Sport specialization and coordination differences in multisport adolescent female basketball, soccer, and volleyball athletes

Context: Early sport specialization, or the participation in 1 sport year-round to the exclusion of all others, is a growing concern in youth athletics because of its possible association with musculoskeletal injury. The underlying injury risk may be the result of coordination differences that sport-specialized athletes have been speculated to exhibit relative to multisport athletes; however, little evidence exists to support or refute this notion. Objective: To examine relative hip- and knee-joint angular-motion variability among adolescent sport-specialized and multisport female adolescent athletes to determine how sport specialization may affect coordination. Design: Cohort study. Setting: Research laboratory. Patients or Other Participants: A total of 366 sport-specialized and 366 multisport adolescent female basketball, soccer, and volleyball players. Intervention(s): Drop-vertical-jump (DVJ) assessment. Main Outcome Measure(s): Average coupling-angle variability (CAV) for hip flexion and knee flexion, knee flexion and ankle flexion, hip flexion and knee abduction, knee flexion and knee abduction, knee flexion and knee internal rotation, and knee abduction and knee internal rotation. Results: The sport-specialized group exhibited increased coupling variability in dominant-limb hip flexion and knee flexion (P =.015), knee flexion and knee abduction (P =.014), and knee flexion and knee internal rotation (P =.048) while landing during the DVJ, although they had small effect sizes (η² = 0.010, 0.010, and 0.007, respectively). No differences were present between groups for any of the other CAV measures of the dominant limb, and no differences were found for any CAV measures of the nondominant limb (all P values >.05). Conclusions: Sport specialization was associated with increased variability of critical hip- and knee-joint couplings responsible for effective landing during the DVJ. Altered coordination strategies that involve the hip and knee joints may underlie unstable landings, inefficient force-absorption strategies, or greater contact forces that can place the lower extremities at risk for injury (or a combination of these).