Does External Focus Instruction Provide Superior Jump-landing Kinematics Compared to Internal Focus

Poor biomechanics during jump-landing are linked to an increased risk of ACL injury. Training using internally (IF) or externally (EF) focused verbal instruction may improve landing mechanics. Further research is needed to determine the effects of instruction on hip and knee biomechanics. The purpose of this investigation was to evaluate differences in knee and hip kinematics between those who receive EF, IF or control (CON) instruction. Participants were screened using the landing error scoring system to determine the presence of poor landing mechanics and randomly assigned to a group (EF, IF, or CON). Pretest kinematic data was recorded while participants completed five trials of a standardized jump-landing task. Immediately after, the respective intervention (EF, IF, CON instruction) was given, the participant performed 6 sets of 6 jump-landings and posttest kinematic data was recorded. Data was analyzed with repeated measures ANOVA comparing knee and hip angles at maximum knee flexion across intervention groups (EF,IF,CON) and time (pretest, posttest). LSD post hoc testing was performed. A priori alpha level was set at p\u3c0.05. Significant main effects were found for time in hip sagittal plane angles (mean difference=5.1° greater hip flexion, p=.001), knee sagittal plane angles (mean difference=9.1° greater knee flexion, p=.0001), hip frontal plane angles (mean difference= 2.5° greater hip abduction, and knee frontal plane angles (mean difference= 4.3° greater knee adduction, p=.001). There was no significant interaction between groups or time for the joint angles. Greater, clinically meaningful changes were noted in hip and knee flexion, regardless of instruction. It is possible that participants experienced fatigue after jump-landing tasks that caused changes in hip and knee mechanics, particularly increased flexion. Participants may have had previous instruction on jump-landing performance that allowed them to make proper changes to hip and knee mechanics, regardless of the instruction being given to them