Assessing skeletal muscle mass: historical overview and state of the art

Skeletal muscle estimation: A review of techniques and their applications

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

A protocol for remote collection of skeletal muscle mass via D3-creatine dilution in community-dwelling postmenopausal women from the Women's Health Initiative

BACKGROUND

There is emerging evidence that cancer and its treatments may accelerate the normal aging process, increasing the magnitude and rate of decline in functional capacity. This accelerated aging process is hypothesized to hasten the occurrence of common adverse age-related outcomes in cancer survivors, including loss of muscle mass and decrease in physical function. However, there is no data describing age-related loss of muscle mass and its relation to physical function in the long-term in cancer survivors.

METHODS

This study protocol describes the use of a novel method of muscle mass measurement, D3-creatine dilution method (D3Cr), in a large sample (n~6000) of community dwelling postmenopausal women from the Women's Health Initiative (WHI). D3Cr will be used to obtain a direct measure of muscle mass remotely. Participants will be drawn from two sub-cohorts embedded within the WHI that have recently completed an in-home visit. Cancer survivors will be drawn from the Life and Longevity After Cancer (LILAC) cohort, and cancer-free controls will be drawn from the WHI Long Life Study 2. The overall objective of this study is to examine the antecedents and consequences of low muscle mass in cancer survivors. The study aims are to: 1) create age-standardized muscle mass percentile curves and z-scores to characterize the distribution of D3- muscle mass in cancer survivors and non-cancer controls, 2) compare muscle mass, physical function, and functional decline in cancer survivors and non- cancer controls, and 3) use machine learning approaches to generate multivariate risk-prediction algorithms to detect low muscle mass.

DISCUSSION

The D3Cr method will transform our ability to measure muscle mass in large-scale epidemiologic research. This study is an opportunity to advance our understanding of a key source of morbidity among older and long-term female cancer survivors. This project will fill knowledge gaps, including the antecedents and consequences of low muscle mass, and use innovative methods to overcome common sources of bias in cancer research. The results of this study will be used to develop interventions to mitigate the harmful effects of low muscle mass in older adults and promote healthy survivorship in cancer survivors in the old (>65) and oldest-old (>85) age groups.

The Emerging Role and Clinical Applications of Morphomics in Diagnostic Imaging

Analytic morphomics refers to the accurate measurement of specific biological markers of human body composition in diagnostic medical imaging. The increasing prevalence of disease processes that alter body composition including obesity, cachexia, and sarcopenia has generated interest in specific targeted measurement of these metrics to possibly prevent or reduce negative health outcomes. Typical morphomic measurements include the area and density of muscle, bone, vascular calcification, visceral fat, and subcutaneous fat on a specific validated axial level in the patient's cross-sectional diagnostic imaging. A distinct advantage of these measurements is that they can be made retrospectively and opportunistically with pre-existing datasets. We provide a narrative review of the current state of art in morphomics, but also consider some potential future directions for this exciting field. Imaging based quantitative assessment of body composition has enormous potential across the breadth and scope of modern clinical practice. From risk stratification to treatment planning, and outcome assessment, all can be enhanced with the use of analytic morphomics. Moreover, it is likely that many new opportunities for personalized medicine will emerge as the field evolves. As radiologists, embracing analytic morphomics will enable us to contribute added value in the care of every patient.

Perioperative changes in radiographic density in erector spinae muscle and mortality after lung transplantation

RATIONALE

The radiographic density of the erector spinae muscle (ESM) is often decreased early after lung transplantation (LTx). The prognostic impact of this change has not been elucidated.

OBJECTIVE

To investigate whether the decrease in the radiographic density of ESMs early after LTx is associated with a poor prognosis.

METHODS

This study is a single center retrospective cohort study. Routine follow-up chest computed tomography scan data just before and 12 weeks after LTx were retrospectively retrieved for adult patients who underwent primary LTx at Kyoto University Hospital. The radiographic density of ESM was quantitatively evaluated as the mean attenuation of the ESM (ESMct), and the impact of the decreased ESMct during the 12 weeks after LTx on overall survival (OS) was examined by Cox proportional hazard regression.

RESULTS

A total of 151 recipients (94 cadaveric LTx, 57 living-donor lobar LTx) were included in this study. The median duration of postoperative observation was 4.4 years, during which time 39 recipients (26%) died. Decreased postoperative ESMct was significantly associated with poor OS (HR, 1.64; 95% CI, 1.14-2.35, P = 0.008 per 1 Z score decrease) in the multivariate model adjusted for age, sex, episodes of acute rejection, and preoperative ESMct. Similar results were obtained when the subjects were limited to those with cadaveric LTx.

CONCLUSION

A decreased perioperative ESMct was strongly associated with a poor prognosis after LTx in addition to low preoperative ESMct. Maintaining postoperative muscle radiographic density, which reflects muscle quality, may be important for a better prognosis after LTx.

Skeletal muscle estimation using magnetic-resonance-imaging-based equations for dual-energy X-ray absorptiometry and bioelectrical impedance analysis

BACKGROUND/OBJECTIVES

Skeletal muscle mass (SMM) estimation is important but challenging in clinical settings. Criterion methods, such as magnetic resonance imaging (MRI), are often inaccessible. However, surrogate methods, such as dual-energy X-ray absorptiometry (DXA) and multi-frequency bioelectrical impedance analysis (MFBIA), can use MRI-based equations to estimate SMM, although the agreement between these methods is unclear.

SUBJECTS/METHODS

Total and segmental SMM were estimated with DXA and MFBIA using MRI-based equations in 313 healthy adults (120 M, 193 F; age 30.2 ± 13.0 y; BMI 24.6 ± 4.0 kg/m2). DXA total SMM was estimated using the Kim and McCarthy equations, and segmental SMM was estimated using the McCarthy equations. Relationships between DXA and MFBIA SMM were examined using Deming regression, Lin's concordance correlation coefficient (CCC), equivalence testing, Bland-Altman analysis, and related tests.

RESULTS

Strong linear relationships were observed for total (R2 0.95, CCC 0.96-0.97), leg (R2 0.90, CCC 0.85) and arm (R2 0.93, CCC 0.93) SMM in the entire sample. Kim equation SMM demonstrated statistical equivalence with MFBIA for total SMM, but the Deming regression slope differed from 1 and proportional bias was present. McCarthy equation total SMM exhibited a regression slope that did not differ from 1, and no proportional bias was present in the entire sample. However, equivalence with MFBIA was not observed. Systematically higher leg and arm SMM values were observed with DXA as compared to MFBIA.

CONCLUSIONS

While DXA and MFBIA total SMM generally exhibited strong agreement, higher appendicular SMM by DXA highlights technical differences between methods.

The diagnostic cut-off points for components of sarcopenia in Finnish Caucasian women: A retrospective cross-sectional study

Objectives

To determine the diagnostic cut-off values of components for sarcopenia in Caucasian women.

Methods

The present retrospective cross-sectional study based on the REFERENCE sample included 400 healthy women aged 20 to 40 years, and the OSTPRE sample included 344 women aged 63 to 75. The subjects of the OSTPRE population were re-measured five and ten years later after the baseline. Both samples underwent grip strength (GS), quadriceps strength (QS), and total-body DXA (TB-DXA) measurements, from which Relative Skeletal Muscle Mass Index (RSMI) was calculated.

Results

In the REFERENCE population, the -1 SD / -2 SD cut-off points were for RSMI 5.8 kg/m2 / 5.1 kg/m2, for GS 32.0 kg / 26.4 kg, and for QS 39.8 kg / 29.8 kg. The prevalence of under -2 SD distributions in REFERENCE were: RSMI 1.8%, GS 1.3%, and QS 2.0%, and in OSTPRE (15/20/25 years measurements): RSMI 1.2 %/1.9 %/0.5 %, GS 52.2%/42.3%/48.8%, and QS 47.4%/55.2%/not available. The distributions of GS and QS were statistically significantly different between REFERENCE and all OSTPRE measurement points (p<0.001 in Chi-squared).

Conclusions

The diagnostic cut-offs for components of sarcopenia are RSMI 5.1 kg/m2, grip strength 26.4 kg, and quadriceps strength 29.8 kg in Finnish Caucasian women.

A Multivariable Model Based on Ultrasound Imaging Features of Gastrocnemius Muscle to Identify Patients With Sarcopenia

OBJECTIVES

Low skeletal muscle mass, strength, or somatic function are used to diagnose sarcopenia; however, effective assessment methods are still lacking. Therefore, we evaluated the effectiveness of ultrasound in identifying patients with sarcopenia.

METHODS

This study included 167 patients, 78 with sarcopenia and 89 healthy participants, from two hospitals. We evaluated clinical factors and five ultrasound imaging features, of which three ultrasound imaging features were used to create the model. In both the training and validation datasets, the sarcopenia detection performances of chosen ultrasonic characteristics and the constructed model were evaluated using receiver operating characteristic (ROC) curves. The predictive performance was evaluated by area under the ROC (AUROC), calibration, and decision curves.

RESULTS

There were statistically significant differences in muscle thickness (MT) of gastrocnemius medialis muscle (GM), flaky myosteatosis echo (FE), pennation angle (PA), average shear wave velocity (SWV) in the relaxed state (RASWV), and average SWV in the passive stretched state (PASWV) between sarcopenic and normal subjects. PA, RASWV, and PASWV were effective predictors of sarcopenia. The AUROC (95% confidence interval) for these three parameters were 0.930 (0.882-0.978), 0.865 (0.791-0.940), and 0.849 (0.770-0.928), respectively, in the training set, and 0.873 (0.777-0.969), 0.936 (0.878-0.993), and 0.826 (0.716-0.935), respectively, in the validation set. The combined model had better detection power. Finally, the calibration curve showed that the combined model had good prediction accuracy.

