Muscle Size Research Articles

Masseter muscle volume measured by MRI correlated with cognitive function in a memory clinic

AbstractBackground“Oral frailty” which indicates a decline in oral function, has been focused on the fact that it can also affect cognitive function in the elderly population. Although Several studies have been attempted for establishing the utility of the cross‐sectional area or volume of masticatory muscles as objective indices reflecting oral frailty, no report has examined the relationship between masticatory muscles volume and cognitive function in detail. In this study, we aimed to clarify the relationship between size of masseter muscle, one of major masticatory muscles, and cognitive function in the elderly.MethodA total of 349 subjects (mean age 77.3 +/‐ 9.2 years, 126 males and 223 females, 58 with subjective cognitive impairment, 88 with mild cognitive impairment, and 203 with dementia), who visited the Memory clinic of Tohoku University Hospital with a chief complaint of forgetfulness by March 2018 were included. Using 3D T1‐weighted images acquired on a 3‐Tesla MRI system, the bilateral masseter muscle cross‐sectional area was automatically calculated for all subjects using a custom deep‐learning image‐processing model trained on a subset of subjects to identify the relevant muscles and consistent section. Then, partial correlations with the MMSE score were conducted, adjusting for age and gender.ResultThe mean left and right masseter muscle cross‐sectional area are 399.3±84.7mm2 in subjective cognitive impairment, 387.9±106.5 mm2 in mild cognitive impairment, and 355.1±88.4 mm2 in dementia, respectively (p < 0.01). Adjusted for age and sex, they showed a significant correlation with MMSE (R = 0.151, p < 0.01). For post‐hoc stratified analysis, there was a significant correlation between mean masseter muscle cross‐sectional area and MMSE with female patients (R = 0.049, p < 0.05), whereas no correlation with male patients after adjusted age (R = 0.025, p > 0.05).ConclusionOur result revealed that the masseter muscle cross‐sectional area obtained from MRI may be related to cognitive function in the patients with complaint of forgetfulness. Therefore the masticatory function may reflect cognitive function in the elderly who are vulnerable in their memory, and the cross‐sectional area of masseter muscle based on MRI could be a potential indicator for predicting dementia risk.

Cycling through the ranks: a cross-sectional analysis of endurance, strength and body composition indicators in junior, elite, and amateur competitive road cyclists.

The objective of the present study was to compare different performance indicators, encompassing endurance, body composition, and maximal and explosive strength markers, among competitive Lithuanian cyclists across different age and performance categories. Thirty Lithuanian male cyclists in elite (EL, N.=10), amateur (AM, N.=10), and junior (JU, N.=10) categories underwent body composition analysis, knee extensors' isometric strength and ultrasound measurements, maximal incremental exercise tests, cycling efficiency protocol, and sprint performance evaluations. Additionally, competition results and power profiles were analyzed. EL cyclists had greater experience and higher annual kilometers (P<0.05). Quadriceps muscle size exhibited significant differences, being greater in EL than JU (P<0.05), whereas no noteworthy variations were observed in body fat or isometric strength. EL athletes demonstrated higher maximal oxygen consumption, maximal aerobic power, and sprint performance compared to JU and AM, particularly when considering absolute power metrics (P<0.05). Interestingly, despite JU achieving lower ranks in competitions, power profiles differed minimally between EL and JU. Furthermore, both JU and AM expended more energy during competitions (P<0.05). The study highlights disparities among Lithuanian cyclists, with EL cyclists showcasing advantages in endurance capacity and better competition outcomes, possibly due to their extensive experience, leading to a more efficient energy utilization. This research enhances our understanding of the multifaceted nature of the sport performance within the realm of Lithuanian cycling.

An Updated Panorama of Blood-Flow-Restriction Methods.

