Differential Neuromuscular Fatigue Responses in Multi- and Single-Joint Force Following a Simulated Soccer Protocol in Youth Players: Evidence for Divergent Assessment Sensitivity

Neuromuscular fatigue monitoring is widely used in soccer to evaluate recovery status, optimize training load, and reduce injury risk during congested training and match schedules. However, different neuromuscular assessments may reflect distinct aspects of fatigue and recovery, and the time-dependent sensitivity of commonly used force-based assessments remains unclear.

The purpose of this randomized crossover trial is to compare the time-course sensitivity of the countermovement jump (CMJ), isometric mid-thigh pull (IMTP), and isometric hamstring 90-90 (IH90-90) tests for detecting neuromuscular fatigue following a standardized soccer-specific fatigue protocol (T-SAFT90) in trained young male soccer players.

Eighteen trained male soccer players participate in the study. Neuromuscular performance is assessed before exercise, immediately after exercise, and at 24 and 48 hours following the fatigue protocol. The study evaluates changes in peak force and rapid force production characteristics obtained from single-joint and multi-joint isometric assessments, together with CMJ performance variables.

Participants complete the T-SAFT90 protocol designed to simulate the physiological and mechanical demands of competitive soccer activity. Following the protocol, participants perform a series of neuromuscular performance assessments across multiple recovery time points.

The study aims to determine which assessments are most sensitive for detecting acute and residual fatigue and whether single-joint and multi-joint force assessments demonstrate different recovery profiles. The findings may contribute to improved fatigue-monitoring strategies in soccer and assist practitioners in managing recovery and injury risk during periods of high training and match density.