Does attentional focus influence performance and motor control on a gross motor task performed with the legs among healthy individuals and individuals with anterior cruciate ligament reconstruction? : A within subject design pilot study

Background: Evidence indicates that an external focus (EF) of attention on the intended effect of one’s movement results in better motor performance and motor control than an internal focus (IF) on one’s own body. Despite this, an IF is predominantly encouraged through instructions and feedback provided by clinicians during sports and rehabilitation from injuries such as anterior cruciate ligament (ACL) injury. Aim: The aim of this pilot study was to investigate the influence of EF and IF on motor control and performance on a bilateral leg extension and flexion task. The secondary aim was to investigate potential differences in the outcomes between a control group and a group with ACL reconstruction (ACLR). Method: Fourteen controls and four individuals with ACLR performed a bilateral leg extension and flexion task with instructions that encouraged either an IF, EF or neutral focus (NF) of attention. The instructions encouraged participants to either keep the individual tubes located on the footplates under the soles of the feet (EF) or the feet themselves (IF) level with each other. A three-dimensional motion capture system was used to record kinematics. Motor control was assessed based on the movement smoothness according to the knee angular velocity profile and performance was assessed based on the absolute mean deviation of the tubes/footplates from parallel. Results: For the control group, IF instructions resulted in significantly better motor control than EF instructions for left knee movement smoothness (p=0.02) and NF instructions resulted in significantly better motor control than EF on a majority of dependent variables. Conclusion: For our task, EF instructions did not result in better outcomes compared to IF instructions which might be explained because the task was proprioceptive demanding with less involvement of the vision. The reason for better motor control with NF instructions compared to EF instructions might be because of differences in angular velocity and instructions between conditions