Recent Research Publications & Presentations
Pelvis and Trunk Energy Flow in Collegiate Softball Pitchers with and without Upper Extremity Pain
Journal: American Journal of Sports Medicine
Nicole Bordelon, Kyle Wasserberger, Jessica Downs-Talmage, Kenzie Friesen, Jeffrey Dugas, and Gretchen Oliver
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.
Methods: A total of 54 female National Collegiate Athletic Association Division I softball pitchers (age, 20.2 ± 6 2.0 years; height, 173.5 ± 6 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.
Figure. Mediolateral ground-reaction force (GRF) on the drive leg during phases of the pitching motion. (–) lateral GRF; (1) medial GRF. Dashed line represents the mean mediolateral GRF. Solid lines represent individual cases. Accel, acceleration.
Drive-Leg Kinematics during the Windup and Pushoff is Associated with Pitching Kinetics at Later Phases of the Pitch
Journal: American Journal of Sports Medicine
Anthony Fava, Jessica Downs-Talmage, Hillary Plummer, and Gretchen Oliver
Background: Inconsistent findings exist between drive-leg ground-reaction forces (GRFs) and pitching mechanics. Previous literature has largely reported drive-leg mechanics and GRFs at the start of the pushoff phase for their role in initiating force development. Little research has assessed drive-leg kinematics that includes a pitcher’s windup motion to determine its effects on subsequent phases in the pitching motion.
Purpose/Hypothesis: The primary aim was to analyze the relationship between drive-leg knee valgus angle during the windup and subsequent pitching mechanics. We hypothesized that the drive-leg knee valgus angle during the early portion of the pitching motion would alter later phases’ pitching mechanics. A secondary aim was to assess GRFs to determine if the drive-leg knee valgus angle was associated with changes in force. We hypothesized that an increased drive-leg knee valgus angle would increase GRFs during the pitching motion.
Methods: A total of 17 high school baseball pitchers (mean age, 16.1 ± 0.9 years; mean height, 180.0 ± 4.8 cm; mean weight, 75.5 ± 7.5 kg) volunteered for the study. Kinematic data and GRFs were collected using an electromagnetic tracking system and force plates. Pitchers threw maximal-effort fastballs from a mound at regulation distance. The drive-leg knee valgus angle was analyzed during the windup and pushoff phases of the pitch to determine its effects on other biomechanical variables throughout the pitching motion.
Results: There was a significant relationship between drive-leg knee valgus angle during the windup (Fchange 1,12) = 16.13; P = .002; R2 = 0.695) and lateral GRF in the arm-cocking phase. Additionally, there was a significant relationship between drive-leg knee valgus angle during pushoff (Fchange (2,11) = 10.21; P = .003; R2 = 0.716) and lateral GRF in the arm-cocking phase and pitching-elbow valgus moment in the acceleration phase.
Conclusion: Drive-leg knee valgus angle during the windup and pushoff had a significant relationship with drive-leg GRF and pitching-elbow valgus moment at later stages of the pitching cycle.
Clinical Relevance: Assessments of drive-leg kinematics during the windup and pushoff may be useful in identifying inefficient movement patterns that can have an effect on the direction of a pitcher’s drive-leg force contribution, which can lead to increased forces on the throwing elbow.
Differences in Lower Extremity Kinematics between Collegiate and Youth Softball Pitchers
Journal: The Orthopaedic Journal of Sports Medicine
Jessica Downs-Talmage, Jessica Gilliam, Ajit Chardhari, and Gretchen Oliver
Background: Softball pitching is a whole-body motion that utilizes the kinetic chain to transfer the large amounts of force generated by the lower extremity to the ball. Although the lower extremity is responsible for generating most of the force in softball pitching, limited research has investigated how lower extremity kinematics vary with age.
Purpose/Hypothesis: The purpose of this study was to compare lower extremity kinematics between collegiate and youth softball pitchers. It was hypothesized that there would be significant lower extremity kinematic differences between age groups.
Study Design: Descriptive laboratory study.
