Skeletal Muscle Mass Measurement Research Articles

Sarcopenia is independently associated with mortality and recovery from dialysis in critically ill patients with sepsis-induced acute kidney injury receiving continuous renal replacement therapy.

Sarcopenia upon admission to the intensive care unit (ICU) consistently correlates with adverse outcomes, including heightened mortality, in critically ill patients. This study aims to investigate the independent association of sarcopenia with both mortality and recovery from dialysis in critically ill patients with sepsis-induced acute kidney injury (SIAKI) undergoing continuous renal replacement therapy (CRRT). This retrospective study included 618 patients with SIAKI who underwent CRRT in our ICU. All patients had abdominal computed tomography (CT) scans within 3 days preceding ICU admission. The cross-sectional area of skeletal muscles at the third lumbar vertebra was quantified, and the skeletal muscle index (SMI), a normalized measure of skeletal muscle mass, was computed. Using Korean-specific SMI cutoffs, patients were categorized into sarcopenic and non-sarcopenic groups. Among the 618 patients, 301 expired within 28 days of ICU admission. Multivariable Cox regression analysis revealed that sarcopenia independently predicted 28-day mortality. Among survivors, sarcopenia was independently associated with recovery from dialysis within 28 days after ICU admission. Kaplan-Meier analysis illustrated that sarcopenic patients had a higher mortality rate and a lower rate of recovery from dialysis within 28 days after ICU admission compared to non-sarcopenic patients. This study underscores the independent association of sarcopenia, assessed via CT-derived SMI, with both mortality and recovery from dialysis in critically ill patients with SIAKI undergoing CRRT. The inclusion of sarcopenia assessment could serve as a valuable tool for physicians in effectively stratifying the risk of adverse outcomes in these patients.

Sarcopenia as a Predictor of Feeding Tube Placement in Individuals with Oropharyngeal Cancer

In oropharyngeal squamous cell carcinoma (OPSCC), systemic loss of skeletal muscle mass (SMM), or sarcopenia, is a strong prognostic predictor of survival outcomes. However, the relationship between sarcopenia and nutrition-related outcomes is not well understood. This investigation evaluated the prognostic significance of sarcopenia for feeding tube (FT) placement in a cohort of OPSCC patients. A retrospective cohort study was conducted with data collected from 194 OPSCC patients treated with definitive radiation therapy (RT) or chemoradiation therapy (CRT). Sarcopenia was assessed from computed tomography imaging at the level of the third cervical (C3) and fourth thoracic (T4) vertebrae. The prognostic nature of pretreatment sarcopenia and its relationship with FT placement was explored using logistic regression. The median age of patients included was 61.0 years, and the majority were male (83%). In this patient cohort, 87.6% underwent concurrent CRT, and 30.9% received a FT over the course of treatment. Sarcopenia was identified at baseline in 72.7% of patients based on C3 SMM measurements and in 41.7% based on measures at the level of T4. Based on measures at both C3 and T4, those with sarcopenia were significantly more likely to receive a FT and had significantly worse freedom from FT placement compared with patients without sarcopenia. Sarcopenia assessed at T4 was a significant predictor of FT placement. SMM measured at T4 may represent a novel and practical biomarker for sarcopenia detection that is associated with the need for FT placement. These findings suggest that the detection of baseline sarcopenia could guide decision-making related to the need for nutritional support in OPSCC patients undergoing RT/CRT.

Association of sarcopenia defined by different skeletal muscle mass measurements with prognosis and quality of life in older patients with heart failure

BackgroundDiagnosing sarcopenia in heart failure (HF) patients is important, but how to assess skeletal muscle mass in HF patients with fluid retention is controversial. We aimed to examine the association between sarcopenia, defined by different skeletal muscle mass measurements, and clinical outcomes in older HF patients. MethodsWe included 546 older HF patients (≥ 65 years) who were assessed for sarcopenia at discharge (median age 77 years, 309 males). Sarcopenia was diagnosed using grip strength, usual gait speed, and skeletal muscle mass according to international criteria. We used mid-upper arm circumference (MUAC), mid-upper arm muscle circumference (MAMC), calf circumference (CC), and skeletal muscle mass index (SMI) assessed by bioelectrical impedance analysis to assess skeletal muscle mass and defined sarcopenia in each of these measurements. Prognostic outcomes were composite events (all-cause death and HF rehospitalization) and cardiovascular disease (CVD) events (CVD death and CVD rehospitalization). Quality of life (QOL) was assessed using the 36-item Short-Form Health Survey physical functioning (SF-36PF) score. ResultsThe sarcopenia defined by MUAC [hazard ratio (HR): 2.50; 95 % confidence interval (95 % CI): 1.64–3.81; p < 0.001] or MAMC (HR: 1.98; 95 % CI: 1.35–2.92; p = 0.001) were associated with higher composite event rates than the non-sarcopenia. The sarcopenia defined by MUAC (HR: 1.88; 95 % CI: 1.25–2.83; p = 0.002) or MAMC (HR: 1.70; 95 % CI: 1.16–2.49; p = 0.007) were associated with higher CVD event rates than the non-sarcopenia. The sarcopenia defined by CC or SMI were not associated with prognoses. The sarcopenia defined by MUAC, MAMC, or CC were associated with low SF-36PF scores (all p < 0.05). ConclusionsThese results suggest that a diagnosis of sarcopenia based on MUAC or MAMC rather than CC or SMI reflects prognosis and QOL in older HF patients.

