Slimming down in old age

Sarcopenia comprises a loss of muscle function and muscle mass. So far, the association between loss of muscle mass and mortality in older adults is inconsistent. A meta-analysis was performed to assess whether muscle mass measured by appendicular skeletal muscle mass index (ASMI) is associated with higher mortality in older adults. Articles of interest were searched for in two databases (PudMed® and Embase®). Cohort and case-control studies reporting ASMI and mortality and enrolling community-dwelling adults aged 65 years or more were included. Nine articles were eligible and included for analysis (n=10,028). All but one study were considered of high quality by Newcastle-Ottawa Scale assessment. We calculated the standardized mean difference (SMD) for ASMI between dead and living individuals during follow-up across studies. A reduced pooled ASMI in individuals who died as compared to those who survived was found (ASMI SMD=-0.18, CI95% -0.23 to -0.12, REM). A meta-regression was performed including ASMI SMD, grip strength SMD, body mass index (BMI), sex, study quality, method used to assess ASMI, site of study and age. BMI and ethnicity were found to significantly impact the difference in ASMI between dead and living individuals. These results reinforce the prognostic importance of assessing muscle mass in older adults.

Background/Objectives: Aging is linked to a loss of muscle mass and strength, which increases the risk of falls, disability, and lower quality of life. Identifying individuals at risk of sarcopenia, cachexia, or malnutrition is important. In settings with limited access to advanced diagnostics, simple anthropometric measurements can serve as practical alternatives. This study aimed to evaluate simple, quick, and non-invasive anthropometric measurements as indicators of muscle mass in older adults, based on body composition analysis (BIA). Methods: The study included 361 patients admitted to a geriatric ward. Standardized protocols were used to measure anthropometric and body composition parameters, including bioelectrical impedance analysis (BIA). Various body composition indices were calculated, such as body mass index (BMI), body adiposity index (BAI), waist-to-hip ratio (WHR), visceral adiposity index (VAI), fat-free mass index (FFMI), and fat mass index (FMI). Results: Strong positive correlations were found between body mass and muscle mass in both women and men. Among anthropometric measures, calf circumference showed the strongest correlation with muscle mass (R = 0.798 in women; R = 0.744 in men, p < 0.001). Other indices, including BMI (R = 0.733 in women; R = 0.606 in men, p < 0.001), FFMI (R = 0.697 in women; R = 0.721 in men, p < 0.001), and FMI (R = 0.600 in women; R = 0.354 in men, p < 0.001), were also positively correlated with muscle mass. Conclusions: Calf circumference is a simple, quick, and non-invasive measure that can effectively estimate muscle mass in older adults. Although other anthropometric parameters, such as body mass, BMI, FMI, and FFMI, also showed positive correlations with muscle mass, calf circumference appears to be the most practical, as it requires minimal equipment, little time, and limited preparation. This makes it particularly useful for routine assessments in primary care and long-term care settings, where access to advanced diagnostic tools like BIA or DXA is limited. These findings support the use of simple anthropometric measurements as cost-effective and easily accessible alternatives for estimating muscle mass in older adults. Further research is needed to determine appropriate cut-off points for specific populations and sexes.

To examine the association between healthy diet and exercise, individually and combined, and low muscle mass in older Korean adults. Population-based cross-sectional study from the Fourth and Fifth Korea National Health and Nutrition Examination Surveys from 2008 to 2011. Community. Nationally representative sample aged 65 and older (1,486 men, 1,799 women) in the Republic of Korea. A food frequency questionnaire was used to determine frequency of food group consumption (meat, fish, eggs, legumes; vegetables; fruits). Participation in exercise (aerobic and resistance) was based on self-report. Combined healthy lifestyle factors were calculated as the number of recommendations met regarding consumption of food groups and exercise performed. Appendicular skeletal muscle mass (ASM) was measured using dual-energy X-ray absorptiometry, and low muscle mass was defined using the variable of ASM adjusted for weight. Logistic regression analysis was performed to examine the association between healthy lifestyle factors and low muscle mass, adjusting for sociodemographic characteristics and health-related variables. In women, after controlling for covariates, vegetable consumption (odds ratio (OR)=0.52, 95% confidence interval (CI)=0.30-0.89) and aerobic exercise (OR=0.62, 95% CI=0.39-1.00) were inversely associated with low muscle mass. Also, the odds of low muscle mass was lower in women with three or more healthy lifestyle factors versus none (OR=0.45, 95% CI=0.23-0.87). In men, there were no associations between food group consumption and exercise and low muscle mass. Older women who exercise and consume a healthy diet have lower odds of low muscle mass. Engaging in multiple healthy behaviors may be important in preventing low muscle mass in late life.

