Muscle Size Research Articles

Investigating sources for variability in volunteer kinematics in a braking maneuver, a sensitivity analysis with an active human body model.

Occupant kinematics during evasive maneuvers, such as crash avoidance braking or steering, varies within the population. Studies have tried to correlate the response to occupant characteristics such as sex, stature, age, and BMI, but these characteristics explain no or very little of the variation. Therefore, hypothesis have been made that the difference in occupant response stems from voluntary behavior. The aim of this study was to investigate the effect from other sources of variability: in neural delay, in passive stiffness of fat, muscle tissues and skin, in muscle size and in spinal alignment, as a first step towards explaining the variability seen among occupants in evasive maneuvers. A sensitivity analysis with simulations of the SAFER Human Body Model in braking was performed, and the displacements from the simulations were compared to those of volunteers. The results suggest that the head and torso kinematics were most sensitive to spinal alignment, followed by muscle size. For head and torso vertical displacements, the range in model kinematics was comparable to the range in volunteer kinematics. However, for forward displacements, the included parameters only explain some of the variability seen in the volunteer experiment. To conclude, the results indicate that the variation in volunteer vertical kinematics could be partly attributed to the variability in human characteristics analyzed in this study, while these cannot alone explain the variability in forward kinematics. The results can be used in future tuning of HBMs, and in future volunteer studies, when further investigating the potential causes of the large variability seen in occupant kinematics in evasive maneuvers.

Blood flow restriction training on physical parameters in elite male canoe athletes.

To investigate the effect blood flow restriction (BFR) exercises on muscle size, strength and athletic performance in elite canoe athletes aged 18 to 25 years. This was a randomized controlled trial. The participants were divided into 2 groups: the intervention group (INT-gr) (n = 17, age: 18.59 ± 0.71 years) and the control group (CONT-gr) (n = 16, age: 18.81 ± 1.11 years). Anthropometric measurements, muscle size measured by ultrasound (US), strength measurements with an isokinetic dynamometer, and ergometer performance with an indoor ergometer were conducted before and after the exercise program. Knee flexion and extension and leg press one-repetition maximum (1 RM) tests were performed to determine the participants' training program. The INT-gr performed 1 RM 30% resistance training + BFR for 8 weeks, while the CONT-gr performed 1 RM 30% resistance training (RT) without BFR with their routine training program. US was used to measure the cross sectional area (CSA) and thickness of the quadriceps femoris (QF) and Hamstring (H) muscles in the pre-post design, and the isokinetic dynamometer was used to measure the strength of bilateral 60˚/s and 300˚/s peak torque (PT) values of the QF and H. Sports performance was tested on an indoor ergometer at distances of 200, 500, and 1000 m. The changes in bilateral rectus femoris (RF) CSA and VL thickness measurements in the INT-gr were significant (P < .05). Ergometer performance measurements showed a significant improvement over CONT-gr at all distances (P < .05). In terms of strength scores measured by the isokinetic dynamometer, the right QF and H 300˚/s and the left QF 60˚/s PT values were significantly in favor of INT-gr. BFR exercises are effective to increase strength, muscle size, and ergometer performance in elite canoe athletes.

Immediate association of navicular bone height and plantar intrinsic muscle size with toe flexion task: An ultrasound-based study

BACKGROUND: Intrinsic foot muscle (IFM) dysfunction and poor foot arch are associated with various foot conditions. Toe flexor exercise (TFE) has been used to improve it; however, the immediate effects of TFE on each IFM and how it relates to changes in navicular bone height (NH) are unclear. OBJECTIVE: This study aimed to investigate acute muscle swelling in the IFM after TFE and the association between changes in NH and IFM size. METHODS: Fourteen adults participated in this study. NH and cross-sectional area (CSA) of the IFM were acquired pre and post- TFE. The CSA of the IFM, including the abductor hallucis (AbH), flexor hallucis brevis, flexor digitorum brevis, and quadratus plantae, was acquired with ultrasonography. In the TFE, each participant completed five sets of eight repetitions with maximum strength. RESULTS: The NH and CSA of all IFM significantly increased significantly post-TFE (p&lt; 0.01). Only the increase in AbH was moderately and positively correlated with the change in NH (r= 0.54, p&lt; 0.01). CONCLUSION: This study suggests that the acute swelling of AbH after TFE is associated with an immediate increase in NH, supporting the important role of AbH in the formation of foot arch.

