Effects of Visual Occlusion on Lower Extremity Biomechanics during a Low-Intensity Single-Leg Landing.

Visual information is crucial for motor control during a jump-landing, allowing for anticipation of landing timing and prediction of the impact. However, the effects of visual occlusion on lower extremity biomechanics are not well understood. To investigate this, we studied the impact of visual occlusion on motor control during a low-intensity single-leg landing. Seventeen female college students participated in the controlled laboratory investigation. They performed low-intensity repetitive vertical hopping on a single leg under eyes-open (EO) and eyes-closed (EC) conditions. Main outcome measurements were taken, including jump height, ground reaction forces, joint angles, and joint moments, using a motion capture system. The significant effects of visual occlusion were as follows: 1) a decrease in the hip flexion angle at ground contact (p = 0.02), 2) an increase in Fx (medio-lateral ground reaction force), knee valgus, and internal rotation angles in the early phase within 80 ms after ground contact (p < 0.05), and 3) an increase in Fz (vertical ground reaction force) and a reduction in hip and knee flexion angles at peak Fz (p < 0.05). The amount of angular change at the ankle joint correlated with the hip and knee joints only under the EC condition (p < 0.05). These changes indicate modifications in landing strategy for safety and/or deficiencies in control for an efficient and accurate landing. In conclusion, visual information contributes to safe and accurate motor control during low-intensity landing movements.