It is desirable to reduce the prevalence of throwing arm injury among children participating in the sport of baseball.  While restricting the number of pitches a player is permitted to offer can be helpful, limiting efforts to this ignores the potential benefits of establishing a method of throwing that minimizes the proportion of energy that depends upon the musculature of the throwing arm. Using the Kinetic Chain model of throwing, a growing literature is exploring the sequence of movement between the many various body segments.  We seek to explore the characteristics associated with movement between the pelvis and thorax and the neuromuscular activity that is presumed to control thoracic rotation.  The angle of interest is the “X-angle” among youth baseball throwers. This X-angle is computed using the x and y coordinates for the bilateral Iliac Crests and the Acromioclavicular landmarks. By projecting these vectors downward into a common plane, the X-angle is determined throughout each throw. Kinetic data is digitized using eight Nexus Vicon v2.2 cameras at 240Hz, calibrated to a “World Error” of 0.3mm or less, within a room that is 21’x21’.  Neuromuscular data for the abdominal External Oblique muscles is recorded using two Delsys Trigno wireless sEMGs model SP-W06, sampling rate of 2000Hz. Kinetic and Neuromuscular data collection were synchronized using the Nexus Vicon 2.12.1 system. 

 

Early results indicate that while young baseball throwers achieve a maximum X-angle similar to that which has previously been reported, bilateral abdominal muscles do not appear to achieve peak activation in sequence as hypothesized. Results indicate that throwing efficiency may be elevated and arm injuries prevented through early efforts to incorporate neuromuscular control exercises into youth league throwing instruction.