Current Status of Sarcopenia in Korea: A Focus on Korean Geripausal Women

Association of Handgrip Strength and Cardiovascular Disease Risk Among Middle-Aged Postmenopausal Women: An Analysis of the Korea National Health and Nutrition Examination Survey 2014-2019

Purpose

Handgrip strength is an indicator of overall muscle strength and has been associated with an increased risk of cardiovascular disease. Evidence suggests that menopause is a risk factor for cardiovascular disease in women, and muscle strength decreases progressively after menopause. Despite the prognostic importance of the decline in muscle strength and increased cardiovascular disease risk among postmenopausal women, evidence of their association is limited. This study aimed to investigate the relationship between handgrip strength and cardiovascular disease risk among postmenopausal, middle-aged Korean women.

Patients and Methods

Using pooled cohort equations, we calculated the 10-year risk of atherosclerotic cardiovascular disease (ASCVD) among postmenopausal women (N = 2019) aged 50-64 years without cardiovascular disease history from the 2014-2019 Korea National Health and Nutrition Examination Survey. Relative grip strength was defined as measured grip strength divided by body mass index. Logistic regression analysis of a complex sampling design was performed to evaluate the association between relative grip strength and a predicted 10-year ASCVD risk ≥7.5%.

Results

The average handgrip strength was 24.8 kg, and 5.2% of women were considered for sarcopenia (<18 kg). The quartile-stratified relative grip strength was negatively associated with 10-year ASCVD risk (p < 0.001). In the multiple logistic regression analysis, the adjusted odds ratio for the highest relative grip strength quartile was 0.53 (95% confidence interval [CI]: 0.36-0.78), and that of the group who breastfed for more than 12 months was 1.75 (95% CI: 1.36-2.25) for 10-year ASCVD risk.

Conclusion

Increased handgrip strength may be associated with lower cardiovascular disease risk among middle-aged postmenopausal women in Korea. Our findings provide critical evidence regarding the importance of increasing handgrip strength among postmenopausal, middle-aged women to reduce cardiovascular disease risk. Handgrip strength measurement might be a valuable screening tool for cardiovascular disease prevention.

Association of low muscle mass and obesity with increased all-cause and cardiovascular disease mortality in US adults

BACKGROUND

Sarcopenic obesity, defined as the coexistence of low muscle mass and high adiposity, is associated with cardiovascular disease (CVD) and mortality. However, to what extent sarcopenia contributes to these risks independently or in conjunction with other cardiovascular risk factors remains unclear. This study aimed to investigate the association of low muscle mass, central obesity (COB), metabolic abnormalities, and their combinations with CVD and mortality risk.

METHODS

This cross-sectional analysis used data from the National Health and Nutrition Examination Survey 1999-2006 and 2011-2018. Participants aged >20 years and with reported whole-body dual X-ray absorptiometry data were included. Participants were divided into eight groups based on low muscle mass, metabolic abnormalities, and COB status.

RESULTS

The mean age of participants was 55 years, and 50.4% of participants were male. Low muscle mass was observed in 2472 (14.6%) out of 16 839 participants. Among the eight groups, the metabolically unhealthy COB group with low muscle mass had the highest hazard ratio (HR) for all-cause mortality (HR, 2.00; 95% CI, 1.56-2.56; P < 0.001), whereas the metabolically healthy COB group with low muscle mass had the highest HR for CVD mortality (HR, 3.18; 95% CI, 1.53-6.65; P = 0.001). The mediation analysis showed that low muscle mass directly increased the risk of both all-cause mortality (HR, 1.56; 95% CI, 1.35-1.79; P < 0.001) and CVD mortality (HR, 1.80; 95% CI, 1.40-2.31; P < 0.001). Additionally, subgroup analysis revealed that low muscle mass significantly increased the risk of all-cause and CVD mortality in participants without a prior CVD history and those with diabetes mellitus.

CONCLUSIONS

Low muscle mass is an independent risk factor for all-cause and CVD mortality, especially in individuals with metabolic abnormalities and COB.

Factors influencing health-related quality of life in older adult women with sarcopenia: analysis of the Korean National Health and Nutrition Examination Survey 2019

PURPOSE

This study aimed to identify factors influencing the health-related quality of life (HRQoL) of older adult women with sarcopenia.

METHODS

The study was secondary data analysis using data from the 2019 Korea National Health and Nutrition Examination Survey. The final sample consisted of 142 women aged 60 years and older with sarcopenia and were selected from 8,110 women. The participants was analyzed using complex descriptive statistics, independent t-test, and regression.

