Muscle Of Individuals Research Articles

TREATMENT OF VENOUS INSUFFICIENCY EMERGING AFTER COVID-19 DISEASE

COVID-19 disease caused by the virus called severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a highly contagious disease leading to hyperinflammation. Lockdown measures implemented due to COVID-19 can lead to weakness in the calf muscles of the elderly individuals who stay at home for a long time and in those receiving COVID-19 treatment in intensive care unit. Thus, venous insufficiency may develop in these circumstances. It is important to treat these patients without delay, as it may prevent the progression to chronic venous insufficiency. Our study includes eight patients who were diagnosed with COVID-19 and were discharged after being treated in various centers, but later developed venous insufficiency. Two of the patients were women and six were men. Their ages ranged from 43 to 70, and the mean age was 56.87 ± 9.70 years. The main complaints of the patients were pain, swelling, itching, tingling, burning, edema, cramping, feeling of heaviness and discoloration in the legs. All patients were hypertensive and five patients were using tobacco products. In addition, two patients had diabetes and one patient had concomitant coronary artery disease. All patients had weak calf muscles and high D-dimer levels. Venous insufficiency was diagnosed because reflux was detected in the deep veins of both lower extremities in the color venous Doppler ultrasonographic examination of the patients. Considering that venous insufficiency may be seen after recovery in COVID-19 patients, intermittent control of these patients should be done after discharge. It is important to closely monitor patients who develop venous insufficiency after COVID-19 treatment, and to strengthen the weakened calf muscles with exercises in addition to medical treatment with venoactive drugs. Since venous insufficiency may regress as a result of the strengthening of calf muscles, it should not be rushed for invasive procedures.

Ocean Warming May Enhance Biochemical Alterations Induced by an Invasive Seaweed Exudate in the Mussel Mytilus galloprovincialis.

Ocean warming and biological invasions are among the most pervasive factors threatening coastal ecosystems with a potential to interact. Ongoing temperature rise may affect physiological and cellular mechanisms in marine organisms. Moreover, non-indigenous species spread has been a major challenge to biodiversity and ecosystem functions and services. The invasive red seaweed Asparagopsis armata has become successfully established in Europe. Its exudate has been considered deleterious to surrounding native species, but no information exists on its effect under forecasted temperature increase. This study evaluated the combined effects of temperature rise and A. armata exudate exposure on the native mussel Mytilus galloprovincialis. Oxidative stress, neurophysiological and metabolism related biomarkers were evaluated after a 96 h-exposure to exudate (0% and 2%) under present (20 °C) and warming (24 °C) temperature scenarios. Short-term exposure to A. armata exudate affected the oxidative stress status and neurophysiology of the mussels, with a tendency to an increasing toxic action under warming. Significant oxidative damage at protein level was observed in the digestive gland and muscle of individuals exposed simultaneously to the exudate and temperature rise. Thus, under a climate change scenario, it may be expected that prolonged exposure to the combined action of both stressors may compromise M. galloprovincialis fitness and survival.

Microcirculatory Responses to Muscle and Tendon Exercises in Individuals With and Without Type 2 Diabetes Mellitus and the Association Between Microcirculatory and Exercise Performance.

Background: This study aimed to measure and compare (1) the microcirculation and microcirculatory responses of the muscles and tendons at rest and during isometric muscle contractions in participants with and without diabetes mellitus (DM) and (2) to determine correlations between microcirculation and muscle strength. Methods: Sixty-three participants with type 2 DM and 42 physically matched controls were recruited. Baseline measurements of the microcirculation of the rectus femoris (RF) and medial gastrocnemius (MG) muscles and patellar (PT) and Achilles tendons (AT), as well as their microcirculatory changes during maximal isometric exercises, were performed and recorded by using near-infrared spectroscopy and a red laser. Data on various laboratory tests (including glycated hemoglobin, triglyceride, high-density cholesterol), the monofilament test, and the ankle-brachial index were also obtained. Results: The baseline measurements indicated that, compared with the controls, the diabetic participants had lower oxygen saturation (SpO2) in their RF and MG muscles (both P < 0.001), and the total hemoglobin in the diabetic PT and AT was higher (P = 0.001 and P = 0.01). The minimal SpO2 levels in the aforementioned muscles during isometric contractions were lower in the diabetes group than in the control group (P ≤ 0.001). Furthermore, there were correlations between the microcirculatory change of the RF muscle and the knee extension force. Conclusions: This study demonstrated the effects of diabetes on the microcirculation of skeletal muscles and tendons during baseline measurements and responses to maximal isometric exercises. The results support the need for preventive strategies for diabetic muscles to prevent adverse complications when performing resistance training.

