A functional modulation for timing a movement: a coordinative structure in baseball hitting.

In baseball hitting, a powerful bat-swing needs to be produced by utilizing ground reaction force (GRF) and it should also be temporally coordinated relative to the flight of the pitch. The temporal organization of hitting movements associated with these task requirements was investigated by analyzing GRF during hitting slow and fast pitches. The timing of stepping with a front foot and shifting weight forward was modulated relative to the pitch's speed. The temporal relation between successive motion phases was compensatory and timing variability progressively reduced up to ball-bat contact. These results demonstrated the coordinative structure of the hitting movement for timing the bat-swing relative to the pitch's flight.