The spine is crucial for transferring energy to the throwing arm! Using the kinetic chain for generation of energy involves a complex interplay of various body segments, including the pelvis and thoracic spine. The pelvis and thoracic spine play critical roles in creating and transferring energy during the pitching motion, contributing to the velocity, accuracy and arm health of the pitcher. Here's how the lower half transfers energy to the trunk and the thoracic spines role in transferring energy to the throwing arm increasing pitching velocity and reducing the risk of injury.

1. Pelvic Rotation:

The pelvis acts as a pivotal point in the pitching motion. As the pitcher starts the wind-up and prepares to deliver the ball, the pelvis plays a significant role in initiating the kinetic chain. The rotation of the pelvis serves as the starting point for the transfer of energy from the lower body to the upper body. The kinematic sequence relies on the proximal to distal energy transfer of the pelvis. The pelvis becomes a focal point of acceleration of energy from the ground being rotationally transferred to the trunk. Pelvis -> Trunk -> Arm. The body being interconnected we cannot discuss the role of the spine in pitching velocity and arm health without discussing the role of the pelvis.

2. Separation of Hips and Shoulders:

One of the key principles in pitching mechanics is the separation between the hips and shoulders. This separation is facilitated by the rotational movement of the pelvis. As the pelvis rotates, it creates a torque that leads to a delayed opening of the hips relative to the shoulders. This separation stores potential energy in the muscles and connective tissues of the torso. It is the X factor of high velocity pitching and requires tremendous timing, sequencing and coordination. Not to mention a very elastic trunk and mobile thoracic spine.

3. Elastic Energy Build-Up Through Thoracic Spine Rotation

The rotation of the pelvis, in conjunction with the delay in hip and shoulder separation, results in the stretching and loading of various muscles and connective tissues. This loading of tissues, often referred to as the "stretch-shortening cycle," stores elastic energy like a coiled spring. The elastic energy stored in the stretched muscles and connective tissues is released, contributing to the rapid acceleration of the thoracic spine's rotation. Professional pitchers land with 55 +/-6 degrees of upper torso rotation at front foot strike. This large range of thoracic rotation and timing of the maximal range of thoracic rotation at front foot strike illustrates the importance of thoracic mobility and the elite sequencing/timing high velocity throwers use. This mobility, timing and sequencing not only increases pitching velocity, but reduces the workload of the rotator cuff, shoulder and elbow thus reducing the risk of injury.

The purpose of this study was to quantify trunk axial rotation and angular acceleration in pitching and batting of elite baseball players. Healthy professional baseball pitchers (n ¼ 40) and batters (n ¼ 40) were studied. Reflective markers attached to each athlete were tracked at 240 Hz with an eight-camera automated digitizing system. Trunk axial rotation was computed as the angle between the pelvis and the upper trunk in the transverse plane. Trunk angular acceleration was the second derivative of axial rotation. Maximum trunk axial rotation (55 +/- 6) and angular acceleration (11,600 ^ 3,100 8/s2 ) in pitching occurred before ball release, approximately at the instant the front foot landed. Maximum trunk axial rotation (46 +/-9) and angular acceleration (7,200 ^ 2,800 8/s2 ) in batting occurred in the follow-through after ball contact. Thus, the most demanding instant for the trunk and spine was near front foot contact for pitching and after ball contact for batting.

4. Spinal Energy Flow Thoracic Rotation -> Thoracic Extension -> Thoracic Flexion

The energy generated by the coordinated movement of the pelvis and thoracic spine continues to travel up the kinetic chain. It eventually goes from thoracic rotation and the violent rotation of the trunk and seamlessly transitions into thoracic extension and supports maximal external rotation of the throwing arm. This final stretch of the arm and chest cavity accumulates with the forward tilt of the trunk and the thoracic spine going from extension into flexion and the arm launching from maximum external rotation into internal rotation and ball release. The thoracic spine helps the body assist with the energy transfer from the lower half to reach the arm, which acts as a whip delivering energy to the baseball. The energy is efficiently transferred to the ball during the arm's acceleration phase, resulting in higher pitch velocity.

Conclusion

In essence, the pelvis and thoracic spine work together to create a sequential transfer of energy through the body, from the lower body's initiation of movement to the final release of the ball. The controlled rotation of the pelvis and thoracic spine is essential for storing and releasing energy effectively, maximizing the pitcher's ability to generate pitching velocity. Proper mobility, mechanics and timing of these movements are crucial for minimizing the risk of injury and optimizing pitching performance.

This study investigated the effects of trunk rotation on shoulder rotational torques during pitching. A total of 38 pitchers from the professional, college, high school, and youth ranks were recruited for motion analysis. Professional pitchers demonstrated the least amount of rotational torque (p = .001) among skeletally mature players, while exhibiting the ability to rotate their trunks signiicantly later in the pitching cycle, as compared to other groups (p = .01). It was concluded that the timing of their rotation was optimized as to allow the throwing shoulder to move with decreased joint loading by conserving the momentum generated by the trunk. These results suggest that a speciic pattern in throwing can be utilized to increase the eficiency of the pitch, which would allow a player to improve performance with decreased risk of overuse injury. (3)

References:

Fleisig, Glenn S., et al. "Trunk axial rotation in baseball pitching and batting." Sports biomechanics 12.4 (2013): 324-333.
Yanai, Toshimasa, Ryan Crotin, and Tanghuizi Du. "Proximal to distal sequencing impacts on maximum shoulder joint angles and the risk of impingement in baseball pitching involving a scapular independent thoracohumeral model." Scandinavian Journal of Medicine & Science in Sports (2023).
Aguinaldo, Arnel L., Janet Buttermore, and Henry Chambers. "Effects of upper trunk rotation on shoulder joint torque among baseball pitchers of various levels." Journal of applied biomechanics 23.1 (2007): 42-51.
APA

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