Pharmacological Inhibition of Myostatin in a Mouse Model of Typical Nemaline Myopathy Increases Muscle Size and Force.

Nemaline myopathy is one of the most common non-dystrophic congenital myopathies. Individuals affected by this condition experience muscle weakness and muscle smallness, often requiring supportive measures like wheelchairs or respiratory support. A significant proportion of patients, approximately one-third, exhibit compound heterozygous nebulin mutations, which usually give rise to the typical form of the disease. Currently, there are no approved treatments available for nemaline myopathy. Our research explored the modulation of myostatin, a negative regulator of muscle mass, in combating the muscle smallness associated with the disease. To investigate the effect of myostatin inhibition, we employed a mouse model with compound heterozygous nebulin mutations that mimic the typical form of the disease. The mice were treated with mRK35, a myostatin antibody, through weekly intraperitoneal injections of 10 mg/kg mRK35, commencing at two weeks of age and continuing until the mice reached four months of age. The treatment resulted in an increase in body weight and an approximate 20% muscle weight gain across most skeletal muscles, without affecting the heart. The minimum Feret diameter of type IIA and IIB fibers exhibited an increase in compound heterozygous mice, while only type IIB fibers demonstrated an increase in wild-type mice. In vitro mechanical experiments conducted on intact extensor digitorum longus muscle revealed that mRK35 augmented the physiological cross-sectional area of muscle fibers and enhanced absolute tetanic force in both wild-type and compound heterozygous mice. Furthermore, mRK35 administration improved grip strength in treated mice. Collectively, these findings indicate that inhibiting myostatin can mitigate the muscle deficits in nebulin-based typical nemaline myopathy, potentially serving as a much-needed therapeutic option.

Strength Training Perceptions Amongst Vocational Circus and Dance Students.

Introduction: The aim of this study was to analyze perceptions of strength training in vocational circus and dance students. It was hypothesized that due to the higher relative strength demands and associated risks of working at height in some aerial and acrobatic disciplines that circus students would be more open to strength training than dancers. Methods: Eighty students completed the Training Information Survey (TIS) (Mean age = 20.74 ± 2.71); 39 circus students and 41 dance students. 97% of circus students and 69% of dance participants reported that strength training was a required part of their training with students participating in strength training 4.24 ± 0.98 and 3.05 ± 1.42 day per week respectively. Results: Perceptions of strength training amongst vocational circus and dance students appear to be favorable, with both sets of students strongly agreeing with the statements "Strength training is essential to my overall development as a dancer/circus artist" (5.00 (IQR 1.00) and 5.00 (IQR 1.00) respectively). Following Bonferonni correction only one statement returned statistically significant results with dance students agreeing more strongly with the statement "Strength training increases muscle size," U = 473.00, P = .001. Students also agreed that strength training helped them to feel better mentally and physically, that strength training is beneficial for both men and women and that it should not be designated as specific to either sex. Conclusion: Results support earlier studies that suggest a cultural shift in perceptions of strength training and ideal esthetic in dance, particularly amongst students and that they are keen to incorporate strength training into their practice. Educational establishments should note students' interest in participating in strength training, reviewing how to embed effective strength training education, more coaching and time allowance for these activities within their timetable. Further research with a greater sample size is recommended to further substantiate these indications of a shift in perceptions.

Assessing the effectiveness of Compare Assistant for improving intra-rater reliability of ultrasound-measured muscle thickness.