The role of estrogen in female skeletal muscle aging: A systematic review.

Aging is associated with a loss of skeletal muscle mass and function that negatively impacts the independence and quality of life of older individuals. Females demonstrate a distinct pattern of muscle aging compared to males, potentially due to menopause, when the production of endogenous sex hormones declines. This systematic review aims to investigate the current knowledge about the role of estrogen in female skeletal muscle aging. A systematic search of MEDLINE Complete, Global Health, Embase, PubMed, SPORTDiscus, and CINHAL was conducted. Studies were considered eligible if they compared a state of estrogen deficiency (e.g. postmenopausal females) or supplementation (e.g. estrogen therapy) to normal estrogen conditions (e.g. premenopausal females or no supplementation). Outcome variables of interest included measures of skeletal muscle mass, function, damage/repair, and energy metabolism. Quality assessment was completed with the relevant Johanna Briggs critical appraisal tool, and data were synthesized in a narrative manner. Thirty-two studies were included in the review. Compared to premenopausal women, postmenopausal women had reduced muscle mass and strength, but the effect of menopause on markers of muscle damage and expression of the genes involved in metabolic signaling pathways remains unclear. Some studies suggest a beneficial effect of estrogen therapy on muscle size and strength, but evidence is largely conflicting and inconclusive, potentially due to large variations in the reporting and status of exposure and outcomes. The findings from this review point toward a potential negative effect of estrogen deficiency on aging skeletal muscle, but further mechanistic evidence is needed to clarify its role.

Is assessment of skeletal muscle mass useful to predict time-to-awake in awake craniotomies?

Awake craniotomy is the gold standard for the resection of brain lesions near eloquent areas. For the commonly used asleep-awake-asleep technique, the patient must be awake and fully cooperative as soon as possible after discontinuation of anesthetics. A shorter emergence time is essential to decrease the likelihood of adverse events. Previous research found no relationship between body mass index (BMI) and time-to-awake for intravenous anesthesia with propofol, which is a lipophilic agent. As BMI cannot differentiate between fat and muscle tissue, we hypothesize that skeletal muscle mass, particularly when combined with BMI, may better predict time-to-awake from propofol sedation. We aimed to evaluate the relationship between skeletal muscle mass and the time-to-awake in patients undergoing awake craniotomy, as well as the interaction between skeletal muscle mass and BMI. In 260 patients undergoing an awake craniotomy, we used preoperative magnetic resonance imaging to assess temporalis muscle and cross-sectional skeletal muscle area of the masseter muscles and at level of the third cervical vertebra. Time-to-awake was dichotomized as ≤20 and >20 minutes. No association between various measures of skeletal muscle mass and time-to-awake was observed, and no interaction between skeletal muscle mass and BMI was found (all P > .05). Likewise, patients with a high BMI and low skeletal muscle mass (indicating an increased proportion of fat tissue) did not have a prolonged time-to-awake. Skeletal muscle mass did not predict time-to-awake in patients undergoing awake craniotomy, neither in isolation nor in combination with a high BMI.

Nutrient Metabolites Associated With Low D3Cr Muscle Mass, Strength, and Physical Performance in Older Men.

