The Influence of an Active Glove Arm in Softball Pitching: A Biomechanical Evaluation

Understanding Shoulder and Elbow Injuries in the Windmill Softball Pitcher

Although pitching-related injuries in the overhead athlete have been studied extensively, injuries associated with windmill pitching are not as clearly elucidated. Windmill pitching produces high forces and torques in the upper extremity, and studies have shown it creates similar shoulder and elbow joint loads to those reported in baseball pitchers. Studies have shown that the windmill pitching motion generates high levels of biceps activation with an eccentric load, placing the biceps at increased risk for overuse injuries. Although the American Orthopaedic Society for Sports Medicine published prevention guidelines including recommendations for maximum pitch counts in softball, these recommendations have not been adopted by most United States softball governing bodies. The repetitive windmill motion in conjunction with high pitch count demands in competitive softball creates notable challenges for the sports medicine physician. As with overhead throwing athletes, identifying and preventing overuse is crucial in preventing injuries in the windmill pitcher, and prevention and rehabilitation should focus on optimizing mechanics and kinematics, core, hip, and lower body strength, and recognition of muscle fatigue. With more than two million fastpitch softball participants in the United States, it is essential to better understand the etiology, evaluation, and prevention of injuries in the windmill pitching athlete.

Range of Motion Adaptations During a Simulated Game Exposure in Softball Pitchers

Hip and shoulder range of motion (ROM) alterations are correlated with increased risk of injury in softball athletes. The purpose of this study was to investigate bilateral shoulder and hip ROM adaptation during a simulated softball double-header exposure. It was hypothesized that shoulder and hip ROM would decrease after simulated game exposure and would not return to baseline following a 30-minute break. Thirty (14.8±1.9 yrs, 162.5±18.3 cm, 71.79±16.03 kg) adolescent softball pitchers participated. Testing included: bilateral hip and shoulder ROM (preSG), simulated game exposure (100 pitches), bilateral hip and shoulder ROM (postSG), 30-minute break, bilateral hip and shoulder ROM (preDH), pitching first inning of a simulated double header (12 pitches), and bilateral hip and shoulder ROM (postDH). Two separate repeated measures multivariate analyses of variance tests determined differences in ROM between time points. Dominant shoulder internal rotation ROM and non-dominant shoulder internal and external rotation ROM significantly decreased from preDG. Stride hip external rotation ROM and drive hip internal and external rotation ROM significantly decreased from preSG to preDH. Key results revealed the break given between games may not be sufficient recovery time for hip ROM. Thus, assessing ROM as workload progresses can be a useful strategy for monitoring a softball pitcher's injury risk.

Evaluating Risk Factors for Biceps Tendon Injuries in Softball Players: A Systematic Review

OBJECTIVE

Softball players commonly suffer overuse injuries due to the demands of repetitive throwing. The biceps tendon plays an important role in stabilizing the shoulder during the windmill pitch. The purpose of this study was to evaluate the measures used to identify and study biceps tendon pathology in softball players.

DESIGN

This was a systematic review.

SETTING

PubMed MEDLINE, Ovid MEDLINE, and EMBASE were searched.

PARTICIPANTS

Studies that investigated biceps tendon injuries in softball players.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Range of motion (ROM), strength, and visual analog scale data were collected.

RESULTS

Of 152 search results, 18 were included. A total of 536 of 705 athletes (76%) were softball players (average age 14-25 years). Five of 18 articles (27.7%) studied changes in external rotation with the shoulder at 90 degrees of abduction, and 4 of 18 (22.2%) studied internal rotation. Two of 18 studies (11.1%) examined ROM or strength changes in forward flexion.

CONCLUSIONS

While researchers agree that the windmill pitch places significant stress on the biceps tendon, our study finds that the metrics used to evaluate shoulder pathology in these players primarily evaluate the rotator cuff without isolating the biceps tendon. Future studies should include clinical tests and biomechanical metrics more specific to identifying biceps and labral pathology (eg, strength, fatigue, and ROM in glenohumeral forward flexion, elbow flexion, and forearm supination) and attempt to clarify differences in pathology between pitchers and position players to better characterize the frequency and severity of biceps tendon pathology in softball players.

