Jump performance and handgrip strength do not reflect acute fatigue in elite trail runners after the 2023 world trail running championship

Purpose Fatigue manifests as a decline in maximal voluntary contraction (MVC), driven by both central and peripheral factors. Studies have shown reduced maximum isometric force in knee extensor and plantar flexor muscles after ultradistance trail running. This study aimed to assess the effectiveness of jump tests [countermovement jump [CMJ] and 30 cm-height drop jump [DJ]] and handgrip strength tests in detecting acute neuromuscular fatigue among elite marathon trail runners following the 2023 Trail Running World Championship. Methods Eight elite athletes (4 males and 4 females; height: 168 ± 8.62 cm; weight: 56.18 ± 9.28 kg; age: 32.98 ± 5.43 years) were recruited. Paired samples T-Test analyses are used. Results No significant differences were found in all jumping variables except for the Reactive Strength Index (RSI) (t = 2.44, df = 7, p = 0.045), with a large effect size (ES = 0.862). Handgrip strength test analyses showed no significant reductions post-run. Conclusion RSI decreased while other performance variables remained unchanged. This suggests the athletes’ fatigue had less impact on their performance in these tests than anticipated, showing a less reactive jump strategy ( p < 0.05 for RSI) after the competition.