor muscle failure. Conclusion. The ultrasound morphometry method, which allows one to assess dynamic changes in the size of muscle and fascial structures, can be used in the clinical practice of an obstetrician-gynecologist. Early diagnosis of a violation of the structure of pelvis myofascial complex will allow early implementation of measures aimed at prevention and timely treatment.

Gracilaria chorda attenuates obesity‐related muscle wasting through activation of SIRT1/PGC1α in skeletal muscle of mice

AbstractGracilaria chorda (GC) is a red algal species that is primarily consumed in Asia. Here, we investigated the effect of GC on obesity‐related skeletal muscle wasting. Furthermore, elucidating its impact on the activation of sirtuin 1 (SIRT1)/peroxisome proliferator‐activated receptor gamma coactivator 1α (PGC1α) constituted a critical aspect in understanding the underlying mechanism of action. In this study, 6‐week‐old male C57BL/6 mice were fed a high‐fat diet (HFD) for 8 weeks to induce obesity, then continued on the HFD for another 8 weeks while orally administered GC. GC decreased ectopic fat accumulation in skeletal muscle and increased muscle weight, size, and function in obese mice. Furthermore, GC reduced skeletal muscle atrophy and increased hypertrophy in mice. We hypothesized that the activation of SIRT1/PGC1α by GC regulates skeletal muscle atrophy and hypertrophy. We observed that GC increased the expression of SIRT1 and PGC1α in skeletal muscle of mice and in C2C12 cells, which increased mitochondrial function and biogenesis. In addition, when C2C12 cells were treated with the SIRT1‐specific inhibitor EX‐527, no changes were observed in the protein levels of SIRT1 and PGC1α in the GC‐treated C2C12 cells. Therefore, GC attenuated obesity‐related muscle wasting by improving mitochondrial function and biogenesis through the activation of SIRT1/PGC1α in the skeletal muscle of mice.

Determining Changes in Muscle Size and Architecture After Exercise Training: One Site Does Not Fit all.

Nunes, JP, Blazevich, AJ, Schoenfeld, BJ, Kassiano, W, Costa, BDV, Ribeiro, AS, Nakamura, M, Nosaka, K, and Cyrino, ES. Determining changes in muscle size and architecture after exercise training: One site does not fit all. J Strength Cond Res 38(4): 787-790, 2024-Different methods can be used to assess muscle hypertrophy, but the effects of training on regional changes in muscle size can be detected only using direct muscle measurements such as muscle thickness, cross-sectional area, or volume. Importantly, muscle size increases vary across regions within and between muscles after resistance training programs (i.e., heterogeneous, or nonuniform, muscle hypertrophy). Muscle architectural changes, including fascicle length and pennation angle, after resistance and stretch training programs are also region-specific. In this paper, we show that the literature indicates that a single-site measure of muscle shape does not properly capture the effects achieved after exercise training interventions and that conclusions concerning the magnitude of muscle adaptations can vary substantially depending on the muscle site to be examined. Thus, we propose that measurements of muscle size and architecture should be completed at multiple sites across regions between the agonist muscles within a muscle group and along the length of the muscles to provide an adequate picture of training effects.

Novel 3D MRI-Based Volumetric Assessment of Rotator Cuff Musculature Demonstrates Stronger Correlation with Preoperative Functional Status When Compared to the Goutallier Grading Scheme