Potential Roles of Numb in Myogenesis, Mitochondrial Metabolism, and Calcium Signaling

Numb, first discovered in Drosophila as a critical genetic determinant of central nervous system development, is a highly conserved protein expressed in other tissues and in all higher organisms. Reduced Numb mRNA levels was found in muscles of older individuals, suggesting the role of Numb in the pathogenesis of aging-related decline of muscle strength. However, its molecular mechanisms remain incompletely understood. Since mitochondrial dysfunction has been linked to muscle aging, and mitochondria are organelles responsible for ATP production, lipid and overall metabolism, and calcium signaling, all closely associated with muscle function, our hypothesis in this study is that downregulation of Numb will perturbe mitochondrial functional, which will eventually contribute to muscle aging. To test this hypothesis, we employed both in vitro and in vivo models in our studies. Mouse primary myoblasts were transfected with control or vivo morpholino of Numb for 48 hours during myoblast differentiation, followed by morphological and functional evaluations. We quantified myogenic differentiation by fusion index, cytosolic calcium homeostasis by the Fura-2 ratio method, and mitochondrial functional tests using the Seahorse analyzer using both the Phenotype test kit and the Mito stress test kit. In addition, lipidomic profiles of gastrocnemius muscles from mice with muscle-specific conditional knockout (cKO) of Numb/NumbL and their control type littermates were measured using a liquid chromatography with tandem mass spectrometry (LC-MS/MS) method recently developed. Our results demonstrated that transfection with Numb morpholino led to approximately 30% reduction in Numb protein levels, ~15% reduction in fusion index, a more quiescent energy phenotype, and a statistically significant decreased basal respiration, maximal respiration, and spare capacity in mitochondria. Moreover, myotubes treated with the Numb morpholino had a 50% reduction in the amplitude of calcium transient induced by caffeine as well as a prolongation of the calcium transients, along with the intriguing appearance of spontaneous small calcium transients similar to those observed in beating hearts. Lipidomic profiling results indicated a significant increase in the levels of key inflammation-related lipid mediators, derived from polyunsaturated fatty acids through lipoxygenase metabolic pathways, in gastrocnemius muscles from cKO mice, such as 12-hydroxyeicosapentaenoic acid (12-HEPE, p=0.035) and 12-hydroxyeicosatetraenoic acid (12-HETE, p=0.024). These findings imply that Numb could be a critical factor in maintaining myogenic differentiation, mitochondrial function and calcium signaling in skeletal muscle. A decline in Numb level during aging could be one of the key drivers responsible for reduced muscle mass and strength that develops during aging.

Daytime Neuromuscular Electrical Therapy of Tongue Muscles in Improving Snoring in Individuals with Primary Snoring and Mild Obstructive Sleep Apnea.

Study Objectives: Evaluating daytime neuromuscular electrical training (NMES) of tongue muscles in individuals with Primary Snoring and Mild Obstructive Sleep Apnea (OSA). Methods: A multicenter prospective study was undertaken in patients with primary snoring and mild sleep apnea where daytime NMES (eXciteOSA® Signifier Medical Technologies Ltd., London W6 0LG, UK) was used for 20 min once daily for 6 weeks. Change in percentage time spent snoring was analyzed using a two-night sleep study before and after therapy. Participants and their bed partners completed sleep quality questionnaires: Epworth Sleepiness Scale (ESS) and Pittsburgh Sleep Quality Index (PSQI), and the bed partners reported on the nighttime snoring using a Visual Analogue Scale (VAS). Results: Of 125 patients recruited, 115 patients completed the trial. Ninety percent of the study population had some reduction in objective snoring with the mean reduction in the study population of 41% (p < 0.001). Bed partner-reported snoring reduced significantly by 39% (p < 0.001). ESS and total PSQI scores reduced significantly (p < 0.001) as well as bed partner PSQI (p = 0.017). No serious adverse events were reported. Conclusions: Daytime NMES (eXciteOSA®) is demonstrated to be effective at reducing objective and subjective snoring. It is associated with effective improvement in patient and bed partner sleep quality and patient daytime somnolence. Both objective and subjective measures demonstrated a consistent improvement. Daytime NMES was well tolerated and had minimal transient side effects.