Sarcopenia is the main cause of disability in an aging society and increases the risk of death in older adults. However, the relationship between cognitive function and muscle mass and the underlying mechanisms are not clear. This study aims to investigate the relationship between cognitive function and muscle mass in the older adults. This study was based on the Chinese Longitudinal Healthy Longevity Survey (CLHLS), phase III from 2011 to 2018. We analyzed 2536 participants aged ≥60 years. SPSS 27.0 software was used for data screening and statistical analysis, and MPLUS 8.7 and R4.4.2 software were used to construct cross-lag models and restricted cubic splints. In this study, out of 2,536 participants, there were 1,283 males (50.6%) and 1,253 females (49.4%), with an average age of 77.54 ± 8.6 years. Correlation analysis showed that cognitive function was positively correlated with muscle mass in older adults. At all time points (P<0.05). The cross-lag model revealed a one-way prediction effect: The path coefficients of ASMI→MMSE in T1→T2 and T2→T3 were statistically significant in the general population, men and women (P<0.05), and the path coefficients β were all greater than 0. The association of MMSE → ASMI was significant only at the T2 → T3 time point in the overall population (β = 0.010, P < 0.05), and not statistically significant at T1 → T2 and T2 → T3 time points in both males and females (P <0.05). RCS results showed that the association between skeletal muscle mass and cognitive impairment in the total population (P overall trend <0.05, P non-linear <0.05), older men (P overall trend <0.05, P non-linear <0.05) and older women (P overall trend <0.05, P non-linear <0.05) showed a nonlinear increasing trend. It is suggested that ASMI should be maintained at 7.45kg/m2 and 5.68kg/m2 or above in older men and women, respectively. Muscle mass had a major predictive effect on cognitive trajectory, especially in females. Maintaining ASMI above gender-specific thresholds may help slow cognitive decline, suggesting that muscle mass can serve as an adjustable biomarker for dementia prevention. Longitudinal studies should verify the validity of these thresholds in different populations.

Ultrasound is emerging as an effective method for measuring muscle mass in older adults, being more cost-effective than other image methods, such as Dual-energy X-ray absorptiometry (DXA) and computed tomography, and more accurate than bioelectrical impedance and anthropometry. We aimed to evaluate the correlation between measurements of muscle thickness (MT) measured by a portable A-mode ultrasound, the total lean mass (TLM) measured by DXA, and grip strength (GS) among community-dwelling Brazilian older adults. This is a cross-sectional pilot study with 30 participants (9 men and 21 women) aged 60–78. MT was assessed in five anatomic sites (triceps, biceps, anterior and posterior thigh, calf) using a portable A-mode ultrasound (BodyMetrix BX-2000 - IntelaMetrix, Inc.); TLM was assessed by DXA (GE Healthcare’s Lunar iDXA), and GS was assessed using a Saehan dynamometer. Pearson′s test was used for correlation analysis between each site MT and TLM; linear regressions were estimated to verify the association between GS and each site MT, controlling for age. Lower limb measurements (anterior and posterior thigh, calf) were not associated with TLM and GP. Triceps MT was significantly correlated to TLM (r=0.565; p=0.001) and associated to GS (β=0.699; p=0.004); biceps MT was also correlated to TLM (r=0.425; p=0.019) and associated to GS (β=0.652; p=0.012). Our results suggest that upper limb ultrasound measurements using portable equipment can be a helpful cost-effective indicator of muscle mass and function in older adults. Further results and conclusions will be reported after completing the study with the total planned sample (n=150).

Low muscle mass in older adults and mortality: A systematic review and meta-analysis.

Our aim was to clarify the association between type 2 diabetes and the risk of low muscle mass in older adults. In the present study, 414 adults aged 65 years or older (144 patients with type 2 diabetes and 270 control participants) were included. Body composition was measured by dual-energy X-ray absorptiometry. Low muscle mass was defined as the appendicular skeletal muscle mass/height(2) (ASM/Ht(2)) or appendicular skeletal muscle mass/weight (ASM/Wt) of <2 SD below the sex-specific normal mean of the young reference group, or <lower 20th percentile of total body skeletal muscle mass/weight (TSM/Wt) from control participants. Older men with type 2 diabetes showed significantly lower appendicular skeletal muscle mass than those without diabetes (19.5 ± 3.5 kg vs 21.0 ± 2.8 kg, P < 0.001). The prevalence of low muscle mass was consistently higher in older men with diabetes than those without diabetes defined by ASM/Ht(2) (57.6% vs 41.5%, P = 0.040), ASM/Wt (23.7% vs 12.3%, P = 0.046) and TSM/Wt (49.2% vs 20.0%, P < 0.001). In older women with diabetes, the prevalence of low muscle mass was higher than those without diabetes by ASM/Wt (25.9% vs 15.0%, P = 0.044) and TSM/Wt (32.9% vs 20.0%, P = 0.030), but not by ASM/Ht(2) (7.1% vs 8.6%, P = 0.685). The risk of low muscle mass was approximately two- to fourfold higher in older adults with type 2 diabetes, even after adjusting for age, body mass index, current smoking and other risk factors. In Korean older adults, type 2 diabetes is associated with low muscle mass.

