Dynamic balance ability in single-leg drop jump landing in junior female athletes after shin splints-assessment from a preventive perspective.

[Purpose] To develop assessment/rehabilitation indices for prevention of chronic and recurrent shin splint injuries among sport athletes, we analyzed the plantar center of pressure trajectories after drop-jump landing on one leg, and compared the foot function on the injured and healthy sides. [Participants and Methods] The participants were 10 female athletes who received consultation at our facility due to shin splints of the lower leg. The exercise task was the "single-leg drop jump landing test", in which the participants maintained a static posture on one leg for 8 s after landing. Using the collected data, the peak value of the vertical component of the floor-reaction force at the landing and the rectangular areas at 20-200 ms and 1-5 s after landing were calculated and compared between the healthy and affected sides. [Results] The peak value of the vertical component and the rectangular area at 20-200-ms were significantly larger on the affected side. However, the value for the 1-5-s rectangular area was significantly larger on the healthy side. [Conclusion] The feedforward function may have been reduced on the affected side in comparison with that on the healthy side, and the reduction in dynamic balance early after landing may have increased the influence of the non-vertical component. The 1-5-s rectangular area was smaller on the affected side than that on the healthy side, suggesting that the feedback function excessively worked on the affected side and caused immobility by excessively locking the joint in single-leg balance and reducing body sway.