CONCLUSION

Our model can be used to identify sarcopenia in primary medical institutions, which is valuable for the early recognition and management of sarcopenia patients.

Estimation of skeletal muscle mass in 4-year-old children using the D3-creatine dilution method

BACKGROUND

Given limited experience in applying the creatine-(methyl-D3) (D3Cr) dilution method to measure skeletal muscle mass (SMM) in young children, the feasibility of deployment in a fielding setting and performance of the method was assessed in a cohort of 4-year-old children in Dhaka, Bangladesh.

METHODS

Following D3Cr oral dose (10 mg) administration, single fasting urine samples were collected at 2-4 days (n = 100). Twenty-four-hour post-dose collections and serial spot urine samples on days 2, 3 and 4 were obtained in a subset of participants (n = 10). Urinary creatine, creatinine, D3Cr and D3-creatinine enrichment were analyzed by liquid chromatography-tandem mass spectrometry. Appendicular lean mass (ALM) was measured by dual-energy x-ray absorptiometry and grip strength was measured by a hand-held dynamometer.

RESULTS

SMM was measured successfully in 91% of participants, and there were no adverse events. Mean ± SD SMM was greater than ALM (4.5 ± 0.4 and 3.2 ± 0.6 kg, respectively). Precision of SMM was low (intraclass correlation = 0.20; 95% CI: 0.02, 0.75; n = 10). Grip strength was not associated with SMM in multivariable analysis (0.004 kg per 100 g of SMM; 95% CI: -0.031, 0.038; n = 91).

CONCLUSIONS

The D3Cr dilution method was feasible in a community setting. However, high within-child variability in SMM estimates suggests the need for further optimization of this approach.

IMPACT

The D3-creatine (D3Cr) stable isotope dilution method was considered a feasible method for the estimation of skeletal muscle mass (SMM) in young children in a community setting and was well accepted among participants. SMM was weakly associated with both dual-energy x-ray absorptiometry-derived values of appendicular lean mass and grip strength. High within-child variability in estimated values of SMM suggests that further optimization of the D3Cr stable isotope dilution method is required prior to implementation in community research settings.

Supplementation of GelMA with Minimally Processed Tissue Promotes the Formation of Densely Packed Skeletal-Muscle-Like Tissues

We present a simple and cost-effective strategy for developing gelatin methacryloyl (GelMA) hydrogels supplemented with minimally processed tissue (MPT) to fabricate densely packed skeletal-muscle-like tissues. MPT powder was prepared from skeletal muscle by freeze-drying, grinding, and sieving. Cell-culture experiments showed that the incorporation of 0.5-2.0% (w/v) MPT into GelMA hydrogels enhances the proliferation of murine myoblasts (C2C12 cells) compared to proliferation in pristine GelMA hydrogels and GelMA supplemented with decellularized skeletal-muscle tissues (DCTs). MPT-supplemented constructs also preserved their three-dimensional (3D) integrity for 28 days. By contrast, analogous pristine GelMA constructs only maintained their structure for 14 days or less. C2C12 cells embedded in MPT-supplemented constructs exhibited a higher degree of cell alignment and reached a significantly higher density than cells loaded in pristine GelMA constructs. Our results suggest that the addition of MPT incorporates a rich source of biochemical and topological cues, such as growth factors, glycosaminoglycans (GAGs), and structurally preserved proteins (e.g., collagen). In addition, GelMA supplemented with MPT showed suitable rheological properties for use as bioinks for extrusion bioprinting. We envision that this simple and cost-effective strategy of hydrogel supplementation will evolve into an exciting spectrum of applications for tissue engineers, primarily in the biofabrication of relevant microtissues for in vitro models and cultured meat and ultimately for the biofabrication of transplant materials using autologous MPT.

Reference values for low muscle mass and myosteatosis using tomographic muscle measurements in living kidney donors

Low muscle mass and myosteatosis are associated with poor clinical outcomes. Computed tomography (CT) imaging is an objective method for muscle mass and quality assessment; however consensus on cut-off values is lacking. This study assessed age-, sex-, and body mass index (BMI)-specific reference values of skeletal muscle parameters and correlated muscle mass with 24-h urinary creatinine excretion (24-h UCE). In total, 960 healthy subjects were included in this study. Muscle mass and quality were determined using axial CT slices at the vertebral level L3. The muscle area was indexed for height (skeletal muscle index [SMI]). The mean age was 53 ± 11 years, and 50% were male. The SMI reference values for low muscle mass in males were 38.8 cm²/m² (20-29 years), 39.2 (30-39 years), 39.9 (40-49 years), 39.0 (50-59 years), 37.0 (60-69 years), and 36.8 (70-79 years). For females, these reference values were 37.5 cm²/m² (20-29 years), 35.5 (30-39 years), 32.8 (40-49 years), 33.2 (50-59 years), 31.2 (60-69 years), and 31.5 (70-79 years). 24-h UCE and SMI were significantly correlated (r = 0.54, p < 0.001) without bias between the two methods of assessing muscle mass. This study provides age-, sex-, and BMI-specific reference values for skeletal muscle parameters that will support clinical decision making.

Electrical impedance myography combined with quantitative assessment techniques in paretic muscle of stroke survivors: Insights and challenges

Aging is a non-modifiable risk factor for stroke and the global burden of stroke is continuing to increase due to the aging society. Muscle dysfunction, common sequela of stroke, has long been of research interests. Therefore, how to accurately assess muscle function is particularly important. Electrical impedance myography (EIM) has proven to be feasible to assess muscle impairment in patients with stroke in terms of micro structures, such as muscle membrane integrity, extracellular and intracellular fluids. However, EIM alone is not sufficient to assess muscle function comprehensively given the complex contributors to paretic muscle after an insult. This article discusses the potential to combine EIM and other common quantitative methods as ways to improve the assessment of muscle function in stroke survivors. Clinically, these combined assessments provide not only a distinct advantage for greater accuracy of muscle assessment through cross-validation, but also the physiological explanation on muscle dysfunction at the micro level. Different combinations of assessments are discussed with insights for different purposes. The assessments of morphological, mechanical and contractile properties combined with EIM are focused since changes in muscle structures, tone and strength directly reflect the muscle function of stroke survivors. With advances in computational technology, finite element model and machine learning model that incorporate multi-modal evaluation parameters to enable the establishment of predictive or diagnostic model will be the next step forward to assess muscle function for individual with stroke.

The possible relation between temporal muscle mass and glioblastoma multiforme prognosis via sarcopenia perspective

BACKGROUND

The optimal sarcopenia measurement method in patients with a diagnosis of glioblastoma multiforme (GBM) is unknown. It has been found that temporal muscle thickness (TMT) may reflect sarcopenia and be associated with survival, but the relationship between temporal muscle area (TMA) and GBM prognosis has never been evaluated before. The primary outcome of the study was to evaluate the relationship between TMA/TMT and overall survival (OS) time in newly diagnosed GBM patients.

METHODS

The data of patients who presented at the university hospital between January 2009 and January 2019 with a confirmed diagnosis of glioblastoma multiforme at the time of diagnosis were analyzed retrospectively. Temporal muscle thickness and TMA were measured retrospectively from preoperative MRIs of patients diagnosed with GBM. Due to the small number of patients and the failure to determine a cut-off value with acceptable sensitivity and specificity using ROC analysis, the median values were chosen as the cut-off value. The patients were basically divided into two according to their median TMT (6.6 mm) or TMA (452 mm2 ) values, and survival analysis was performed with the Kaplan-Meier analysis.

RESULTS

The median TMT value was 6.6 mm, and the median TMA value was 452 mm2 . The median overall survival (OS) was calculated as 25.8 months in patients with TMT < 6.6 mm, and 15.8 months in patients with TMT ≥ 6.6 mm (p = 0.29). The median overall survival (OS) of patients with TMA < 452mm2 was 26.3 months, and the group with TMA ≥ 452mm2 was 14.6 months (p = 0.06). The median disease-free survival was 18.3 months (%95 CI: 13.2-23.4) in patients with TMT < 6.6mm, while mDFS was 10.9 (%95 CI: 8.0-13.8) months in patients with TMT ≥ 6.6mm (p = 0.21). The median disease-free survival was found to be 21.0 months (%95 CI: 15.8-26.1) in patients with TMA < 452 mm2 and 10.5 months (%95 CI: 7.8-13.2) in patients with TMA ≥ 452 mm2 (p = 0.018).

DISCUSSION

No association could be demonstrated between TMT or TMA and OS of GBM patients. In addition, the median DFS was found to be longer in patients with low TMA. There is an unmet need to determine the optimal method of sarcopenia in GBM patients.

ANALYSIS OF JOGGING ON MUSCLE FATIGUE AND BODY BALANCE

ABSTRACT Introduction: The changes in muscle condition during jogging are studied according to their characteristics to formulate a correct fitness plan. With a medium effort intensity, studies on jogging have shown positive effects on mental de-stress and motor coordination. Objective: Study the effect of running training on muscle fatigue and body balance. Methods: A total of 60 sedentary freshmen from a university were selected, including 30 male and 30 female students. The volunteers were randomly divided into experimental and control groups. While the control performed routine sports activities according to the teaching plan during physical education class, the students in the experimental group performed a jogging training protocol. Data were collected before and after the intervention for comparison and statistical analysis. Results: The vestibular step test changed from 20.56 to 13.87, evidencing that jogging training significantly improved body balance ability in addition to providing body flexibility. Conclusion: Combined with curriculum standards and the level of physical training required, jogging can be integrated into physical education classes to promote student health. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

The Muscle Thickness Assessment Using Ultrasonography is a Useful Alternative to Skeletal Muscle Mass by Bioelectrical Impedance Analysis

Purpose

Muscle mass, a key index for the diagnosis of sarcopenia, is currently assessed using the appendicular skeletal muscle mass index (ASMI) by bioelectrical impedance analysis (BIA). Muscle thickness (MT) assessed by ultrasonography (US) may be a better determinant and/or predictor of muscle condition than ASMI. Thus, we compared it to the ASMI determined by the BIA.