The acute effect of knee brace on the electromyography activity of lower limb muscles in individuals with genu valgus during walking

Background: Different factors affect walking biomechanics disturb the postural control. Genu valgus is one of the most important lower limb malalignments that affects the postural control and disrupts the posture. The purpose of the present study was to investigate the acute effect of knee brace on the electromyography activity of lower limb muscles in individuals with genu valgus during walking. Methods: In this semi-experimental and a laboratory typ study,. 24 boys with genu valgum (20-30 years old) volunteered to participate in the study. The electrical activity of the selected muscles was recorded by an electromyography system during walking with and without knee brace. Paired t-test was used for statistical analysis at a significance level of 0.05. Results: There was a significant increase in electrical activity of the semitendinosus muscle during walking with knee brace compared to walking without it (p = 0.037, d = 0.89). The electrical activity of other lower limb muscles did not show any significant differences during acute use of knee brace (P &gt;0.05). Conclusion: The semitendinosus muscle in individuals with genu valgus is weak. Therefore, significant increase in the electrical activity of the semitendinosus muscle during wearing of knee brace means delaying the fatigue and indicating improvement in the muscular function.

Effect of walking on sand on co-Contraction of the lower limb muscles in individuals with overpronated foot

Background: Foot pronation is in the open kinetic chain composed of eversion, abduction, and ankle dorsiflexion. Foot overpronation may be associated with different lower limb injuries. The purpose of this study was to investigate the effect of walking on the sand on co-Contraction of the lower limb muscles in individuals with overpronated foot. Methods: The present study was a semi-experimental and laboratory type. Thirty healthy individuals and 30 individuals with foot overpronation volunteered to participate in this study. Muscle activity was recorded by an 8-channel electromyography system with a surface electrode during walking on sand. Two-way ANOVA test was used for statistical analysis at the significant level P&lt;0/05. Results: The results demonstrated lower ankle-directed co-Contraction during walking on sand compared with walking on level ground (P&lt;0/001). Other components of ankle-directed co-Contraction did not demonstrate any significant differences between walking on sand compared with walking on level ground (P&gt;0/05). Conclusion: Individuals with overpronated foot demonstrated lower ankle-directed co-Contraction during walking on sand compared with walking on stable level ground. Individuals with overpronated foot showed a greater ankle-directed co-Contraction than the healthy group. Decreased ankle-directed co-Contraction indicated a positive effect of walking on sand in individuals with foot overpronation.

Relationships Between Relative Ankle Muscle Ratios, Severity of Symptoms, and Radiologic Parameters in Adolescent Patients With Symptomatic Flexible Flat Feet.

Objective To investigate differences in the relative sizes of the ankle-stabilizing muscles in individuals with versus without flexible flat feet and to determine predictors of symptom severity.MethodsThis cross-sectional study included 30 patients with symptomatic flexible flat feet and 24 normal controls. The following were evaluated: foot posture index, resting calcaneal stance position angle, radiographic findings (calcaneal pitch, Meary’s angle, talocalcaneal angle, talonavicular coverage angle [TNCA]), foot function index (FFI), and cross-sectional areas (CSA) of the tibialis anterior (TA), tibialis posterior (TP), and peroneus longus (PL) upon ultrasonographic examination. To address morphometric differences among participants, individual muscle measurements were normalized to proportions of total muscle CSA. Between-group differences were evaluated with independent t-tests. Correlations between muscle ratios, radiographic parameters, and FFI scores were investigated. Logistic regression analysis was performed to determine which parameters predicted severe symptoms.ResultsThe relative size of the TP was significantly greater and those of the TA and PL were significantly smaller in patients with flat feet than in normal controls. Correlations were found among relative muscle CSA ratios, radiographic parameters, and FFI score. Linear regression analysis confirmed that the TNCA and the relative CSA of the PL were independent predictors of symptom severity.ConclusionThis study found significant differences in the relative CSAs of the ankle muscles in patients with flexible flat feet versus individuals without flat feet; these differences were significantly correlated with anatomic abnormalities. Symptoms were more severe in patients with relatively greater forefoot abduction and relatively smaller PL.

