Recent Progression in Sarcopenia and Sarcopenic Obesity

Sarcopenic Obesity: Involvement of Oxidative Stress and Beneficial Role of Antioxidant Flavonoids

Sarcopenic obesity, which refers to concurrent sarcopenia and obesity, is characterized by decreased muscle mass, strength, and performance along with abnormally excessive fat mass. Sarcopenic obesity has received considerable attention as a major health threat in older people. However, it has recently become a health problem in the general population. Sarcopenic obesity is a major risk factor for metabolic syndrome and other complications such as osteoarthritis, osteoporosis, liver disease, lung disease, renal disease, mental disease and functional disability. The pathogenesis of sarcopenic obesity is multifactorial and complicated, and it is caused by insulin resistance, inflammation, hormonal changes, decreased physical activity, poor diet and aging. Oxidative stress is a core mechanism underlying sarcopenic obesity. Some evidence indicates a protective role of antioxidant flavonoids in sarcopenic obesity, although the precise mechanisms remain unclear. This review summarizes the general characteristics and pathophysiology of sarcopenic obesity and focuses on the role of oxidative stress in sarcopenic obesity. The potential benefits of flavonoids in sarcopenic obesity have also been discussed.

Dysregulated Autophagy Mediates Sarcopenic Obesity and Its Complications via AMPK and PGC1α Signaling Pathways: Potential Involvement of Gut Dysbiosis as a Pathological Link

Sarcopenic obesity (SOB), which is closely related to being elderly as a feature of aging, is recently gaining attention because it is associated with many other age-related diseases that present as altered intercellular communication, dysregulated nutrient sensing, and mitochondrial dysfunction. Along with insulin resistance and inflammation as the core pathogenesis of SOB, autophagy has recently gained attention as a significant mechanism of muscle aging in SOB. Known as important cellular metabolic regulators, the AMP-activated protein kinase (AMPK) and the peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α) signaling pathways play an important role in autophagy, inflammation, and insulin resistance, as well as mutual communication between skeletal muscle, adipose tissue, and the liver. Furthermore, AMPK and PGC-1α signaling pathways are implicated in the gut microbiome-muscle axis. In this review, we describe the pathological link between SOB and its associated complications such as metabolic, cardiovascular, and liver disease, falls and fractures, osteoarthritis, pulmonary disease, and mental health via dysregulated autophagy controlled by AMPK and/or PGC-1α signaling pathways. Here, we propose potential treatments for SOB by modulating autophagy activity and gut dysbiosis based on plausible pathological links.

Measurement and Interpretation of Handgrip Strength for Research on Sarcopenia and Osteoporosis

Handgrip strength (HGS) is associated with several chronic diseases, cognitive decline, length of hospital-stay, and mortality. More importantly, HGS is one of the diagnostic criteria of sarcopenia and gaining attention because of its relevance to bone mineral density (BMD) and osteoporotic fractures. As the measurement of HGS is widely used in clinical practice as well as in research, its accurate measurement and interpretation are becoming more crucial. This review describes how to use different types of dynamometers accurately, the impact of body and arm positions and anthropometric parameters on HGS, the current reference values of HGS for sarcopenia research, and the updates on the relationship between HGS and BMD and osteoporotic fractures.

Relationship between osteosarcopenic obesity and dietary inflammatory index in postmenopausal Korean women: 2009 to 2011 Korea National Health and Nutrition Examination Surveys