The relationship between amino acids, B vitamins, and their metabolites with D3-creatine (D3Cr) dilution muscle mass, a more direct measure of skeletal muscle mass, has not been investigated. We aimed to assess associations of plasma metabolites with D3Cr muscle mass, as well as muscle strength and physical performance in older men from the Osteoporotic Fractures in Men cohort study. Out of 1 425 men (84.2 ± 4.1 years), men with the lowest D3Cr muscle mass (n = 100), slowest walking speed (n = 100), lowest grip strength (n = 100), and a random sample (n = 200) serving as a comparison group to the low groups were included. Metabolites were analyzed using liquid chromatography-tandem mass spectrometry. Metabolite differences between the low groups and random sample and their relationships with the muscle outcomes adjusted for confounders and multiple comparisons were assessed using t-test/Mann-Whitney-Wilcoxon and partial correlations, respectively. For D3Cr muscle mass, significant biomarkers (p < .001) with ≥10% fold difference and largest partial correlations were tryptophan (Trp; r = 0.31), kynurenine (Kyn)/Trp; r = -0.27), nicotinamide (Nam)/quinolinic acid (Quin; r = 0.21), and alpha-hydroxy-5-methyl-tetrahydrofolate (hm-THF; r = -0.25). For walking speed, hm-THF, Nam/Quin, and Quin had the largest significance and fold difference, whereas valine (r = 0.17), Trp (r = 0.17), HKyn/Xant (r = -0.20), neopterin (r = -0.17), 5-methyl-THF (r = -0.20), methylated folate (r = -0.21), and thiamine (r = -0.18) had the strongest correlations. Only hm-THF was correlated with grip strength (r = -0.21) and differed between the low group and the random sample. Future interventions focusing on how the Trp metabolic pathway or hm-THF influences D3Cr muscle mass and physical performance declines in older adults are warranted.

Alcohol Consumption and Measures of Sarcopenic Muscle Risk: Cross-Sectional and Prospective Associations Within the UK Biobank Study

Alcohol intake is a major modifiable risk factor for many diseases. Alcohol can also damage skeletal muscle health during ageing which in turn increases risk of sarcopenia, frailty and falls but this relationship is understudied. The aim of this study was to model the relationship between a full range of alcohol consumption and components of sarcopenic risk, skeletal muscle mass and function, in middle-aged and younger older-aged men and women. A cross-sectional analyses was undertaken of 196,561 white participants from the UK Biobank with longitudinal analysis also in 12,298 of these participants, with outcome measures for the latter repeated after around four years. For the cross-sectional analysis fractional polynomial curves were fitted in models of measures of skeletal muscle mass, appendicular lean mass/body mass index (ALM/BMI), fat-free mass as a percentage of body weight (FFM%) and grip strength, all predicted from alcohol consumption with models fitted for men and women separately. Alcohol consumption at baseline was based on the mean of up to five dietary recalls, typically over 16 months. Linear regression was used for longitudinal analyses to model the effects of alcohol consumption groups on these measures. All models were adjusted for covariates. In the cross-sectional analysis, modelled values of the muscle mass measures all showed a peak at medium levels of alcohol consumption and a steep decline with increasing alcohol consumption. Modelled differences in muscle mass from zero consumption of alcohol to 160 g/d ranged from 3.6 to 4.9% for ALM/BMI for men and women, respectively, and 3.6 to 6.1% for FFM%. Grip strength consistently increased with alcohol consumption. No association between alcohol consumption and muscle measures were seen in the longitudinal results. Our results suggest that higher levels of alcohol consumption could have detrimental effects on muscle mass in middle- and older-aged men and women.

Isolation and antioxidant characterization of theaflavin for neuroprotective effect in mice model.

The mandate of the current investigation was to elucidate the therapeutic and antioxidant perspective of black tea. Purposely, black tea compositional analysis followed by polyphenol extraction and antioxidant characterization was done. Moreover, the theaflavin from black tea extract was also isolated through the solvent partition method. Lastly, the neuroprotective effect of isolated theaflavin was assessed through a bio-efficacy trial. The outcomes delineated that black tea showed promising nutritional composition with special reference to protein and fiber. Among the extraction solvent, ethanol performed better as compared to methanol and water likewise, higher extraction was noticed at 60 min followed by 90 and 30 min. All the extracts indicated antioxidant activity reflected through significant DPPH, TPC, FRAP, and beta carotene as-69.13 ± 3.00, 1148.92 ± 14.01, 752.44 ± 10.30, and 65.74 ± 3.28, respectively. However, isolated theaflavin exhibited higher antioxidant capacity as-737.74 ± 12.55, 82.60 ± 2.33, and 853.77 ± 9.55, for TPC, DPPH, and FRAP, respectively, as compared to extracts. In 15 days' efficacy was physically induced with sciatic nerve injury h sciatic nerve injury physically and treated with isolated theaflavin. A total of 12 healthy albino mice were randomly assigned to either the control (n=6) or theaflavin (5.0 mg/kg (n=6)) groups. In these groups, behavioral tests were used to assess and compare enhanced functional recovery as well as skeletal muscle mass measurement. Serum samples included oxidative stress markers. In theaflavin leaves, behavioral tests revealed a statistically significant (p < .001) improvement in sensorimotor function restoration, muscle mass restoration, a substantial decrease in TOS, a significant increase in TAC, and enhanced antioxidative enzyme activity. Considering the above-mentioned therapeutic perspectives of theaflavin, the current research was planned to optimize the isolation of theaflavin from black tea and probed for their neuroprotective effect in mice models.

