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Aim: Phase angle (PhA) can be determined through bioelectrical impedance analysis and is a unique variable for skeletal muscle. The objective of this study was to evaluate the relationship between PhA and muscle mass/quality in older adults. In addition, we attempted to determine the cutoff value of PhA for poor muscle function., Methods: Community-dwelling Japanese older men (n=285, 81.1±7.1 years) and women (n=724, 80.4±6.8 years) participated in this study and were classified into four groups based on the Asian Working Group for Sarcopenia (normal, presarcopenia, dynapenia, and sarcopenia). We measured PhA using bioelectrical impedance analysis, muscle quantity and quality indicators using ultrasonography, muscle strength, and physical performance and compared them in four groups. We also tried to determine the cutoff value of PhA for poor muscle function., Results: We found a significant difference in PhA among the four groups in men (P<0.05), and the dynapenia (3.61±0.75°) and sarcopenia groups (3.40±0.74°) showed significantly lower values than the normal group (4.50±0.86°) (P<0.05), but not the presarcopenia group (4.12±0.85°). In women, a significant difference was also observed among the four groups (P<0.05), and the dynapenia (3.41±0.65°) and sarcopenia groups (3.31±0.66°) showed significantly lower measures than the normal group (4.14±0.71°) (P<0.05), but not the presarcopenia group (4.07±0.51°). The receiver-operating characteristic curve analysis indicated the best cutoff value of PhA (men: 4.05°, women: 3.55°) to discriminate sarcopenia and dynapenia from normal and presarcopenia., Conclusion: These findings suggest that PhA is a useful indicator for muscle function., Competing Interests: The authors have no potential conflicts of interest to disclose

Purpose: To examine the relationship between oral function and sarcopenia staging, including dynapenia and presarcopenia, in community-dwelling older adults., Methods: A cross-sectional study was performed in community-dwelling older women aged 65 years and above. We measured oral muscle strength using maximum tongue pressure, oral muscle performance using oral diadochokinesis, and subjective swallowing difficulties using the Eating Assessment Tool. We measured skeletal muscle mass and function and other variables. All participants were divided into 4 groups (normal, presarcopenia, dynapenia, and sarcopenia) using an algorithm that operationally defines sarcopenia staging by skeletal muscle characteristics. A general linear model was used to analyze differences in oral function among the 4 groups., Results: A total of 245 participants were enrolled (median age [IQR], 81.0 [75.0-85.0]). The proportion of normal participants and those with presarcopenia, dynapenia, and sarcopenia was 48.6% (n = 119), 9.4% (n = 23), 30.2% (n = 74), and 11.8% (n = 29), respectively. The sarcopenia and dynapenia groups had significantly lower maximum tongue pressure and oral diadochokinesis than the normal group. In the multivariate analysis, after adjusting for age, maximum tongue pressure and oral diadochokinesis were found to be significantly lower in the sarcopenia and dynapenia groups than in the normal group., Conclusions: In this study, participants with sarcopenia and dynapenia showed low oral function, and similar trends were indicated for oral function and skeletal muscle according to progression of sarcopenia staging. Future research should clarify the characteristics of swallowing-related muscles, including muscle mass, strength, and performance at each sarcopenia stage., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Although several previous studies have found benefits for amino acid supplementation in terms of muscle function, the role of plasma amino acid concentrations on sarcopenia are not well addressed yet., Objective: The aim of this study was to compare the amino acid concentrations at each stage of sarcopenia (normal, pre-sarcopenia, dynapenia, and sarcopenia) in community-dwelling older Japanese adults., Setting and Subjects: Community-dwelling older Japanese women (n=232, 79.4±7.0 years) participated in this study., Measurements: We measured plasma amino acid concentrations, 5-m walking speed, grip strength, and skeletal muscle mass using a bioelectrical impedance data acquisition system and compared them among participants at each stage of sarcopenia., Results: The proportions of normal, pre-sarcopenia, dynapenia, and sarcopenia patients were 40.5% (n=94), 12.1% (n=28), 26.3% (n=61), and 21.1% (n=49), respectively. Significant differences were observed for concentrations of leucine, branched-chain amino acid (BCAAs), and essential amino acid (EAAs) among the four groups (p<0.05), and the dynapenia and sarcopenia groups showed significantly lower concentrations of leucine than the normal group (p<0.05)., Conclusions: This study indicated a positive relationship between plasma leucine, BCAA and EAA concentrations and muscle function. A longitudinal study is needed to determine the causal relationship between leucine/BCAA concentrations and muscle function., Competing Interests: The authors have no potential conflicts of interest to disclose