The Goutallier classification (GC) is used to assess fatty atrophy in rotator cuff (RC) tears, yet limitations exist. A battery of 3D-magnetic resonance imaging (MRI) volumetric scores (VS) was developed to provide comprehensive characterization of RC pathology. The purposes of this study were to: (1) Describe the correlation between GC and VS for supraspinatus changes in RC tears, (2) Characterize the chronicity of RC tears using the battery of 12 VS measurements, and (3) Compare GC and VS to determine which method most closely corresponds with preoperative patient reported outcome measures (PROMs). Preoperative shoulder MRIs were reviewed after arthroscopic RC repair. Preoperative GC stage and Patient-Reported Outcomes Measurement Information System (PROMIS) physical function (PF) and pain interference (PI) scores were collected. The battery of VS included fat infiltration (FIS), muscle size (MSS) and relative volume contribution (RCS) for each RC muscle. Backwards linear regression was performed to compare GC stage with preoperative PROMIS PF/PI to determine which VS measurement most closely correlated with preoperative PROMs. Eighty-two patients underwent RC repair (mean age 55±8.2 years, 63% male, 68% GC stage ≤1). In evaluation of the supraspinatus, there was a moderate positive correlation between GC and FIS (r = 0.459, p < 0.001); strong negative correlations were observed between MSS (r = -0.800, p < 0.001) and RCS (r = -0.745, p < 0.001) when compared to GC. A negligible linear correlation was observed between GC and preoperative PROMIS PF (r = -0.106, p = 0.343) and PI (r = -0.071, p = 0.528). On multivariate analysis, subscapularis MSS (beta > 0, p = 0.064) was a positive predictor, and subscapularis FIS (beta < 0, p = 0.137), teres minor MSS (beta < 0, p = 0.141) and FIS (beta < 0, p = 0.070) were negative predictors of preoperative PF (r = 0.343, p = 0.044); while supraspinatus MSS (beta > 0, p = 0.009) and FIS (beta > 0, p = 0.073), teres minor FIS (beta > 0, p = 0.072) and subscapularis FIS (beta > 0, p = 0.065) were positive predictors of preoperative PI (r = 0.410, p = 0.006). Although gold standard in evaluation of RC pathology, GC demonstrated negligible correlation with preoperative functional disability. Alternatively, a battery of 3D VS showed strong correlation with GC through a quantitative, comprehensive evaluation of the RC unit including several moderate predictors of preoperative functional disability.

Greater protein intake emphasizing lean beef does not affect resistance training-induced adaptations to skeletal muscle and tendon in older women: A randomized controlled feeding trial

BackgroundWhile experimental research supports that resistance training (RT), especially with greater dietary protein intake, improves muscle mass and strength in older adults, comparable research on tendons is needed. ObjectiveWe assessed the effects of a protein-rich diet emphasizing lean beef, compared to two control diets, on RT-induced changes in skeletal muscle and tendon size and strength in older women. MethodsWe randomly assigned women [age: 66±1y, body mass index (BMI): 28±1 kg/m2] to groups that consumed 1) 0.8 g total protein/kg body weight/day from mixed food sources (normal protein control, n=16); 2) 1.4 g/kg/d protein from mixed food sources (high protein control, n=17); or 3) 1.4 g/kg/d protein emphasizing unprocessed lean beef (high protein experimental group, n=16). Participants were provided with all foods and performed RT 3x/week, 70% of 1-repetition maximum (1RM) for 12 weeks. We measured quadriceps muscle volume via magnetic resonance imaging (MRI). We estimated patellar tendon biomechanical properties and cross-sectional area (CSA) using ultrasound and MRI. ResultsDietary intake did not influence RT-induced increases in quadriceps strength (p<0.0001) or muscle volume (p<0.05). We noted a trend for a RT effect on mean tendon CSA (p=0.07), with no differences among diets (p>0.05). Proximal tendon CSA increased with RT (p<0.05) with no difference among dietary groups (p>0.05). Among all participants, mid-tendon CSA increased with RT (p≤0.05). We found a decrease in distal CSA in the 0.8 g group (p<0.05) but no change in the 1.4 g groups (p>0.05). Patellar tendon MRI signal or biomechanical properties were unchanged. ConclusionsOur findings indicated that greater daily protein intake, emphasizing beef, did not influence RT-induced changes in quadriceps muscle strength or muscle volume of older women. While we noted trends in tendon CSA, we did not find a statistically significant impact of greater daily protein intake from beef on tendon outcomes. Clinical Trial RegistryClinicalTrials.gov (NCT04347447)

Skeletal muscle fiber type and TMS-induced muscle relaxation in unfatigued and fatigued knee-extensor muscles.