Exercise with blood-flow restriction (BFR) is being increasingly used by practitioners working with athletic and clinical populations alike. Most early research combined BFR with low-load resistance training andconsistently reported increased muscle size and strength without requiring the heavier loads that are traditionally used for unrestricted resistance training. However, this field has evolved with several different active and passive BFR methods emerging in recent research. This commentary aims to synthesize the evolving BFR methods for cohorts ranging from healthy athletes to clinical or load-compromised populations. In addition, real-world considerations for practitioners are highlighted, along with areas requiring further research. The BFR literature now incorporates several active and passive methods, reflecting a growing implementation of BFR in sport and allied health fields. In addition to low-load resistance training, BFR is being combined with high-load resistance exercise, aerobic and anaerobic energy systems training of varying intensities, and sport-specific activities. BFR is also being applied passively in the absence of physical activity during periods of muscle disuse or rehabilitation or prior to exercise as a preconditioning or performance-enhancement technique. These various methods have been reported to improve muscular development; cardiorespiratory fitness; functional capacities; tendon, bone, andvascular adaptations; and physical and sport-specific performance and to reduce pain sensations. However, in emerging BFR fields, many unanswered questions remain to refine best practice.

Age-Related Differences in Muscle Size and Strength between Individuals with Cerebral Palsy and Individuals with Typical Development

Aim Examine age-related differences in muscle size and strength of the knee extensors in individuals with cerebral palsy (CP) and individuals with typical development (TD). Methods 54 individuals with CP (14.5 ± 4.5 years, GMFCS I–V) and 33 individuals with TD (16.2 ± 5.5 years) were included. Relationships between rectus femoris (RF) and vastus lateralis (VL) muscle volume and isokinetic knee extensor strength with age were examined with linear regression and ANCOVA to test age-related differences between groups. Results Linear regression for muscle volume with age was statistically significant in TD (VL: r 2 = 0.48, RF: r 2 = 0.56, p < .05) and those with CP (VL: r = 0.36, RF: r 2 = 0.27, p < .05) with no differences in regression slopes between groups (p > .05). Age-related strength differences were observed in TD (r 2 = 0.66, p < .001) and those with CP (r 2 = 0.096, p = .024), but the slopes were significantly different between CP and TD (p < .001). Conclusion Age-related linear differences in muscle volume and strength were observed in both groups. The linear slope of the age-related differences in knee extensor muscle strength and strength-to-body mass ratio were significantly lower in individuals with CP compared to individuals with TD, suggesting that strength is insufficient to keep up with gains in body mass during growth.

Development of a Novel Artificial Intelligence Tool to Measure Psoas Volumes in Patients with Diffuse Large B Cell Lymphoma

Introduction Sarcopenia is associated with poor outcomes in cancer patients. However, it is poorly defined, and its clinical assessment can be tedious. Studies have shown psoas muscle volume (PV), measured on computed tomography (CT) scans, correlate with validated measures of frailty and clinical outcomes (Yamada Y., et al. 2023), with better predictive value than another frequently used radiological surrogate - the psoas muscle area measured on a single axial cut at the L3 vertebral level. The labor-intensive nature of PV measurement, lack of validated reference ranges, and inter-observer variability has limited its adoption as a marker of sarcopenia. We hence aim to investigate if an artificial intelligence (AI) model can be developed and trained to automate the measurement of PV in patients with diffuse large B cell lymphoma (DLBCL). Methods This was a retrospective cohort study. Consecutive patients with DLBCL treated at our center from 2010 to 2018 were included. For inclusion, patients had to have at least one contrast-enhanced CT scan performed after diagnosis. Patients who only had positron electron tomography (PET) scans were excluded. The CT scan temporally closest to diagnosis was selected for segmentation. Manual full PV segmentation (Figure 1) was performed on axial CT images using a cloud-based annotation tool (https://darwin.v7labs.com/) by two radiologists, encompassing the entire muscle from origin to insertion. The segmentation data from the first 10 patients (650 images) were then used to train an AI model (Ultralytics YOLOv8) to automatically segment the psoas muscles (Figure 1). Segmented psoas muscles on CT imaging were converted to volume measurements using a code. This was calculated for every patient using the metadata of pixel area and slice thickness contained within each unique CT image. Muscle volumes for the entire patient cohort were generated using this machine learning model and correlated with patient age, height, weight, body mass index (BMI), lean body weight (LBW) (Janmahasatian S., et al. 2005) and body surface area (BSA) determined by the Mosteller formula. Correlation was determined using Pearson's correlation coefficient. Results Data from 123 patients were available for analysis. The median age was 62 years (IQR 53.0 - 70.0), with 89 (72.4%) males. 83 (67.5%) patients were Chinese and 27 (22.0%) were Malay. 111 (90.2%) patients had an Eastern Cooperative Oncology Group (ECOG) performance status of ≤1, and 9 (7.3%) patients had a body mass index (BMI) &amp;lt;18kg/m 2. The median weight was 62.6kg (IQR 54.1 - 72.8), median BMI 23.5kg/m 2 (IQR 20.8 - 26.1), median LBW 48.5kg (IQR 40.2 - 54.3) and median BSA 1.69m 2 (IQR 1.53 - 1.83). 7 (7.4%), 18 (19.1%), 8 (8.5%) and 61 (64.9%) patients were stages 1, 2, 3 and 4 at diagnosis, respectively. 56 (45.6%) of patients had an International Prognostic Index (IPI) of ≥3. Psoas volumes for our population were successfully generated using our deep learning model. The model was able to accurately identify the psoas muscle and distinguish it from other intra-abdominal and intra-pelvic tissue, across a range of body and psoas muscle sizes. It was also able to distinguish the psoas from the iliacus within the pelvis. The median PV was 158.27ml (IQR 105.10 -190.71). There were positive correlations between PV and all physical measures analyzed including height (r = 0.60, p &amp;lt; 0.001), weight (r = 0.47, p &amp;lt; 0.001), BMI (r = 0.28, p 0.002), LBW (r = 0.66, p &amp;lt; 0.001), and BSA (r = 0.55, p = &amp;lt;0.001), and a negative correlation between PV and age (r = -0.22, p = 0.015). Conclusion We have developed a novel AI tool that can identify and distinguish the psoas muscle from other tissue on CT scans. The volumes measured by our AI correlate, as expected, positively with all physical indices analyzed, and negatively with age. Further work is required to determine the accuracy and quantify the efficiency of the AI model compared with trained radiologists, as well as to assess if AI-measured PV changes temporally or predicts clinical outcome.