Abstract P3-05-29: Use of Bioimpedance Spectroscopy as a Surrogate for Bone Mineral Content in Oncology Patients: Practical Application of the SOZO Device

Abstract Background: Many cancer patients, particularly those with breast or prostate cancer, receive hormonal manipulation therapies that can significantly impact their bone mineral content (BMC), potentially leading to osteoporotic associated life-threatening fractures, particularly given the median age of patients diagnosed with these malignancies. Bioimpedance spectroscopy (BIS) is a non-invasive tool that measures fluid and body composition values including skeletal muscle mass (SMM) and fat free mass (FFM). BIS devices can be used easily and quickly at point-of-care at the time of vital signs, with the patient standing on the device placing their hands and feet on metal electrodes and a reading obtained in less than a minute. Multiple previous studies have shown strong correlation between SMM and BMC, suggesting that a BIS reading can provide a reproducible, simple and quick estimate of BMC. To that end, we present initial findings correlating BIS readings obtained with a SOZO device (ImpediMed) with dual x-ray absorptiometry (DXA) to determine if BIS readings can be applied as an accurate point of care surrogate measure of BMC. Materials and Methods: Concurrent BIS measures and DXA scans, were performed in 75 healthy volunteers and 93 cancer patients (during and after cancer treatment) Group 1: 75 healthy volunteers (32 male, 43 female), mean age 27.4 (18-66 years); Group 2: 44 patients undergoing cancer treatment (11 male, 33 female; 18 breast, 7 lung, 4 endometrial, 4 colorectal, 4 prostate, 7 other), mean age 61.3 (38-79 years); and Group 3: 49 patients participating in a 12-week exercise program after cancer treatment (15 males, 34 females; 22 breast, 6 prostate, 3 colorectal, 3 endometrial, 2 lung, 13 other), mean age 57.8 (19-79 years). The healthy volunteers in Group 1 were further randomized into two subsets. Group A was used to develop a BIS predicted BMC algorithm and Group B was used to validate the algorithm. Results: The Pearson correlation coefficients (R) for DXA BMC and SOZO SMM were strong for all 3 groups (R=0.92, 0.85, and 0.80 for Groups 1, 2, and 3, respectively). Stepwise multiple linear regression for BMC was performed for Group A based on BIS parameters. For Group A, SMM resulted in a multiple correlation coefficient of 0.94 (P&amp;lt; 0.0001). The correlation coefficient between the BIS predicted BMC and DXA BMC of Group B was 0.87 (P&amp;lt; 0.0001, 95%CI 0.78-0.93). For Groups 2 and 3 combined, the correlation coefficient between the BIS predicted BMC and DXA BMC was 0.82 (P&amp;lt; 0.0001, 95%CI 0.73-0.87). Conclusions: Concurrent measures of SMM obtained with BIS using SOZO correlated strongly with DXA BMC, demonstrating that SOZO SMM may be a useful surrogate in the clinic to provide a quick, easy, and reproducible indicator of change in BMC, particularly for those patients undergoing treatments that may affect BMC. Tracking SMM during or after cancer treatment with SOZO may provide an estimate of changes in BMC allowing clinicians to obtain additional diagnostic testing and/or consider treatment modifications. Citation Format: Frank Vicini, Chirag Shah. Use of Bioimpedance Spectroscopy as a Surrogate for Bone Mineral Content in Oncology Patients: Practical Application of the SOZO Device [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-05-29.

Association of Computed Tomography Measures of Muscle and Adipose Tissue and Progressive Changes throughout Treatment with Clinical Endpoints in Patients with Advanced Lung Cancer Treated with Immune Checkpoint Inhibitors

To investigate the association between skeletal muscle mass and adiposity measures with disease-free progression (DFS) and overall survival (OS) in patients with advanced lung cancer receiving immunotherapy, we retrospectively analysed 97 patients (age: 67.5 ± 10.2 years) with lung cancer who were treated with immunotherapy between March 2014 and June 2019. From computed tomography scans, we assessed the radiological measures of skeletal muscle mass, and intramuscular, subcutaneous and visceral adipose tissue at the third lumbar vertebra. Patients were divided into two groups based on specific or median values at baseline and changes throughout treatment. A total number of 96 patients (99.0%) had disease progression (median of 11.3 months) and died (median of 15.4 months) during follow-up. Increases of 10% in intramuscular adipose tissue were significantly associated with DFS (HR: 0.60, 95% CI: 0.38 to 0.95) and OS (HR: 0.60, 95% CI: 0.37 to 0.95), while increases of 10% in subcutaneous adipose tissue were associated with DFS (HR: 0.59, 95% CI: 0.36 to 0.95). These results indicate that, although muscle mass and visceral adipose tissue were not associated with DFS or OS, changes in intramuscular and subcutaneous adipose tissue can predict immunotherapy clinical outcomes in patients with advanced lung cancer.

