Lower-extremity ground reaction forces in collegiate baseball pitchers.

The purpose of this study was to investigate ground reaction forces (GRF) in collegiate baseball pitchers and their relationship to pitching mechanics. Fourteen healthy collegiate baseball pitchers participated in this study. High-speed video and force plate data were collected for fastballs from each pitcher. The average ball speed was 35 ± 3 m/sec (78 ± 7 mph). Peak GRFs of 245 ± 20% body weight (BW) were generated in an anterior or braking direction to control descent. Horizontal GRFs tended to occur in a laterally directed fashion, reaching a peak of 45 ± 63% BW. The maximum vertical GRF averaged 202 ± 43% BW approximately 45 milliseconds after stride foot contact. A correlation between braking force and ball velocity was evident. Because of the downward inclination and rotation of the pitching motion, in addition to volume, shear forces may occur in the musculoskeletal tissues of the stride limb leading to many of the lower-extremity injuries seen in this athletic population.

Throwing arm dominance in collegiate baseball pitching: a biomechanical study.

BACKGROUND: Left-handed individuals make up about 10% of the general population, yet left-handers comprise approximately 30% of the pitching staffs in Major League and Division I college baseball. Despite speculation regarding differences between right- and left-handed pitchers, distinction between right- and left-handed pitching mechanics has not been documented in the literature at any level of play. HYPOTHESIS: Left-hand-dominant pitchers display similar pitching mechanics and upper extremity joint loads when compared to their right-hand-dominant counterparts. STUDY DESIGN: Controlled laboratory study. METHODS: Three-dimensional, high-speed (240-Hz) video data were collected on fastballs from 84 collegiate baseball pitchers. Kinematic parameters related to pitching mechanics and resultant kinetics on the throwing shoulder and elbow were calculated. The 28 left-handed pitchers in the database were matched with 28 right-handed pitchers for age, height, mass, and ball velocity, and paired t tests were used to compare the kinematic and kinetic parameters. RESULTS: Six parameters were found to have statistically significant differences between left- and right-handed pitchers. Passive nonthrowing shoulder external rotation (right, 113 degrees +/- 9 degrees ; left, 124 degrees +/- 8 degrees ), elbow flexion at stride-foot contact (right, 79 degrees +/- 16 degrees ; left, 94 degrees +/- 20 degrees ), and shoulder abduction during acceleration (right, 72 degrees +/- 11 degrees ; left, 105 degrees +/- 8 degrees ) were greater in left-handed pitchers than right-handed pitchers. Shoulder abduction at stride-foot contact (right, 115 degrees +/- 13 degrees ; left, 73 degrees +/- 10 degrees ), shoulder horizontal abduction at stride-foot contact (right, 25 degrees +/- 12 degrees ; left, 15 degrees +/- 12 degrees ), and peak horizontal adduction angular velocity (right, 707 +/- 185 deg/s; left, 551 +/- 160 deg/s) were less for the left-handed pitchers. CONCLUSION: Biomechanical differences between left- and right-handed pitchers have been demonstrated in a collegiate population. CLINICAL RELEVANCE: The results of the current study indicate that left-handed pitchers may be at increased risk for certain shoulder injuries compared with their right-handed counterparts. Information has been provided for athletes, coaches, and sports medicine providers to further improve preventive and rehabilitative protocols for college pitchers. The results of the study also suggest that different normative data sets may need to be developed for left- and right-handed pitchers, independently of one another.

Lower-extremity ground reaction forces in youth windmill softball pitchers.

Ground reaction forces are important in pitching given that the only external contact a pitcher has is between the foot and the ground. Windmill softball pitchers are routinely seen clinically for injuries to the lower extremities, and lower-extremity kinetics have not been well studied. The purpose of this study was to investigate the relationships between ground reaction forces and throwing mechanics in youth windmill pitchers and to provide a scientific basis for the improvement of preventive and rehabilitative protocols. Fifty-three youth softball pitchers were tested in an indoor facility. High-speed video and force plate data were collected for fastballs from each pitcher. Average ball speed was 25 m/sec. Peak vertical ground reaction force averaged 139 % body weight (BW), peak anterior force averaged 24 %BW, and the medially directed component of the ground reaction force averaged 42 %BW. Loading rates to peak force in all 3 directions were high. Preventive and rehabilitative protocols for windmill softball pitchers can begin to be improved on the basis of knowledge of the magnitudes and times to peak forces under the stride foot.

Relationships between ball velocity and throwing mechanics in collegiate baseball pitchers.

Although ball speed is considered a measure of success in baseball pitching, little is known about the relationship between ball velocity and pitching mechanics. Investigation of this relationship has been limited, and the studies carried out have varied in methodology. Three-dimensional, high-speed (240 Hz) video data were collected on fastballs from 54 collegiate baseball pitchers. Kinematic parameters related to pitching mechanics and resultant kinetics on the throwing shoulder and elbow were calculated. Multiple linear regression analysis was used to relate ball velocity and pitching mechanics. Ball velocity averaged 35 m/sec (79 mph) for the 54 college pitchers. Nearly 70% of the variability in ball speed can be explained by a combination of 10 parameters related to pitching mechanics. Body mass and 9 temporal and kinematic parameters related to pitching mechanics combine to account for 68% of the variance in ball velocity for a collegiate population of athletes. These variables can be manipulated via mechanical changes and sport-specific training to affect ball velocity. The results of the study can be used to increase ball velocity while at the same time minimizing stresses on the throwing arm elbow and shoulder. Improved training programs can begin to be developed based on these data.