Potential of whole-body dual-energy X-ray absorptiometry to predict muscle size of psoas major, gluteus maximus and back muscles

BackgroundMeasurement of trunk muscle cross-sectional area (CSA) using axial magnetic resonance imaging (MRI) is considered clinically meaningful for understanding several spinal pathologies, such as low back pain and spinal sagittal imbalance. However, it remains unclear whether trunk muscle mass (TMM) measured using dual-energy X-ray absorptiometry (DXA) can predict the trunk muscle CSA. The aim of this study is to determine if DXA-derived TMM is associated and predicts with CSA of paraspinal muscles and gluteus maximus measured using MRI in healthy volunteers.MethodsA total of 48 healthy volunteers underwent whole-body DXA and MRI of the spinopelvic region. The CSA of the psoas major, back muscles, and gluteus maximus were measured on axial MRI. Correlations and linear regressions between the TMM measured using DXA and the CSA of each musculature were investigated.ResultsThere was a weak correlation between TMM and CSA of the psoas major in men (r = 0.39, P = 0.0678), and the linear regression was y = 301.74x – 401.24 (R2 = 0.2976, P = 0.0070). A moderate correlation was found in women (r = 0.58, P = 0.0021), and the linear regression was y = 230.21x − 695.29 (R2 = 0.4445, P = 0.0003). Moderate correlations were observed between TMM and CSA of the back muscles in both men (r = 0.63, P = 0.0012) and women (r = 0.63, P = 0.0007), the linear regression was y = 468.52x + 3688.5 (R2 = 0.5505, P < 0.0001) in men and y = 477.39x + 2364.1 (R2 = 0.564, P < 0.0001) in women. There was a strong correlation between TMM and CSA of the gluteus maximus in men (r = 0.72, P < 0.0001), and the linear regression was y = 252.69x − 880.5 (R2 = 0.6906, P < 0.0001). A moderate correlation was found in women (r = 0.69, P < 0.0001), and the linear regression was y = 230.74x – 231.32 (R2 = 0.6542, P < 0.0001).ConclusionsThe DXA-derived TMM was able to predict the CSA of the psoas major, back muscles, and gluteus maximus, and significantly correlated with the CSA of the back muscles and gluteus maximus. It might be a safer and cheaper alternative for evaluating the size of the back muscles and gluteus maximus.