Muscle thickness measured via ultrasound is commonly used to assess muscle size. The purpose of this study was to determine if the reliability of this measurement will improve if using the Compare Assistant tool, and whether this depends on technician experience and the muscle being assessed. Individuals came to the laboratory for two visits each separated by 24h. On day 1, two ultrasound images were taken on the individual's anterior upper arm (elbow flexors) and anterior lower leg (tibialis anterior) by two inexperienced and one experienced ultrasound technician. On day 2, three images were taken: (1) without looking at the previous images taken on day 1; (2) after re-examining the images taken on day 1, and (3) side-by-side with the images taken on day 1 via Compare Assistant. Bayes Factors (BF10) were used to provide evidence for the null (< 0.33) or alternative (> 3) hypotheses. There was no rater by measurement technique interaction (upper body: BF10 = 0.04, lower body: BF10 = 0.138), nor was there a main effect of measurement technique (upper body: BF10 = 0.052, lower body: BF10 = 0.331), indicating that reliability measures were not improved for either the upper body (CV%, no look: 2.92 vs. Compare Assistant: 2.87) or lower body (CV%, no look: 1.81 vs. Compare Assistant: 1.34) as a result of using Compare Assistant. The results of this study suggest that day-to-day reliability of muscle thickness measurement may be limited by random biological variability as opposed to technician error.

SAT392 A Case Of Idiopathic Intracranial Hypertension in Gender Dysphoria: Is Testosterone The Culprit?

Abstract Disclosure: S. Saad-Omer: None. D. John: None. M. Matos: None. C. Botero Suarez: None. S.K. Suryanarayanan: None. Background: The role of gender affirming Testosterone therapy in female-to-male patients with idiopathic intracranial hypertension (IIH) remains controversial. Case: A 32-year-old transgender male (Female-to-Male) was admitted after ophthalmologic evaluation for difficulties with night vision revealed papilledema. On admission, the patient reported a 2-month history of worsening bifrontal headaches accompanied by nausea, photophobia, and hyperacusis. Physical examination revealed papilledema and photophobia with BMI (34) and BP (132/86mmHg). CT Head was normal. Lumbar puncture showed an opening pressure of 22 cm water consistent with elevated intracranial pressure. Cerebrospinal fluid (CSF) lab results were grossly unremarkable. He reported being on 4 pumps daily of testosterone gel 1% (50mg) which was started approximately 3 months prior to admission with the last dose administered the day prior to admission. Initial labs showed bioavailable testosterone of 48.7 ng/dl, sex hormone binding globulin 29 nmol/l, free testosterone 24.2ng/dl, albumin 4.4g/dl, total testosterone 178ng/dl, estradiol 67pg/ml, FSH 6.7 mIU/ml, and LH 3.66 IU/ml. MRI Brain and Orbits revealed signs consistent with intracranial hypertension with no masses or bleeding to suggest an alternative cause. He was treated with Solumedrol, Acetazolamide, a brief course of Topiramate. Due to the suspected role of testosterone therapy in development of IIH, it was held during hospitalization. The risks and benefits of testosterone were discussed with the patient and he elected to restart it for gender affirmation at the time of discharge. However, his severe headache recurred after one week and he was asked to hold therapy for 30 days. He had no significant symptomatic improvement while off testosterone and therapy was resumed. Discussion: Several theories have been proposed to explain the occurrence of IIH in transgender patients with the leading hypothesis suggesting a “physiological window” of abnormal hormone levels, shared by women with elevated androgen levels and men with low androgen levels, where the risk of developing IIH is increased. Testosterone levels in women who have hyperandrogenism is similar to those in men with hypoandrogenism and these levels are likely contributing to the increase in volume of visceral fat and decrease in the size of muscles. It is therefore feasible that IIH is a distinct neuro-metabolic complication of circulating testosterone levels within this range. Conclusion: Our patient reported no symptomatic improvement despite withholding testosterone therapy for 30 days. Given the scarcity of evidence, it is important to discuss the potential risk of IIH with transgender patients, but not to withhold gender affirming hormone therapy for these patients. More research is required to better explore the mechanism of this association and possible methods to prevent its occurrence. Presentation: Saturday, June 17, 2023

