Five vertical jump metrics provide a comprehensive assessment of recovery following anterior cruciate ligament reconstruction

OBJECTIVES: To identify and compare the unique physical qualities measured during vertical jump testing in individuals following anterior cruciate ligament reconstruction (ACLR), and explore how these qualities change over time. DESIGN: Longitudinal, cohort study. PARTICIPANTS: Thirty participants completed testing at 6-, 9-, and 12-months following primary ACLR. MAIN OUTCOMES: Vertical ground reaction forces during single and double leg countermovement jumps (CMJ) and drop vertical jumps (DVJ) were recorded using dual force platforms. Sparse principal component analyses were conducted, and linear mixed models were used to explore how principal component (PC) scores changed over time. RESULTS: Five PCs were identified in both limbs: PC1) force/impulse/power, PC2) contraction time, PC3) concentric velocity/jump height, PC4) contact time/depth, and PC5) eccentric peak velocity. Scores for PC1, PC3 and PC5 increased over time, while PC4 decreased (P < 0.001). Scores for PC1, PC3 and PC5 were lower in the reconstructed limb compared to the uninjured contralateral limb (P < 0.001) and displayed a reduction in between-limb asymmetry over time (P < 0.05). CONCLUSIONS: Considerable redundancies are present in conventional vertical jump testing practices used during ACLR rehabilitation. Testing batteries could likely be refined to one or two jump types and a small subset of metrics without loss of meaningful information.