High-fat diet effects on contractile performance of isolated mouse soleus and extensor digitorum longus when supplemented with high dose vitamin D.

Evidence suggests vitamin D3 (VD) supplementation can reduce accumulation of adipose tissue and inflammation and promote myogenesis in obese individuals, and thus could mitigate obesity-induced reductions in skeletal muscle (SkM) contractility. However, this is yet to be directly investigated. This study, using the work-loop technique, examined effects of VD (cholecalciferol) supplementation on isolated SkM contractility. Female mice (n = 37) consumed standard low-fat diet (SLD) or high-fat diet (HFD), with or without VD (20,000IU/kg-1 ) for 12weeks. Soleus and EDL (n = 8-10 per muscle per group) were isolated and absolute and normalized (to muscle size and body mass) isometric force and power output (PO) were measured, and fatigue resistance determined. Absolute and normalized isometric force and PO of soleus were unaffected by diet (P>0.087). However, PO normalized to body mass was reduced in HFD groups (P<0.001). Isometric force of extensor digitorum longus (EDL) was unaffected by diet (P>0.588). HFD reduced EDL isometric stress (P=0.048) and absolute and normalized PO (P<0.031), but there was no effect of VD (P>0.493). Cumulative work during fatiguing contractions was lower in HFD groups (P<0.043), but rate of fatigue was unaffected (P>0.060). This study uniquely demonstrated that high-dose VD had limited effects on SkM contractility and did not offset demonstrated adverse effects of HFD. However, small and moderate effect sizes suggest improvement in EDL muscle performance and animal morphology in HFD VD groups. Given effect sizes observed, coupled with proposed inverted U-shaped dose-effect curve, future investigations are needed to determine dose/duration specific responses to VD, which may culminate in improved function of HFD SkM.

Fuzhuan brick tea extract ameliorates obesity-induced skeletal muscle atrophy by alleviating mitochondrial dysfunction in mice

Fuzhuan brick tea (FBT) is a post-fermented tea fermented by the fungus Eurotium cristatum and is mainly produced in Hunan Province, China. Our previous study revealed that FBT extract prevents obesity by increasing energy expenditure and mitochondrial content in mice. Therefore, in this study, we hypothesized that FBT extract could be effective in alleviating obesity-induced muscle atrophy by addressing mitochondrial dysfunction, and aimed to explore the underlying molecular mechanism of FBT extract in high-fat diet-induced obese mice. FBT extract increased skeletal muscle weight and size, myosin heavy chain isoforms, and muscle performance in obese mice. Additionally, FBT extract reduced obesity-induced intramuscular lipids, skeletal muscle inflammation, and the expression of skeletal muscle atrophy markers, and increased the expression of fibronectin type III domain-containing protein 5 in skeletal muscles. Obesity-induced skeletal muscle mitochondrial dysfunction was improved by FBT extract as analyzed through mitochondrial morphology, fatty acid oxidation, respiratory chain complexes, and mitochondrial dynamics and biogenesis. Epigallocatechin, a major bioactive compound in FBT extract, attenuated palmitic acid-induced muscle atrophy by regulating mitochondrial functions in C2C12 cells. In conclusion, FBT extract may prevent obesity-induced muscle atrophy by alleviating mitochondrial dysfunction in mice.

The effect of creatine on human body

The impact of creatine on the human body used as supplementation is explored in this research paper, delving into the analysis of the effects of supplementing with creatine on the human body. A naturally occurring amino acid, creatine can be obtained from our diet and is primarily stored in muscle tissues, acting as an essential source of energy metabolism. For ages, athletes have used creatine as a dietary supplement to enhance muscle strength and size, sporting performance, and cognitive functionality, given its critical role in human body. The focal point of this article is the effect that creatine supplementation has on muscle development, cognitive abilities, aging musculoskeletal health, type 2 diabetes, and oxidative stress, as well as the potential negative outcomes. Based on the data, adding creatine to a routine can have advantageous impact on muscle growth, mental function, oxidant pressure, type 2 diabetes, and the effects of aging on bone and joint health. Although creatine supplementation is commonly deemed as safe, it is crucial to exercise caution when consuming large quantities or using it for an extended period, particularly in individuals with pre-existing health conditions. The study concludes that incorporating creatine supplementation into one's routine may prove beneficial for those seeking to enhance their athletic abilities, muscle mass, strength, and overall well-being. Nevertheless, to fully understand, research is required the potential advantages and risks related to creatine supplementation. Furthermore, it is imperative to ascertain the ideal dosages and protocols that would be suitable for diverse populations and varying conditions.