The larynx in 3 dimensions: A digital anatomical model derived from radiographic imaging, refined with peer-reviewed literature, and optimized with medical illustration

ObjectivesDevelopment of an anatomically accurate three-dimensional (3D) digital model of the human larynx derived from published literature and radiographic imaging. Materials and MethodsThe laryngeal framework was segmented from a computed tomography (CT) angiogram of a healthy 29-year-old female. Data derived from published anatomical studies were compiled to provide additional anatomical detail to each structure. Anatomical details beyond the resolution of the imaging study or which could not be elucidated from the study were refined according to descriptions in the anatomic literature. The 3D model was refined by the medical illustrator, and its mesh was reformatted to optimize online viewing and manipulation. ResultsDue to the small size of the laryngeal muscles, there was no attempt to segment these muscles using radiographic imaging. All intrinsic laryngeal muscles were generated de novo, as were the superior laryngeal nerve and recurrent laryngeal nerve. CT imaging was utilized to generate meshes of the hyoid bone, epiglottis, thyroid cartilage, cricoid cartilage, and thyrohyoid membrane. Additionally, the airway space was segmented to provide size and spatial location to the vallecula, false vocal folds, true vocal folds, piriform sinus, subglottis, and a scaffold for the mucosa. These meshes were processed to limit radiographic artifact and serve as a foundation for the construction of the remainder of the laryngeal anatomy. The model was uploaded to a 3D repository, which can be accessed here (https://shorturl.at/nJPYZ). ConclusionThe larynx is a highly specialized organ essential for speech, swallowing, and airway protection. This study describes a digital 3D model of the larynx, created by combining radiographic imaging with critical review of anatomic literature. Utilizing the expertise of neuroradiology, laryngeal surgery, and medical illustration, we highlight surgically-relevant anatomic relationships and important aspects to consider during laryngeal surgery.

Longitudinal trajectory of medial gastrocnemius muscle growth in the first years of life.

To define the longitudinal trajectory of gastrocnemius muscle growth in 6- to 36-month-old children with and without spastic cerebral palsy (SCP) and to compare trajectories by levels of gross motor function (Gross Motor Function Classification System, GMFCS) and presumed brain-lesion timing. Twenty typically developing children and 24 children with SCP (GMFCS levels I-II/III-IV = 15/9), were included (28/16 females/males; mean age at first scan 15.4 months [standard deviation 4.93, range 6.24-23.8]). Three-dimensional freehand ultrasound was used to repeatedly assess muscle volume, length, and cross-sectional area (CSA), resulting in 138 assessments (mean interval 7.9 months). Brain lesion timing was evaluated with magnetic resonance imaging classification. Linear mixed-effects models defined growth rates, adjusted for GMFCS levels and presumed brain-lesion timing. At age 12 months, children with SCP showed smaller morphological muscle size than typically developing children (5.8 mL vs 9.8 mL, p < 0.001), while subsequently no differences in muscle growth were found between children with and without SCP (muscle volume: 0.65 mL/month vs 0.74 mL/month). However, muscle volume and CSA growth rates were lower in children classified in GMFCS levels III and IV than typically developing children and those classified in GMFCS levels I and II, with differences ranging from -56% to -70% (p < 0.001). Muscle growth is already hampered during infancy in SCP. Muscle size growth further reduces with decreasing functional levels, independently from the brain lesion. Early monitoring of muscle growth combined with early intervention is needed.

In situ forming biomaterials as muscle void fillers for the provisional treatment of volumetric muscle loss injuries.