RESULTS

In terms of HRQoL, three general characteristics were found to be influential, with an explanatory power of 56.0%: difficulty climbing stairs, difficulty working, and perceived health status. Having no or mild difficulty when climbing stairs (B=.20, p=.001; B=.21, p<.001) and no or mild difficulty when working (B=.25, p=. 002; B=.208, p=.013) had a significant effect on HRQoL compared to severe difficulty. Having good or ordinary perceived health status had a significant effect on the HRQoL (B=.11, p<.001; B=.09, p<.001).

CONCLUSION

Based on study findings that the HRQoL of older adult women with sarcopenia were influenced by difficulty climbing stairs and working, as well as good perceived health status, healthcare providers should assist elderly women to maintain physical activities in their daily lives.

Association between body composition and the risk of mortality in the obese population in the United States

Background

Recent studies have presented the concept of the obesity paradox, suggesting that individuals with obesity have a lower risk of death than those without obesity. This paradox may arise because body mass index (BMI) alone is insufficient to understand body composition accurately. This study investigated the relationship between fat and muscle mass and the risk of mortality in individuals with overweight/obesity.

Methods

We used data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2006 and 2011 to 2018, which were linked to mortality information obtained from the National Death Index. Multiple Cox regression analyses were performed to estimate mortality risk. Subgroup analysis was conducted using propensity score-matched (PSM) data for age, sex, and race/ethnicity.

Results

This study included 16,555 participants who were overweight/obese (BMI≥25 kg/m2). An increase in appendicular skeletal muscle mass index was associated with a lower mortality risk (hazard ratio [HR]: 0.856; 95% confidence interval [CI]: 0.802-0.915). This finding was consistent with the subgroup analysis of the PSM data. Contrastingly, a high fat mass index was associated with an increased risk of mortality. Sarcopenic overweight/obesity was significantly associated with high mortality compared to obesity without sarcopenia (HR: 1.612, 95%CI: 1.328-1.957). This elevated risk was significant in both age- and sex-based subgroups. This finding was consistent with the subgroup analysis using PSM data.

Conclusion

In contrast to the obesity paradox, a simple increase in BMI does not protect against mortality. Instead, low body fat and high muscle mass reduce mortality risk.

Effectiveness of Combined Exercise and Nutrition Interventions in Preventing and Improving Sarcopenia in Frail or Healthy Older Adults: A Systematic Review

The current systematic review compared whether combined exercise and nutrition interventions are effective in preventing or improving sarcopenia in frail older adults and healthy older adults. Medline, Embase, Cochrane Library, and CINAHL were searched for randomized controlled trials. Of the 1,596 citations, 22 trials (N = 1,767) were included in the final sample. In frail older adults, significant improvement after combined exercise and nutrition interventions was observed in seven indicators: skeletal muscle index, 0.16 kg/m2; handgrip, 1.41 kg; knee extension strength, 0.24 Nm; five-repetition chair-stand test, -1.89 sec; gait speed, 0.06 m/s; Short Physical Performance Battery, 0.43; and Timed Up and Go test, -0.56 sec. In healthy older adults, two indicators improved and showed statistically significant differences: handgrip, 2.15 kg; and 6-Minute Walking Test, 9.71 m. Combined exercise and nutritional interventions can improve skeletal muscle quality, strength, and physical performance in frail and healthy older adults. [Research in Gerontological Nursing, 16(6), 312-320.].

Relationship between DNA methylation changes and skeletal muscle mass

BACKGROUND

Sarcopenia is a disease diagnosed in the elderly. In patients with sarcopenia, the muscle mass decreases every year. The occurrence of sarcopenia is greatly affected by extrinsic factors such as eating habits, exercise, and lifestyle. The present study aimed to determine the relationship between muscle mass traits and genes affected by epigenetic factors with three different adjustment methods using Korean Genome and Epidemiology Study (KOGES) data.

RESULTS

We conducted a demographic study and DNA methylation profiling by three studies according to the muscle mass index (MMI) adjustment methods: appendicular skeletal muscle mass divided by body weight (MMI1); appendicular skeletal muscle mass divided by square of height (MMI2); appendicular skeletal muscle mass divided by BMI (MMI3). We analyzed differentially methylated regions (DMRs) for each group. We then restricted our subjects to be top 30% (T30) and bottom 30% (B30) based on each MMI adjustment method. Additionally, we performed enrichment analysis using PathfindR to evaluate the relationship between identified DMRs and sarcopenia. A total of 895 subjects were included in the demographic study. The values of BMI, waist, and hip showed a significant difference in all three groups. Among 446 participants, 44 subjects whose DNA methylation profiles were investigated were included for DNA methylation analysis. The results of enrichment analysis showed differences between groups. In the women group through MMI1 method, only the glutamatergic synapse pathway showed a significant result. In the men group through MMI2 method, the adherens junction pathway was the most significant. Women group through MMI2 method showed similar results, having an enriched Rap1 signaling pathway. In men group through MMI3 method, the Fc epsilon RI signaling pathway was the most enriched. Particularly, the notch signaling pathway was significantly enriched in women group through MMI3 method.

