Segmental Body Composition, Perceived Exertion, and Central Adiposity as Independent Determinants of Cardiorespiratory Fitness in Young Asian Adults

<title>Abstract</title> <p> <bold>Background</bold> Cardiorespiratory fitness (VO _2max ) is a key indicator of cardiovascular and metabolic health in young adults. While overall body mass and total body fat percentage (TBF) influence aerobic capacity, the independent predictive value of localized regional subcutaneous fat (SF) and regional skeletal muscle mass (SM) compartments remains unclear. This study evaluated the independent anthropometric, segmental body composition, clinical, and exertional correlates of VO _2max in young adults. <bold>Methods</bold> A cross-sectional study was conducted among 726 young Asian adults (57.7% females; median age 21 ± 2 years) in Malaysia. Physical health metrics, central adiposity (waist circumference [WC]), and bioelectrical impedance measures of TBF and segmental tissue percentages—including whole-body, trunk, arm, and leg subcutaneous fat (SF) and skeletal muscle (SM)—were assessed. VO _2max was evaluated via the three-minute step test, and submaximal Rating of Perceived Exertion (RPE) was recorded. A multivariable Generalized Linear Model identified independent predictors of VO _2max . <bold>Results</bold> Male sex emerged as the strongest positive predictor of VO _2max (B = 17.769, <italic>p</italic> &lt; 0.001). Overall TBF (B = -0.295, <italic>p</italic> = 0.013) and WC (B = -0.237, <italic>p</italic> = 0.027) maintained significant negative independent associations with VO _2max . Controlling for TBF and WC eliminated the statistical significance of all individual segmental SF ( <italic>p</italic> &gt; 0.05). In adjusted models, upper-body muscle parameters exhibited mathematical suppression effects (Trunk SM: B = -0.013, <italic>p</italic> = 0.009; Arms SM: B = -0.285, <italic>p</italic> = 0.022), while submaximal RPE acted as a strong, inverse independent predictor of aerobic capacity (B = -0.486, <italic>p</italic> &lt; 0.001). <bold>Conclusion</bold> Male sex, lower TBF, lower central adiposity (WC), and lower submaximal perceived exertion (RPE) are the primary independent predictors of superior VO _2max in young Asian adults. Systemic total fat burden and central abdominal adiposity exert a more pronounced negative impact on aerobic capacity than regional subcutaneous fat distribution. </p>