The force drop after transcranial magnetic stimulation (TMS) delivered to the motor cortex during voluntary muscle contractions could inform about muscle relaxation properties. Because of the physiological relation between skeletal muscle fiber type distribution and size and muscle relaxation, TMS could be a non-invasive index of muscle relaxation in humans. By combining a non-invasive technique to record muscle relaxation in vivo (TMS) with the gold standard technique for muscle tissue sampling (muscle biopsy), we investigated the relation between TMS-induced muscle relaxation in unfatigued and fatigued states, and muscle fiber type distribution and size. Sixteen participants (7F/9M) volunteered to participate. Maximal knee-extensor voluntary isometric contractions were performed with TMS before and after a 2-min sustained maximal voluntary isometric contraction. Vastus lateralis muscle tissue was obtained separately from the participants' dominant limb. Fiber type I distribution and relative cross-sectional area of fiber type I correlated with TMS-induced muscle relaxation at baseline [r = 0.67, adjusted P = 0.01; r = 0.74, adjusted P = 0.004, respectively] and normalized TMS-induced muscle relaxation as a percentage of baseline [r = 0.50, adjusted P = 0.049; r = 0.56, adjusted P = 0.031, respectively]. The variance in the normalized peak relaxation rate at baseline (59.8%, P < 0.001) and in the fatigue resistance (23.0%, P = 0.035) were explained by the relative cross-sectional area of fiber type I to total fiber area. Fiber type I proportional area influences TMS-induced muscle relaxation, suggesting TMS as an alternative method to non-invasively inform about skeletal muscle relaxation properties.

Network visualization of genes involved in skeletal muscle myogenesis in livestock animals

BackgroundMuscle growth post-birth relies on muscle fiber number and size. Myofibre number, metabolic and contractile capacities are established pre-birth during prenatal myogenesis. The aim of this study was to identify genes involved in skeletal muscle development in cattle, sheep, and pigs - livestock.ResultsThe cattle analysis showed significant differences in 5043 genes during the 135–280 dpc period. In sheep, 444 genes differed significantly during the 70–120 dpc period. Pigs had 905 significantly different genes for the 63–91 dpc period.The biological processes and KEGG pathway enrichment results in each species individually indicated that DEGs in cattle were significantly enriched in regulation of cell proliferation, cell division, focal adhesion, ECM-receptor interaction, and signaling pathways (PI3K-Akt, PPAR, MAPK, AMPK, Ras, Rap1); in sheep - positive regulation of fibroblast proliferation, negative regulation of endothelial cell proliferation, focal adhesion, ECM-receptor interaction, insulin resistance, and signaling pathways (PI3K-Akt, HIF-1, prolactin, Rap1, PPAR); in pigs - regulation of striated muscle tissue development, collagen fibril organization, positive regulation of insulin secretion, focal adhesion, ECM-receptor interaction, and signaling pathways (PPAR, FoxO, HIF-1, AMPK). Among the DEGs common for studied animal species, 45 common genes were identified. Based on these, a protein-protein interaction network was created and three significant modules critical for skeletal muscle myogenesis were found, with the most significant module A containing four recognized hub genes - EGFR, VEGFA, CDH1, and CAV1. Using the miRWALK and TF2DNA databases, miRNAs (bta-miR-2374 and bta-miR-744) and transcription factors (CEBPB, KLF15, RELA, ZNF143, ZBTB48, and REST) associated with hub genes were detected. Analysis of GO term and KEGG pathways showed that such processes are related to myogenesis and associated with module A: positive regulation of MAP kinase activity, vascular endothelial growth factor receptor, insulin-like growth factor binding, focal adhesion, and signaling pathways (PI3K-Akt, HIF-1, Rap1, Ras, MAPK).ConclusionsThe identified genes, common to the prenatal developmental period of skeletal muscle in livestock, are critical for later muscle development, including its growth by hypertrophy. They regulate valuable economic characteristics. Enhancing and breeding animals according to the recognized genes seems essential for breeders to achieve superior gains in high-quality muscle mass.

YTHDF2 governs muscle size through a targeted modulation of proteostasis

The regulation of proteostasis is fundamental for maintenance of muscle mass and function. Activation of the TGF-β pathway drives wasting and premature aging by favoring the proteasomal degradation of structural muscle proteins. Yet, how this critical post-translational mechanism is kept in check to preserve muscle health remains unclear. Here, we reveal the molecular link between the post-transcriptional regulation of m6A-modified mRNA and the modulation of SMAD-dependent TGF-β signaling. We show that the m6A-binding protein YTHDF2 is essential to determining postnatal muscle size. Indeed, muscle-specific genetic deletion of YTHDF2 impairs skeletal muscle growth and abrogates the response to hypertrophic stimuli. We report that YTHDF2 controls the mRNA stability of the ubiquitin ligase ASB2 with consequences on anti-growth gene program activation through SMAD3. Our study identifies a post-transcriptional to post-translational mechanism for the coordination of gene expression in muscle.