Effect of conscious abdominal contraction on the activation of periscapular muscles in individuals with subacromial pain syndrome

BackgroundSynergism between shoulder and trunk muscles seems to be effective to increase periscapular muscle activation in asymptomatic subjects. The influence of conscious contraction of the abdominal muscles has not yet been studied in non-athlete subjects with pain. The study aimed to investigate the effect of the instruction for conscious activation of the abdominal muscles on the activity of the scapulothoracic muscles during shoulder exercises in subjects with subacromial pain syndrome. MethodThirty subjects with unilateral pain (mean age 52 ± 11 years) participated in this study. Three isometric and five dynamic exercises for the scapulothoracic muscles were assessed. The group without instruction just repeated the exercises, while the instruction group was evaluated before and after conscious abdominal training. The linear mixed model analysis was used to compare the muscle activation between groups. FindingsDifferences between groups after the conscious abdominal contraction for activation of middle and lower trapezius on the symptomatic side in the “Full can”(p = 0.03; effect size:0.92 middle trapezius); (p = 0.02; effect size:0.96 lower trapezius) and “Knee Push” (p = 0.01; effect size:0.75 lower trapezius). For asymptomatic side, the exercises “External Rotation Kneeling” (p = 0.04; effect size: 0.81 lower trapezius); (p = 0.00; effect size: 2.09 serratus anterior), “Knee Push” (p = 0.04; effect size:1.24 serratus anterior) and “Wall Slide” (p = 0.01; effect size: 1.03 serratus anterior). InterpretationConscious contraction of the abdominal muscle immediately alter the activation of the serratus anterior muscle during closed kinetic chain exercises on the asymptomatic side and increased activation of trapezius on the symptomatic side during shoulder open kinetic chain exercise.

Skeletal muscle transcriptome in healthy aging

Age-associated changes in gene expression in skeletal muscle of healthy individuals reflect accumulation of damage and compensatory adaptations to preserve tissue integrity. To characterize these changes, RNA was extracted and sequenced from muscle biopsies collected from 53 healthy individuals (22–83 years old) of the GESTALT study of the National Institute on Aging–NIH. Expression levels of 57,205 protein-coding and non-coding RNAs were studied as a function of aging by linear and negative binomial regression models. From both models, 1134 RNAs changed significantly with age. The most differentially abundant mRNAs encoded proteins implicated in several age-related processes, including cellular senescence, insulin signaling, and myogenesis. Specific mRNA isoforms that changed significantly with age in skeletal muscle were enriched for proteins involved in oxidative phosphorylation and adipogenesis. Our study establishes a detailed framework of the global transcriptome and mRNA isoforms that govern muscle damage and homeostasis with age.

Effect of electromyographic biofeedback training on motor function of quadriceps femoris in patients with incomplete spinal cord injury: A randomized controlled trial.

Electromyographic biofeedback (EMG BF) training is an effective method of promoting motor learning and control in neurorehabilitation, but its effect on quadriceps femoris muscle in individuals with spinal cord injury (SCI) is unknown. The aim of the study was to investigate the therapeutic effect of EMG BF training on motor function of quadriceps femoris in patients with incomplete SCI. Thirty-three incomplete paraplegic patients with quadriceps femoris strength ranging grade 1 to grade 3 less than 6 months post-injury were enrolled. Control group (n = 16) received conventional physical therapy to enhance quadriceps femoris strength, while intervention group (n = 17) was treated with conventional physical therapy and EMG BF training. All received treatment once a day for 30 days. Surface electromyograph (sEMG), muscle strength and thigh circumference size were assessed to evaluate motor function of quadriceps femoris. Activities of daily living (ADL) was evaluated by Modified Barthel Index (MBI). All the measures evaluated three times in total. Compared to the control group, intervention group significantly improved on sEMG values and strength of quadriceps femoris (PsEMG < 0.001, Pstrength < 0.05). sEMG values of quadriceps femoris increased earlier than strength of quadriceps femoris in intervention group (Prest = 0.07, Pactive = 0.031). There were no statistical differences in thigh circumference size and ADL scores between groups (Pthigh > 0.05, PADL = 0.423). EMG BF training appeared to be a useful tool to enhance motor function of quadriceps femoris in patients with incomplete SCI. sEMG could quantify the changes of single muscle myodynamia precisely before visible or touchable changes occur.

