623 The windmill style fastpitch involves an array of motor skills requiring sequential coordination of the upper and lower extremities. Characteristic of the motion is a powerful drive and rapid transfer of force on to the striding lower extremity. This may result in a substantial breaking force over a short period of time. The purpose of this study was to determine the kinematic responses and magnitude of ground reaction forces (GRF) created by the stride leg in selected windmill pitches. Five female intercollegiate fastpitch softball pitchers (age: 22.6 yrs, body mass: 69.0 kg) performed 5 pitches of the fastball (FB), change-up (CH), dropball (DB), curveball (CB) and riseball (RB). Simultaneous recordings of video (60hz) and GRF (1000 hz) were obtained and synchronized for each trial. Kinematic variables evaluated were joint angle at contact (JAC), maximum angle (MAX) and minimum angle (MIN). Primary kinetic variables evaluated were first peak force (F1), second peak force (F2) and maximum brake force (Fb). Single factor ANOVAs revealed significant kinematic differences (p < 0.05) between pitches for MAX and MIN for hip, knee and ankle, as well as, differences in JAC for hip and knee. Greatest JAC occurred during the FB for the hip (23.0°) and CB for the knee (11.3°). MAX hip (23.7°) was recorded in the CB while MAX knee and ankle (21.0 & 8.8°) occurred in the CH. MIN hip and knee (12.63&6.5°) occurred in CH. MIN ankle (−8.7°-plantarflexion) occurred in RB. Kinetic results revealed greatest F1 occurred in RB (25.18 N/kg), whereas FB (25.4 N/kg) exhibited the highest values for F2. Overall, F2 was greater than F1 in all pitches except for the RB. RB (−16.2 N/kg) demonstrated significantly higher Fb. These findings may have relevance in injury prevention, mechanisms and rehabilitation, as well as optimal pitching technique.