Volumetric muscle loss (VML) represents a devastating extremity injury which leads to chronic functional deficits and disability and is unrecoverable through normal healing pathways. When left untreated, the VML pathophysiology creates many challenges towards successful treatment, such as altered residual muscle architecture, excessive fibrosis, and contracture(s). As such, innovative approaches and technologies are needed to prevent or reverse these adverse sequelae. Development of a rationally designed biomaterial technology which is intended to be acutely placed within a VML defect - i.e., to serve as a muscle void filler (MVF) by maintaining the VML defect - could address this clinical unmet need by preventing these adverse sequelae as well as enabling multi-staged treatment approaches. To that end, three biomaterials were evaluated for their ability to serve as a provisional MVF treatment intended to stabilize a VML defect in a rat model for an extended period (28 days): polyvinyl alcohol (PVA), hyaluronic acid and polyethylene glycol combination (HA+PEG), and silicone, a clinically used soft tissue void filler. HA+PEG biomaterial showed signs of deformation, while both PVA and silicone did not. There were no differences between treatment groups for their effects on adjacent muscle fiber count and size distribution. Not surprisingly, silicone elicited robust fibrotic response resulting in a fibrotic barrier with a large infiltration of macrophages, a response not seen with either the PVA or HA+PEG. Taken together, PVA was found to be the best material to be used as a provisional MVF for maintaining VML defect volume while minimizing adverse effects on the surrounding muscle.

Flight muscle size reductions and functional changes following long-distance flight under variable humidity conditions in a migratory warbler.

Bird flight muscle can lose as much as 20% of its mass during a migratory flight due to protein catabolism, and catabolism can be further exacerbated under dehydrating conditions. However, the functional consequences of exercise and environment induced protein catabolism on muscle has not been examined. We hypothesized that prolonged flight would cause a decline in muscle mass, aerobic capacity, and contractile performance. This decline would be heightened for birds placed under dehydrating environmental conditions, which typically increases lean mass losses. Yellow-rumped warblers (Setophaga coronata) were exposed to dry or humid (12 or 80% relative humidity at 18°C) conditions for up to 6 h while at rest or undergoing flight. The pectoralis muscle was sampled after flight/rest or after 24 h of recovery, and contractile properties and enzymatic capacity for aerobic metabolism was measured. There was no change in lipid catabolism or force generation of the muscle due to flight or humidity, despite reductions in pectoralis dry mass immediately post-flight. However, there was a slowing of myosin-actin crossbridge kinetics under dry compared to humid conditions. Aerobic and contractile function is largely preserved after 6 h of exercise, suggesting that migratory birds preserve energy pathways and function in the muscle.

Resistance training in humans and mechanical overload in rodents do not elevate muscle protein lactylation.

Although several reports have hypothesized that exercise may increase skeletal muscle protein lactylation, empirical evidence in humans is lacking. Thus, we adopted a multi-faceted approach to examine if acute and subchronic resistance training (RT) altered skeletal muscle protein lactylation levels. In mice, we also sought to examine if surgical ablation-induced plantaris hypertrophy coincided with increases in muscle protein lactylation. To examine acute responses, participants' blood lactate concentrations were assessed before, during, and after eight sets of an exhaustive lower body RT bout (n = 10 trained college-aged men). Vastus lateralis biopsies were also taken before, 3-h post, and 6-h post-exercise to assess muscle protein lactylation. To identify training responses, another cohort of trained college-aged men (n = 14) partook in 6weeks of lower-body RT (3x/week) and biopsies were obtained before and following the intervention. Five-month-old C57BL/6 mice were subjected to 10 days of plantaris overload (OV, n = 8) or served as age-matched sham surgery controls (Sham, n = 8). Although acute resistance training significantly increased blood lactate responses ∼7.2-fold (p < 0.001), cytoplasmic and nuclear protein lactylation levels were not significantly altered at the post-exercise time points, and no putative lactylation-dependent mRNA was altered following exercise. Six weeks of RT did not alter cytoplasmic protein lactylation (p = 0.800) despite significantly increasing VL muscle size (+3.5%, p = 0.037), and again, no putative lactylation-dependent mRNA was significantly affected by training. Plantaris muscles were larger in OV versus Sham mice (+43.7%, p < 0.001). However, cytoplasmic protein lactylation was similar between groups (p = 0.369), and nuclear protein lactylation was significantly lower in OV versus Sham mice (p < 0.001). The current null findings, along with other recent null findings in the literature, challenge the thesis that lactate has an appreciable role in promoting skeletal muscle hypertrophy.