Pelvis and Trunk Energy Flow in Collegiate Softball Pitchers With and Without Upper Extremity Pain

BACKGROUND

The softball pitch is a full-body motion, where efficient proximal to distal energy flow through the kinetic chain is said to reduce stress at the upper extremity. Although altered trunk kinematic parameters are associated with upper extremity pain in softball pitchers, further research is needed to determine whether differences exist in proximal energy flow between softball pitchers with and without pain.

HYPOTHESIS/PURPOSE

To examine pelvis and trunk energy flow during the acceleration phase of the pitch in collegiate softball pitchers with and without upper extremity pain. It was hypothesized that those with upper extremity pain would have less energy flowing into the proximal ends of the pelvis and trunk as well as less energy flowing out of the distal ends of the pelvis and trunk during the acceleration phase when compared with pitchers who did not have upper extremity pain.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 54 female National Collegiate Athletic Association Division I softball pitchers (age, 20.2 ± 2.0 years; height, 173.5 ± 6.9 cm; weight, 78.5 ± 11.5 kg) were assigned to pain (n = 17) and pain-free (n = 38) groups. Participants pitched 3 maximal effort rise-balls for a strike, and the average of the 3 trials was used for analysis. Kinematic data were collected at 100 Hz using an electromagnetic tracking system. A segment power analysis was performed to quantify energy flow for the pelvis and trunk. The Mann-Whitney U test was used to compare pelvis and trunk energy flow during the acceleration phase of the pitch as well as pitch velocity between collegiate softball pitchers with and without upper extremity pain.

RESULTS

No significant differences were found between pelvis and trunk energy flow during the acceleration phase or pitch velocity between collegiate softball pitchers with and without upper extremity pain (all P values >.057).

CONCLUSION

Previous research determined that kinematic parameters differ between collegiate pitchers with and without upper extremity pain. However, the current study found no difference in pelvis and trunk energy flow or pitch velocity. Although altered kinematics in collegiate pitchers with upper extremity pain may serve as compensation patterns to maintain pitch velocity and proximal energy flow, future research is needed to confirm this postulation.

CLINICAL RELEVANCE

The lack of energy flow differences between upper extremity pain groups suggests that pitchers may adapt their biomechanics to maintain trunk and pelvis energy flow patterns. Coaches, athletes, and clinicians should know that movement adaptations can allow for maintained performance levels but may result in the presence of pain that may manifest in other deleterious and injury-susceptible biomechanics.

Peak Elbow Flexion Does Not Influence Peak Shoulder Distraction Force or Ball Velocity in NCAA Division I Softball Pitchers

Background:

High shoulder distraction force has been observed in softball pitchers during the acceleration phase (top of the pitch to ball release) of a pitch. Increasing elbow flexion may reduce shoulder forces and the susceptibility to pain by shortening the lever arm of the throwing arm.

Purpose:

To determine the association of peak elbow flexion during the acceleration phase of the pitch with peak shoulder distraction force and ball velocity.

Study Design:

Descriptive laboratory study.

Methods:

A total of 61 female collegiate softball pitchers (mean age, 19.9 ± 1.9 years; mean height, 175.7 ± 5.7 cm; mean weight, 83.6 ± 12.7 kg; 49 right-handed) volunteered for this study. Biomechanical data were collected with a 3-dimensional electromagnetic tracking system while the pitchers threw 3 maximal-effort fastballs at a regulation distance. Peak elbow flexion and peak shoulder distraction force were calculated for the acceleration phase and averaged across the 3 trials. Ball velocity was assessed with a radar gun.

