## 4 Discussion  
The present study aimed to examine whether muscular variables, including skeletal muscle mass, muscular strength, and anaerobic power, are related to arterial stiffness, an independent risk factor for cardiovascular disease. The major findings of the present study were that higher skeletal muscle mass, muscular strength, and anaerobic power were associated with decreased AIx, while baPWV was not associated with these muscular variables in physically-active young male adults. This finding is consistent with the previous study, which reported a negative correlation between muscle mass and AIx in both males and females over 65 years of age [32]. In addition, according to study by [PERSON] et al., it represented a negative correlation between muscle strength and cf-PWV in 79 young male adults [21]; nevertheless, whether a correlation exists between AIx as a determinant of cf-PWV and muscle strength remains unknown. However, this study presented negative correlations between muscle strength and AIx, including corrected age, height, and heart rate 75 bpm. Interestingly, anaerobic power showed a negative correlation with AIx in the present study. Anaerobic power, which is an ability to express explosive energy, is an essential element for independent daily life [23]. It is well known that anaerobic power increases with elevated muscle mass and muscular strength and is improved with anaerobic training via short-term whole-body exercise [33]. Furthermore, it was reported that anaerobic power was reduced with aging and that the anaerobic energy system declined across the aging process without alteration in aerobic capacity in trained masters athletes [34]. For the most part, previous studies have examined anaerobic power in relation to sports-related performance in athletes [35; 36], however, few studies have confirmed its correlation with cardiovascular risk factors [23; 37]. According to previous studies, anaerobic exercise performed along with aerobic exercise has a positive effect on enhancing cardiovascular health by improving lipid components and BMI, and it improves vascular function by promoting vasodilators such as nitric oxide through high-intensity interval training [23; 24; 38]. Based on the results of this study and on those of previous studies, maintaining and increasing anaerobic power to a higher level may have a positive effect on AIx. In the present study, skeletal muscle mass, muscular strength, and anaerobic power were not correlated with baPWV. [PERSON] et al. have shown that baPWV was positively correlated with aortic PWV as well as with leg PWV [15]. Particularly, they suggested that baPWV was associated with central arterial stiffness, suggesting that baPWV may reflect central arterial stiffness as well as peripheral arterial stiffness [15; 39]. However, [PERSON] et al. indicated that baPWV was correlated with both central and peripheral arterial stiffness, but its correlation with peripheral arterial stiffness was stronger [40]. In addition, [PERSON] et al. suggested that it is clinically meaningful to evaluate central arterial stiffness rather than peripheral arterial stiffness while assessing cardiovascular diseases [16]. Taken together, central arterial stiffness may be an accurate indicator for the assessment of cardiovascular risk factors in a relatively younger age group [41]. Arterial stiffness shows a high incidence in patients with hypertension, and blood pressure is an index for predicting arterial stiffness even in young adolescents. Moreover, peripheral SBP was higher than central SBP even in adolescents, suggesting that peripheral arterial stiffness is greatly affected by blood pressure even in a relatively younger age group [42]. In case of young male adults in this study, the systolic (119.4 mmHg \(\pm\) 2.1) and diastolic (66.9 mmHg \(\pm\) 2.0) blood pressure measurements were within the normal range. Hence, baPWV may not show significant correlation in younger individuals unlike other age groups.