Comparison of Drop Jump and Tuck Jump Knee Joint Kinematics in Elite Male Youth Soccer Players: Implications for Injury Risk Screening

Context: Despite the popularity of jump-landing tasks being used to identify injury risk factors, minimal data currently exist examining differences in knee kinematics during commonly used bilateral jumping tasks. This is especially the case for rebounding-based protocols involving young athletes. Objective: The purpose of this study was to compare the frontal plane projection angle (FPPA) during the drop vertical jump (DVJ) and tuck jump assessment (TJA) in a cohort of elite male youth soccer players of varying maturity status. Methods: A total of 57 male youth soccer players from an English championship soccer club participated in the study. Participants performed three trials of the DVJ and TJA, during which movement was recorded with two-dimensional video cameras. FPPA for both right (FPPA-r) and left (FPPA-l) legs, with values <180º indicative of medial knee displacement. Results: On a whole-group level, FPPA-r (172.7 ± 7.4 º versus 177.2 ± 11.7 º; p < 0.05; ES = 0.46) and FPPA-l (173.4 ± 7.3 º versus 179.2 ± 11.0 º; p < 0.05; ES = 0.62) was significantly greater for both limbs in the TJA compared to the DVJ; however, these differences were less consistent when grouped by maturity status. FPPA-r during the TJA was significantly and moderately greater in the circa-PHV group compared to the post-PHV cohorts (169.4 ± 6.4 º versus 175.3 ± 7.8 º; p < 0.05; ES = 0.49). Whole group data showed moderate relationships for FPPA-r and FPPA-l between the TJA and DVJ; however, stronger relationships were shown in circa and post-PHV players compared to the pre-PHV cohort. Conclusions: Considering that the TJA exposed players to a larger FPPA and was sensitive to between-group differences in FPPA-r, the TJA could be viewed as a more suitable screen for identifying FPPA in young male soccer players