Results:

Simple linear regression analyses indicated that peak elbow flexion did not influence peak shoulder distraction force during the acceleration phase of the pitch (F(1,59) = 2.412; P = .126), with R² = 0.023. Additionally, peak elbow flexion during the acceleration phase of the pitch did not influence ball velocity (F(1,59) = 2.435; P = .124), with R² = 0.023. A bivariate correlation analysis showed a significant association between ball velocity and shoulder distraction force (R² = 0.343; P = .007) in which ball velocity constituted approximately 34% of the variance in shoulder distraction force.

Conclusion:

Peak elbow flexion did not influence ball velocity or peak shoulder distraction force during the acceleration phase of a windmill softball pitch. However, there was a significant and positive relationship between ball velocity and peak shoulder distraction force. These results may indicate that ball velocity and other kinematic variables may be more related to shoulder distraction force than elbow flexion.

Clinical Relevance:

Increasing elbow flexion can shorten the lever arm, but it did not reduce shoulder distraction force or increase ball velocity. Therefore, elbow flexion may be more useful as a description of the pitching style rather than a single measure related to increased performance or the risk of injuries. Future research should continue to examine the relationship between other kinematic parameters with shoulder distraction force.

Decreased Shoulder and Elbow Joint Loads During the Changeup Compared With the Fastball and Curveball in NCAA Division I Collegiate Softball Pitchers

BACKGROUND

Baseball leagues have implemented pitch count and pitch type restrictions based on biomechanical concepts associated with pitch type. Softball has not yet adopted these practices, although softball pitchers continue to pitch at a high volume and learn multiple pitches at a young age.

PURPOSE

To examine shoulder and elbow kinetics between the fastball, curveball, and changeup, as well as to provide descriptive upper extremity pain data in National Collegiate Athletic Association (NCAA) softball pitchers.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Study participants consisted of 27 female NCAA Division I softball pitchers (age, 20.2 ± 1.9 years; height, 175.7 ± 5.7 cm; weight, 83.6 ± 12.7 kg). The participants pitched 3 balls of each pitch type, and kinetic data were recorded. A one-way within-participants repeated-measures multivariate analysis of variance was used to determine significant differences in kinetics and pitch speed between pitch types.

RESULTS

Results revealed a statistically significant main effect for pitch type (Wilks λ = .087; F = 36.523; P < .001). Post hoc testing showed that the changeup produced less anterior elbow force compared with the fastball (P < .001) and the curveball (P = .012). In addition, the changeup produced less shoulder distraction force compared with the fastball (P < .001) and the curveball (P = .001). Additionally, there was a significant difference in pitch speed between all 3 pitch types (P = .006). The curveball revealed no statistically significant kinetic differences compared with the fastball.

CONCLUSION

The fastball and curveball placed similar stress on the upper extremity in collegiate softball pitchers. However, in comparison with the changeup, the fastball and curveball placed increased stress on the upper extremity. More research is needed to fully explain the differences seen between pitch type and injury risk.

CLINICAL RELEVANCE

Sports medicine professionals, coaches, and athletes should use the current study results to note these differences in shoulder distraction and elbow anterior forces between softball pitch types. The study results can be used as a reference and basis for future research investigating kinetic differences across varying pitch types.

Kinematic Differences Exist Between the Fastball, Changeup, Curveball, and Dropball Pitch Types in Collegiate Softball Pitchers

BACKGROUND

A majority of softball literature focuses on the mechanics associated with pain and injury within a single pitch type per study; however, the generalizability of these findings is unknown since a kinematic comparison has yet to be performed between pitch types. Understanding kinematic differences between pitch types can be used to identify risk factors for injury, improve safety guidelines, and improve performance by linking specific mechanics with desired pitch outcomes.

HYPOTHESIS/PURPOSE

The purpose of this study was to compare kinematics between the fastball, changeup, curveball, and dropball pitch types in collegiate softball pitchers. It was hypothesized that there would be significant kinematic differences between pitch types.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 28 female collegiate softball pitchers pitched 3 trials of each pitch type to a catcher at regulation distance. Pitch speed, stride length, trunk extension, trunk rotation, trunk lateral flexion, elbow flexion, and center of mass for each trial were calculated using an electromagnetic motion capture system and were averaged for analysis. A 1-way analysis of variance (ANOVA) was used to investigate pitch speed differences between the 4 pitch types. A 4 (pitch type) × 5 (event) within-athlete multivariate ANOVA was also used to determine kinematic differences.