Patients and Methods

Our study included 165 ambulatory older adults (84 males, 81 females, mean age: 76.82 years). The ASMI by the BIA method, MT by US, and the distribution of body mass index (BMI) and body fat percentage (BFP) were examined using defined values for men and women. These were used as the basis for examining the association of MT and ASMI with handgrip strength (HGS), leg muscle strength (LMS), gait speed (GS), and echo intensity (EI). We compared HGS, LMS, GS, and EI for high and low ASMI among lower BMI or BFP. The same was also done for MT assessed by US.

Results

MT, as well as ASMI, was strongly associated with HGS and LMS. There was a correlation between MT and GS and EI but not between ASMI and GS and EI. There were significant differences in the prevalence between high ASMI and high MT or low ASMI and low MT in those with lower BMI or BFP. In non-overweight participants, HGS, LMS, GS, and EI were significantly higher in those with high MT than in those with low MT; however, there were no significant differences in them between those with high and low ASMI.

Conclusion

In the non-overweight group, the MT assessment by US showed a stronger relationship to muscle strength and muscle quality than the ASMI assessment by BIA. The MT assessment using US is a useful alternative to BIA-assessed ASMI, especially in non-overweight participants.

Using exergame-based exercise to prevent and postpone the loss of muscle mass, muscle strength, cognition, and functional performance among elders in rural long-term care facilities: A protocol for a randomized controlled trial

Objective

Elderly individuals in long-term care facilities (LTCFs) have a higher prevalence of sarcopenia than those in the community. Exercise is the gold standard for preventing and treating sarcopenia. Regarding exercise, multicomponent exercises, including progressive resistance training (PRT), are beneficial. However, developing routine, structured exercise programs for the elderly in LTCFs is difficult because of a shortage of healthcare providers, particularly in rural regions. Exergame-based exercises can increase a player's motivation and reduce staff time for an intervention. Nintendo Switch RingFit Adventure (RFA) is a novel exergame that combines resistance, aerobic, and balance exercises. In this study, we aim to investigate the clinical effectiveness of RFA on muscle and functional performance parameters among the elderly in LTCFs.

Methods

The EXPPLORE (using EXergame to Prevent and Postpone the LOss of muscle mass, muscle strength, and functional performance in Rural Elders) trial is a single-center randomized controlled trial involving elderly individuals (≥60 years) living in LTCFs in rural southern Taiwan. The participants will be equally randomized to the intervention group (exergame-based exercise plus standard care) or the control group (standard care alone). Both groups will receive standard care except that the intervention group will receive exergame-based exercises at the time previously scheduled for sedentary activities in the LTCFs. The exergame-based exercise will be performed using RFA in the sitting position with a specialized design, including arm fit skills and knee assist mode. Each session of the exercise lasts 30 mins and will be performed two times per week for 12 weeks. The primary outcomes will be the osteoporotic fracture index, appendicular skeletal muscle mass index, dominant handgrip strength, and gait speed. Meanwhile, the secondary outcomes will be the dexterity and agility, muscle strength and thickness, range of motion of the joints of the dominant upper extremity, Kihon checklist, Medical Outcomes Study 36-Item Short-Form Health Survey, and Brain Health Test.

Discussion

This trial will provide valuable knowledge on whether exergames using RFA can counteract physical decline and improve quality of life and cognition among the elderly in LTCFs.

Clinical trial registration

[www.ClinicalTrials.gov], identifier [NCT05360667].

The impact of body position on measurement of equine lumbar and hindquarter volume using 3-dimensional scans

Well-developed musculature is important for performance yet difficult to quantify. Recently, we validated infrared 3-dimensional (3-D) photonic scanning as an accurate measure of body volume and proxy for regional muscle mass in horses. Our current objective was to determine the impact of body position on measures of lumbar (LV) and hindquarter (HQV) volume. Anatomic markers were placed on 8 horses, positioned at: (1) four hooves square, (2) neck turned ~25°, (3) head raised mean 17 cm, (4) one hind hoof (HH) forward 14±5 cm, (5) a front and contralateral HH ~15 cm all offset, (6) one HH resting. A handheld Occipital Structure Sensor photonic scanner, iPad, Skanect and Materialise 3-Matic programs captured LV and HQV. Measured LV and HQV for whole, same and opposite-side with altered head positions and whole LV and HQV with altered HH positions were compared to volume standing square using repeated measures ANOVA. The volumes of the opposite-side or same-side with altered HH positions were compared to the corresponding side when square using a paired t test with multiple test correction (P<0.017). Head elevated negatively impacted measured left LV (-10% difference, P=0.1) compared to square, however, differences were not significant. Head turned did not impact measured LV. Resting HH significantly increased measured whole (18%, P=0.04) and same-side LV (49%, P=0.001) versus square but not the opposite-side LV. One HH forward (whole 16%, P=0.02; same-side 19%, P=0.01) or all offset (whole 14%, P=0.002; same-side 27%, P=0.0001) significantly increased measured whole or same-side LV versus square. Measured HQV was not impacted by head elevated or limb position but was 2% higher on the opposite-side of the turned head (P=0.01). We conclude that alterations in body position have minimal impact on measured HQV, whereas accurate assessment of LV requires horses stand squarely.

Nutritional and Nutrition-Related Biomarkers as Prognostic Factors of Sarcopenia, and Their Role in Disease Progression

Due to the multifactorial pathogenesis of sarcopenia, it is crucial to identify biomarkers that are risk factors for sarcopenia, and which therefore have a prognostic function. Aim: This narrative review aims to define a set of biomarkers associated with nutrition and sarcopenia. These biomarkers could contribute to individualized monitoring and enable preventive and therapeutic methods. Methods: Two electronic databases, PubMed and Google Scholar, were used. The search strategy was based on a controlled vocabulary (MeSH) and includes studies published up to February 2022. Discussion: Higher levels of serum uric acid are associated with higher handgrip strength and better muscle function in elderly people and, thus, may slow the progression of sarcopenia. Leptin, an adipokine secreted by adipose tissue, promotes the production of pro-inflammatory cytokines, which in turn lead to sarcopenia. This makes leptin a significant indirect biomarker for physical disability and sarcopenic obesity. Additionally, creatinine is a reliable biomarker for muscle mass status because of its easy accessibility and cost-effectiveness. Vitamin D status acts as a useful biomarker for predicting total mortality, hip fractures, early death, and the development of sarcopenia. Therefore, there is an increasing interest in dietary antioxidants and their effects on age-related losses of muscle mass and function. On the other hand, 3-Methylhistidine is a valuable biomarker for detecting increased muscle catabolism, as it is excreted through urine during muscle degradation. In addition, IGF-1, whose concentration in plasma is stimulated by food intake, is associated with the loss of skeletal muscle mass, which probably plays a crucial role in the progression of sarcopenia. Conclusions: Many nutritional biomarkers were found to be associated with sarcopenia, and can therefore be used as prognostic indexes and risk factors. Nutrition plays an important role in the prevention and management of sarcopenia, affecting muscle mass, strength, and function in elderly people.

HR-pQCT for the Evaluation of Muscle Quality and Intramuscular Fat Infiltration in Ageing Skeletal Muscle

Myosteatosis is the infiltration of fat in skeletal muscle during the onset of sarcopenia. The quantification of intramuscular adipose tissue (IMAT) can be a feasible imaging modality for the clinical assessment of myosteatosis, important for the early identification of sarcopenia patients and timely intervention decisions. There is currently no standardized method or consensus for such an application. The aim of this study was to develop a method for the detection and analysis of IMAT in clinical HR-pQCT images of the distal tibia to evaluate skeletal muscle during the ageing process, validated with animal and clinical experimentation. A pre-clinical model of ovariectomized (OVX) rats with known intramuscular fat infiltration was used, where gastrocnemii were scanned by micro-computed tomography (micro-CT) at an 8.4 μm isotropic voxel size, and the images were analyzed using our modified IMAT analysis protocol. IMAT, muscle density (MD), and muscle volume (MV) were compared with SHAM controls validated with Oil-red-O (ORO) staining. Furthermore, the segmentation and IMAT evaluation method was applied to 30 human subjects at ages from 18 to 81 (mean = 47.3 ± 19.2). Muscle-related parameters were analyzed with functional outcomes. In the animal model, the micro-CT adipose tissue-related parameter of IMAT% segmented at −600 HU to 100 HU was shown to strongly associate with the ORO-positively stained area (r = 0.898, p = 0.002). For the human subjects, at an adjusted threshold of −600 to −20 HU, moderate positive correlations were found between MV and MD (r = 0.642, p < 0.001), and between MV and IMAT volume (r = 0.618, p < 0.01). Moderate negative correlations were detected between MD and IMAT% (r = −0.640, p < 0.001). Strong and moderate associations were found between age and MD (r = −0.763, p < 0.01), and age and IMAT (r = 0.559, p < 0.01). There was also a strong correlation between IMAT% and chair rise time (r = 0.671, p < 0.01). The proposed HR-pQCT evaluation protocol for intramuscular adipose-tissue produced MD and IMAT results that were associated with age and physical performance measures, and were of good predictive value for the progression of myosteatosis or sarcopenia. The protocol was also validated on animal skeletal muscle samples that showed a good representation of histological lipid content with positive correlations, further supporting the clinical application for the rapid evaluation of muscle quality and objective quantification of skeletal muscle at the peripheral for sarcopenia assessment.

