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An eight-segment angle-driven simulation model of the trunk and upper limbs plus ball was developed to determine which joint angle changes have most influence on ball release speed. 15 overarm throwing trials were recorded, and the joint angle time histories of each trial were input into the simulation model. Systematically replacing specific joint angle time histories with a constant value and observing the effect on ball release speed showed that overarm throwing was most sensitive to trunk extension/flexion, trunk ext./internal rotation, scapula ext./internal rotation, upper arm flexion/extension, upper arm add/abduction, upper arm ext./internal rotation and forearm extension/flexion. During coaching or performance, attention should be focused on these angles because any changes could have a substantial effect on the ball release speed.