The Biomechanics of Throwing

Abstract

The majority of shoulder injuries occur due to repetitive overhead movements, with baseball pitching being the most common mechanism for overuse injury. Before studying the treatment of these shoulder injuries, it is paramount that the health professional have an understanding of the etiology of and the underlying mechanisms for shoulder pathology. The act of overhead throwing is an eloquent full-body motion that requires tremendous coordination from the time of force generation to follow-through. The shoulder complex is a crucial component of the upper body kinetic chain as it transmits force created in the lower body to the arm and hand to produce velocity and accuracy with ball release. The focus of this article is on the biomechanics of the throwing motion, with emphasis on the kinematics of the shoulder. The established phases of the throwing motion will be reviewed in a stepwise manner and the contributions of osseous and soft-tissue structures to the successful completion of each phase will be discussed.

The Kinetic Chain Revisited: New Concepts on Throwing Mechanics and Injury

“…The thrower then transfers weight onto the back, stance leg. The trunk and upper body then rotate 90°, and the stride leg is elevated and flexed [2,10]. At the end of the wind‐up phase, the thrower should be in a balanced position on the single stance leg [2].…”

“…The overhead throwing motion is a complex activity that involves the entire body to achieve accuracy and velocity [1,2]. This activity is accomplished through activation of the kinetic chain , which refers to the mechanical linkages of body segments that allows for the sequential transfer of forces and motions when performing a task such as throwing [3,4].…”

“…This activity is accomplished through activation of the kinetic chain , which refers to the mechanical linkages of body segments that allows for the sequential transfer of forces and motions when performing a task such as throwing [3,4]. The kinetic chain has been studied with regard to its role in the normal overhead throwing motion and its impact on injury and decreased performance [1‐6]. The throwing motion is a fluid, continuous movement that starts with the lower extremities and core, which provides a base of support and helps generate kinetic energy that translates through the throwing arm, eventually culminating with the ball release from the hands and fingers.…”

“…The overhead throwing motion traditionally has been divided into 6 phases that primarily focus on upper extremity function: windup, stride, arm cocking, acceleration, deceleration, and follow‐through (Figure 1) [2,5,10]. The kinetic chain temporarily links multiple body segments during the phases of throwing motion, including the feet, which provide contact with the ground, maximize the ground reaction force, and create a stable proximal base for distal arm mobility [4].…”

Frequent Immediate Knowledge of Results Enhances the Increase of Throwing Velocity in Overarm Handball Performance

“…The velocity of the ball in an overarm throw depends on optimal throwing mechanics and body segments’ characteristics. The overarm throw is determined by a proximal-to-distal principle (Calabrese, 2013; Putnam, 1993; Wagner et al, 2012; Weber et al, 2014) which describes progressive contribution of body segments to the momentum of the throwing object, beginning from the base of support and progressing through to the hand. This progression can be observed by monitoring peak angular velocities of the involved segments or by monitoring the activation of the muscles moving these segments (Escamilla and Andrews, 2009; Hancock and Hawkins, 1996; Hirashima et al, 2002; Kelly et al, 2002).…”