The control of slippage between a hand and an object is a fundamental factor to improving athletic performance in sports that require a strong grip, such as baseball. The friction between the ball and the fingertips during baseball pitching is thought to relate to pitching performance such as a ball spin rate and ball control. Previous studies showed that the pitching performance such as ball spin rate and ball control was decreased when the finger and ball was wet with water. This would be due to the reduction of friction between the finger and ball. However, it is unclear whether a slippage occurs between the finger and ball during the ball releasing process of baseball pitching. In this study, we conducted the fastball pitching experiment under different conditions of friction between the fingertips and the ball by applying water, rosin powder, and pine resin to the fingertips and investigated a slippage between the finger and ball during the ball releasing process from the ball and finger behavior based on high-speed camera images. The results indicated that a slippage occurred between a finger and ball during ball releasing process regardless of finger lubrication conditions. However, we found that a larger slippage occurred when the finger was wet with water compared to the other lubrication conditions.