Texture-modified diets (TMD) have significantly lower energy and protein content than normal diets. Therefore, TMD can cause malnutrition and loss of muscle mass. However, few studies have reported the relationship between TMD and decreased skeletal muscle mass. The aim of the present study was to clarify the association between TMD and decreased skeletal muscle mass. We reviewed data of 188 older adult patients who were admitted to a rehabilitation hospital. TMD were defined based on the Japanese Dysphagia Diet Criteria 2013 proposed by the Japanese Society of Dysphagia Rehabilitation. The Mini Nutritional Assessment-Short Form was used to assess nutritional status; dual-energy X-ray absorptiometry was used to measure the skeletal muscle mass index, and the cut-off values for decreased skeletal muscle mass index were based on the Asian Working Group for Sarcopenia; the Functional Independence Measure was used to evaluate activities of daily living. The patients' mean age was 80.6 ± 7.5 years, and 62% were women. A total of 22 patients (11.7%) consumed TMD. A total of 104 patients (55.3%) had decreased skeletal muscle mass, and approximately 90% of them consumed TMD. Decreased skeletal muscle mass index (odds ratio 7.199, 95% confidence interval 1.489-34.805, P ≤ 0.01) and Functional Independence Measure scores (odds ratio 0.972, 95% confidence interval 0.952-0.992, P ≤ 0.01) were independently related to TMD in the multivariate analysis. The TMD group was associated with decreased skeletal muscle mass. Future, prospective studies are necessary to investigate causality. Geriatr Gerontol Int 2018; 18: 698-704.

Author response for "Relationship Between Swallowing Frequency and Swallowing‐Related Muscle Mass in Older Adults"

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Assessment of Skeletal Muscle Mass in Older People: Comparison Between 2 Anthropometry-Based Methods and Dual-Energy X-ray Absorptiometry

Different Associations of Skeletal Muscle Mass Index and Creatinine-To-Cystatin C Ratio With Muscle Mass and Myosteatosis: The J-SHIPP Study.

This study aimed to develop appendicular skeletal muscle mass (ASM) estimating formulas that also consider the presence of paralysis for older adults and people with disabilities. This retrospective study analyzed 315 consecutive patients, post-stroke, aged ≥65 years, in a rehabilitation hospital. Six different ASM estimating formulas were developed using a five-fold cross-validation method and compared with the measured ASM obtained from bioelectrical impedance analysis. These formulas included age, gender, height, weight, arm circumference, triceps skinfold, calf circumference and presence of paralysis. Using Pearson's correlation coefficients (r) and intraclass correlation coefficient (ICC), we examined the correlation between the formulas and the measured ASM. The accuracy of the ASM estimating formula for detecting decreased muscle mass was evaluated using the F-value and Matthew's correlation coefficient. Patients' mean ± SD age was 79.0 ± 8.1 years, and 51.4% of them were men. The mean ± SD bioelectrical impedance analysis-measured ASM was 13.7 ± 4.3 kg. Furthermore, 241 (76.5%) patients had decreased measured ASM. The mean adjusted R2 of the developed six formulas was 0.861-0.871. In all formulas, the r and ICC of the estimated ASM for the measured ASM were strong (r = 0.936-0.930 and ICC = 0.928-0.934). These formulas revealed excellent sensitivity (86.0-88.2%), specificity (72.5-81.1%), accuracy (0.838-0.870), F-value (0.899-0.918) and Matthew's correlation coefficient (0.509-0.612) for measured ASM depletion. We successfully developed ASM estimating formulas using anthropometric measurements considering the presence of paralysis. Thus, these formulas are beneficial for diagnosing sarcopenia in older adults, without requiring any special equipment. Geriatr Gerontol Int 2020; 20: 1145-1150.

Skeletal muscle atrophy during bed rest is attributed, at least in part, to slower basal muscle protein synthesis (MPS). Essential amino acids (EAA) stimulate mammalian target of rapamycin (mTORC1) signaling, amino acid transporter expression, and MPS and are necessary for muscle mass maintenance, but there are no data on the effect of inactivity on this anabolic mechanism. We hypothesized that bed rest decreases muscle mass in older adults by blunting the EAA stimulation of MPS through reduced mTORC1 signaling and amino acid transporter expression in older adults. Six healthy older adults (67 ± 2 yr) participated in a 7-day bed rest study. We used stable isotope tracers, Western blotting, and real-time qPCR to determine the effect of bed rest on MPS, muscle mTORC1 signaling, and amino acid transporter expression and content in the postabsorptive state and after acute EAA ingestion. Bed rest decreased leg lean mass by ∼4% (P < 0.05) and increased postabsorptive mTOR protein (P < 0.05) levels while postabsorptive MPS was unchanged (P > 0.05). Before bed rest acute EAA ingestion increased MPS, mTOR (Ser(2448)), S6 kinase 1 (Thr(389), Thr(421)/Ser(424)), and ribosomal protein S6 (Ser(240/244)) phosphorylation, activating transcription factor 4, L-type amino acid transporter 1 and sodium-coupled amino acid transporter 2 protein content (P < 0.05). However, bed rest blunted the EAA-induced increase in MPS, mTORC1 signaling, and amino acid transporter protein content. We conclude that bed rest in older adults significantly attenuated the EAA-induced increase in MPS with a mechanism involving reduced mTORC1 signaling and amino acid transporter protein content. Together, our data suggest that a blunted EAA stimulation of MPS may contribute to muscle loss with inactivity in older persons.