Effects of myofascial release on flexibility and electromyographic activity of the lumbar erector spinae muscles in healthy individuals

ObjectiveTo investigate the effects of myofascial release on the flexibility and electromyographic activity of the lumbar erector spinae muscle in healthy individuals. MethodsTen healthy subjects were recruited to an intervention protocol of myofascial release techniques: (1) superficial myofascial release; (2) deep myofascial release apply along 10 sessions, twice a week, with 40 min per sessions. The outcomes evaluated were flexibility (Toe-Touch Test) and electromyography activity (EMG) of the lumbar erector spinae muscle (Iliocostalis and Longissimus bilaterally) during the movement of extension-flexion of the trunk. Paired t-test was used to compare the electromyographic outcomes, while the Wilcoxon test was used to compare the flexibility outcomes. ResultsThe myofascial release techniques increased the flexibility (p = 0.005; r = 0.88) and have no influence over the electromyographic activity of the right iliocostalis (p = 0.179; r = 0.43), right longissimus (p = 0.877; r = 0.05), left iliocostalis (p = 0.386; r = 0.29) and left longissimus (p = 0.418; r = 0.27). ConclusionsThe application of myofascial release techniques increase flexibility and did not influence over the electromyographic activity of the lumbar erector spinae muscles in healthy individuals. Further studies should include a larger sample with a sham group and/or compare EMG activity of the lumbar erector spinae muscles with patients with low back pain during the movement of extension-flexion of the trunk.

NLRP3 Inflammasome: Potential Role in Obesity Related Low-Grade Inflammation and Insulin Resistance in Skeletal Muscle.

Among multiple mechanisms, low-grade inflammation is critical for the development of insulin resistance as a feature of type 2 diabetes. The nucleotide-binding oligomerization domain-like receptor family (NOD-like) pyrin domain containing 3 (NLRP3) inflammasome has been linked to the development of insulin resistance in various tissues; however, its role in the development of insulin resistance in the skeletal muscle has not been explored in depth. Currently, there is limited evidence that supports the pathological role of NLRP3 inflammasome activation in glucose handling in the skeletal muscle of obese individuals. Here, we have centered our focus on insulin signaling in skeletal muscle, which is the main site of postprandial glucose disposal in humans. We discuss the current evidence showing that the NLRP3 inflammasome disturbs glucose homeostasis. We also review how NLRP3-associated interleukin and its gasdermin D-mediated efflux could affect insulin-dependent intracellular pathways. Finally, we address pharmacological NLRP3 inhibitors that may have a therapeutical use in obesity-related metabolic alterations.

Racial differences in the limb skeletal muscle transcriptional programs of patients with critical limb ischemia.

Critical limb ischemia (CLI) is the most severe manifestation of peripheral artery disease (PAD) and is characterized by high rates of morbidity and mortality. As with most severe cardiovascular disease manifestations, Black individuals disproportionately present with CLI. Accordingly, there remains a clear need to better understand the reasons for this discrepancy and to facilitate personalized therapeutic options specific for this population. Gastrocnemius muscle was obtained from White and Black healthy adult volunteers and patients with CLI for whole transcriptome shotgun sequencing (WTSS) and enrichment analysis was performed to identify alterations in specific Reactome pathways. When compared to their race-matched healthy controls, both White and Black patients with CLI demonstrated similar reductions in nuclear and mitochondrial encoded genes and mitochondrial oxygen consumption across multiple substrates, indicating a common bioenergetic paradigm associated with amputation outcomes regardless of race. Direct comparisons between tissues of White and Black patients with CLI revealed hemostasis, extracellular matrix organization, platelet regulation, and vascular wall interactions to be uniquely altered in limb muscles of Black individuals. Among traditional vascular growth factor signaling targets, WTSS revealed only Tie1 to be significantly altered from White levels in Black limb muscle tissues. Quantitative reverse transcription polymerase chain reaction validation of select identified targets verified WTSS directional changes and supports reductions in MMP9 and increases in NUDT4P1 and GRIK2 as unique to limb muscles of Black patients with CLI. This represents a critical first step in better understanding the transcriptional program similarities and differences between Black and White patients in the setting of amputations related to CLI and provides a promising start for therapeutic development in this population.

