Background Soccer performance involves frequent high-intensity efforts and often insufficient recovery, making neuromuscular fatigue a critical factor in player monitoring. The drop jump (DJ) test, particularly the reactive strength index (RSI), has gained attention as a practical tool for assessing neuromuscular readiness. This study examined the relationship between accumulated external training load and neuromuscular status, assessed via DJ-derived metrics, in semi-professional soccer players. Methods Nineteen semi-professional outfield players (20.7 ± 1.4 years) were monitored over a 30-week competitive season, including 144 training sessions and 30 official matches. External load was tracked using 10 Hz Global Positioning System (GPS) devices. Neuromuscular performance was assessed weekly via the DJ test, measuring RSI, contact time (CT), and jump height (JH) with Optojump. Repeated-measures ANOVA evaluated longitudinal changes, and individual correlations were calculated across acute (7-day), chronic (28-day), and acute: chronic workload ratio periods. Results External load metrics varied significantly across microcycles, whereas DJ performance metrics remained stable at the group level. However, individual-level analyses revealed significant associations between external load and DJ-derived metrics (particularly between accelerations, decelerations, and high metabolic load distance with CT and JH) in both acute and chronic windows. Conclusion Neuromuscular responses to external training load appear highly individual among semi-professional soccer players. RSI and its components (CT and JH) should be interpreted separately to enhance decision-making regarding training and recovery. A multi-metric, individualized monitoring approach is recommended to optimize performance and reduce injury risk.
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