@article{ref1,
title="Effect of heading a soccer ball as an external focus during a drop vertical jump task",
journal="Orthopaedic journal of sports medicine",
year="2023",
author="Akbari, Hadi and Kuwano, Satoshi and Shimokochi, Yohei",
volume="11",
number="4",
pages="e23259671231164706-e23259671231164706",
abstract="BACKGROUND: Research has demonstrated that performing a secondary task during a drop vertical jump (DVJ) may affect landing kinetics and kinematics. <br><br>PURPOSE: To examine the differences in the trunk and lower extremity biomechanics associated with anterior cruciate ligament (ACL) injury risk factors between a standard DVJ and a DVJ while heading a soccer ball (header DVJ). STUDY DESIGN: Descriptive laboratory study. <br><br>METHODS: Participants comprised 24 college-level soccer players (18 female and 6 male; mean ± SD age, 20.04 ± 1.12 years; height, 165.75 ± 7.25 cm; weight, 60.95 ± 8.47 kg). Each participant completed a standard DVJ and a header DVJ, and biomechanics were recorded using an electromagnetic tracking system and force plate. The difference (Δ) in 3-dimensional trunk, hip, knee, and ankle biomechanics between the tasks was analyzed. In addition, for each biomechanical variable, the correlation between the data from the 2 tasks was calculated. <br><br>RESULTS: Compared to the standard DVJ, performing the header DVJ led to significantly reduced peak knee flexion angle (Δ = 5.35°; P =.002), knee flexion displacement (Δ = 3.89°; P =.015), hip flexion angle at initial contact (Δ = -2.84°; P =.001), peak trunk flexion angle (Δ = 13.11°; P =.006), and center of mass vertical displacement (Δ = -0.02m; P =.010), and increased peak anterior tibial shear force (Δ = -0.72 N/kg; P =.020), trunk lateral flexion angle at initial contact (Δ = 1.55°; P <.0001), peak trunk lateral flexion angle (Δ = 1.34°; P =.003), knee joint stiffness (Δ = 0.002 N*m/kg/deg; P =.017), and leg stiffness (Δ = 8.46 N/kg/m; P =.046) compared to those in standard DVJs. In addition, individuals' data for these variables were highly and positively correlated between conditions (r = 0.632-0.908; P <.001). <br><br>CONCLUSION: The header DVJ task showed kinetic and kinematic parameters that suggested increased risk of ACL injury as compared with the standard DVJ task. CLINICAL RELEVANCE: Athletes may benefit from acquiring the ability to safely perform header DVJs to prevent ACL injury. To simulate real-time competition situations, coaches and athletic trainers should incorporate such dual tasks in ACL injury prevention programs.<p /> <p>Language: en</p>",
language="en",
issn="2325-9671",
doi="10.1177/23259671231164706",
url="http://dx.doi.org/10.1177/23259671231164706"
}