Factors associated with changes in activities of daily living from admission to discharge among older patients with pneumonia

IntroductionIt has not been fully elucidated that nutritional parameters affect the change of activities of daily living (ADL) during pneumonia treatment. This study assessed the impact of nutritional status, including erector spinae muscle (ESM) size on ADL changes from admission to discharge among older patients with community-acquired pneumonia (CAP). MethodsWe retrospectively included patients (age: ≥65 years) who were admitted to the hospital for CAP and underwent chest computed tomography (CT) on admission. ADL was evaluated using the Barthel index, and patients were divided into the maintained or improved ADL group and the declined ADL group from admission through discharge. The ESM cross-sectional area was measured on a single-slice CT image. Logistic regression models were applied for assessing factors associated with changes in ADL. ResultsA total of 523 patients hospitalized for CAP (median age 86 years) were evaluated. The declined group had significantly higher ADL levels on admission, a greater frequency of smoking history and malignancy, and a lower frequency of cerebrovascular disease and dementia. No significant difference in ESM size was observed between the groups. Multivariate analysis revealed that higher ADL levels on admission (odds ratio 1.034, interquartile range 1.026–1.043) and malignancy (3.002, 1.150–7.836) were associated with a decline in ADL, whereas cerebrovascular disease (0.579, 0.373–0.900) was related to improvement or maintenance of ADL. ConclusionsAlthough nutritional status might not affect the change of ADL among older patients hospitalized with pneumonia, a cerebrovascular disease history may be a good predictor for ADL improvement.

Model of Electrical Stimulation of Back Muscles in the Treatment of Scoliosis

The article presents a three-dimensional model of the tissues of the human back in the ZBrush and SolidWorks software packages. Modeling of the spinal column with a bend, muscles, adipose tissue and skin was performed. Using the COMSOL Multiphysics environment, the effects of electrical stimulation on biological objects are modeled, and characteristics are determined. When modeling, in the properties of each biological tissue, the values of electrical conductivity and relative permittivity were set, the electrodes were adjusted, a grid was created to divide the models into smaller parts and elements, and the required frequency was adjusted. To verify the simulation results, a study was carried out on the patient, the calculation and analysis of the results obtained. The developed models can be used in clinical medicine to determine the strength of the stimulating current and set the parameters of electrical stimulation. When building a model, one can change the thickness of adipose tissue, skin, muscle and bone sizes, change the size of the electrodes, and thereby select the most optimal parameters for electrical stimulation. Models can be used in the development of the most effective method of electrical stimulation and the scheme for applying electrodes for a certain type of scoliosis.

Skeletal muscle adaptations in patients with lung cancer: Longitudinal observations from the whole body to cellular level.

