Acute neuromuscular responses in young trail runners: Immediate, post-, and delayed effects on squat and countermovement jump performance

Abstract

This study investigated the acute neuromuscular responses to a competitive mountain trail race in young elite and well-trained runners by analyzing changes in squat jump (SJ), countermovement jump (CMJ), and the derived elastic component (CMJ–SJ). Thirty-six participants (29 men, 7 women; 18.3 ± 1.2 years), competed in a 14.20 km trail running race with a positive elevation gain of 420 m. Each participant performed two SJ and two CMJ trials at three points: before the race (PRE), immediately after finishing (POST), and approximately 5-7 min post-race (POST5). The best attempt of each test was recorded using a Chronojump Bosco System® platform. Data satisfied normality assumptions and were analyzed using a two-way repeated-measures ANOVA (time × sex). Significant main effects of time were observed for both SJ (F(1.33, 45.34) = 17.75, p < .001, η²ₚ = .34) and CMJ (F(1.16, 39.54) = 23.71, p < .001, η²ₚ = .41). Post hoc analyses revealed a potentiation effect immediately after the race (PRE < POST, p < .001) followed by a significant decrease after 5-7 minutes (POST > POST5, p < .01), with values falling below baseline (PRE > POST5, p < .05). No significant changes were detected in the elastic component (p = .60), suggesting that the stretch–shortening efficiency remained stable. These findings indicate that short-duration trail running elicits a transient enhancement of lower-limb power likely associated with post-activation potentiation, followed by neuromuscular fatigue. Monitoring jump performance may therefore provide a sensitive tool for tracking acute load and recovery in young endurance athletes.