Muscle Architectural Predictors of Athlete Power: Integrating Muscle Thickness, Pennation, and Fascicle Length Using Structural Equation Modeling Approach

Muscle architecture parameters, including muscle thickness (MT), fascicle length (FL), and pennation angle (PA), play a critical role in determining muscle performance. This study utilized structural equation modeling (SEM) to investigate the structural relationships between these morphological features and key performance metrics in athletes. By examining how architectural variations contribute to force production and explosive power, the research aims to bridge gaps in understanding muscle–performance dynamics. The primary objective was to evaluate the influence of muscle architecture parameters (MT, FL, and PA) on muscle performance tests, including vertical jump height, leg press power, and one-repetition maximum (1RM) squat strength, through SEM analysis. The study selected 50 male athletes aged 18–25 years, each possessing at least three years of structured training experience. Muscle architecture was assessed via B-mode ultrasonography targeting the vastus lateralis muscle. Performance evaluations encompassed vertical jump height, leg press power output, and 1RM squat strength. Data normality was verified using the Shapiro–Wilk test, which indicated normal distribution for most variables except squat strength. SEM was employed to test hypothesized pathways, with model fit assessed through χ 2 , RMSEA, SRMR, and CFI indices. SEM demonstrated excellent model fit (χ 2 = 4.88, p = 0.770; RMSEA = 0.000; SRMR = 0.044; CFI = 1.000), confirming the validity of the proposed relationships. Muscle thickness was the strongest morphological predictor (β = 0.580), emphasizing its role in hypertrophy and force generation. Fascicle length showed a significant negative association (β = –0.410, p = 0.002), indicating potential limitations in maximal strength tasks despite benefits in speed-related activities. Pennation angle had a weak, non-significant effect (β = –0.167, p = 0.178), suggesting its influence is highly context-specific. Among performance measures, 1RM squat strength exerted the greatest impact (β = 0.963, p < 0.001), followed by vertical jump (β = 0.737) and leg press power (β = 0.630). These results highlight muscle thickness as a key driver of explosive performance, while maximal dynamic strength (1RM squat) emerges as the most reliable performance indicator. The findings offer practical implications for refining training protocols, enhancing talent scouting, and advancing theoretical frameworks of muscle–performance interactions in elite athletes.