Cancer and its treatment can adversely affect skeletal muscle, impacting physical function, treatment response and survival. No studies, however, have comprehensively characterized these muscle adaptations longitudinally in human patients at the cellular level. We examined skeletal muscle size and function from the whole body to the sub-cellular level in 11 patients with non-small cell lung cancer (NSCLC; 6 male/5 female, mean age 58±3years) studied over a 2-month observation period starting during their first cycle of standard of care cancer treatment and in 11 age- and sex-matched healthy controls (HC) without a current or past history of cancer. Biopsies of the vastus lateralis were performed to assess muscle fibre size, contractility and mitochondrial content, along with assessments of physical function, whole muscle size and function, and circulating cytokines. Body weight, composition and thigh muscle area and density were unaltered over time in patients with NSCLC, while muscle density was lower in patients with NSCLC versus HC (P=0.03). Skeletal muscle fibre size decreased by 18% over time in patients (all P=0.02) and was lower than HC (P=0.02). Mitochondrial fractional area and density did not change over time in patients, but fractional area was lower in patients with NSCLC compared with HC (subsarcolemmal, P=0.04; intermyofibrillar, P=0.03). Patients with NSCLC had higher plasma concentrations of IL-6 (HC 1.40±0.50; NSCLC 4.71±4.22; P<0.01), GDF-15 (HC 569±166; NSCLC 2071±1168; P<0.01) and IL-8/CXCL8 (HC 4.9±1.8; NSCLC 10.1±6.0; P=0.02) compared with HC, but there were no changes in inflammatory markers in patients with NSCLC over time. No changes were observed in markers of satellite cell activation or DNA damage in patients and no group differences were noted with HC. Whole-muscle strength was preserved over time in patients with NSCLC coincident with improved single fibre contractility. This study is the first to comprehensively examine longitudinal alterations in skeletal muscle fibre size and function in patients with NSCLC and suggests that muscle fibre atrophy occurs during cancer treatment despite weight stability and no changes in conventional clinical measurements of whole body or thigh muscle size over this period.

The Effects of Combined Motor Control and Isolated Extensor Strengthening versus General Exercise on Paraspinal Muscle Morphology, Composition, and Function in Patients with Chronic Low Back Pain: A Randomized Controlled Trial.

Low back pain (LBP), a globally widespread and persistent musculoskeletal disorder, benefits from exercise therapy. However, it remains unclear which type leads to greater changes in paraspinal muscle health. This study aimed to (1) compare the effects of a combined motor control and isolated lumbar extension exercise (MC+ILEX) versus a general exercise (GE) intervention on paraspinal muscle morphology, composition, and function, and (2) examine whether alterations in paraspinal muscle health were correlated with improvements in pain, function, and quality of life. Fifty participants with chronic LBP were randomly assigned to each group and underwent a 12-week supervised intervention program. Magnetic resonance imaging and ultrasound assessments were acquired at baseline, 6 and 12 weeks to examine the impact of each intervention on erector spinae (ES) and multifidus (MF) muscle size (cross-sectional area, CSA), composition, and function at L4-L5 and L5-S1. Self-reported questionnaires were also acquired to assess participant-oriented outcomes. Our findings indicated that the MC+ILEX group demonstrated greater improvements in MF and ES CSA, along with MF thickness at both levels (all p < 0.01). Both groups significantly improved in pain, function, and quality of life. This study provided preliminary results suggesting that an MC+ILEX intervention may improve paraspinal morphology while decreasing pain and disability.

Sex differences in muscle health in simulated micro- and partial-gravity environments in rats

Skeletal muscle size and strength are important for overall health for astronauts. However, how male and female muscle may respond differently to micro- and partial-gravity environments is not fully understood. The purpose of this study was to determine how biological sex and sex steroid hormones influence the progression of muscle atrophy after long term exposure to micro and partial gravity environments in male and female rats. Male and female Fisher rats (n ​= ​120) underwent either castration/ovariectomy or sham surgeries. After two weeks recovery, animals were divided into microgravity (0g), partial-gravity (40% of weight bearing, 0.4g), or full weight bearing (1g) interventions for 28 days. Measurements of muscle size and strength were evaluated prior to and after interventions. At 0g, females lost more dorsiflexion strength, plantar flexion strength, and other metrics of muscle size compared to males; castration/ovariectomy did not influence these differences. Additionally, at 0.4g, females lost more dorsiflexion strength, plantar flexion strength, and other metrics of muscle strength compared to males; castration/ovariectomy did not influence these differences. Females have greater musculoskeletal aberrations during exposure to both microgravity and partial-gravity environments; these differences are not dependent on the presence of sex steroid hormones. Correspondingly, additional interventions may be necessary to mitigate musculoskeletal loss in female astronauts to protect occupational and overall health.

