Effect of anticipation on knee kinematics during a stop-jump task

- Knee rotational stability test is important after ligament reconstruction.
- A laboratory test usually does not consider the effect of anticipation.
- This study tested the knee stability during unanticipated stop-jumps.
- A short duration of 0.2 s was allowed in the test before a jump was made.
- Greater knee external rotation was found in unplanned jumps in some directions.

Knee stability during a functional assessment of the stop-jump task is a key factor to determine if an athlete is adequately rehabilitated after knee ligamentous injury. This study aimed to investigate knee stability due to the effect of anticipation on landing maneuvers during planned and unplanned stop-jump tasks. Knee kinematics of ten healthy male participants were collected using an optical motion analysis system during stop-jump tasks. Stop jumps were performed in four different landing positions either in planned movement or in an unplanned movement on a signal triggered as participants passed through a photocell gate. Kinematic data at the time of foot strike at landing in the stop-jump considered for investigating the anticipation effect during the stop-jump tasks. Two-way multivariate analysis of variance (MANOVA) with repeated measures and stratified paired t-tests were conducted to compare the knee kinematics data between planned and unplanned tasks. Statistical significance was set at the p < 0.05 level. External rotational angle showed a significant decrease in unplanned stop-jump tasks during forward (p < 0.05) and right (p < 0.05) jumps when compared to that of planned tasks. Flexion angle and abduction angle during forward, vertical and right jumps were significantly decreased in the unplanned tasks. Anticipation significantly influenced the landing maneuvers of stop-jump task. The results indicated that both planned and unplanned stop-jump tasks should be considered when monitoring the rehabilitation progress after a ligamentous injury.