Relationships between throwing mechanics and shoulder distraction in collegiate baseball pitchers.

A distraction force occurs at the shoulder joint in all throwing motions. At the professional level, the relationship between this force and pitching mechanics has been explained. Three-dimensional, high-speed (240 Hz) video data were collected on fastballs from 48 collegiate baseball pitchers. Kinematic parameters related to pitching mechanics and resultant kinetics on the throwing arm elbow and shoulder joints were calculated. Multiple linear regression analysis was used to investigate the relationships between shoulder distraction and pitching mechanics. Shoulder distraction stress averaged 81% body weight for the collegiate pitchers. The mean ball velocity was 81 mph. Ten parameters of pitching mechanics accounted for 89% of the variance in shoulder distraction. Two of the variables (maximum shoulder abduction torque and elbow angle at release) previously shown to affect shoulder distraction in professional baseball pitchers appear to be important for collegiate pitchers as well. These data provide a scientific basis for clinicians, athletes, and coaches to establish methods to reduce distraction force at the shoulder joint through modification of pitching mechanics.

Reactive Neuromuscular Training: A Multi-level Approach to Rehabilitation of the Unstable Shoulder.

In this clinical commentary, the use of reactive neuromuscular training (RNT) will be discussed as part of an overall functional rehabilitation program in the treatment of the unstable glenohumeral joint. The RNT program is designed to restore the synchrony and synergy of muscle firing patterns about the shoulder, which are required for dynamic joint stability and fine motor control. Reactive neuromuscular training allows the clinician to bridge the gap between the achievement of clinical based goals and a return to athletic competition. The possible effects of RNT on central nervous system (CNS) programming to establish appropriate reflex responses and functional stability at the glenohumeral joint will be explored. The issues reviewed in this article will highlight the need for future research in this area.

Kinematics and kinetics of elite windmill softball pitching.

BACKGROUND: A significant number of time-loss injuries to the upper extremity in elite windmill softball pitchers has been documented. The number of outings and pitches thrown in 1 week for a softball pitcher is typically far in excess of those seen in baseball pitchers. Shoulder stress in professional baseball pitching has been reported to be high and has been linked to pitching injuries. Shoulder distraction has not been studied in an elite softball pitching population. HYPOTHESIS: The stresses on the throwing shoulder of elite windmill pitchers are similar to those found for professional baseball pitchers. STUDY DESIGN: Descriptive laboratory study. METHODS: Three-dimensional, high-speed (120 Hz) video data were collected on rise balls from 24 elite softball pitchers during the 1996 Olympic Games. Kinematic parameters related to pitching mechanics and resultant kinetics on the throwing shoulder were calculated. Multiple linear regression analysis was used to relate shoulder stress and pitching mechanics. RESULTS: Shoulder distraction stress averaged 80% of body weight for the Olympic pitchers. Sixty-nine percent of the variability in shoulder distraction can be explained by a combination of 7 parameters related to pitching mechanics. CONCLUSION: Excessive distraction stress at the throwing shoulder is similar to that found in baseball pitchers, which suggests that windmill softball pitchers are at risk for overuse injuries. Normative information regarding upper extremity kinematics and kinetics for elite softball pitchers has been established.

Biomechanics of youth windmill softball pitching.

BACKGROUND: Limited research attention has been paid to the potentially harmful windmill softball pitch. No information is available regarding lower extremity kinetics in softball pitching. HYPOTHESIS: The stresses on the throwing arm of youth windmill pitchers are clinically significant and similar to those found for college softball pitchers. STUDY DESIGN: Descriptive laboratory study. METHODS: Three-dimensional, high-speed (240-Hz) video and stride foot force plate (1200 Hz) data were collected on fastballs from 53 youth softball pitchers. Kinematic parameters related to pitching mechanics and resultant kinetics on the throwing-arm elbow and shoulder joints were calculated. Kinetic parameters were compared to those reported for baseball pitchers. RESULTS: Elbow and shoulder joint loads were similar to those found for baseball pitchers and college softball pitchers. Shoulder distraction stress averaged 94% body weight for the youth pitchers. Stride foot ground reaction force patterns were not similar to those reported for baseball pitchers. Vertical and braking force components under the stride foot were in excess of body weight. CONCLUSIONS: Excessive distraction stress and joint torques at the throwing-arm elbow and shoulder are similar to those found in baseball pitchers, which suggests that windmill softball pitchers are at risk for overuse injuries. Normative information regarding upper and lower extremity kinematics and kinetics for 12- to 19-year-old softball pitchers has been established.