Effect of total knee replacement on skeletal muscle mass measurements using dual energy X-ray absorptiometry

Sarcopenia is becoming prevalent in an increasing number of older adults undergoing total knee replacement (TKR) surgery. Metal implants may overestimate lean mass (LM) measured using dual-energy X-ray absorptiometry (DXA). This study aimed to examine the effects of TKR on LM measurements according to automatic metal detection (AMD) processing. The participants from Korean Frailty and Aging Cohort Study, who had underwent TKR were enrolled. A total of 24 older adults (mean age 76.4 ± 4.0 years, 92% female) were included in the analysis. The SMI with AMD processing was 6.1 ± 0.6 kg/m2, which was lower than that without AMD processing of 6.5 ± 0.6 kg/m2 (p < 0.001). The LM of the right leg with AMD processing was lower than that without AMD in 20 participants who had underwent TKR surgery on the right (5.5 ± 0.2 kg vs. 6.0 ± 0.2 kg, p < 0.001), and that of the left leg was also lower in with AMD processing than in without AMD processing in 18 participants who had underwent TKR surgery on the left (5.7 ± 0.2 kg vs. 5.2 ± 0.2 kg, p < 0.001). Only one participant was classified as having low muscle mass without AMD processing, but this came to four after AMD processing. LM assessment in individuals who had TKR could be significantly different according to the use of AMD.

Evaluation of Associations of Growth Differentiation Factor-11, Growth Differentiation Factor-8 and their Binding Proteins Follistatin and Follistatin-like protein-3 with Measures of Skeletal Muscle Mass, Muscle Strength and Physical Function in Older Adults.

Based on studies from animal models, growth differentiation factor-11 (GDF-11) may have rejuvenating effects in humans. GDF-11 has high sequence homology with GDF-8 (also known as myostatin); follistatin, and follistatin like 3 protein (FSTL3) are inhibitory proteins of both GDF-8 and GDF-11. Using highly specific LC-MS/MS assays for GDF-11 and GDF-8 and immunoassays for follistatin and FSTL3, we quantified the association of these factors with muscle size, strength and physical performance in two prospective cohort studies of community-dwelling older adults (Health ABC and CHS). GDF-8 levels were positively associated with thigh muscle cross sectional area and density in Health ABC (data not available in CHS). GDF-8 levels were positively associated with lean mass (a surrogate of muscle mass) in Health ABC but not CHS, and grip strength in CHS but not Health ABC. FSTL3 (and perhaps follistatin) were negatively associated with lean mass and had variable associations with other variables. In contrast, GDF-11 was not significantly associated with strength or performance. GDF-8 and its binding proteins, follistatin and FSTL3, may constitute a counter-regulatory system (chalones) to restrain age-related loss of muscle mass and strength.

The association between healthy beverage index and sarcopenic obesity among women with overweight and obesity: a cross-sectional study

IntroductionSarcopenic obesity is related to changes in body composition, loss of muscle mass, and raised adipose tissue. Beverage patterns are effective with changes in health status. Therefore, the aim of this study was to investigate the association between sarcopenic obesity (SO) and the healthy beverage index (HBI) in women with overweight and obesity.MethodsThis cross-sectional study conducted on 210 overweight and obese (BMI ≥25 kg/m2) women aged 18–56 years. The measurement of skeletal muscle mass (SMM) and fat mass (FM) done by bioelectric impedance analyzer (BIA) (Inbody Co., Seoul, Korea) based on guidelines. The two lowest quintiles SMM and the two highest quintiles FM and body mass index (BMI) ≥30 are considered sarcopenic obesity in women. A validated and reliable semi-quantitative food-frequency questionnaire (FFQ) was used to evaluate the beverage dietary data. and RFS and NRFS was calculated. Biochemical assessments were quantified by standard approaches, and physical activity were evaluated by international physical activity questionnaire (IPAQ).ResultIn this cross-sectional study, 210 overweight and obese females took part (18–56) years old). The studies were carried out using binary logistic regression. After controlling for a wide variety of confounding variables such as age, energy intake, physical activity, education, and economic status, we found a negative association between HBI and risk of SO (OR = 0.29, 95% CI = 0.35 to 1.01, P = 0.05).ConclusionWe observed that the odds of SO was reduced by 69% in participants with higher HBI score. More well-designed studies need to confirm our findings.

Usefulness of muscle ultrasound in appendicular skeletal muscle mass estimation for sarcopenia assessment.