CONCLUSION

This study presents results about which factor should be concerned first in muscle mass index (MMI) adjustment. The present study suggested that GAB2 and JPH3 in MMI1 method, HLA-DQB1 and TBCD in MMI2 method, GAB2, NDUFB4 and ISPD in MMI3 method are potential genes that can have an impact on muscle mass. It could enable future epigenetic studies of genes based on annotation results. The present study is a nationwide study in Korea with the largest size up to date that compares adjustment indices for MMI in epigenetic research.

Regional differences in the associations of diet quality, obesity, and possible sarcopenia using the seventh Korea National Health and Nutrition Examination Survey (2016-2018)

OBJECTIVES

Sarcopenic obesity is closely related to aging and the prevalence of various chronic diseases and frailty. The purpose of this study was to analyze whether diet quality is related to obesity, sarcopenia, and sarcopenic obesity, and if so, to explore the difference in that relationship between urban and rural settings.

METHODS

Using data from the Korea National Health and Nutrition Examination Survey of 2016-2018, a total of 7,151 participants aged 40 years or older were analyzed. Sarcopenia was diagnosed using handgrip strength. Diet quality was assessed using Korea Healthy Eating Index (KHEI) scores, and obesity was determined based on participants' abdominal circumference. Multinomial logistic analysis was used for testing statistical significance.

RESULTS

Rural participants had significantly lower KHEI scores and a higher prevalence of sarcopenic obesity than urban participants. The study findings demonstrate that participants without obesity, sarcopenia, or sarcopenic obesity had significantly higher KHEI scores in both rural and urban settings. Multinomial regression analysis further revealed that a higher KHEI score was associated with a lower risk of sarcopenia and sarcopenic obesity among urban residents, while only the risk of obesity was lower with higher diet quality scores among rural residents.

CONCLUSIONS

Since diet quality and health status were lower in rural areas, it is important to address this regional disparity with appropriate policy measures. To mitigate urban health disparities, urban residents in poor health with few resources should also be supported.

Predicting Sarcopenia of Female Elderly from Physical Activity Performance Measurement Using Machine Learning Classifiers

Purpose

Sarcopenia is a symptom in which muscle mass decreases due to decreasing in the number of muscle fibers and muscle cross-sectional area as aging. This study aimed to develop a machine learning classification model for predicting sarcopenia through a inertial measurement unit (IMU)-based physical performance measurement data of female elderly.

Patients and Methods

Seventy-eight female subjects from an elderly population (aged: 78.8±5.7 years) volunteered to participate in this study. To evaluate the physical performance of the elderly, the experiment conducted timed-up-and-go test (TUG) and 6-minute walk test (6mWT) with worn a single IMU. Based on literature review, 132 features were extracted from collected data. Feature selection was performed through the Kruskal–Wallis test, and features datasets were constructed according to feature selection. Three major machine learning-based classification algorithms classified the sarcopenia group in each dataset, and the performance of classification models was compared.

Results

As a result of comparing the classification model performance for sarcopenia prediction, the k-nearest neighborhood algorithm (kNN) classification model using 40 major features of TUG and 6mWT showed the best performance at 88%.

Conclusion

This study can be used as a basic research for the development of self-monitoring technology for sarcopenia.

Receptor-Mediated Muscle Homeostasis as a Target for Sarcopenia Therapeutics

Sarcopenia is a disease characterized by age-related decline of skeletal muscle mass and function. The molecular mechanisms of the pathophysiology of sarcopenia form a complex network due to the involvement of multiple interconnected signaling pathways. Therefore, signaling receptors are major targets in pharmacological strategies in general. To provide a rationale for pharmacological interventions for sarcopenia, we herein describe several druggable signaling receptors based on their role in skeletal muscle homeostasis and changes in their activity with aging. A brief overview is presented of the efficacy of corresponding drug candidates under clinical trials. Strategies targeting the androgen receptor, vitamin D receptor, Insulin-like growth factor-1 receptor, and ghrelin receptor primarily focus on promoting anabolic action using natural ligands or mimetics. Strategies involving activin receptors and angiotensin receptors focus on inhibiting catabolic action. This review may help to select specific targets or combinations of targets in the future.

Associations between the quality of life in sarcopenia measured with the SarQoL® and nutritional status

BACKGROUND

The purpose of this study was to evaluate the relationship between nutritional status and health-related quality of life after adjusting for essential factors of muscle mass, calf circumference, grip strength, and the timed up and go (TUG) test for diagnosis of sarcopenia.