11-beta-hydroxysteroid dehydrogenase type 1 (HSD11B1) gene expression in muscle is linked to reduced skeletal muscle index in sarcopenic patients

BackgroundGlucocorticoids play a significant role in metabolic processes and pathways that impact muscle size, mass, and function. The expression of 11-beta-hydroxysteroid dehydrogenase type 1 (HSD11B1) has been previously described as a major regulator of skeletal muscle function in glucocorticoid-induced muscle atrophy and aging humans. Our study aimed to investigate glucocorticoid metabolism, including the expression of HSD11B1 in skeletal muscle, in patients with sarcopenia.MethodsMuscle biopsies were taken from the vastus lateralis muscle of thirty-three patients over 60 years of age with hip fractures. Sarcopenia status was assessed according to the criteria of the European Working Group on Sarcopenia in Older People 2. Skeletal muscle mass was measured by bioelectrical impedance analysis. Cortisol and cortisone concentrations were measured in serum. Gene expression analysis of HSD11B1, NR3C1, FBXO32, and TRIM63 in muscle biopsies was performed. Serial cross sections of skeletal muscle were labeled with myosin heavy chain slow (fiber type-1) and fast (fiber type-2) antibodies.ResultsThe study included 33 patients (21 women) with a mean age of 82.5 ± 6.3 years, 17 patients revealed sarcopenic (n = 16 non-sarcopenic). Serum cortisone concentrations were negatively correlated with muscle mass (ß = − 0.425; p = 0.034) and type-2 fiber diameter (ß = − 0.591; p = 0.003). Gene expression of HSD11B1 (ß = − 0.673; p = 0.008) showed a negative correlation with muscle mass in the sarcopenic group. A significant correlation was found for the non-sarcopenic group for NR3C1 (ß = 0.548; p = 0.028) and muscle mass.ConclusionThese findings suggest a pathogenetic role of HSD11B1 in sarcopenic muscle.

Determination of Malondialdehyde (MDA) and Some Antioxidant Activities in Rheumatoid arthritis Patients

Background: Muscle weakness is a common comorbidity of several severe diseases which results in a reduced independence and quality of life and for the afflicted patients. Patients with rheumatoid arthritis (RA), a disease characterized by a chronic inflammation of the joints, commonly report of muscle weakness as a complication. Muscle weakness is the result of reduced muscle size and intramuscular impairments (i.e., intrinsic muscle dysfunction).

Compromised Muscle Properties in a Severe Hypophosphatasia Murine Model.

Hypophosphatasia (HPP) is a rare metabolic bone disorder characterized by low levels of tissue non-specific alkaline phosphatase (TNAP) that causes under-mineralization of the bone, leading to bone deformity and fractures. In addition, patients often present with chronic muscle pain, reduced muscle strength, and an altered gait. In this work, we explored dynamic muscle function in a homozygous TNAP knockout mouse model of severe juvenile onset HPP. We found a reduction in skeletal muscle size and impairment in a range of isolated muscle contractile properties. Using histological methods, we found that the structure of HPP muscles was similar to healthy muscles in fiber size, actin and myosin structures, as well as the α-tubulin and mitochondria networks. However, HPP mice had significantly fewer embryonic and type I fibers than wild type mice, and fewer metabolically active NADH+ muscle fibers. We then used oxygen respirometry to evaluate mitochondrial function and found that complex I and complex II leak respiration were reduced in HPP mice, but that there was no disruption in efficiency of electron transport in complex I or complex II. In summary, the severe HPP mouse model recapitulates the muscle strength impairment phenotypes observed in human patients. Further exploration of the role of alkaline phosphatase in skeletal muscle could provide insight into mechanisms of muscle weakness in HPP.