Methods: Overall, 83 softball pitchers participated in the study: 40 youth and 43 collegiate players. Kinematic data were collected using an electromagnetic motion capture system. All participants threw 3 fastballs to a catcher for a strike at regulation distance. Owing to nonnormally distributed data, Mann-Whitney U tests were used to determine group differences at 5 events during the pitching motion. The alpha level was set a priori at .006.
Results: Collegiate pitchers had significantly higher drive-knee extension angular velocity at the 3 o’clock position than youth pitchers (182.30 ± 145.44 vs – 34.66 ± 219.66 rad/s; P < .001). Collegiate pitchers also had greater peak drive-knee flexion angle than youth pitchers at the top of the arm circle (37.98° ± 18.09° vs 25.38° ± 17.58°; P = .004), while youth pitchers had a significantly more anteriorly shifted center of mass than collegiate pitchers at the top of the arm circle (49.93% ± 5.09% vs 46.47% ± 6.44%; P = .003). Conclusion: The authors found increased drive-knee flexion angle and angular extension velocity in collegiate compared with youth pitchers, although it is unknown if these differences were due to lack of experience or strength. Athletes should work on improving drive-leg mechanics to develop optimal push-off performance.
Clinical Relevance: This information can be applied to develop strength and conditioning programs for softball pitchers. Player performance may be improved through performing exercises to strengthen knee and hip extension musculature and learning to eccentrically load the drive leg to activate the stretch shortening cycle.
Background: Though chronic overhand throwing is known to result in range of motion and strength adaptations, there is limited research regarding interventions for maintenance of these characteristics.
Purpose: The purposes of this study were to explore the use of a pre-throwing protocol focusing on lumbopelvic-hip complex musculature in high school baseball players and examine its effects on shoulder and hip range of motion and isometric strength over the course of a season.
Study Design: Descriptive Laboratory.
Methods: Thirty-nine participants (174.14 ± 1.22 cm, 72.71 ± 13.66 kg, 15.64 ± 1.22 years) were included. Seventeen participants (172.1 ± 7.1 cm, 68.3 ± 12.0 kg, 15.5 ± 1.2 years) on the intervention team and 22 participants (175.7 ± 8.1 cm, 76.2 ± 14.1 kg, 15.8 ± 1.2 years) were included on the control team.Four exercises were added to the intervention team’s warm-up routine. The control and intervention teams’ passive bilateral hip and shoulder range of motion and isometric strength were assessed pre/post-season. A multivariate analysis of variance revealed significant differences in delta scores between the teams for multiple shoulder and hip range of motion and isometric strength variables.
Results: Key results were the intervention team lost significantly more stride hip external rotation but gained more isometric strength than the control team. The intervention team was also able to better maintain shoulder range of motion than the control team.
Conclusion: Practitioners should use the results of this study and consider incorporating exercises that target lumbopelvic- hip complex musculature into their current training program.
This abstract has a full manuscript that has been published in the International Journal of Sports Medicine. You can get full access at https://www.thieme-connect.com/products/ejournals/pdf/10.1055/a-1214-6278.pdf.
Increased Upper Arm Length and Loading Rate Identified as Potential Risk Factors for Injury in Youth Baseball Pitchers
Jessica Downs Talmage, Kyle Wasserberger, Jeff Barfield, Michael Saper, Gretchen Oliver
Background: In the throwing elbow, increased elbow torque has been correlated with increased injury risk. Additional insight into the relationships between anthropometric factors and elbow joint loading is warranted.
Purpose: To investigate the relationship among physical limb length characteristics, elbow kinetics, and elbow kinematics in youth baseball pitchers and to examine the relationship between elbow varus loading rate and elbow kinetics.