METHODS

The subjects of this study were those who visited a health care center or a senior welfare center among the aged 65 years or older living in a community in two counties (Jinju, Sacheon), and the survey was conducted from April to August 2019. Among them, those with cardiovascular disease, cognitive disorder, or malignancy were excluded. To determine the nutritional status of the elderly subjects, a questionnaire-based screening tool called DETERMINE was used. Developed as a health-related quality of life tool for sarcopenia, the Sarcopenia-specific Quality of Life (SarQoL) questionnaire was used. For screening of sarcopenia, a rapid questionnaire based on self-reported information about falls, mobility, and strength known as the SARC-F questionnaire was used. Assessment of sarcopenia included skeletal muscle mass, calf circumference, grip strength, and the TUG test.

RESULTS

A total of 324 elderly people living in rural villages who were able to move to senior and welfare centers was surveyed. As a result of evaluating the association between SarQoL and nutritional risk in elderly subjects, the association was statistically significant in the moderate-risk group (B = - 5.542, p = 0.001) and in the high-risk group (B = - 8.136, p < 0.001) in comparison to the low-risk group. Significant correlations were found in all seven domains of SarQoL, except the fear domain.

CONCLUSIONS

This study confirms an association between quality of life dimensions surveyed by the SarQoL questionnaire and nutritional status in elderly subjects. Therefore, appropriate interventions are needed following brief evaluation of sarcopenia and nutritional deficiency among elderly people in communities.

Systemic and Local Phenotypes of Barium Chloride Induced Skeletal Muscle Injury in Mice

Skeletal muscle regeneration in mice has traditionally been studied using local freeze burn or snake venom injection models. More recently, a barium chloride (BaCl2)-induced muscle injury model has been established and is gaining popularity due to the relatively simple procedure and accessibility to required reagents. Here we sought to characterize the local and systemic effects of BaCl2-induced muscle injury. For this study, a 1.2% BaCl2 solution was locally administered to the tibialis anterior (TA) muscle and local and systemic phenotypes were analyzed at different timepoints. When 50 μL of the solution was injected unilaterally in the TA muscle, no mortality was observed. However, when 100 μL of the solution was injected, 50% of the mice died within 24 h. Serum analysis of the mice injected with 50 μL of BaCl2 solution at days 1 and 7 revealed changes resembling rhabdomyolysis. At day 1 post-injection of 50 μL of the BaCl2 solution, acute suppurative inflammation was observed in gross examination of the TA muscle, while extensive hemorrhagic necrosis was revealed on histological examination. At day 7, regenerated myofibers with centralized nuclei appeared with the resolution of acute inflammatory infiltration and the muscle tissue displayed molecular signatures consistent with myofiber differentiation. The overall muscle injury and regeneration phenotypes in the BaCl2-induced muscle injury model were similar to those of the well-established freeze burn or snake venom injection models. Taken together, the BaCl2-induced muscle injury model is comparable to conventional muscle injury and regeneration models, with considerations for possible systemic effects.

Protein Intake Recommendation for Korean Older Adults to Prevent Sarcopenia: Expert Consensus by the Korean Geriatric Society and the Korean Nutrition Society

Sarcopenia, a common clinical syndrome in older adults, is defined as decreased muscle mass, strength, and physical performance. Since sarcopenia is associated with the incidence of functional decline, falls, and even mortality in older adults, researchers and health care providers have been keen to accumulate clinical evidence to advocate the screening and prevention of sarcopenia progression in older adults. The factors that may accelerate the loss of muscle mass and function include chronic diseases, inactivity, and deficiency in appropriate nutritional support. Among these, nutritional support is considered an initial step to delay the progression of muscle wasting and improve physical performance in community-dwelling older adults. However, a nationwide study suggested that most Korean older adults do not consume sufficient dietary protein to maintain their muscle mass. Furthermore, considering age-associated anabolic resistance to dietary protein, higher protein intake should be emphasized in older adults than in younger people. To develop a dietary protein recommendation for older adults in Korea, we reviewed the relevant literature, including interventional studies from Korea. From these, we recommend that older adults consume at least 1.2 g of protein per kg of body weight per day (g/kg/day) to delay the progression of muscle wasting. The amount we recommend (1.2 g/kg/day) is 31.4% higher than the previously suggested recommended daily allowance (i.e., 0.91 g/kg/day) for the general population of Korea. Also, evidence to date suggests that the combination of exercise and nutritional support may enhance the beneficial effects of protein intake in older adults in Korea. We found that the current studies are insufficient to build population-based guidelines for older adults, and we call for further researches in Korea.