Of mice and men: opposing effects of nicotinamide riboside on skeletal muscle physiology at rest and during exercise.

Of mice and men: opposing effects of nicotinamide riboside on skeletal muscle physiology at rest and during exercise.

Type 2 Diabetes Mellitus Patients Manifest Greater Muscle Fatigability Than Healthy Individuals During Dynamic Fatigue Protocol

ObjectiveThe present study aimed to investigate the electromyographic (EMG) indices of muscle fatigue along with biochemical marker of fatigue—that is, blood lactate—during a dynamic fatigue protocol in individuals with type 2 diabetes mellitus (T2DM) vs a healthy control group. Secondarily, it aimed to examine the association between EMG indices of muscle fatigue and blood lactate in these patients. MethodsThirty-four participants took part in the study: 19 individuals with T2DM (age, 53.5 ± 6.85 years) and 15 age-matched healthy controls (age, 50.2 ± 3.55 years). Participants performed a dynamic fatigue protocol consisting of 5 sets of 10 repetitions each at an intensity of the 10-repetition maximum. Surface EMG of the vastus medialis and vastus lateralis muscles was recorded during the dynamic fatigue protocol, and EMG indices such as median frequency (MF), slope of MF (MFslope), Dimitrov muscle fatigue spectral index, and root-mean-square were evaluated for each contraction across all the 5 sets. Blood lactate concentrations were also assessed 3 times during the fatigue protocol. ResultsFindings revealed that EMG muscle fatigue indices such as MF, MFslope, and Dimitrov muscle fatigue spectral index were significantly altered in individuals with T2DM vs healthy individuals across the sets and repetitions for both the vastus medialis (P < .001) and vastus lateralis muscles (P < .001). There was a significantly greater rise in blood lactate in individuals with T2DM than in healthy individuals (P < .001), which was not found to be associated with changes in EMG indices of muscle fatigue. ConclusionFindings suggest the existence of significantly greater fatigue in the knee extensor muscles of individuals with T2DM than healthy individuals.

Aged Skeletal Muscle Retains the Ability to Remodel Extracellular Matrix for Degradation of Collagen Deposition after Muscle Injury.

Aging causes a decline in skeletal muscle function, resulting in a progressive loss of muscle mass, quality, and strength. A weak regenerative capacity is one of the critical causes of dysfunctional skeletal muscle in elderly individuals. The extracellular matrix (ECM) maintains the tissue framework structure in skeletal muscle. As shown by previous reports and our data, the gene expression of ECM components decreases with age, but the accumulation of collagen substantially increases in skeletal muscle. We examined the structural changes in ECM in aged skeletal muscle and found restricted ECM degradation. In aged skeletal muscles, several genes that maintain ECM structure, such as transforming growth factor β (TGF-β), tissue inhibitors of metalloproteinases (TIMPs), matrix metalloproteinases (MMPs), and cathepsins, were downregulated. Muscle injury can induce muscle repair and regeneration in young and adult skeletal muscles. Surprisingly, muscle injury could not only efficiently induce regeneration in aged skeletal muscle, but it could also activate ECM remodeling and the clearance of ECM deposition. These results will help elucidate the mechanisms of muscle fibrosis with age and develop innovative antifibrotic therapies to decrease excessive collagen deposition in aged muscle.