The measurement of skeletal muscle mass is essential for the diagnosis of sarcopenia. Muscle ultrasonography has emerged as a useful tool for evaluating sarcopenia because it can be used to assess muscle quality and quantity. This study investigated whether muscle ultrasonography is effective for estimating appendicular skeletal muscle mass (ASM) and screening for sarcopenia. This study prospectively enrolled 212 healthy volunteers aged 40-80 years. ASM was measured using the bioelectrical impedance analysis. Muscle thickness (MT) and echo-intensity (EI) were measured in four muscles (biceps brachii, BB; triceps brachii, TB; rectus femoris, RF; biceps femoris, BF) on the dominant hand. A hold-out cross-validation method was used to develop and validate the ASM prediction equation. In the model development group, the ASM prediction equations were deduced as follows: estimated ASM for men (kg) = 0.167 × weight (kg) + 0.228 × height (cm) + 0.143 × MT of BF (mm)- 0.822 × EI to MT ratio of BB- 28.187 (R2 = 0.830) and estimated ASM for women (kg) = 0.115 × weight + 0.215 × height (cm) + 0.139 × MT of RF-0.638 × EI to MT ratio of BB- 23.502 (R2 = 0.859). In the cross-validation group, the estimated ASM did not significantly differ from the measured ASM in both men (p = 0.775; intraclass correlation coefficient [ICC] = 0.948) and women (p = 0.516; ICC = 0.973). In addition, multiple logistic regression analysis revealed that the ratios of EI to MT in the BF and RF muscles in men and MT in the BB muscle in women could be valuable parameters for sarcopenia screening. Therefore, our study suggests that muscle ultrasound could be an effective tool for estimating ASM and screening sarcopenia.

Association of muscle mass measured by D3-Creatine (D3Cr), sarcopenic obesity, and insulin-glucose homeostasis in postmenopausal women.

The D3-Creatine (D3Cr) dilution method is a direct and accurate measure of skeletal muscle mass. In this study, we examined the association of D3Cr muscle mass with measures of insulin-glucose homeostasis in community dwelling postmenopausal women. Additionally, we examined association of sarcopenic obesity, defined as low D3Cr muscle mass and high percent body fat, with fasting plasma glucose, insulin, hemoglobin A1c and insulin resistance. Insulin resistance was measured by the homeostatic measure of insulin resistance (HOMA-IR). This pilot study included 74 participants (mean age = 82.3 years) from the Women's Health Initiative-Buffalo site. The D3Cr method was initiated at a clinic visit and used to measure muscle mass via remote urine sample collection. Descriptive and graphical approaches and age-adjusted linear regression models were used to analyze study data. We examined muscle mass as an absolute value (kg) and scaled to body weight (D3Cr muscle mass/kg). There was an inverse relationship between skeletal muscle mass, and impaired insulin-glucose homeostasis. Women with low muscle mass had higher levels of insulin (uIU/mL; β = -0.40; 95% CI: -0.79, -0.01), fasting plasma glucose (mg/dL; β = -0.1; 95% CI: -0.2, 0.03), HbA1c (%; β = -2.30; 95% CI: -5.7, 1.1), and calculated homeostatic model of insulin resistance, HOMA-IR, (β = -1.49; 95% CI: -2.9, -0.1). Sarcopenic obesity was common in this population of women; 41% of participants were categorized as having low muscle mass and high percent body fat. Results demonstrate that D3Cr muscle mass is independently associated with measures of insulin-glucose homeostasis, but obesity is a stronger predictor of insulin resistance than muscle mass.

Skeletal muscle mass can be estimated by creatine (methyl-d3) dilution and is correlated with fat-free mass in active young males.

Assessing whole-body skeletal muscle mass (SMM) and fat-free mass (FFM) is essential for the adequate nutritional management and training evaluation of athletes and trained individuals. This study aimed to determine the relationship between SMM assessed using the creatine (methyl-d3) dilution (D3-creatine) method and SMM estimated by whole-body magnetic resonance imaging (MRI) in healthy young men undergoing exercise training. Additionally, we examined the association between FFM measured using the four-component (4C) method (FFM4C) and the total body protein value estimated using 4C (TBpro4C). We analyzed the data of 29 males (mean age, 19.9 ± 1.8 years) who exercised regularly. SMM measurements were obtained using the D3-creatine method (SMMD3-creatine) and MRI (SMMMRI). The SMMD3-creatine adjusted to 4.3 g/SMM kg was significantly higher than SMMMRI (p < 0.01). The fit of the creatine pool size compared with SMMMRI was 5.0 g/SMMMRI kg. SMMMRI was significantly correlated with both SMMD3-creatine adjusted to 4.3 g/kg and 5.1 g/kg. TBpro4C was significantly lower than SMMMRI (p < 0.01). Contrastingly, FFM4C was significantly higher than SMMMRI (p < 0.01). SMMD3-creatine adjusted to 4.3 g/SMM kg-a previously reported value-may differ for athletes and active young males. We believe that a value of 5.0-5.1 g/SMM kg better estimates the total muscle mass in this population. Traditional FFM estimation highly correlates with SMMMRI in well-trained young males, and the relationships appear strong enough for total body protein or SMM to be estimated through the FFM value.

