Dayna LeClair, “Does Instruction Provide Changes in Jump Landing Mechanics?”
Mentor: Hayley Ericksen, Kinesiology
Increased knee abduction and hip adduction angles during jump-landing have been linked to increased risk of non-contact ACL injury in females. Exercise interventions to reduce injury risk include using internally(IF) or externally(EF) focused verbal instruction. The purpose of this investigation was to evaluate differences in hip and knee kinematics between those who received EF, IF instruction and controls (CON). Participants were randomly assigned to one of 3 groups EF (n=15), IF (n=14), or CON (n=10). Pretest kinematic data was recorded while participants completed five trials of a standardized jump-landing task. Immediately after, EF, IF, or CON instruction was given while the participant performed 6 sets of 6 jump landings. Following the intervention, posttest kinematic data was recorded while participants performed the same jump-landing task. Data were analyzed with a repeated measures ANOVA comparing hip and knee angles at maximum knee flexion across groups (EF,IF,CON) and time (pretest, posttest). Alpha levels were set at p<0.05. Significant main effects for time were found in hip and knee sagittal plane angles (p=0.0001), hip frontal plane angles (p=0.001), and knee frontal plane angles (p=0.0001). Specifically, mean differences from pretest and posttest included 5.1 degrees of increased hip flexion, 9.1 degrees of increased knee flexion, 2.5 degrees of increased hip abduction and 4.3 degrees of increased knee adduction. No significant interactions between groups and time were found. This study found increases in hip flexion, hip abduction, knee flexion, and adduction in all participants, regardless of group. These changes reflect an improved movement pattern, thought to be less risky for knee injuries. The EF and IF instruction both created the desired result and demonstrated improvements in jump-landing mechanics. We found that the CON group also made improvements even though the instruction they received did not directly address changing landing mechanics.