The Effect of Acute Focus of Attention Instructions on Biomechanical Indexes Associated With Anterior Cruciate Ligament Injury Prevention

Anterior cruciate ligament (ACL) injury is one of the most common and serious injuries of the knee joint, which accounts for 80% of all knee ligament surgeries. Studies have shown that a significant percentage of this injury (70%) occurs in a non-contact form, usually during activities like deceleration, landing, or side cutting. Studies have shown that focus instructions could improve and promote performance. This study aimed to investigate the acute effect of focus instructions on biomechanical indexes associated with ACL injury prevention.

In this research, 24 young football players from the two clubs of the Tehran Premier League, Tehran City, Iran, were randomly divided into two groups: external focus attention (n=12) and internal focus attention (n=12). First, the dynamic postural stability index (DPSI), the peak of vertical, anteroposterior, and mediolateral GRF components, and the rate of loading during the jump-landing movement from a box with 30 cm height were calculated using a force plate with a sampling frequency of 1000 Hz. Then, the internal and external focus instructions were taught to the participants, and the two groups performed a posttest to examine the changes. Statistical methods of repeated measures analysis of variance and paired t test were used to evaluate the changes.

The results showed significant changes in the vertical component and rate of loading variables in both groups of internal and external focus attention (P≤0.05). However, no significant difference was observed between the two groups in the DPSI, anteroposterior and mediolateral GRF.

The results of this study showed that acute instructions of both internal and external focus attention can improve landing mechanics and landing-related kinetic variables. It seems that the external focus instructions have increased the motor control of the limb, leading to a further reduction of vertical GRF and the load applied to the lower limb compared to the instructions of internal focus, thus reducing the risk of ACL injury.