Author Response to LTE JPEN-2022-04-138. Reply to: Evans WJ. Lean body mass should not be used as a surrogate measurement of muscle mass in malnourished men and women: Comment on Compher et al. JPEN J Parenter Enteral Nutr. 2022 Apr 19. doi: 10.1002/jpen.2384. Epub ahead of print. PMID: 35437790

Professor Evans comments (1) on our recent Global Leadership Initiative on Malnutrition (GLIM) Guidance published in the journal (2). In the title of his letter, Dr. Evans uses the term "lean body mass", an archaic body component description long abandoned by experts in the field. We believe this term is being used to refer to fat-free mass, the now accepted terminology for the component derived as the difference between body weight and fat mass This article is protected by copyright. All rights reserved.

The importance of muscle mass in predicting intradialytic hypotension in patients undergoing maintenance hemodialysis

Background

Patients undergoing hemodialysis are susceptible to sarcopenia. As intracellular reservoirs of water, skeletal muscles are important contributors to intradialytic hypotension. This study was designed to determine the role of skeletal muscle mass in intradialytic hypotension.

Methods

In a cross-sectional study, the body composition of 177 patients was measured immediately after hemodialysis using bioelectrical impedance analysis. The parameters measured were skeletal muscle mass, intracellular and extracellular water contents, total body water, and cell-membrane functionality (in phase angle at 50 kHz). Data from laboratory tests, chest radiography, measurements of handgrip strength and mid-arm circumference, and questionnaires were collected. The main outcome was intradialytic hypotension, defined as more than two episodes of hypotension (systolic blood pressure of <90 mmHg) with intervention over the 3 months following enrollment. Logistic regression models including each parameter related to sarcopenia were compared with a clinical model.

Results

Patients with a low ratio of skeletal muscle mass to dry body weight (SMM/WT) had a higher rate of intradialytic hypotension (41%). Most low-SMM/WT patients were female, obese, diabetic, and had a lower handgrip strength compared with the other patients. In the high-SMM/WT group, the risk of intradialytic hypotension was lower, with an odds ratio of 0.08 (95% confidence interval [CI], 0.02-0.28) and adjusted odds ratio of 0.06 (95% CI, 0.01-0.29).

Conclusion

Measurement and maintenance of skeletal muscle can help prevent intradialytic hypotension in frail patients undergoing hemodialysis.

Assessment of Osteogenesis Enhancement in Rats Using Bone Densitometry: An In Vivo Study

Background: Human survival depends on the availability of water. Safe drinking water is a fundamental human right as well as a basic need for a good health. At the mineral and organic levels of water composition, exposure to electromagnetic fields can cause considerable changes in the quality of drinking water. As a result, water is more easily absorbed into the cell walls throughout the body, making it better suited for organ growth and development. When drunk on a daily basis, magnetic water causes dramatic changes in bone mineral density and content. Due to the necessity for distinct beam filtering and near-perfect spatial discography of the two attenuations, DXA (DualEnergy X-ray Absorptiometry) was included with general-purpose X-ray systems. In rats that drink magnetized water on a daily basis, the DXA can be used to calculate the weight and area of all head compartments. Objective: By employing a Bone Densitometry scan on the head regions of rats, this study aims to assess the changes in the rat's skull bone measures (area, weight, bone mineral content, and bone mineral density) after feeding the animal with magnetized water. Methods: This study involved thirty adult male rats (6 weeks old). For 30 days, 15 rats were given a magnetized water to drink and used as experimental animals. For comparison purposes, the remaining 15 rats were given regular water for 30 days. After the experimental procedure was done, each rat's head was scanned with a DXA to determine bone weight, area, bone mineral content, and bone mineral density. Before drinking water, each rat in both the experimental and control groups was examined. The head of each rate was scanned using a DXA to get the values of bone: weight, area, mineral density, and mineral content after 30 days of consuming magnetized water. The four bone measures were statistically compared in the experimental and control rats, p-values below 0.05 were considered significant. Results: Comparing to control rats, experimental rats showed a significant increase in the bone’s weight and area of the skull (p<0.05, Wilcoxon test).  Bone marrow content and bone marrow density enhanced significantly as well in experimental rats after drinking the magnetized water for 30 days. Conclusions: Drinking water that has been subjected to electromagnetic fields for 30 days can improve bone marrow content and density in rats. Drinking magnetized water also has a substantial impact on bone mass and area.

Rectus Abdominis Muscle Thickness is a Valid Measure of Cross-Sectional Area: Implications for Ultrasound

RATIONALE AND OBJECTIVES

The rectus abdominis muscle exhibits early and significant muscle atrophy, which has largely been characterized using ultrasound measured muscle thickness. However, the validity of rectus abdominis muscle thickness as a metric of muscle size has not been established, limiting precise interpretation of age-related changes. In a heterogeneous cohort of women and men, our objectives were to: (1) evaluate the association between rectus abdominis muscle thickness and cross-sectional area (CSA), and (2) examine if the visceral adipose tissue (VAT) compartment confounds the validity of rectus abdominis muscle thickness.

MATERIALS AND METHODS

Abdominal computed tomography scans of the third lumbar vertebrae from clinical and healthy populations were used to evaluate rectus abdominis thickness and CSA, and VAT CSA. Computed tomography scans were utilized due to the limited field of view of ultrasound imaging to capture the rectus abdominis CSA.

RESULTS

A total of 348 individuals (31% women) were included in this analysis, with a mean ± standard deviation age and body mass index of 51.2 ± 15.4 years and 28.0 ± 5.1 kg/m², respectively. Significant correlations were observed between rectus abdominis thickness and CSA for women (r = 0.758; p < 0.001) and men (r = 0.688; p < 0.001). Independent of age, VAT CSA was negatively associated with rectus abdominis thickness in men (p = 0.011), but not women (p = 0.446).

CONCLUSION

These data support the use of rectus abdominis muscle thickness as a measurement of muscle size in both women and men; however, the VAT compartment may confound its validity to a minor extent in men.

Inverse association between sarcopenia and displacement in the early phase of fragility fractures of the pelvis

Objectives

Fragility fractures of the pelvis (FFP) commonly occur in the frail elderly. Displacement in the posterior pelvic ring is recognized as the key sign of instability. This study aims to elucidate the relationship between computer tomography (CT)-based frailty markers and displacement of the posterior pelvic ring within 7 days after injury.

Methods

This retrospective study included 49 patients (42 females, 7 males) with FFP (type I 10, type II 24, type III 12, type IV 3). On a CT slice at the level of the third lumbar vertebra, skeletal muscle area, skeletal muscle radiation attenuation, and skeletal muscle index (SMI) were calculated as sarcopenia markers. Osteopenia was measured with trabecular region of interest attenuation technique on the same CT slice.

Results

There was no difference in the demographics between non-displaced and displaced FFP. CT-based data showed that patients with FFP had osteopenia. However, no difference was found between non-displaced and displaced FFP. SMI was higher in FFP types III/IV than non-displaced FFP when CT-based data on sarcopenia were compared among all patients. Female patients with FFP demonstrated similar results. Logistic regression analysis using the demographics and CT-based markers on sarcopenia and osteopenia revealed that SMI was a potential determinant of displacement of the posterior pelvic ring fractures.

Conclusions

There was inverse association between sarcopenia and displacement of the posterior pelvic ring in the early phase of FFP. Relatively preserved muscle may develop displacement in the elderly with osteopenia.

Obesity history, physical exam, laboratory, body composition, and energy expenditure: An Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) 2022

Background

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) on History, Physical Exam, Body Composition and Energy Expenditure is intended to provide clinicians an overview of the clinical and diagnostic evaluation of patients with pre-obesity/obesity.

Methods

The scientific information for this CPS is based upon published scientific citations, clinical perspectives of OMA authors, and peer review by the Obesity Medicine Association leadership.

Results

This CPS outlines important components of medical, dietary, and physical activity history as well as physical exams, with a focus on specific aspects unique to managing patients with pre-obesity or obesity. Patients with pre-obesity/obesity benefit from the same preventive care and general laboratory testing as those without an increase in body fat. In addition, patients with pre-obesity/obesity may benefit from adiposity-specific diagnostic testing - both generally and individually - according to patient presentation and clinical judgment. Body composition testing, such as dual energy x-ray absorptiometry, bioelectrical impedance, and other measures, each have their own advantages and disadvantages. Some patients in clinical research, and perhaps even clinical practice, may benefit from an assessment of energy expenditure. This can be achieved by several methods including direct calorimetry, indirect calorimetry, doubly labeled water, or estimated by equations. Finally, a unifying theme regarding the etiology of pre-obesity/obesity and effectiveness of treatments of obesity centers on the role of biologic and behavior efficiencies and inefficiencies, with efficiencies more often associated with increases in fat mass and inefficiencies more often associated with decreases in fat mass.

Conclusion

The Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) on History, Physical Exam, Body Composition and Energy Expenditure is one of a series of OMA CPSs designed to assist clinicians in the care of patients with the disease of pre-obesity/obesity.

Evaluation of Muscle Mass and Stiffness with Limb Ultrasound in COVID-19 Survivors

BACKGROUND

acute illnesses, like COVID-19, can act as a catabolic stimulus on muscles. So far, no study has evaluated muscle mass and quality through limb ultrasound in post-COVID-19 patients.

METHODS

cross sectional observational study, including patients seen one month after hospital discharge for SARS-CoV-2 pneumonia. The patients underwent a multidimensional evaluation. Moreover, we performed dominant medial gastrocnemius ultrasound (US) to characterize their muscle mass and quality.

