Fastpitch · fundamentals
The windmill, from the ground up.
The windmill, in four phases
Biomechanics splits the delivery into four phases: wind-up, stride, acceleration, and follow-through. Each phase continues the motion started by the one before it.
Wind-up
From the onset of movement until the stride-foot toe leaves the ground. The pitcher shifts weight onto the drive leg while the arm and glove action set the delivery in motion.
Stride
From drive-leg lift to stride-foot contact. The drive leg extends to move the body toward the plate while the arm climbs the back of the circle.
Acceleration
From stride-foot contact through ball release. The arm moves down the front of the circle and the hand delivers the ball from the low release slot.
Follow-through
From release through the end of the motion. The arm continues forward while the trunk and lower half carry the pitcher into a balanced finish.
Where the speed comes from
The windmill is a whole-body sequence. The lower half starts the move, the trunk carries it forward, and the arm circle completes it at release.
The drive-leg push moves the pitcher toward the plate while the arm circle develops behind it.
Hip extension and rotation contribute to the stride and help set the trunk in motion before release.
The delivery follows a lower-body-to-trunk-to-arm sequence; changing that order changes the timing and pace of the pitch.
The broad sequence is well supported; exact timing within the windmill remains an active research question.
The rules that shape the craft
A few rules define a legal fastpitch delivery. They shape what the lower half can do off the rubber and how far the ball travels.
Competitive fastpitch is thrown from 43 feet at the college and high-school levels, with the underhand windmill as the game’s defining delivery.
Starting in 2023-24, the NCAA made leaping legal: a pitcher may push off and have both feet airborne during the stride. Replanting the pivot foot before delivering remains illegal.
A recent change in what the lower half may do after leaving the rubber.
Next: the arsenal that lives on this delivery. The rise, the drop, and the rest.
The softball wing