Changes in Drop-Jump Landing Biomechanics During Prolonged Intermittent Exercise

Abstract

Background:As injury rates rise in the later stages of sporting activities, a better understanding of lower extremity biomechanics in the later phases of gamelike situations may improve training and injury prevention programs.Hypothesis:Lower extremity biomechanics of a drop-jump task (extracted from a principal components analysis) would reveal factors associated with risk of anterior cruciate ligament injury during a 90-minute individualized intermittent exercise protocol (IEP) and for 1 hour following the IEP.Study Design:Controlled laboratory study.Level of Evidence:Level 4.Methods:Fifty-nine athletes (29 women, 30 men) completed 3 sessions. The first session assessed fitness for an IEP designed to simulate the demands of a soccer match. An experimental session assessed drop-jump biomechanics, after a dynamic warm-up, every 15 minutes during the 90-minute IEP, and for 1 hour following the IEP. A control session with no exercise assessed drop-jump performance at the same intervals.Results:Two biomechanical factors early in the first half (hip flexion at initial contact and hip loading; ankle loading and knee shear force) decreased at the end of the IEP and into the 60-minute recovery period, while a third factor (knee loading) decreased only during the recovery period (P ≤ 0.05).Conclusion:The individualized sport-specific IEP may have more subtle effects on landing biomechanics when compared with short-term, exhaustive fatigue protocols.Clinical Relevance:Potentially injurious landing biomechanics may not occur until the later stages of soccer activity.

Changes in Fatigue, Multiplanar Knee Laxity, and Landing Biomechanics During Intermittent Exercise

“…Yo-Yo IR1 results by sport have been previously reported 25 and are consistent with the range in values seen in athletes performing at the recreational and subelite levels. 29 Table 1 provides a clinical description of each of the 11 biomechanical factors derived from the principal components analysis and the combination of kinematic and kinetic variables that loaded strongly on each factor.…”

“…29 Table 1 provides a clinical description of each of the 11 biomechanical factors derived from the principal components analysis and the combination of kinematic and kinetic variables that loaded strongly on each factor. 25 For descriptive purposes, Figure 3 displays the direction and magnitude of changes in SP TIME and multiplanar knee laxity during the IEP for each sex. A full reporting of these results is provided by Shultz et al 15 5.08.S1), display the direction and magnitude of changes in each of the 11 biomechanical factor scores during the IEP for each sex.…”

“…Given the purpose of the study, only the experimental condition is reported. Researchers have described the development of the IEP in detail 24 and have characterized knee-laxity changes 15 and biomechanical changes 25 in response to this IEP by comparing data between control and experimental conditions.…”

“…15 Collectively, these findings provide additional insight into the mechanisms by which greater knee-joint laxity may be associated with ACL injury risk. [1][2][3]5,6,25 Although knee laxity often is considered a nonmodifiable anatomic risk factor, researchers 40 who noted strong correlations between knee-joint laxity and muscle mass about the knee have suggested that reductions in knee laxity through strength-training interventions may be plausible.…”

Real‐time biofeedback integrated into neuromuscular training reduces high‐risk knee biomechanics and increases functional brain connectivity: A preliminary longitudinal investigation

“…Risk of musculoskeletal injury, specifically anterior cruciate ligament (ACL) injury, is associated with decreased neuromuscular control and coordination during dynamic activities (Griffin et al, ; Hewett et al, ; Hewett, Torg, & Boden, ; Ireland, ; Krosshaug, Slauterbeck, Engebretsen, & Bahr, ; Zazulak, Hewett, Reeves, Goldberg, & Cholewicki, ). Advances in 3D motion analyses and force platforms have permitted the assessment of neuromuscular coordination using the drop vertical jump (DVJ) (Chaudhari et al, ; Cruz et al, ; DiCesare, Kiefer, Bonnette, & Myer, ; Doherty et al, ; Earl, Monteiro, & Snyder, ; Etnoyer, Cortes, Ringleb, Van Lunen, & Onate, ; Ford, Myer, & Hewett, , ; Hewett et al, ; Limroongreungrat & Boonkerd, ; McLean et al, ; Paterno et al, ; Popovic et al, ; Schmitz et al, ; Taylor et al, ). During the landing phase of the DVJ, tri‐planar hip, knee, and ankle motion that results in the knee collapsing toward the midline, or “dynamic valgus,” is quantified via an external peak knee abduction moment (pKAM) (Carson & Ford, ; Ford, Myer, & Hewett, ; Ford et al, ; Ford, Shapiro, Myer, Van Den Bogert, & Hewett, ; Galloway et al, ; Hewett et al, ; Malfait et al, ; Myer et al, , , ).…”