RESULTS

two hundred fifty-nine individuals (median age 67, 59.8% males) were included in the study. COVID-19 survivors with reduced muscle strength had a lower muscle US thickness (1.6 versus 1.73 cm, p =0.02) and a higher muscle stiffness (87 versus 76.3, p = 0.004) compared to patients with normal muscle strength. Also, patients with reduced Short Physical Performance Battery (SPPB) scores had a lower muscle US thickness (1.3 versus 1.71 cm, p = 0.01) and a higher muscle stiffness (104.9 versus 81.07, p = 0.04) compared to individuals with normal SPPB scores. The finding of increased muscle stiffness was also confirmed in patients with a pathological value (≥ 4) at the sarcopenia screening tool SARC-F (103.0 versus 79.55, p < 0.001). Muscle stiffness emerged as a significant predictor of probable sarcopenia (adjusted OR 1.02, 95% C.I. 1.002 - 1.04, p = 0.03). The optimal ultrasound cut-offs for probable sarcopenia were 1.51 cm for muscle thickness (p= 0.017) and 73.95 for muscle stiffness (p = 0.004).

DISCUSSION

we described muscle ultrasound characteristics in post COVID-19 patients. Muscle ultrasound could be an innovative tool to assess muscle mass and quality in this population. Our preliminary findings need to be confirmed by future studies comparing muscle ultrasound with already validated techniques for measuring muscle mass and quality.

Brazilian Nutritional Consensus in Hematopoietic Stem Cell Transplantation: children and adolescents

The Brazilian Nutritional Consensus in Hematopoietic Stem Cell Transplantation: Children and Adolescents was developed by dietitians, physicians, and pediatric hematologists from 10 Brazilian reference centers in hematopoietic stem cell transplantation. The aim was to emphasize the importance of nutritional status and body composition during treatment, as well as the main characteristics related to patient´s nutritional assessment. This consensus is intended to improve and standardize nutrition therapy during hematopoietic stem cell transplantation. The consensus was approved by the Brazilian Society of Bone Marrow Transplantation.

Imaging modalities for diagnosis and monitoring of cancer cachexia

Cachexia, a multifactorial wasting syndrome, is highly prevalent among advanced-stage cancer patients. Unlike weight loss in healthy humans, the progressive loss of body weight in cancer cachexia primarily implicates lean body mass, caused by an aberrant metabolism and systemic inflammation. This may lead to disease aggravation, poorer quality of life, and increased mortality. Timely detection is, therefore, crucial, as is the careful monitoring of cancer progression, in an effort to improve management, facilitate individual treatment and minimize disease complications. A detailed analysis of body composition and tissue changes using imaging modalities—that is, computed tomography, magnetic resonance imaging, (¹⁸F) fluoro-2-deoxy-d-glucose (¹⁸FDG) PET and dual-energy X-ray absorptiometry—shows great premise for charting the course of cachexia. Quantitative and qualitative changes to adipose tissue, organs, and muscle compartments, particularly of the trunk and extremities, could present important biomarkers for phenotyping cachexia and determining its onset in patients. In this review, we present and compare the imaging techniques that have been used in the setting of cancer cachexia. Their individual limitations, drawbacks in the face of clinical routine care, and relevance in oncology are also discussed.

Evaluation of skeletal muscle mass using prediction formulas at the level of the 12th thoracic vertebra

OBJECTIVES

People with cancer have a high risk of cachexia and sarcopenia, which are associated with worse clinical outcomes. We evaluated the prediction accuracy of the Matsuyama et al. and Ishida et al. formulas using computed tomography (CT) slices from the twelfth thoracic vertebra (Th12) level in people with cancer.

METHODS

This retrospective study included patients with advanced cancer who underwent thoracic and abdominal CT scans (n = 173). The cross-sectional area (CSA) on CT images was measured at the levels of Th12 and the third lumbar vertebra (L3). The Matsuyama et al. formula used the Th12 CSA, whereas the Ishida et al. formula used only the Th12 CSA of the spinal erectors; thus, the measurements were performed separately. The correlation between predicted and actual L3 CSA was assessed using r and the intraclass correlation coefficient. A prediction-accuracy analysis of the predicted values was also performed.

RESULTS

The mean participant age was 66.2 ± 12.8 y; 50.3% of participants were women and 49.7% were men. Strong correlations were observed between the predicted and measured L3 values calculated from the two prediction formulas. The prediction-accuracy analysis using previously reported cutoff values showed that the Ishida et al. method had high sensitivity and the Matsuyama et al. method had high specificity for low skeletal muscle index determined by the predicted and measured L3 skeletal muscle index.

CONCLUSIONS

Both the Matsuyama et al. and Ishida et al. formulas had good reliability on CT slices at the Th12 level in people with advanced cancer, indicating that these formulas can be applied in clinical practice.

MRI-Determined Psoas Muscle Fat Infiltration Correlates with Severity of Weight Loss during Cancer Cachexia

PURPOSE

To evaluate the suitability of psoas and erector spinae muscle proton density fat fraction (PDFF) and fat volume as biomarkers for monitoring cachexia severity in an oncological cohort, and to evaluate regional variances in muscle parameters over time.

METHODS

In this prospective study, 58 oncological patients were examined by a 3 T MRI receiving between one and five scans. Muscle volume and PDFF were measured, segmentation masks were divided into proximal, middle and distal muscle section.

RESULTS

A regional variation of fat distribution in erector spinae muscle at baseline was found (p < 0.01). During follow-ups significant relative change of muscle parameters was observed. Relative maximum change of erector spinae muscle showed a significant regional variation. Correlation testing with age as a covariate revealed significant correlations for baseline psoas fat volume (r = -0.55, p < 0.01) and baseline psoas PDFF (r = -0.52, p = 0.02) with maximum BMI change during the course of the disease.

CONCLUSION

In erector spinae muscles, a regional variation of fat distribution at baseline and relative maximum change of muscle parameters was observed. Our results indicate that psoas muscle PDFF and fat volume could serve as MRI-determined biomarkers for early risk stratification and disease monitoring regarding progression and severity of weight loss in cancer cachexia.

Erector spinae muscle radiographic density is associated with survival after lung transplantation

OBJECTIVE

The study objective was to verify whether low preoperative radiographic density of erector spinae muscles is associated with poor prognosis after lung transplantation.

METHODS

Preoperative chest computed tomography scans for patients who underwent deceased-donor lung transplantation between 2013 and 2019 at Kyoto University Hospital were retrospectively retrieved. The radiographic density of erector spinae muscles was quantitatively evaluated as the mean attenuation of erector spinae muscles, and low mean radiographic density of the erector spinae muscles was defined as a mean radiographic density of the erector spinae muscles value below the median value for all patients. Overall survival and chronic lung allograft dysfunction-free survival with high and low mean radiographic density of the erector spinae muscles were estimated using the Kaplan-Meier method and evaluated by the log-rank test, as well as by univariate and multivariate Cox proportional hazard analyses.

RESULTS

Of the 107 adult patients who underwent primary transplantation, 96 underwent at least 1 chest computed tomography scan within 24 hours before lung transplantation. The median mean radiographic density of the erector spinae muscles in these 96 patients was 49.2 Hounsfield units. A low mean radiographic density of the erector spinae muscles value was significantly associated with decreased overall survival (hazard ratio, 4.50; P = .030) and chronic lung allograft dysfunction-free survival (hazard ratio, 3.18; P = .028) in the multivariate analysis. Additionally, patients with preoperative steroid use and a low mean radiographic density of the erector spinae muscles value had a worse overall survival (P < .001) and chronic lung allograft dysfunction-free survival (P < .001) than patients with preoperative steroid use and a high mean radiographic density of the erector spinae muscles value and those without preoperative steroid use.

CONCLUSIONS

Low mean radiographic density of the erector spinae muscles was closely associated with a poor prognosis after lung transplantation. The prognosis was particularly poor in patients with preoperative steroid use and a low mean radiographic density of the erector spinae muscles. These results may be useful when considering the indications for lung transplantation or preoperative interventions. VIDEO ABSTRACT.

Venous creatinine as a biomarker for loss of fat-free mass and disease progression in patients with amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE

To establish the utility of venous creatinine as a biomarker to monitor loss of fat-free mass in patients with amyotrophic lateral sclerosis (ALS).

METHODS

In this multicenter natural history study, body composition and venous creatinine were assessed in 107 patients with ALS and 52 healthy controls. Longitudinal patterns of venous creatinine and its association with the risk of death during follow-up were determined in a cohort of patients with ALS from Australia (n = 69) and the Netherlands (n = 38).

RESULTS

The mean levels of venous creatinine were 75.78 ± 11.15 μmol/L for controls, 70.25 ± 12.81 μmol/L for Australian patients, and 59.95 ± 14.62 μmol/L for Dutch patients with ALS. The relationship between measures of venous creatinine and fat-free mass was similar between all groups (r = 0.36, p < 0.001). Within patients, fat-free mass declined by 0.31 (95% confidence interval [CI]: 0.22-0.40) kg/month, and venous creatinine declined by 0.52 (95% CI: 0.38-0.66) μmol/L/month, with a longitudinal correlation of 0.57 (95% CI: 0.35-0.76, p < 0.001). Lower levels of venous creatinine were associated with increased risk for earlier death in patients with ALS (hazard ratio = 0.94, 95% CI: 0.90-0.98, p = 0.007).

CONCLUSIONS

Venous creatinine is decreased in ALS and declines alongside a decline in fat-free mass over the course of the disease, and may serve as a practical marker to monitor the change of fat-free mass in patients with ALS. This could inform clinical care and provide an alternative endpoint for the evaluation of therapeutic interventions that focus on slowing the loss of fat-free mass and disease progression in ALS.