Body Image During Puberty: What Happens to How Kids Feel About Their Bodies?

Adolescence, the period between childhood and adulthood, is a time when significant changes happen to the human body. These changes, called puberty, signify the time during which humans develop into adults. During puberty, changes in weight, height, and muscle size leave many adolescents feeling unhappy with their appearance. We describe how these changes affect body image, which is the way that adolescents feel about their bodies. First, we discuss how a negative body image can be a risk factor for eating disorders and depression. Second, we highlight the body positivity movement, which encourages people to love their bodies no matter what they look like. Lastly, we describe body neutrality, an attitude that celebrates bodies for what they allow us to do, rather than for their appearance. Together, these body image concepts can help people to understand how physical changes that accompany puberty might affect mental health.

Cross-Education Effects of Isokinetic Eccentric Plantarflexor Training on Flexibility, Strength, and Muscle-Tendon Mechanics.

Large increases in joint range of motion (ROM) have been reported after eccentric resistance training, however limited data exist describing the associated mechanisms or potential cross-education effects in the contralateral limb. Therefore, the effects of a 6-week isokinetic eccentric plantarflexor training program were examined in 26 participants. Before and after the training program, dorsiflexion ROM, plantarflexor strength, and muscle-tendon unit (MTU) morphology and mechanics were measured in control (n = 13) and experimental (n = 13) young adult groups. Training consisted of 5 sets of 12 maximal isokinetic eccentric plantarflexor contractions twice weekly on the right limb. Significant (P < 0.05) increases in dorsiflexion ROM (4.0-9.5°), stretch tolerance (40.3-95.9%), passive elastic energy storage (47.5-161.3%), and isometric (38.1-40.6%) and eccentric (46.7-67.0%) peak plantarflexor torques were detected in both trained and contralateral limbs in the experimental group. Significant increases in gastrocnemius medialis (GM) and soleus thickness (5.4-6.1%), GM fascicle length (7.6 ± 8.5%), passive plantarflexor MTU stiffness (30.1 ± 35.5%) and Achilles tendon stiffness (5.3 ± 4.9%) were observed in the trained limb only. Significant correlations were detected between the changes in trained and contralateral limbs for dorsiflexion ROM (r = 0.59) and both isometric (r = 0.79) and eccentric (r = 0.73) peak torques. No significant changes in any metric were detected in the control group. Large ROM increases in the trained limb were associated with neurological, mechanical, and structural adaptations, with evidence of a cross-education effect in the contralateral limb being primarily driven by neurological adaptation (stretch tolerance). The large improvements in ROM, muscle size, and strength confirm that isokinetic eccentric training is a highly effective training tool, with potential for use in athletic and clinical populations where MTU function is impaired and current therapies are ineffective.

Sex Differences in Quadriceps Atrophy After Anterior Cruciate Ligament Tear.

Female athletes lag behind their male counterparts in recovery from anterior cruciate ligament (ACL) injury. Quadriceps muscle size and strength are crucial factors for regaining function after ACL injury, but little is known about how these metrics vary due to biological sex. Female patients have reduced vastus lateralis fiber cross-sectional area (CSA) and lower quadriceps strength after ACL injury than male patients. Cross-sectional study. Level 4. A total of 60 participants with recent ACL tear were evaluated for vastus lateralis muscle fiber CSA, isometric quadriceps peak torque, and quadriceps rate of torque development. Linear mixed models were fit to determine differences across sex and limb for each variable of interest. The female group averaged almost 20% atrophy between limbs (P < 0.01), while the male group averaged just under 4% (P = 0.05). Strength deficits between limbs were comparable between female and male groups. Immediately after ACL injury, female patients have greater between-limb differences in muscle fiber CSA but between-limb strength deficits comparable with those of male patients. These results indicate that the underpinnings of strength loss differ based on biological sex, and thus individual patients could benefit from a sex-specific treatment approach to ACL injury.

Are trunk muscle sizes different between acute lumbar spondylolysis and nonspecific low back pain?