RESULTS

The results revealed a significant difference in pitch speed between pitch types; a pitch type main effect for trunk extension, trunk rotation, trunk lateral flexion, and center of mass; and an event main effect for all variables except stride length. The results also revealed a pitch type by event interaction for trunk flexion, trunk lateral flexion, and center of mass. Specifically, the dropball type had less trunk extension than the fastball at all pitching events. Similarly, the curveball type had a more posteriorly shifted center of mass than the dropball at the last 3 pitching events of foot contact, ball release and follow-through.

CONCLUSION

Significant kinematic differences exist between pitch types, but these differences may be necessary to execute desired pitch outcomes.

CLINICAL RELEVANCE

This is the first study to analyze kinematic differences between pitch types in softball pitchers. Understanding the effects of different pitch types on kinematic parameters may enhance injury prevention and performance strategies for softball pitchers.

Impact of Engaging the Nonthrowing Arm on Maximal Ball Velocity From an Overhand Throw With Both the Dominant and Nondominant Arms: A Pilot Study

The overhand throw is a complex whole-body motor skill that is fundamental to many sports and activities. When throwing properly, the momentum generated to complete the movement begins in the lower body and transfers through the trunk to the throwing arm. This proof-of-concept study’s primary purpose was to evaluate the impact of the nonthrowing arm on the ball speed during an overhand throw with both the dominant and nondominant arms. Eighteen participants (age: 20.20 ± 2.90 years, nine women) were divided into two intervention groups: a pulling group taught to engage the nonthrowing arm through a pull toward the body and a nonpulling group taught the overhand throw using a component-based physical education curriculum. Each participant completed 12 total throws, six for each side (dominant and nondominant arm). Ball speed and kinematic data were collected using an eight-camera motion analysis system and were assessed using a pre–post study design. The two groups showed significant improvements pre–post when throwing with both the dominant and nondominant arms. Based on effect size comparisons, engaging the nonthrowing arm makes a meaningful difference in maximal ball velocity.

The Association of Upper-Body Kinematics and Earned Run Average of National Collegiate Athletic Association Division I Softball Pitchers

Friesen, KB, Barfield, JW, Murrah, WM, Dugas, JR, Andrews, JR, and Oliver, GD. The association of upper-body kinematics and earned run average of national collegiate athletic association Division I softball pitchers. J Strength Cond Res XX(X): 000-000, 2019-Although recent literature has increased examination of the association of injury and biomechanics, there remains a lack of evidence supporting optimal windmill pitch mechanics. Therefore, the purpose of this study was to investigate trunk and pitching arm kinematics and their association with performance outcome: earned run average (ERA), in collegiate softball pitchers. Twenty-three NCAA Division I collegiate softball pitchers (20.14 ± 1.07 years; 173.93 ± 6.68 cm; and 85.79 ± 11.06 kg) performed 3 maximal effort rise ball pitches to a catcher located at a distance of 43 ft. (13.11 m). Kinematic data of the trunk and pitching arm were collected using an electromagnetic tracking system. A multiple regression analysis was performed at each pitch event: top of backswing, foot contact, ball release, and follow-through. The multiple regression at foot contact showed an overall statistically significant regression equation (F6, 16 = 3.7, p = 0.017) and explained approximately 42% of the variance in ERA (R = 0.579, Adj. R = 0.421). Results revealed that those pitchers who had greater trunk (SE = 0.018, t = -2.5, p = 0.023) and elbow flexion (SE = 0.006, t = -4.2, p = 0.001) at the event of foot contact had lower ERAs. This study supported previous research on the importance of trunk and elbow angle at front foot contact on rise ball pitch performance. These key technique points and the importance of elbow flexors should be explored in future research and potentially visually attended to by coaches and strength professionals.