D3 -creatine dilution for skeletal muscle mass measurement: historical development and current status.

The French chemist Michel Eugène Chevreul discovered creatine in meat two centuries ago. Extensive biochemical and physiological studies of this organic molecule followed with confirmation that creatine is found within the cytoplasm and mitochondria of human skeletal muscles. Two groups of investigators exploited these relationships five decades ago by first estimating the creatine pool size in vivo with 14 C and 15 N labelled isotopes. Skeletal muscle mass (kg) was then calculated by dividing the creatine pool size (g) by muscle creatine concentration (g/kg) measured on a single muscle biopsy or estimated from the literature. This approach for quantifying skeletal muscle mass is generating renewed interest with the recent introduction of a practical stable isotope (creatine-(methyl-d3 )) dilution method for estimating the creatine pool size across the full human lifespan. The need for a muscle biopsy has been eliminated by assuming a constant value for whole-body skeletal muscle creatine concentration of 4.3g/kg wet weight. The current single compartment model of estimating creatine pool size and skeletal muscle mass rests on four main assumptions: tracer absorption is complete; tracer is all retained; tracer is distributed solely in skeletal muscle; and skeletal muscle creatine concentration is known and constant. Three of these assumptions are false to varying degrees. Not all tracer is retained with urinary isotope losses ranging from 0% to 9%; an empirical equation requiring further validation is used to correct for spillage. Not all tracer is distributed in skeletal muscle with non-muscle creatine sources ranging from 2% to 10% with a definitive value lacking. Lastly, skeletal muscle creatine concentration is not constant and varies between muscles (e.g. 3.89-4.62g/kg), with diets (e.g. vegetarian and omnivore), across age groups (e.g. middle-age, ~4.5g/kg; old-age, 4.0g/kg), activity levels (e.g. athletes, ~5g/kg) and in disease states (e.g. muscular dystrophies, <3g/kg). Some of the variability in skeletal muscle creatine concentrations can be attributed to heterogeneity in the proportions of wet skeletal muscle as myofibres, connective tissues, and fat. These observations raise serious concerns regarding the accuracy of the deuterated-creatine dilution method for estimating total body skeletal muscle mass as now defined by cadaver analyses of whole wet tissues and in vivo approaches such as magnetic resonance imaging. A new framework is needed in thinking about how this potentially valuable method for measuring the creatine pool size in vivo can be used in the future to study skeletal muscle biology in health and disease.

Machine learning-based muscle mass estimation using gait parameters in community-dwelling older adults: A cross-sectional study

BackgroundLoss of skeletal muscle mass is associated with numerous factors such as metabolic diseases, lack of independence, and mortality in older adults. Therefore, developing simple, safe, and reliable tools for assessing skeletal muscle mass is needed. Some studies recently reported that the risks of the incidence of geriatric conditions could be estimated by analyzing older adults’ gait; however, no studies have assessed the association between gait parameters and skeletal muscle loss in older adults. In this study, we applied machine learning approach to the gait parameters derived from three-dimensional skeletal models to distinguish older adults’ low skeletal muscle mass. We also identified the most important gait parameters for detecting low muscle mass. MethodsSixty-six community-dwelling older adults were recruited. Thirty-two gait parameters were created using a three-dimensional skeletal model involving 10-meter comfortable walking. After skeletal muscle mass measurement using a bioimpedance analyzer, low muscle mass was judged in accordance with the guideline of the Asia Working Group for Sarcopenia. The eXtreme gradient boosting (XGBoost) model was applied to discriminate between low and high skeletal muscle mass. ResultsEleven subjects had a low muscle mass. The c-statistics, sensitivity, specificity, precision of the final model were 0.7, 59.5%, 81.4%, and 70.5%, respectively. The top three dominant gait parameters were, in order of strongest effect, stride length, hip dynamic range of motion, and trunk rotation variability. ConclusionMachine learning-based gait analysis is a useful approach to determine the low skeletal muscle mass of community-dwelling older adults.