Evaluation of sex-based differences in resistance exercise training-induced changes in muscle mass, strength, and physical performance in healthy older (≥60 y) adults: A systematic review and meta-analysis.

The objective of this systematic review and meta-analysis was to determine if there are sex-based differences in adaptations to resistance exercise training in healthy older adults. Following the screening process, data from 36 studies comparing older males and females (602 males; 703 females; ≥60 years of age) for changes in skeletal muscle size, muscle strength, and/or physical performance following the same resistance exercise training intervention were extracted. Mean study quality was 16/29 (modified Downs and Black checklist), considered moderate quality. Changes in absolute upper-body (Effect Size [ES] = 0.81 [95% CI 0.54, 1.09], P<0.001), and lower-body (ES = 0.40 [95% CI 0.24, 0.56], P<0.001) strength were greater in older males than females. Alternatively, changes in relative upper-body (ES = -0.46 [95% CI -0.77, -0.14], P<0.01), and lower-body (ES = -0.24 [95% CI -0.42, -0.06], P<0.01) strength were greater in older females than males. Changes in absolute, but not relative, whole-body fat-free mass (ES = 0.18 [95% CI 0.04, 0.33], P<0.05) were greater in older males than females. There were no sex-based differences for absolute or relative changes in limb muscle size, muscle fiber size, or physical performance.

Maternal folic acid supplementation does not impact skeletal muscle function and metabolism in male and female CD-1 mouse offspring.

Folic acid fortification of all white flour, enriched pasta, and cornmeal products became mandatory in Canada to reduce risk of neural tube defects at birth. Furthermore, Health Canada and the Society of Obstetricians and Gynaecologists of Canada recommend women take daily prenatal folic acid supplements in addition to folic acid fortified foods during pregnancy. However, the influence of maternal folic acid supplementation on offspring development, specifically the highly abundant and metabolically active skeletal muscle, is currently unknown. Thus, the purpose of this study was to determine the effect of supplemental folic acid (four times higher than normal dietary consumption), in utero and throughout suckling on muscle size, function, and metabolism in male and female CD-1 mouse offspring. The major findings were that maternal exposure to supplemental folic acid (i) had no impact on postpartum growth rates or muscle mass in female and male offspring, (ii) had no impact on skeletal muscle contractile kinetics in females and male offspring, and (iii) increased maximal phosphofructokinase activity in extensor digitorum longus of female and male offspring. These findings suggest that exposure to folic acid supplementation in utero and throughout suckling at levels four times higher than recommended had minimal effect on skeletal muscle size, function, and metabolism regardless of sex. Future research is needed explore the underlying biological pathways and mechanisms affected by folic acid supplementation during pregnancy and lactation on offspring skeletal muscle tissue, specifically in humans.

Impact of biological sex and sex hormones on molecular signatures of skeletal muscle at rest and in response to distinct exercise training modes

Substantial divergence in cardio-metabolic risk, muscle size, and performance exists between men and women. Considering the pivotal role of skeletal muscle in human physiology, we investigated and found, based on RNA sequencing (RNA-seq), that differences in the muscle transcriptome between men and women are largely related to testosterone and estradiol and much less related to genes located on the Y chromosome. We demonstrate inherent unique, sex-dependent differences in muscle transcriptional responses to aerobic, resistance, and combined exercise training in young and older cohorts. The hormonal changes with age likely explain age-related differential expression of transcripts. Furthermore, in primary human myotubes we demonstrate the profound but distinct effects of testosterone and estradiol on amino acid incorporation to multiple individual proteins with specific functions. These results clearly highlight the potential of designing exercise programs tailored specifically to men and women and have implications for people who change gender by altering their hormone profile.

Skull Biomechanics and Simplified Cephalometric Lines for the Estimation of Muscular Lines of Action.