Osteosarcopenic obesity syndrome is a condition including osteopenia, sarcopenia and obesity. A pro-inflammatory dietary pattern has been reported to be associated with obesity and osteoporosis. However, studies on the association of dietary inflammatory index with osteosarcopenic obesity syndrome in the Korean population are lacking. The aim of this study was to analyze the relationship between dietary inflammatory index and osteosarcopenic obesity syndrome among Korean postmenopausal women. We analyzed the 2009-2011 Korea National Health and Nutrition Examination Survey, consisting of 1,344 postmenopausal women aged 50 years or older. Body composition was evaluated by dual-energy X-ray absorptiometry. Dietary inflammatory index was estimated after analyzing 36 nutrients and 9 foods using a 24-h dietary recall data. The association between dietary inflammatory index levels and the body composition was analyzed by logistic regression models with dietary inflammatory index fit as a dichotomous variable. The dietary inflammatory index was -0.96 ± 0.22 in the normal group, 0.12 ± 0.16 in the osteopenic obesity group, 0.00 ± 0.18 in the osteosarcopenia group, 0.12 ± 0.33 in the sarcopenic obesity group, and -0.02 ± 0.14 in the osteosarcopenic obesity group (p<0.001). After adjusting for potential covariates, women with higher dietary inflammatory index scores were more likely to have risk of osteopenic obesity (OR = 2.757, 95% CI: 1.398-5.438, p<0.01) and that of osteosarcopenic obesity (OR = 2.186, 95% CI: 1.182-4.044, p<0.05). The results indicate that pro-inflammatory diet was associate with increased odds of the osteosarcopenic obesity in postmenopausal Korean women. Therefore, studies are needed to identify the effects of anti-inflammatory diets, which can reduce the degree of inflammation through dietary intake.

Association between Sleep Duration and Body Composition Measures in Korean Adults: The Korea National Health and Nutrition Examination Survey 2010

Background

The association between sleep duration and body composition measures in Korean adults remains unclear.

Methods

This cross-sectional study included 3,532 subjects aged ≥40 years (1,542 men and 1,990 women) who participated in the 2010 Korea National Health and Nutrition Examination Survey V-1. Self-reported sleep duration and anthropometric data were collected. Appendicular skeletal muscle mass (ASM) was quantified via dual-energy X-ray absorptiometry. Obesity was defined according to the body mass index and waist circumference. Sarcopenia was defined as the muscle mass percentage (ASM/weight) below the lowest quintile computed for the study population. Multivariate logistic regressions with or without adjustment for sociodemographic and lifestyle factors were used to evaluate the association of sleep duration with obesity and sarcopenia for participants who slept ≤5, 6–8, and ≥9 h/d. The results were expressed as odds ratios (ORs) with 95% confidence intervals (95% CIs).

Results

In women, the association between sleep duration and sarcopenia was stronger for individuals who slept ≥9 h/d than for those who slept 6–8 h/d (unadjusted OR, 1.99; 95% CI, 1.19–3.34; adjusted OR, 1.77; 95% CI, 1.06– 2.96).

Conclusion

Longer sleep duration is associated with a significantly higher incidence of sarcopenia in Korean women aged ≥40 years.

Evaluation of factors influencing grip strength in elderly koreans

Objectives

Grip strength has been used as a measure of function in various health-related conditions. Although grip strength is known to be affected by both physical and psychological factors, few studies have looked at those factors comprehensively in a population-based cohort regarding elderly Koreans. The aim of this study was to evaluate potential factors influencing grip strength in elderly Koreans.

Methods

We evaluated dominant hand grip strengths in 143 men and 123 women older than 65 years who participated in a population-based cohort study, the Korean Longitudinal Study on Health and Aging (KLoSHA). Individuals who had a history of surgery for musculoskeletal disease or trauma in the upper extremity were excluded. Factors assessed for potential association with grip strength were; 1) demographics such as age and gender, 2) body constructs such as height, body mass index (BMI), and bone mineral density (BMD), 3) upper extremity functional status using disabilities of the arm, shoulder and hand (DASH) scores, and 4) mental health status using a depression scale and the short form-36 (SF36) mental health score. Multivariate analyses were performed in order to identify factors independently associated with grip strength.

Results

Grip strengths of dominant hands in elderly Koreans were found to generally decrease with aging, and were significantly different between men and women, as expected. Multivariate analyses indicated that grip strength was independently associated with age, height and BMI in men (R² = 21.3%), and age and height (R² = 19.7%) in women. BMD, upper extremity functional status, or mental health status were not found to be associated with grip strength.

Conclusions

This study demonstrates that in elderly Koreans, grip strength is mainly influenced by age and height in both men and women, and additionally by BMI in men. BMD or self-reported physical or mental health status was not found to influence grip strength in elderly Koreans. This information may be helpful in future studies using grip strength as a measure of function in elderly Koreans.