Triangulating lower-extremity neuromuscular function in soccer players: The incremental value of twitch kinetics and neural activation over muscle architecture in performance testing

This study determined the physiological correlates of lower-extremity performance capacity in trained male soccer players by integrating assessments of muscle twitch mechanics, neural activation, and architecture. Forty-four trained male soccer players underwent vastus lateralis (VL) assessments using tensiomyography (TMG), surface electromyography (normalised to maximal voluntary contraction; %MVC), and ultrasonography (muscle thickness, pennation angle, and estimated fascicle length). Lower-extremity performance capacity was operationalised as countermovement jump (CMJ) height and half-squat one-repetition maximum (1RM). Stepwise multiple linear regression analyses were performed to identify the variables most strongly associated with performance. The models explained 34% of the variance in CMJ height and 42% of the variance in 1RM strength (p < 0.001). Jump performance was independently associated with greater neural activation (%MVC) and twitch displacement (Dm), and with shorter sustained time (Ts). Maximal strength was associated with longer contraction time (Tc), greater Dm, and higher %MVC. Muscle thickness was not retained in the final multivariate models despite its bivariate correlation with strength; estimated fascicle length was unrelated to jump performance and did not improve model fit. In trained male soccer players, lower-extremity performance capacity was more closely related to evoked twitch electro-mechanical characteristics and activation intensity than to resting muscle architecture.Trial registration: ClinicalTrials.gov NCT06982937 (registered 5 May 2025).