Browsing by Author "Lawson, Drew"

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    Evaluation of Lower Body Strength and Landing Strategy of Elite Athletes After Anterior Cruciate Ligament Reconstruction with Hamstring Tendon Autograft
    (2021-09) Lawson, Drew; Herzog, Walter; Jordan, Matt; Edwards, W. Brent; Heard, S. Mark; Bertram, John
    The purpose of this study was to identify the effects of anterior cruciate ligament reconstruction (ACLR) using the semitendinosus tendon autograft on lower body strength capacity and landing strategy in athletes who had returned to competition. Additionally, we sought to identify strength metrics that influenced landing characteristics previously identified as risk factors for primary or subsequent ACL injury. In our first study, plyometric-trained athletes performed bilateral vertical drop landings (VDLs) initiated with a step off technique with each limb serving as the leading leg. Peak vertical ground reaction force (Fzpeak) and impulse in the first 100 ms after ground contact (Impulse100ms) was calculated for each limb under each lead leg condition. We identified that lead leg selection altered force-time characteristics and between limb symmetry, which may impact return to sport decision making after injury. In our second study, we recruited athletes with ACLR, non-injured, sport performance matched controls and non-injured, sport-matched but development-level controls to perform single leg landings from 25 cm and 50 cm heights and maximum voluntary contractions to assess strength about the knee and hip joints. The ACLR limb had knee flexion strength deficits compared to the contralateral limb and was stronger in hip abduction compared to the contralateral limb. The ACLR limb did not differ in any other comparisons, including across landing kinetics and kinematics. However, we observed main effects of strength on landing variables, highlighting the importance of lower body maximal strength on landing strategy. Together, these results suggest that it is important to use caution when assessing bilateral landing technique using VDL tasks, a common practice in clinical assessments following ACLR. Furthermore, we determined that lower body strength can largely be regained following ACLR, and as such movement strategies after ACLR can mimic that of healthy, elite athlete peers.