Our study introduces a novel cephalometric analysis aimed at facilitating biomechanical simulations by elucidating the intricate relationship between craniofacial morphology and the size and inclination of the masseter muscle (MM) while incorporating muscle values. Our study analyzes the line of action of the MM drawn between the Gonion (Go) and Orbital (Or) points concerning dental and skeletal references (occlusal and Frankfort planes). A total of 510 pre-treatment lateral cephalometric tracings (217 males, 293 females, aged 6-50 years) and lateral Bolton standard tracings were examined. The key parameters investigated include (a) skeletal-cutaneous class (linear distance between projections of points A' and B' on the occlusal plane), (b) the angle between the perpendicular line to the occlusal plane and the Go-Or line at the molar occlusal point, and (c) the angle between the Go-Or line and the Frankfort plane. The assessment of anterior-posterior jaw discrepancy, measured as the skeletal-cutaneous class, ranged from -14.5 to 15.5 mm. Abnormal values were identified in two adolescents, showing no gender- or age-related patterns. The angle between the MM's line of action (Go-Or) and the normal to the occlusal plane averaged 39.3°, while the angle between Go-Or and Po-Or (Frankfort plane) averaged 41.99°. Age had an impact on these angles, with an average 3° decrease in adults and a 4° increase between ages 6 and 50. A weak relationship was observed between sagittal jaw discrepancy and the angle between Go-Or and the Frankfort plane, with about 20% of the variance explained by the anteroposterior maxillary-mandibular relationship. In conclusion, the study presents a cephalometric analysis of the relationship between craniofacial morphology and masseter muscle parameters. It finds that age influences the angles between key reference points, while the skeletal-cutaneous class does not exhibit age- or gender-specific trends. These findings can contribute to a better understanding of craniofacial biomechanics and aid in clinical orthodontic assessments and treatment planning.

Effect of Low-Load Blood Flow Restriction Training on Patients With Functional Ankle Instability: A Randomized Controlled Trial.

Decreased muscle strength and balance in patients with functional ankle instability (FAI) can be effectively improved by ankle strength training. Low-load blood flow restriction (LL-BFR) training increases muscle size and strength, but there is limited evidence from studies on muscle strength and balance in FAI patients. To study the effects of LL-BFR training versus high-load training (HLT) on muscle strength and balance in FAI patients. Randomized controlled trial. Forty-six young adults with a history of FAI. Participants in the LL-BFR and HLT groups performed 4 sets (30 × 15 × 15 × 15) of ankle training at 20% to 40% of the one-repetition maximum and 70% to 85% one-repetition maximum, respectively, twice a week for 6weeks. Plantar flexion, dorsiflexion, inversion, and eversion muscle strength, and the Y-balance test scores were assessed at baseline and after 3 and 6weeks; the thickness of the tibialis anterior, triceps surae, and peroneus longus muscles were assessed at baseline and after 6weeks. Inversion, eversion, dorsiflexion, and plantar flexion muscle strength; tibialis anterior, triceps surae, and peroneus longus thickness; and Y-balance test scores were significantly increased in the LL-BFR group after 3 and 6weeks compared with baseline (P < .05), with no significant difference between the LL-BFR and HLT groups after 6weeks (P > .05). However, at the end of 3weeks, eversion muscle strength and Y-balance test scores were significantly higher in the LL-BFR group than in the HLT group (P < .05). Over 6weeks, LL-BFR training was as effective as HLT in improving ankle muscle strength, muscle thickness, and balance in FAI patients, but LL-BFR training improved the ankle eversion muscle strength and dynamic balance more than HLT did in the early stages of the intervention. This finding will provide a new intervention strategy for the clinical rehabilitation of FAI patients.

Muscle Mass and Muscle Strength Following 6 Weeks of Blood Flow Restriction Combined with Low-Intensity Strength Training in Overweight Adolescents

Background and Study purpose. Blood flow restriction training is a new training technique that involves low-intensity exercise and can generate physiological changes equivalent to high-intensity exercise. The aim of this study is to assess the impact of blood flow restriction in conjunction with low-intensity resistance exercise on muscle mass and muscle strength among overweight adolescents, in comparison to conventional resistance exercise. Materials and methods. The study involved two randomized groups: an experimental group, which performed 40% of one repetition maximum (1RM) resistance exercise combined with 60% of arterial occlusion pressure (AOP), and a traditional resistance exercise group, which performed 70% of 1RM resistance exercise. All participants underwent pre-test and post-test evaluations for body composition, 1RM, and muscle circumference. The training program lasted for six weeks and consisted of upper and lower body training, including exercises such as leg press, leg curl, arm curl, and arm extension. Results. The group that underwent low-load blood flow restriction (LLBFR) training showed a notable increase in muscle mass (p&lt;0.049) as well as arm and leg circumference (p&lt;0.047 and p&lt;0.046, respectively) compared to before the training program, similar to the results of high-intensity resistance exercise. Conclusions. Combining blood flow restriction with low-intensity resistance training is a potentially effective approach to increase muscle size and strength, especially in overweight adolescents. Moreover, this type of training can decrease the amount of exercise load, making it a feasible option for individuals who may not tolerate high loads due to certain medical conditions or other limitations.