IntroductionMorphological differences in the trunk muscles between adolescent athletes with lumbar spondylolysis (LS) and nonspecific low back pain (NSLBP) have not been fully elucidated. This study aimed to investigate the differences in physiological cross-sectional areas (CSA) of the trunk muscles between athletes with acute LS and those with acute NSLBP. MethodsMagnetic resonance images of 48 patients aged 13–14 years diagnosed with acute LS or NSLBP were retrospectively evaluated. The CSA of the paraspinal, psoas major, and rectus abdominis muscles at the L4-5 intervertebral disc level were measured. ResultsCSA of the left and right paraspinal muscles in the acute LS group were significantly larger than those in the acute NSLBP group (left: mean difference, 276.0 mm2; 95% confidence interval [CI], 68.5–483.6 mm2; P = 0.01; right: mean difference, 228.8 mm2; 95% CI, 7.6–450.1 mm2; P = 0.04). The ratio between the left paraspinal muscles and left psoas major in the acute LS group was significantly larger than that in the acute NSLBP group (mean difference, 0.2; 95% CI, 0.0–0.4; P = 0.03). ConclusionsTrunk muscle size may differ between adolescent athletes with acute LS and those with NSLBP. Future research involving healthy controls is required to better understand the morphological characteristics of these injuries.

Associations of Preoperative Nutritional Status and Sarcopenia With Mortality in Patients With Abdominal Aortic Aneurysm After Open and Endovascular Abdominal Aortic Aneurysm Repair: A Retrospective Study

Objective: The effect of preoperative malnutrition and sarcopenia on outcomes in patients with abdominal aortic aneurysm (AAA) after open (OSR) and endovascular abdominal aortic aneurysm repair (EAR) are undefined. We conducted the study to address this issue in this population. DesignRetrospective observational study. SettingA large tertiary hospital. ParticipantsPatients with AAA who underwent OSR and EVAR. InterventionsEvaluation of nutritional status [Nutritional Risk Screening 2002 (NRS2002) and the controlling nutritional status (CONUT) scores], muscle size (skeletal muscle index, SMI) and postoperative parameters. Measurements and main results199 patients were reviewed from January 2020 to December 2022. Patients are categorized into group A (CONUT < 4) and group B (CONUT ≥ 4) based on whether their CONUT scores are less than 4. The mortality (P = 0.004) and the incidence of Clavien-Dindo class III complications (P = 0.007) in Group B were higher than those in group A. CONUT score was an independent risk factor for mid-term mortality (hazard ratio [HR], 1.329; 95% CI, 1.104-1.697; P = 0.002) and Clavien-Dindo class III complications (odds ratio [OR], 1.225; 95% CI, 1.012-1.482; P = 0.037) according to univariate and multivariate analyses, whereas NRS2002 score and sarcopenia were not. Kaplan-Meier curves showed a lower mid-term survival rate in Group B (log-rank P < 0.001). Conclusion: In patients with AAA undergoing OSR or EVAR, CONUT score ≥ 4 was associated with increased Clavien-Dindo class III complications and mortality. Preoperative nutritional status should be evaluated and optimized in this high-risk population.

Skeletal muscle estimation: A review of techniques and their applications.

Quantifying skeletal muscle size is necessary to identify those at risk for conditions that increase frailty, morbidity, and mortality, as well as decrease quality of life. Although muscle strength, muscle quality, and physical performance have been suggested as important assessments in the screening, prevention, and management of sarcopenic and cachexic individuals, skeletal muscle size is still a critical objective marker. Several techniques exist for estimating skeletal muscle size; however, each technique presents with unique characteristics regarding simplicity/complexity, cost, radiation dose, accessibility, and portability that are important factors for assessors to consider before applying these modalities in practice. This narrative review presents a discussion centred on the theory and applications of current non-invasive techniques for estimating skeletal muscle size in diverse populations. Common instruments for skeletal muscle assessment include imaging techniques such as computed tomography, magnetic resonance imaging, peripheral quantitative computed tomography, dual-energy X-ray absorptiometry, and Brightness-mode ultrasound, and non-imaging techniques like bioelectrical impedance analysis and anthropometry. Skeletal muscle size can be acquired from these methods using whole-body and/or regional assessments, as well as prediction equations. Notable concerns when conducting assessments include the absence of standardised image acquisition/processing protocols and the variation in cut-off thresholds used to define low skeletal muscle size by clinicians and researchers, which could affect the accuracy and prevalence of diagnoses. Given the importance of evaluating skeletal muscle size, it is imperative practitioners are informed of each technique and their respective strengths and weaknesses.