Background Methods that facilitate muscle quality measurement may improve the diagnosis of sarcopenia. Current research has focused on the phase angle (PhA) obtained through bioelectrical impedance analysis (BIA) as an indicator of cellular health, particularly cell membrane integrity and cell function. The current study therefore aimed to evaluate the relationship between the PhA and muscle quality and muscle‐related parameters and to determine factors associated with the PhA. Moreover, we attempted to determine the cut‐off value of PhA for predicting sarcopenia. Methods First‐year university students (830 male students, 18.5 ± 0.6 years old; 422 female students, 18.3 ± 0.5 years old) and community‐dwelling elderly individuals (70 male individuals, 74.4 ± 5.5 years old; 97 female individuals, 73.1 ± 6.4 years old) were included. PhA and other body composition data were measured using BIA, while muscle quality was calculated by dividing handgrip strength by upper limbs muscle mass. The relationship between PhA and the aforementioned parameters were then analysed, after which the cut‐off value of PhA for predicting sarcopenia was examined. Results Multiple linear regression analysis revealed that age, skeletal muscle mass index (SMI), and muscle quality were independently associated with PhA in both sexes [male (age: standardized regression coefficient (β) = −0.43, P < 0.001, SMI: β = 0.61, P < 0.001, muscle quality: β = 0.13, P < 0.001) and female (age: β = −0.56, P < 0.001, SMI: β = 0.52, P < 0.001, muscle quality: β = 0.09, P = 0.007)]. Participants with sarcopenia had a significantly lower PhA compared with those without it (sarcopenia vs. non‐sarcopenia: young male participants, 5.51 ± 0.41° vs. 6.25 ± 0.50°, P < 0.001; young female participants, 4.88 ± 0.16° vs. 5.37 ± 0.44°, P = 0.005; elderly female participants: 4.14 ± 0.29° vs. 4.63 ± 0.42°, P = 0.009). Although no significant findings were observed in elderly male participants, the same tendency was noted. Receiver operating characteristic (ROC) curve analysis indicated that PhA had good predictive ability for sarcopenia in young male, elderly male, young female, and elderly female participants (area under the ROC curve of 0.882, 0.838, 0.865, and 0.850, with cut‐off PhA values of 5.95°, 5.04°, 5.02°, and 4.20° for predicting sarcopenia, respectively). Conclusions The PhA reflected muscle quality and exhibited good accuracy in detecting sarcopenia, suggesting its utility as an index for easily measuring muscle quality, which could improve the diagnosis of sarcopenia.

Purpose To identify obese patients at high risk of cardiovascular disease (CVD) using a combined index of obesity and sarcopenia. Methods In this cross-sectional study, we firstly conducted analysis of covariance to select each index most associated with the CVD risk score, the number of concomitant CVD risk factors, among obesity- (body mass index, percentage body fat, or waist circumference [WC]) and sarcopenia-evaluated indices (skeletal muscle mass index, handgrip strength, or muscle quality [MQ]), respectively in 188 Japanese obese patients (BMI ≥ 25 kg/m2, 73 men and 115 women). Next, we conducted multivariate logistic regression analysis to compare the four groups (Group A–D) classified by medians of the selected indices. Results WC and MQ were selected as the indices most associated with the CVD risk scores, respectively. The CVD risk score was significantly higher in Group B (low WC and low MQ) and Group D (high WC and low MQ) with higher prevalence of diabetes as compared with Group A (low WC and high MQ). Adjusted for sex and age, odds ratios for CVD risk scores = 2 were significantly higher in Group B, Group C (high WC and high MQ), and Group D compared with Group A. Furthermore, odds ratios for CVD risk scores = 3 were significantly higher only in Group D compared with Group A (4.29 [95% confidence interval: 1.49–12.33], p = 0.007). Conclusion Combined index of WC and MQ was useful in Japanese obese patients at high risk of CVD, regardless sex and age.

Background: Aging individuals are prone to sarcopenic obesity (SO). SO is associated with higher risks of low physical function, metabolic diseases, cardiovascular disease (CVD), and mortality. Worldwide diagnostic criteria for SO and its cutoff values have not yet been established. In this study, from among obesity- and sarcopenia-evaluated indices, we determined a combined index most associated with the accumulation of CVD risk factors in obese patients.Methods: In this cross-sectional study, we evaluated body composition using a multifrequency bioelectrical impedance analysis device and measured handgrip strength in 188 obese patients (73 men and 115 women). We selected each index most associated with the accumulation of CVD risk factors among obesity- (body mass index, percentage body fat, or waist circumference [WC]) and sarcopenia-evaluated indices (skeletal mass index, handgrip strength, or muscle quantity [MQ]), respectively. We then classified obese patients into four groups (group C, control; group O, obesity alone; group S, sarcopenia alone; and group SO, sarcopenic obesity) using the two selected indices with each median value and compared the CVD risk score, the number of concomitant CVD risk factors, among the four groups.Results: Based on the dichotomous comparison, WC and MQ were selected as the indices most associated with CVD risk factor accumulation. The CVD risk score was significantly higher in groups S and SO as compared with group C (1.94 ± 0.80, 1.95 ± 0.91 vs. 1.41 ± 0.84, all p < 0.05). Odds ratios for CVD risk scores ≥2 were significantly higher in groups S, O, and SO compared with group C (4.78 [95% confidence interval {CI} 1.79-12.81], p = 0.002; 3.28 [95% CI 1.37-7.88], p = 0.008; 3.92 [95% CI 1.74-8.81], p = 0.001; respectively). Furthermore, odds ratios for CVD risk scores = 3 were significantly higher only in group SO compared with group C (4.29 [95% CI 1.49-12.33], p = 0.007).Conclusion: In obese patients, WC and MQ were most associated with the accumulation of CVD risk factors, respectively. Furthermore, classification using the combined index of WC and MQ reflects the accumulation of CVD risk factors in obese patients, regardless sex and age.