Effects of 16 Weeks of Resistance Training on Muscle Quality and Muscle Growth Factors in Older Adult Women with Sarcopenia: A Randomized Controlled Trial

This study examined the effects of resistance training on muscle quality, muscle growth factors, and functional fitness in older adult women with sarcopenia. Twenty-two older adult women aged over 65 with sarcopenia were randomly assigned to either resistance training (RT, n = 12) or non-exercise control group (CG, n = 10). The body weight-based and elastic band RT were performed three times a week, 60 min per session, for 16 weeks. Body composition and thigh muscle quality were estimated by dual-energy X-ray absorptiometry (DEXA) and computed tomography (CT), respectively. The muscle growth factors, including growth differentiation factor-8 (GDF-8), growth differentiation factor-15 (GDF-15), activin A, and follistatin, were analyzed via blood samples. Statistical analyses were performed using repeated measures multivariate analysis of variance (MANOVA), analysis of variance (ANOVA), and effect size (i.e., cohen’s d, partial eta square), and the significance level was set at 0.05. The RT group improved their functional fitness, grip strength, gait speed, and isometric muscle strength (p < 0.01, d > 0.99; large), while these variables did not change in the CG. An increase in intramuscular fat was only observed in the CG (p < 0.01, 1.06; large). Muscle growth factors such as follistatin were significantly increased in the RT (p < 0.05, 0.81; large), but other variables did not change following resistance training. Sixteen weeks of resistance training improved functional fitness and prevented age-related increases in intramuscular fat in the thigh area. However, there were only some changes in muscle growth factors, such as follistatin, suggesting that the effectiveness of resistance training on muscle growth factors is limited. Body weight-based and elastic band resistance training is an alternative training method for sarcopenia to minimize the age-related adverse effects on muscle function and quality.

Potential Utility of Electrical Impedance Myography in Evaluating Age-Related Skeletal Muscle Function Deficits

Skeletal muscle function deficits associated with advancing age are due to several physiological and morphological changes including loss of muscle size and quality (conceptualized as a reduction in the intrinsic force-generating capacity of a muscle when adjusted for muscle size). Several factors can contribute to loss of muscle quality, including denervation, excitation-contraction uncoupling, increased fibrosis, and myosteatosis (excessive levels of inter- and intramuscular adipose tissue and intramyocellular lipids). These factors also adversely affect metabolic function. There is a major unmet need for tools to rapidly and easily assess muscle mass and quality in clinical settings with minimal patient and provider burden. Herein, we discuss the potential for electrical impedance myography (EIM) as a tool to evaluate muscle mass and quality in older adults. EIM applies weak, non-detectible (e.g., 400 μA), mutifrequency (e.g., 1 kHz–1 MHz) electrical currents to a muscle (or muscle group) through two excitation electrodes, and resulting voltages are measured via two sense electrodes. Measurements are fast (~5 s/muscle), simple to perform, and unaffected by factors such as hydration that may affect other simple measures of muscle status. After nearly 2 decades of study, EIM has been shown to reflect muscle health status, including the presence of atrophy, fibrosis, and fatty infiltration, in a variety of conditions (e.g., developmental growth and maturation, conditioning/deconditioning, and obesity) and neuromuscular diseases states [e.g., amyotrophic lateral sclerosis (ALS) and muscular dystrophies]. In this article, we describe prior work and current evidence of EIM’s potential utility as a measure of muscle health in aging and geriatric medicine.

Muscle Composition Analysis of Ultrasound Images: A Narrative Review of Texture Analysis

Skeletal muscle composition, often characterized by the degree of intramuscular adipose tissue, deteriorates with aging and disease and contributes to impairments in function and metabolism. Ultrasound can provide surrogate measures of muscle composition through measurement of echo intensity; however, there are several limitations associated with its analysis. More complex image processing features, broadly known as texture analysis, can also provide surrogates of muscle composition and may circumvent some of the limitations associated with muscle echo intensity. Here, texture features from the intensity histogram, gray-level co-occurrence matrix, run-length matrix, local binary pattern, blob analysis, texture anisotropy index and wavelet analysis are discussed. The purpose of this review was to provide a conceptual understanding of texture analysis as it pertains to muscle composition of ultrasound images.

Weight stability masks changes in body composition in colorectal cancer: a retrospective cohort study

BACKGROUND

There is an emerging viewpoint that change in body weight is not sufficiently sensitive to promptly identify clinically meaningful change in body composition, such as skeletal muscle depletion.

OBJECTIVES

We aimed to determine whether body weight stability is associated with skeletal muscle depletion and whether skeletal muscle depletion is prognostic of death independently of change in body weight.

METHODS

This retrospective cohort included 1921 patients with stage I-III colorectal cancer. Computed tomography (CT)-based skeletal muscle characteristics and body weight were measured at diagnosis and after a mean 15.0-mo follow-up. Body weight stability was defined as weight change less than ±5% during follow-up. Sarcopenia and myosteatosis were defined using established thresholds for patients with cancer. Multivariable-adjusted logistic and flexible parametric proportional hazards survival models were used to quantify statistical associations.

RESULTS

At follow-up, 1026 (53.3%) patients were weight stable. Among patients with weight stability, incident sarcopenia and myosteatosis occurred in 8.5% (95% CI: 6.3%, 10.6%) and 13.5% (95% CI: 11.1%, 15.9%), respectively. Men were more likely to be weight stable than were women (56.7% compared with 49.9%; P = 0.04). Weight-stable men were less likely to develop incident sarcopenia (5.4% compared with 15.4%; P = 0.003) and myosteatosis (9.3% compared with 20.8%; P = 0.001) than weight-stable women. Among all patients, the development of incident sarcopenia (HR: 1.40; 95% CI: 1.02, 1.91) and of myosteatosis (HR: 1.41; 95% CI: 1.05, 1.90) were associated with a higher risk of death, independently of change in body weight. Patient sex did not modify the relation between skeletal muscle depletion and death.

CONCLUSIONS

Body weight stability masks clinically meaningful skeletal muscle depletion. Body composition quantified using clinically acquired CT images may provide a vital sign to identify patients at increased risk of death. These data may inform the design of future cachexia trials.

Using Virtual Reality-Based Rehabilitation in Sarcopenic Older Adults in Rural Health Care Facilities-A Quasi-Experimental Study

Because of a shortage of health care providers, providing rehabilitation in health care facilities is difficult. Virtual reality-based rehabilitation is effective in older populations. There are only a few studies among patients with sarcopenia. This is a quasi-experimental, single-group, pretest-posttest design evaluating the clinical effectiveness of virtual reality-based progressive resistance training among residents aged over 60 years with sarcopenia in rural care facilities. The authors used Oculus Rift with headsets to provide the virtual reality-based progressive resistance training. The authors administered the program twice per week, 30 min per session, for 12 weeks. The primary outcomes were dominant handgrip strength, walking speed, and appendicular skeletal muscle mass index. Data from 30 participants were analyzed. Significant improvements in handgrip strength and walking speed were observed. Although an increasing trend in appendicular skeletal muscle mass index was observed, it did not reach statistical significance. The authors concluded that the virtual reality-based progressive resistance training is partially effective in older sarcopenic adults in health care facilities.

The eccentric mechanotransduction, neuro-muscular transmission, and structural reversibility of muscle fatty infiltration. An experimental advanced disuse muscle-wasting model of rabbit supraspinatus

INTRODUCTION

Full-thickness rotator cuff tear is present in almost 50% of patients over age 65 years, and its degree is known to be a good predictor of the severity of muscle-wasting (MW) sarcopaenia, also known as fatty degeneration (FD). A FD CT grade > 2° is recognized as a borderline of its reversibility. A disuse model of supraspinatus FD (grade 2) in rabbits provides clinically relevant data. Therefore, the present study evaluates the correlation between eccentric mechanotransduction, neuromuscular transmission (NT), and reversibility of muscle fatty infiltration (MFI) in rabbit supraspinatus FD > 2°.

MATERIAL AND METHODS

The supraspinatus tendon was detached from the greater tubercle, infraspinatus, and subscapularis in 16 rabbits. The tendon was reinserted after 12 weeks, and the animals were euthanized 24 weeks after reconstruction. MFI was measured in the middle part of the supraspinatus. Single-fibre EMG (SFEMG) examination of the supraspinatus NT was performed on 4 animals.

RESULTS

The power of analysis was 99%. Significant differences in MFI volume were found between the operated (4.6 ±1.1%) and the opposite control sides (2.91 ±0.61%) (p < 0.001). SFEMG revealed no significant differences between the disuse and the control supraspinatus muscles (p > 0.05); however, 6.5% of the examined muscle fibres exhibited NT disorders combined with blockade of conduction in 2.5% of muscle fibres.

CONCLUSIONS

Critical MFI in a disuse model of rabbit supraspinatus FD, CT grade > 2°, is substantially reversible by eccentric training despite subclinical impairment of neuromuscular transmission. In addition, 0.63% reversal of MFI is correlated with 1% hypertrophy of type I and II muscle fibre diameter.

Measuring Muscle Mass and Strength in Obesity: a Review of Various Methods

Lower muscle mass in populations with obesity is associated obesity-related diseases like hypertension and type 2 diabetes mellitus. Bariatric surgery leads to sustained weight loss. During the weight reduction, loss of muscle should be minimized. Thus reliable quantification of muscle mass is much needed and therefore the also the need for validated methods. Imaging methods, magnetic resonance imaging and computed tomography scan, have been the gold standard for many years. However, these methods are costly and have limitations such as the maximum weight. Dual-energy X-ray absorptiometry is currently the most used alternative. Other, less expensive methods are very limited in their validation in populations with morbid obesity. This narrative review summarizes the current knowledge regarding measuring muscle mass and strength in obesity.