Thigh muscle thickness on ultrasonography for diagnosing sarcopenia: The Kyoto-Kameoka study.

The Asian Working Group for Sarcopenia 2019 consensus reported that evidence for the diagnosis of sarcopenia based on ultrasonography findings is lacking. The revised European Working Group on Sarcopenia in Older People consensus stated that ultrasonography is reliable and valid for assessing muscle size in older adults. The present study aimed to determine the predictive accuracy of ultrasonography for sarcopenia in older adults in Japan. A total of 1229 participants aged 65-91 years were included in this cross-sectional study. The thickness of the anterior compartment of the right thigh was assessed using B-mode ultrasonography. The measurement position was at the midpoint of the thigh. In addition, the grip strength, gait speed, Five-Time Sit-to-Stand Test, Short Physical Performance Battery score and skeletal muscle mass index were evaluated. Sarcopenia was diagnosed based on the Asian Working Group for Sarcopenia 2019 algorithm. We calculated the area under the receiver operating characteristic curve. The area under the receiver operating characteristic curves (95% confidence intervals) and cutoff values for the thigh muscle thickness in sarcopenia were 0.901 (0.856-0.946) and 4.0 cm in men, respectively, and 0.923 (0.851-0.995) and 3.1 cm in women, respectively. The area under the receiver operating characteristic curve for each subdomain of sarcopenia, such as grip strength and gait speed, ranged from 0.618 to 0.872. In the present study, the suggested cutoff mid-thigh muscle thicknesses on ultrasonography for predicting sarcopenia were 4.0 cm in men and 3.1 cm in women. Geriatr Gerontol Int 2024; 24: 156-161.

The role of muscle degeneration and spinal balance in the pathophysiology of lumbar spinal stenosis: Study protocol of a translational approach combining in vivo biomechanical experiments with clinical and radiological parameters.

To describe a study protocol for investigating the functional association between posture, spinal balance, ambulatory biomechanics, paraspinal muscle fatigue, paraspinal muscle quality and symptoms in patients with symptomatic lumbar spinal stenosis (sLSS) before and 1-year after elective surgical intervention. Single-centre prospective, experimental, multimodal (clinical, biomechanical, radiological) study with three instances of data collection: baseline (study visit 1), 6-month follow-up (remote) and 1-year follow-up (study visit 2). Both study visits include an in vivo experiment aiming to elicit paraspinal muscle fatigue for postural assessment in a non-fatigued and fatigued state. At baseline and 1-year follow-up, 122 patients with sLSS will be assessed clinically, perform the back-performance scale assessment and complete several patient-reported outcome measure (PROMs) questionnaires regarding overall health, disease-related symptoms and kinesiophobia. Posture and biomechanical parameters (joint kinematics, kinetics, surface electromyography, back curvature) will be recorded using an optoelectronic system and retroreflective markers during different tasks including overground walking and movement assessments before and after a modified Biering-Sørensen test, used to elicit paraspinal muscle fatigue. Measurements of muscle size and quality and the severity of spinal stenosis will be obtained using magnetic resonance imaging (MRI) and sagittal postural alignment data from EOS radiographies. After each study visit, physical activity level will be assessed during 9 days using a wrist-worn activity monitor. In addition, physical activity level and PROMs will be assessed remotely at 6-month follow-up. The multimodal set of data obtained using the study protocol described in this paper will help to expand our current knowledge on the pathophysiology, biomechanics, and treatment outcome of degenerative sLSS. The results of this study may contribute to defining and/or altering patient treatment norms, surgery indication criteria and post-surgery rehabilitation schedules. The protocol was approved by the regional ethics committee and has been registered at clinicaltrials.gov (NCT05523388).