It is estimated that nearly 6% of youth baseball participants seek medical attention for injuries sustained during play. Most injuries are overuse injuries, and 26% are to the shoulder or upper arm. By quantifying youth pitching biomechanics, knowledge can be gained concerning the manner in which these injuries are sustained during play.
Sixteen healthy right hand-dominant baseball pitchers participated in this study. After digitization of 21 bony landmarks, kinematic calculations were conducted using the 3-dimensional coordinates from each video frame. Data were time normalized, forcing major temporal components of the movement to occur at specific intervals. Segment-based reference frames were established, and resultant joint kinetics were projected onto each reference frame. Kinetic data were normalized and calculated along or about the anterior/posterior, medial/lateral, and proximal/distal axes.
Maximum trunk rotation and external shoulder rotation were observed during arm cocking. Each of the remaining kinematic parameters peaked after ball release. All maximum values for joint kinetics were measured during arm cocking with the exception of compressive forces experienced at the shoulder and elbow, which peaked after the instant of ball release.
Data produced in this study indicate that youth pitchers initiate trunk rotation early in the movement, which can lead to shoulder hyperangulation. Opposing torques at each end of the humerus also produce a large net torque about the longitudinal axis of the humerus during late arm cocking and may increase humeral retrotorsion in youth pitchers. Underdeveloped musculature in the rotator cuff may lead to difficulty controlling throwing-arm deceleration, causing an increase in horizontal adduction across the torso.
An improved understanding of youth pitching mechanics is gained from the data collected, analyzed, and discussed in this study. Through increases in the knowledge pertaining specifically to the mechanics of youth pitchers, the opportunity to develop pitching mechanics specifically designed for preventing injuries in little league pitchers arises.
This study is a Level 4 study describing youth pitching biomechanics and how they relate to possible injuries.
"A JUGS radar gun (OpticsPlanet, Inc., Northbrook, IL) positioned in the direction of the shot determined speed of each shot. The shot with the fastest ball speed was then selected for detailed analysis (Sabick et al. 2004; Keeley et al. 2008). Previous research, using video analysis, has divided the lacrosse shot into six key phases (Mercer & Nielson 2013). "
[Show abstract][Hide abstract] ABSTRACT: Lacrosse is one of the oldest team sports in the United States and it has become the fastest growing sport in the country. The purpose of this study was to describe the kinematics of the overhead shot in youth male lacrosse players in attempt to gain an understanding of the movement patterns of the upper extremity. It was hypothesized that the kinematics observed with the overhead lacrosse shot would be similar to the mechanics of an overhead throw. Ten male youth lacrosse players (10.69 ± 2.06 years; 153.87 ± 12.90 cm; and 43.33 ± 9.25 kg) volunteered. Three accurate overhead shots were performed and the fastest shot was then selected for detailed analysis. The overhead lacrosse shot relies on trunk extension and rotation as the shot progresses and less on shoulder external rotation than a throw. Additionally, the lacrosse shot also appears to be less dependent on humeral elevation, compared to throwing, as 15.38 ± 12.10° of elevation was observed.
"The kinematics and kinetics of baseball pitching have been well documented (Dapena, 1978; Escamilla, Fleisig, Barrentine, Zheng, & Andrews, 1998; Feltner & Dapena, 1986; Fleisig, Andrews, Dillman, & Escamilla, 1996; Fleisig, Escamilla, Andrews, Matsuo, Satterwhite et al., 1996; Keeley, Hackett, Keirns, Sabick, & Torry, 2008) while those of softball are beginning to evolve (Oliver, Dwelly, & Kwon, 2010; Oliver & Plummer, 2011; Rojas, Provencher, Bhatia, Foucher, Bach et al., 2009; Werner, Gill, Murray, Cook, & Hawkins, 2001; Werner, Guido, McNeice, Richardson, Delude et al., 2005; Werner, Jones, Guido, & Brunet, 2006). The great interest in baseball pitching is that it is the most dynamic human movement thus placing the upper extremity at increased risk of injury (Fleisig, Barrentine, Escamilla, & Andrews, 1996). "
[Show abstract][Hide abstract] ABSTRACT: Abstract The catcher has the most demanding position in the games of baseball and softball with no regulations on how many throws they make during game. It was the purpose of this study to describe the kinematics and kinetics of the throwing motion in catchers when throwing down to second base. It was hypothesised that younger and older catchers would display significantly different throwing kinematics and kinetics. Thirty-eight baseball and softball catchers volunteered to participate. Twenty participants were considered younger (aged 9-14, 10.95 ± 1.76 years, 151.11 ± 15.64 cm, 47.94 ± 18.84 kg) and 18 were deemed the older group (aged 15-23, 18.11 ± 2.61 years, 170.91 ± 8.67 cm, 74.88 ± 10.74 kg). Participants received a pitch and completed five accurate throws to second base in full catching gear. The average ball speed of the older catchers was 21 ± 3.58 meters per second (47 ± 8.02 mph) while the younger catchers averaged 17.2 ± 4.0 meters per second (38.6 ± 8.96 mph). Older catchers had greater shoulder elevation at ball release and significantly greater shoulder external rotation at foot contact and shoulder maximum external rotation than younger catchers. It is clear that chronological age plays a role in the throwing mechanics observed in catchers throwing down to second base, however the effects of these differences are not fully understood (i.e., skeletal maturity, experience, strength).
"Body segment masses and inertial parameters were obtained from previous literature and scaled to participant height and mass (Clauser et al., 1969; Hinrichs, 1990). Shoulder anterior force was defined as the anterior component of the resultant force acting along the anterior/posterior axis of the shoulder, while shoulder proximal force was defined as the component of the resultant force acting along the longitudinal axis of the shoulder (Keeley et al., 2008; Sabick et al., 2004a; Sabick et al., 2004b). Each of these forces was modeled using a convention that calculated the force applied by the torso to the proximal humerus and were normalized to percent bodyweight. "
[Show abstract][Hide abstract] ABSTRACT: Previous work has postulated that shoulder pain may be associated with increases in both peak shoulder anterior force and peak shoulder proximal force. Unfortunately these relationships have yet to be quantified. Thus, the purpose of this study was to associate these kinetic values with reported shoulder pain in youth baseball pitchers. Nineteen healthy baseball pitchers participated in this study. Segment based reference systems and established calculations were utilized to identify peak shoulder anterior force and peak shoulder proximal force. A medical history questionnaire was utilized to identify shoulder pain. Following collection of these data, the strength of the relationships between both peak shoulder anterior force and peak shoulder proximal force and shoulder pain were analyzed. Although peak anterior force was not significantly correlated to shoulder pain, peak proximal force was. These results lead to the development of a single variable logistic regression model able to accurately predict 84.2% of all cases and 71.4% of shoulder pain cases. This model indicated that for every 1 N increase in peak proximal force, there was a corresponding 4.6% increase in the likelihood of shoulder pain. The magnitude of peak proximal force is both correlated to reported shoulder pain and capable of being used to accurately predict the likelihood of experiencing shoulder pain. It appears that those pitchers exhibiting high magnitudes of peak proximal force are significantly more likely to report experiencing shoulder pain than those who generate lower magnitudes of peak proximal force.
Journal of Human Kinetics 10/2012; 34(1):15-20. DOI:10.2478/v10078-012-0059-8 · 1.03 Impact Factor
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