Relationship between Center of Pressure Index and Foot Alignment in Single Leg Stepping with Different Loads by College Baseball Players

[Purpose] This study compared the postural balance among three posture conditions, single leg standing (Condition I), single leg forward stepping (Condition II), and single leg forward stepping from a box (Condition III), and examined the relationship between balance and the foot alignment indices. [Participants and Methods] The participants were 64 college baseball players. The foot alignment indices were the medial longitudinal arch height, the lateral angles of the first and fifth toes, the angle between the first and fifth toes, and the foot width/length ratio. The balance indices were defined as the center of pressure (COP) velocity and area during the acute and stable phases of each condition. [Results] The COP velocity in the acute phase became significantly higher as the load increased on the foot, but significant difference was not observed between the COP velocity in Condition II and Condition III during the stable phase. No significant correlations were found between the foot alignment indices and COP velocity in Condition III. [Conclusion] The postural balance during the acute phase was affected by the movement direction of the center of gravity and the impact force, and the preparatory movement before foot contact might have been affected in the stable phase. It is possible that the center of gravity sway was related to joint movements above the foot in Condition III.