Loss of α-actinin-3 during human evolution provides superior cold resilience and muscle heat generation

SummaryThe protein α-actinin-3 expressed in fast-twitch skeletal muscle fiber is absent in 1.5 billion people worldwide due to homozygosity for a nonsense polymorphism in ACTN3 (R577X). The prevalence of the 577X allele increased as modern humans moved to colder climates, suggesting a link between α-actinin-3 deficiency and improved cold tolerance. Here, we show that humans lacking α-actinin-3 (XX) are superior in maintaining core body temperature during cold-water immersion due to changes in skeletal muscle thermogenesis. Muscles of XX individuals displayed a shift toward more slow-twitch isoforms of myosin heavy chain (MyHC) and sarcoplasmic reticulum (SR) proteins, accompanied by altered neuronal muscle activation resulting in increased tone rather than overt shivering. Experiments on Actn3 knockout mice showed no alterations in brown adipose tissue (BAT) properties that could explain the improved cold tolerance in XX individuals. Thus, this study provides a mechanism for the positive selection of the ACTN3 X-allele in cold climates and supports a key thermogenic role of skeletal muscle during cold exposure in humans.

MRI-based Measurement of Effects of Strength Training on Intramuscular Fat in People with and without Spinal Cord Injury.

The accurate quantification of the proportion of fat in human muscles could help monitor disease status and test effectiveness of interventions in people with neurological conditions whose skeletal muscles are frequently infiltrated with fat. We compared two commonly used magnetic resonance imaging methods to quantify fat in muscles. Measurements were obtained before and after 6 or 8 wk of strength training in a total of 116 muscles spanning the range of intramuscular fat proportions observed in able-bodied young adults and people with spinal cord injury. We successfully measured fat proportions in all muscles using the mDixon method but were unable to obtain plausible measurements with the T1-weighted method from muscles of able-bodied individuals or from the leaner 23% of muscles of people with spinal cord injury (muscles with less than approximately 8% fat). In muscles with more fat, measurements obtained with the two methods agreed well (intraclass correlation coefficient, 0.88; mean absolute difference, 5%). We also found that, compared with the T1-weighted method, the mDixon method provides a more detailed characterization of fat infiltration in muscle and a less variable measurement of the effect of training on the proportion of fat. The mDixon method showed that 6 or 8 wk of strength training did not appreciably change the proportion of intramuscular fat in either people with spinal cord injury or able-bodied people. On the basis of these findings, we recommend the use of mDixon methods in preference to T1-weighted methods to determine the effectiveness of interventions aimed at reducing intramuscular fat.

The prevalence of anconeus epitrochlearis muscle and Osborne's ligament in cubital tunnel syndrome patients and healthy individuals: An anatomical study with meta-analysis

BackgroundAnconeus epitrochlaeris muscle and Osborne's ligament are anatomical variants that are occasionally found at the cubital tunnel of the elbow. In certain individuals, these two structures may compress the ulnar nerve resulting in a cubital tunnel syndrome. Although these variants have been reported extensively, its prevalence is still unclear and its contribution to cubital tunnel syndrome is debatable. The aim of this study is to generate weighted frequency values of the anconeus epitrochlearis and Osborne's ligament, as well as to identify any association of these two structures with gender, side, ethnicity and the development of cubital tunnel syndrome. MethodsAn anatomical study and a meta-analysis were performed to more accurately study the prevalence of anconeus epitrochlearis and Osborne's ligament. A total of 40 original studies including the present study met the inclusion criteria for meta-analysis and 6 case reports for descriptive analysis. ResultsCrude pooled prevalence estimate of the anconeus epitrochlearis was significantly higher (p < 0.001) in healthy subjects (14.2%) than in subjects diagnosed with cubital tunnel syndrome (4.5%). No significant difference was found for gender, side or laterality. The anconeus epitrochlearis was significantly more common in Europeans populations (18.2%) when compared with North American (6.8%) (p = 0.012) and Asian populations (7.5%) (p < 0.001). Anconeus epitrochlearis had a tendency to be hypertrophied when associated with cubital tunnel syndrome. The definition of Osborne's ligament is unclear, resulting in inconsistent reported prevalence across studies. ConclusionThe present study provides a more accurate estimate of anconeus epitrochlearis across the populations. There was a negative correlation between the presence of anconeus epitrochlearis and the development cubital tunnel syndrome, supporting the idea that the muscle may be protective against cubital tunnel syndrome. Future studies are needed to give proper definition of Osborne's ligament and accurately study its prevalence across populations.