Predictive Value of Temporal Muscle Thickness Measurements on Cranial Magnetic Resonance Images in the Prognosis of Patients With Primary Glioblastoma

Objective: To investigate the predictive value of prognosis of primary GBM patients using TMT on three-dimensional (3D) MR images of the brain. Methods: Data of 130 patients with primary GBM from the TCGA-GBM database were analyzed retrospectively. TMT was measured on the axial plane by multi-planar reformation (MPR) of T1WI MR images perpendicular to the long axis of the temporal muscle at the level of the orbital roof. The axial MR plane was oriented parallel to the anterior commissure-posterior commissure line. Student's t-test or Mann-Whitney U-test was utilized to determine whether there were significant differences in the TMT and OS between male and female patients. The Pearson correlation analysis was adopted to evaluate the correlation between the age at GBM diagnosis and TMT. All patients were divided into two groups based on their median TMT, and the Kaplan-Meier curve was used to calculate the OS curve. The association between TMT and OS of GBM patients, as well as the multivariate analysis of TMT and other clinical factors affecting the survival time, was evaluated with Cox regression model. Results: TMT was a risk factor for the prognosis of GBM with its hazard ratio (HR) of 0.802 (95% CI 0.698-0.922; P = 0.002; Cox regression model). Grouped by median TMT, the group with above-median TMT demonstrated a significant increase in survival time (15.6 months) compared with the one with below-median TMT (11.2 months) (P < 0.001; log-rank test). In the multivariate survival analysis using a Cox regression model, TMT (HR 0.863; 95% CI 0.748-0.996; P = 0.044), age at the diagnosis of GBM (HR 1.042; 95% CI 1.024-1.060; P < 0.001), and concurrent chemoradiotherapy (HR 0.510; 95% CI 0.336-0.775; P = 0.002) were significantly associated with survival time. Conclusion: TMT as an independent predictor is sensitive to the survival prognosis of primary GBM patients, which has potential to predict the survival time.

Impact of Obesity and Visceral Fat on Mortality in Hematopoietic Stem Cell Transplantation

RATIONALE

Many studies have shown the importance of body composition parameters, muscle, and fat mass, evaluated by several methods in hematopoietic stem cell transplantation (HSCT) outcomes. Ultrasound (US) is an efficient and low-cost method to evaluate body composition, even though there have not been many studies in HSCT.

OBJECTIVES

Our goal was to investigate the muscle, visceral fat (VF), and echogenicity before HSCT and after engraftment, evaluated by US and its association with outcomes.

METHODS

All adult patients with hematological malignances admitted for HSCT autologous and allogeneic were eligible to enter this prospective study. Their thigh muscle thickness, VF, and echogenicity were evaluated by US on the first day of hospitalization (baseline) and after engraftment (15-25 days post-HSCT).

RESULTS

We evaluated 50 patients; 42% were male and 58% had undergone allogeneic HSCT. Most patients were <55 years old (68%) and had normal body mass index (50%). We found a significant reduction of right and left muscle thickness (P < .001) and echogenicity (P = .002) after engraftment compared with baseline. Our elderly patients had significantly bigger right-thigh muscle thickness (P = .02) and more VF (P = .009). The following data were higher in obese patients: right and left muscle thickness (P < .001), VF (P = .003), and echogenicity (P = .04). Death in the first 100 days had a positive association with obesity (P = 0.001) and VF (P = .002). VF was the only variable independent of HSCT type and age in mortality risk.

CONCLUSION

Obesity and VF had an important impact in mortality. US could be a useful tool and strategy for evaluating body composition in HSCT patients.

Racialized algorithms for kidney function: Erasing social experience

The rise of evidence-based medicine, medical informatics, and genomics --- together with growing enthusiasm for machine learning and other types of algorithms to standardize medical decision-making --- has lent increasing credibility to biomedical knowledge as a guide to the practice of medicine. At the same time, concern over the lack of attention to the underlying assumptions and unintended health consequences of such practices, particularly the widespread use of race-based algorithms, from the simple to the complex, has caught the attention of both physicians and social scientists. Epistemological debates over the meaning of "the social" and "the scientific" are consequential in discussions of race and racism in medicine. In this paper, we examine the socio-scientific processes by which one algorithm that "corrects" for kidney function in African Americans became central to knowledge production about chronic kidney disease (CKD). Correction factors are now used extensively and routinely in clinical laboratories and medical practices throughout the US. Drawing on close textual analysis of the biomedical literature, we use the theoretical frameworks of science and technology studies to critically analyze the initial development of the race-based algorithm, its uptake, and its normalization. We argue that race correction of kidney function is a racialized biomedical practice that contributes to the consolidation of a long-established hierarchy of difference in medicine. Consequentially, correcting for race in the assessment of kidney function masks the complexity of the lived experience of societal neglect that damages health.

High-dose leucine supplementation does not prevent muscle atrophy or strength loss over 7 days of immobilization in healthy young males

BACKGROUND

Unavoidable periods of disuse lead to muscle atrophy and functional decline. Preventing such declines can reduce the risk of re-injury and improve recovery of normal physiological functioning.

OBJECTIVES

We aimed to determine the effectiveness of high-dose leucine supplementation on muscle morphology and strength during 7 d of unilateral lower-limb immobilization, and the role of myofibrillar (MyoPS) and mitochondrial (MitoPS) protein synthesis in disuse atrophy.

METHODS

Sixteen healthy males (mean ± SEM age: 23 ± 1 y) underwent 7 d of unilateral lower-limb immobilization, with thrice-daily leucine (LEU; n = 8) or placebo (PLA; n = 8) supplementation (15 g/d). Before and after immobilization, muscle strength and compartmental tissue composition were assessed. A primed continuous infusion of l-[ring-13C6]-phenylalanine with serial muscle biopsies was used to determine postabsorptive and postprandial (20 g milk protein) MyoPS and MitoPS, fiber morphology, markers of protein turnover, and mitochondrial function between the control leg (CTL) and the immobilized leg (IMB).

RESULTS

Leg fat-free mass was reduced in IMB (mean ± SEM: -3.6% ± 0.5%; P = 0.030) but not CTL with no difference between supplementation groups. Isometric knee extensor strength declined to a greater extent in IMB (-27.9% ± 4.4%) than in CTL (-14.3% ± 4.4%; P = 0.043) with no difference between groups. In response to 20 g milk protein, postprandial MyoPS rates were significantly lower in IMB than in CTL (-22% ± 4%; P < 0.01) in both LEU and PLA. Postabsorptive MyoPS rates did not differ between legs or groups. Postabsorptive MitoPS rates were significantly lower in IMB than in CTL (-14% ± 5%; P < 0.01) and postprandial MitoPS rates significantly declined in response to 20 g milk protein ingestion (CTL: -10% ± 8%; IMB: -15% ± 10%; P = 0.039), with no differences between legs or groups. There were no significant differences in measures of mitochondrial respiration between legs, but peroxisome proliferator-activated receptor γ coactivator 1-α and oxidative phosphorylation complex II and III were significantly lower in IMB than in CTL (P < 0.05), with no differences between groups.

CONCLUSIONS

High-dose leucine supplementation (15 g/d) does not appear to attenuate any functional declines associated with 7 d of limb immobilization in young, healthy males.This trial was registered at clinicaltrials.gov as NCT03762278.

Formula for the Cross-Sectional Area of the Muscles of the Third Lumbar Vertebra Level from the Twelfth Thoracic Vertebra Level Slice on Computed Tomography

The purpose of this study was to investigate a means by which to reflect muscle mass using chest computed tomography (CT). A cross-sectional study was conducted with patients aged ≥ 65 years having abdominal and chest CT scans. The formula to predict third lumbar vertebra (L3) cross-sectional area (CSA) of the muscles from the erector muscles of the spine at the twelfth thoracic vertebra (Th12) level slice on CT was created using the five-fold cross-validation method. Correlation between predicted L3 CSA and measured L3 CSA of the muscles was assessed by intraclass correlation coefficients (ICC) and correlation coefficients (r) in the data of the development, and predictability was examined with accuracy and F-values in the validation study. The development study included 161 patients. The developed formula was as follows: −1006.38 + 16.29 × age + 1161.80 × sex (if female, 0; if male, 1) + 55.91 × body weight + 2.22 × CSA of the erector muscles at Th12. The formula demonstrated strong concordance and correlation (ICC = 0.849 [0.800–0.887] and r = 0.858 [0.811–0.894]). The validation study included 34 patients. The accuracy and F-value between predicted CSA and measured CSA were high (accuracy = 0.889–0.944, F-value = 0.931–0.968). We developed a formula predicting CSA at L3 using Th12 CT slice. This formula could be used to assess decreased muscle mass even with chest CT alone.

Diagnostic and clinical values of non-cardiac ultrasound in COPD: A systematic review

BACKGROUND

Clinical and research utility of non-cardiac ultrasound (US) in chronic obstructive pulmonary disease (COPD) has been widely investigated. However, there is no systematic review assessing the clinical values of non-cardiac US techniques in COPD.

METHODS

We systematically searched electronic databases from inception to 24 June 2020. Two independent reviewers in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines extracted data. A narrative synthesis of the results was conducted considering non-cardiac US techniques that looked for diaphragm, muscles and bones in patients with COPD.