MRI thigh measurements predict whole‐body skeletal muscle mass in patients with type 2 diabetes: a comparison with DXA

AbstractBackgroundSarcopenia is an age‐related loss of skeletal muscle mass (SMM) and function, associated with falls, frailty, and functional decline. It is more prevalent and often accelerated in people with Type 2 diabetes (T2D), especially when co‐existing with obesity (sarcopenic obesity). Accurate whole‐body SMM measurement, feasible using dual‐energy X‐ray absorptiometry (DXA) or magnetic resonance imaging (MRI), has utility both in clinical practice and in epidemiological and mechanistic research, considering the dual mechanical and metabolic function of skeletal muscle. Compared with MRI, DXA may underestimate age‐related muscle mass by up to 30%, and so direct comparison of DXA/MRI‐derived SMM measurements may be invalid in patients with obesity and T2D, who have potentially even more pronounced sarcopenia/sarcopenic obesity. We aimed to validate single‐slice or multiple‐slice measures of SMM, using MRI, with whole‐body SMM measures derived from DXA scans of appendicular lean soft tissue, specifically in patients with obesity and T2D.MethodsWe undertook a cross‐sectional study in which we performed paired DXA and whole‐body 3.0‐T MRI on 36 people with T2D and obesity (body mass index [BMI] &gt; 30 kg/m2). Single‐slice and seven‐slice estimates of muscle mass, taken from mid‐thigh/thigh MRI images, respectively, were determined, and compared with whole‐body SMM derived from DXA scans of appendicular lean soft tissue, in men and women separately.ResultsSeventeen men (age 48.4 ± 8.2 years, BMI 37.5 ± 5.1 kg/m2, body fat 39.1 ± 6.0%) and 19 women (age 51.8 years ± 9.7, BMI 37.8 ± 5.8 kg/m2, body fat 47.6 ± 5.1%) were recruited. Whole‐body SMM estimated by seven‐slice thigh MRI correlated strongly with DXA‐derived SMM in both men (r = 0.94, P &lt; 0.001) and women (r = 0.94, P &lt; 0.001). Single‐slice thigh estimates of whole‐body SMM by MRI also showed strong relationships to DXA‐derived SMM in both men (r = 0.88, P &lt; 0.001) and women (r = 0.87, P &lt; 0.001). There was no evidence of a statistically significant difference when comparing the performance of using single‐slice vs. multiple‐slices to determine SMM (P = 0.10 for males and P = 0.13 for females).ConclusionsThis study demonstrates that accurate determination of whole‐body SMM is possible using either single‐slice mid‐thigh or seven‐slice thigh MRI in men and women with obesity and T2D in whom there may be significant alterations in body composition. Its application may be of use clinically and in obesity‐related, metabolic, and gerontological research where accurate assessments of body composition add mechanistic insight.

Skeletal Muscle Mass Measurement Using Cone-Beam Computed Tomography in Patients With Head and Neck Cancer.

Background and purposeHead and neck cancer (HNC) patients usually present with malnutrition during radiotherapy, leading to loss of skeletal muscle mass (SMM) and poor clinical outcomes. CT has been used in clinical practice for measuring SMM in cancer patients. However, its clinical application for monitoring SMM is limited by the expensive price and high radiation exposure. This study aimed to investigate the feasibility of cone-beam computed tomography (CBCT) for assessing SMM and its changes in HNC patients undergoing radiotherapy.Materials and methodsThis study was divided into two parts. In part 1 (n = 32), the cross-sectional of skeletal muscle area (SMA) at the third cervical vertebra (C3) based on CBCT and computed tomography (CT) was assessed. In part 2 (n = 30), CT and CBCT were performed, and patients’ weight was measured before and at four different time points during radiotherapy. SMAs at C3 were independently identified by three senior radiation oncologists. The interobserver agreement of SMA on CBCT (SMACBCT) findings was analyzed using the intraclass correlation coefficient (ICC). One-way analysis of variance was used to evaluate the interobserver variability and statistical significance for SMA measurements. CBCT and CT measurement differences and correlations were analyzed using paired sample t-test and Pearson correlation analysis, respectively. The Krouwer variant of the Bland–Altman plot was used to analyze the agreement of SMA measurements between CBCT and CT. A simple linear regression model was used to analyze the relationship of SMA measurements between the two imaging techniques, and the equation was established. A repeated-measures ANOVA was performed to evaluate the effects and interactions between weight loss, SMA loss, and time.ResultsSMACBCT demonstrated excellent interobserver reliability; no significant difference between SMACBCT and SMA on CT (SMACT) at C3 was observed in all patients. The SMACBCT and SMACT were highly correlated (r = 0.966; 95% confidence interval = 0.955–0.975; p < 0.001). Bland–Altman analysis revealed that SMACBCT was generally higher than SMACT. The predicted SMA value at C3 on CT using CBCT was similar to the actual value. Moreover, significant differences between SMA and weight loss (F =10.99, p = 0.002), groups (weight loss and SMA loss) and times (4 time points) (F = 3.93, p = 0.013), and mean percent loss over time (F = 7.618, p < 0.001) were noted.ConclusionCBCT may be used as an alternative for CT to measure SMA in HNC patients during radiotherapy.