Atrophy of the Posterior Cricoarytenoid Muscle as an Indicator of a Recurrent Laryngeal Nerve Injury History Before Revision Anterior Cervical Spine Surgery.

Retrospective study. In our recent study, we observed some cases of symptomatic normal vocal cord motility instead of asymptomatic vocal cord palsy (VCP) in preoperative laryngoscopy of a revision anterior cervical spine surgery (ACSS) cohort. We assumed the intrinsic muscle atrophy caused by recurrent laryngeal nerve injury could cause vocal cord-related symptoms. Thus, radiological examinations were reviewed in relation to the posterior cricoarytenoid (PCA) muscle, one of the intrinsic muscles. We retrospectively analyzed 64 patients who underwent a revision ACSS. Patients with vocal cord-related symptoms were classified as symptomatic group (group S, n = 11), and those without symptoms as asymptomatic group (group AS, n = 53). The bilateral size and signal intensity of the PCA muscles in these patients were measured in the axial view with preoperative computed tomography (CT) and magnetic resonance imaging (MRI) evaluations. Since the size and signal intensity values were different on each image, the ratios of the contralateral and ipsilateral muscle values were analyzed for each modality. There was no VCP on laryngoscopy study. However, the mean ratio of the PCA muscle size on CT was 1.40 ± .37 in group S and 1.02 ± .12 in group AS (P = .007). These values on the MRI were 1.49 ± .45 in group S and 1.02 ± .14 in group AS, which was also a significant difference (P = .008). Evaluating the size of the PCA muscle before revision ACSS may predict a previous recurrent laryngeal nerve injury. Careful planning for the appropriate approach should be undertaken if vocal cord-related symptoms and atrophy of PCA muscle are evident.

Muscular Adaptations to Concurrent Resistance Training and High-Intensity Interval Training in Adults with Type 2 Diabetes: A Pilot Study.

This pilot study aimed to compare the effects of eight weeks of concurrent resistance training (RT) and high-intensity interval training (HIIT) vs. RT alone on muscle performance, mass and quality in adults with type 2 diabetes (T2DM). Twelve T2DM adults were randomly allocated to the RT + HIIT (n = 5) or RT (n = 7) group. Before and after training, maximal oxygen uptake (VO2max), muscle strength and power were evaluated by calorimetry, dynamometry and one-repetition maximum (1RM) test. Quadriceps muscle volume was determined by MRI, and muscle quality was estimated. After RT, VO2max (+12%), knee muscle power (+20%), quadriceps muscle volume (+5.9%) and quality (leg extension, +65.4%; leg step-up, +223%) and 1RM at leg extension (+66.4%), leg step-up (+267%), lat pulldown (+60.9%) and chest press (+61.2%) significantly increased. The RT + HIIT group improved on VO2max (+27%), muscle volume (+6%), muscle power (+9%) and 1RM at lat pulldown (+47%). No other differences were detected. Among groups, changes in muscle quality at leg step-up and leg extension and VO2max were significantly different. The combination of RT and HIIT effectively improves muscle function and size and increases cardiorespiratory fitness in adults with T2DM. However, HIIT combined with RT may interfere with the development of muscle quality.

Androgenic anabolic steroid abuse

Androgen anabolic steroid abuse is a broad term describing the use of structural derivatives of testosterone with the aim to increase body mass and muscle size, or to enhance athletic performance. These drugs are typically used in large doses, much higher than would be prescribed for the treatment of medical conditions. This use of steroids is illegal and can lead to multiple adverse effects including cardiovascular, hepatic, metabolic and psychological issues. Many patients abusing steroids will not typically disclose this information when presenting to their GP. This article aims to help raise awareness of signs and symptoms of abuse, as well as highlight the common long-term risks and discuss a GP’s role in managing these complex scenarios.