RESULTS

In total, 2573 abstracts were screened, and 94 full-text papers were reviewed. A total of 54 studies met the inclusion criteria. Thirty-five studies assessed the diaphragm, while 19 studies evaluated different muscles, including limb muscles and pulmonary lesions in COPD using US. Of the 54 included studies, 30% (16/54) evaluated the changes in either limb muscles or diaphragmatic features before and after physical interventions; 67% (36/54) assessed the correlations between sonographic features and COPD severity. Indeed, 14/15 and 9/13 studies reported a significant reduction in diaphragm excursion and thickness in COPD compared with healthy subjects, respectively; this was correlated significantly with the severity and prognosis of COPD. Three studies reported links between diaphragm length and COPD, where lower diaphragm length correlated with poorer prognosis and outcomes. Quadriceps (rectus femoris), ankle dorsiflexor (tibialis anterior) and vastus lateralis were the most common muscles in COPD assessed by US. More than 70% (12/17) of the studies reported a significant reduction in the cross-sectional area (CSA) of the rectus femoris, rectus femoris and vastus lateralis thickness in COPD compared with healthy subjects. Quadriceps CSA and thickness correlated positively with COPD prognosis, in which patients with reduced quadriceps CSA and thickness have higher risk of exacerbation, readmission and death.

CONCLUSION

US measurements of diaphragm excursion and thickness, as well as lower limb muscles strength, size and thickness, may provide a safe, portable and effective alternative to radiation-based techniques in diagnosis and prognosis as well as tracking improvement postintervention in patients with COPD.

Panoramic ultrasound vs. MRI for the assessment of hamstrings cross-sectional area and volume in a large athletic cohort

We investigated the validity of panoramic ultrasound (US) compared to magnetic resonance imaging (MRI) for the assessment of hamstrings cross-sectional area (CSA) and volume. Hamstrings CSA were acquired with US (by an expert operator) at four different sites of femur length (FL) in 85 youth competitive alpine skiers (14.8 ± 0.5 years), and successively compared to corresponding scans obtained by MRI, analyzed by a trained vs. a novice rater. The agreement between techniques was assessed by Bland–Altman analyses. Statistical analysis was carried out using Pearson’s product moment correlation coefficient (r). US-derived CSA showed a very good agreement compared to MRI-based ones. The best sites were 40% FL (0 = mid patellar point) for biceps femoris long head (r = 0.9), 50% for semitendinosus (r = 0.9), and 30% for semimembranosus (r = 0.86) and biceps femoris short head (BFsh, r = 0.8). US-based vs. MRI-based hamstrings volume showed an r of 0.96. Poorer r values were observed for the novice compared to the trained rater, with the biggest difference observed for BFsh at 50% (r = 0.001 vs. r = 0.50, respectively) and semimembranosus at 60% (r = 0.23 vs. r = 0.42, respectively). Panoramic US provides valid CSA values and volume estimations compared to MRI. To ensure optimal US-vs.-MRI agreement, raters should preferably possess previous experience in imaging-based analyses.

Impaired ECM Remodeling and Macrophage Activity Define Necrosis and Regeneration Following Damage in Aged Skeletal Muscle

Regenerative capacity of skeletal muscle declines with age, the cause of which remains largely unknown. We investigated extracellular matrix (ECM) proteins and their regulators during early regeneration timepoints to define a link between aberrant ECM remodeling, and impaired aged muscle regeneration. The regeneration process was compared in young (three month old) and aged (18 month old) C56BL/6J mice at 3, 5, and 7 days following cardiotoxin-induced damage to the tibialis anterior muscle. Immunohistochemical analyses were performed to assess regenerative capacity, ECM remodeling, and the macrophage response in relation to plasminogen activator inhibitor-1 (PAI-1), matrix metalloproteinase-9 (MMP-9), and ECM protein expression. The regeneration process was impaired in aged muscle. Greater intracellular and extramyocellular PAI-1 expression was found in aged muscle. Collagen I was found to accumulate in necrotic regions, while macrophage infiltration was delayed in regenerating regions of aged muscle. Young muscle expressed higher levels of MMP-9 early in the regeneration process that primarily colocalized with macrophages, but this expression was reduced in aged muscle. Our results indicate that ECM remodeling is impaired at early time points following muscle damage, likely a result of elevated expression of the major inhibitor of ECM breakdown, PAI-1, and consequent suppression of the macrophage, MMP-9, and myogenic responses.

Accuracy of surrogate methods to estimate skeletal muscle mass in non-dialysis dependent patients with chronic kidney disease and in kidney transplant recipients

BACKGROUND & AIMS

Bioelectrical impedance analysis (BIA) and anthropometric predictive equations have been proposed to estimate whole-body (SMM) and appendicular skeletal muscle mass (ASM) as surrogate for dual energy X-ray absorptiometry (DXA) in distinct population groups. However, their accuracy in estimating body composition in non-dialysis dependent patients with chronic kidney disease (NDD-CKD) and kidney transplant recipients (KTR) is unknown. The aim of this study was to investigate the accuracy and reproducibility of BIA and anthropometric predictive equations in estimating SMM and ASM compared to DXA, in NDD-CKD patients and KTR.

METHODS

A cross-sectional study including adult NDD-CKD patients and KTR, with body mass index (BMI) ≥18.5 kg/m². ASM and estimated SMM were evaluated by DXA, BIA (Janssen, Kyle and MacDonald equations) and anthropometry (Lee and Baumgartner equations). Low muscle mass (LowMM) was defined according to cutoffs proposed by guidelines for ASM, ASM/height² and ASM/BMI. The best performing equation as surrogate for DXA, considering both groups of studied patients, was defined based in the highest Lin's concordance correlation coefficient (CCC) value, the lowest Bland-Altman bias (<1.5 kg) combined with the narrowest upper and lower limits of agreement (LoA), and the highest Cohen's kappa values for the low muscle mass diagnosis.

RESULTS

Studied groups comprised NDD-CKD patients (n = 321: males = 55.1%; 65.4 ± 13.1 years; eGFR = 28.8 ± 12.7 ml/min) and KTR (n = 200: males = 57.7%; 47.5 ± 11.3 years; eGFR = 54.7 ± 20.7 ml/min). In both groups, the predictive equations presenting the best accuracy compared to DXA were SMM-BIA-Janssen (NDD-CKD patients: CCC = 0.88, 95%CI = 0.83-0.92; bias = 0.0 kg; KTR: CCC = 0.89, 95%CI = 0.86-0.92, bias = -1.2 kg) and ASM-BIA-Kyle (NDD-CKD patients: CCC = 0.87, 95%CI = 0.82-0.90, bias = 0.7 kg; KTR: CCC = 0.89, 95%CI = 0.86-0.92, bias = -0.8 kg). In NDD-CKD patients and KTR, LowMM frequency was similar according to ASM-BIA-Kyle versus ASM-DXA. The reproducibility and inter-agreement to diagnose LowMM using ASM/height² and ASM/BMI estimated by BIA-Kyle equation versus DXA was moderate (kappa: 0.41-0.60), in both groups. Whereas female patients showed higher inter-agreement (AUC>80%) when ASM/BMI index was used, male patients presented higher AUC (70-74%; slightly <80%) for ASM/height² index.

CONCLUSIONS

The predictive equations with best performance to assess muscle mass in both NDD-CKD patients and KTR was SMM-BIA by Janssen and ASM-BIA by Kyle. The reproducibility to diagnose low muscle mass, comparing BIA with DXA, was high using ASM/BMI in females and ASM/height² in males in both groups.

Skeletal Muscle Aging Atrophy: Assessment and Exercise-Based Treatment

In the ordinary course of aging, individuals change their body composition, mainly reducing their skeletal muscle mass and increasing their fat mass. In association, muscle strength and functionality also decrease. The geriatric assessment allows knowing the baseline situation of the patients, determines the impact of diseases, and defines specific treatments. There are various tools to evaluate the health condition of older people. These tools include the assessment scales of necessary Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL), physical and functional assessment scales, and instruments that assess the cognitive state of the person. There are several strategies that have been proposed to combat skeletal muscle atrophy due to aging, such as physical exercise, nutritional supplements, or drugs. Some researchers have highlighted the efficacy of the combination of the mentioned strategies. In this chapter, we will focus only on physical exercise as a strategy to reduce skeletal muscle loss during aging.

Muscle Strength Is Independently Related to Brain Atrophy in Patients with Alzheimer's Disease

BACKGROUND/AIMS

Alzheimer's disease (AD) is the most common cause of dementia worldwide. Interestingly, muscle mass (MM) and muscle strength (MS) are related to AD. In addition to the muscle profile, brain atrophy is also a prominent feature of AD. There is substantial evidence showing an association between muscle profile and dementia, but the role of the muscle profile and cerebral cortical atrophy within this association is less well understood. The objective of this study was to determine if there is any association between muscle profile and brain regional volume in AD. A secondary objective was to determine whether this relationship continues as the clinical stage of AD progresses.

METHODS

We recruited 28 patients with probable AD without weakness. We assessed the patients' basic demographic characteristics, Mini-Mental State Examination score, and brain magnetic resonance images. MM was measured using body dual-energy X-ray absorptiometry. MS was assessed in Nm/kg with an isokinetic knee extensor using an isokinetic device at an angular velocity of 60°/s. An automatic analysis program was used for brain regional volumetric measurements. Dementia was divided into two stages: mild and moderate.

RESULTS

MS was related to left hippocampal volume ratio. After adjusting for age and cognitive status, the relationship remained. MS did not demonstrate any relationship to any brain regional volume ratio in the mild stage; however, in the moderate stage, it was positively related to both the right and the left hippocampal volume ratio.

CONCLUSIONS

Our findings imply a shared underlying pathology relating MS and brain volume and suggest cognitive functional declines through the muscle-brain axis. Further longitudinal studies are needed to find possible and related causes of reduced MS and cortical atrophy in patients with dementia.