The descriptive statistics for all groups.

ObjectivesThe aim of the present study is to examine the developmental trajectory of 3D-MOT performance in young soccer players, and to investigate the age-related 3D-MOT performance training effect.MethodsFirst, Experiment 1 assessed 3D-MOT performance of 404 male soccer players aged 12–18 years. Then, 127 athletes in Experiment 1 aged 13, 15, and 17 were selected as participants in Experiment 2, randomly assigned to intervention group and the control group. The intervention group but not the control group received 15 sessions of 3D-MOT training (3 sessions per day for 20 minutes for 5 days). Subsequently, post-test of 3D-MOT performance was conducted on the two groups.ResultsExperiment 1 showed that there was a significant main effect of age on the peak speed (p p = .018, d = −0.559). Experiment 2 revealed a significant main effect of the intervention, including peak speed (p p p ConclusionsThis research provide evidence that the 3D-MOT performance of young soccer players exhibits an increase between 13 and 15. Moreover, the results showed a significant training improvement in youth soccer players, but there was no significant relationship between the age-related development of 3D-MOT and the training effect in young soccer players. The above results provide new insights into soccer science and practice. Given the lack of data for those players younger than 12, this restricts the inference of whether there are potential sensitive periods. The study suggest that in the future, more evidence on athletes under the age of 12 be added to enhance the understanding of the full developmental trajectory of 3D-MOT performance in soccer players.