Methods: A total of 27 male youth baseball pitchers participated (mean ± SD: age, 15.8 ± 2.7 years; height, 176.3 ± 13.0 cm; weight, 71.7 ± 16.4 kg). Upper arm (UA) and forearm (FA) lengths were measured using a moveable sensor to digitize bony landmarks. Kinematic data were collected at 240 Hz using an electromagnetic tracking system. Participants threw 3 fastballs to a catcher at a regulation distance (60 ft 6 in), and the fastest velocity trial was used for analysis. Linear regression was used to determine the relationship among limb length characteristics, elbow kinetics, and elbow kinematics after accounting for the effects of body weight and height.
Results: Pitchers with longer UA length experienced increased maximum elbow varus torque (P = .005) and maximum net elbow force (P = .001). Pitchers with an increased forearm to UA ratio had decreased elbow compression force (P < .001) and exhibited a more flexed elbow at foot contact (P = .001). Pitchers with greater maximum loading rates experienced greater elbow varus torque (P = .002).
Conclusion: In youth baseball pitchers, longer UA length and greater loading rate increase varus torque about the elbow during a fastball pitch.
Clinical Relevance: Longer UA length and greater loading rate may place pitchers at risk of injury because of their relationship with kinetic values.
Full manuscript available at: https://journals.sagepub.com/doi/abs/10.1177/03635465211028555
Decreased Shoulder and Elbow Joint Loads During the Changeup Compared With the Fastball and Curveball in NCAA Division I Collegiate Softball Pitchers
Gretchen Oliver, Jess Downs Talmage, Kenzie Friesen, Michael Saper, Jeffrey Dugas
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.
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.
The full manuscript is available at: https://journals.sagepub.com/doi/full/10.1177/23259671211026625
Predicting Shoulder Force to Prevent Injury: Body Fat Mass Increases Shoulder Stress among Pitchers
Kenzie Friesen, Gretchen Oliver
Purpose: The purpose of this study was to examine the relationship between whole body and throwing arm composition and length with throwing shoulder distraction and anterior force. While literature shows a relationship between shoulder force and pain, as well as between body mass and pain, it was hypothesized that pitchers with greater body fat mass would display increased throwing shoulder force during the acceleration phase of the softball pitch.
Methods: Thirty-eight high school softball pitchers from southern United States agreed to participate (1.69 ± .07 m, 74.71 ± 16.36 kg, 15.2 ± 1.1 years). All procedures were completed within one visit. Pitchers underwent a dual-energy x-ray absorptiometry scan then threw fastballs at regulation distance while motion was measured using an electromagnetic motion capture system. Data from the three fastest pitches were averaged and analyzed. Peak shoulder distraction and anterior force during the acceleration phase of the softball pitch were extracted and used as dependent variables in two separate regression analyses. Whole body and throwing arm fat mass and lean mass, as well as throwing arm length were entered as independent variables into both regression equations.
Results: The first regression equation was statistically significant, F(5,37) = 13.28, p < .001 and explained approximately 62% of the variance in peak shoulder distraction force (R2 = .675, Adj. R2 = .624). Increased whole body fat mass (B = 13.76, SE = 5.39, Beta = .91, t = 2.553, p = .016) significantly predicted peak throwing shoulder distraction force. The second regression equation predicting peak anterior force was not significant.
Conclusion: Increased fat mass may exacerbate the high force observed at the throwing shoulder and further increase injury susceptibility to pitchers.
The full manuscript is available at: https://europepmc.org/article/med/34628450
Comparison of Pelvis and Trunk Kinematics Between Youth and Collegiate Windmill Softball Pitchers
Kyle Wasserberger, Kenzie Friesen, Jess Downs Talmage, Nicole Bordelon, Gretchen Oliver
Background: The windmill softball pitch is a dynamic sporting movement that places softball pitchers at high risk of injury. Unlike baseball, there is limited research into the mechanical differences between softball pitchers of varying skill levels.
Purpose: The purpose of this study was to compare pelvis and trunk kinematics between youth and collegiate softball pitchers. It was hypothesized that there would be significant differences in pelvis and trunk kinematics between these 2 groups.
Methods: The pelvic and trunk kinematics of 90 softball pitchers were collected during full-effort pitching using a 3-dimensional motion capture system. Participants were grouped based on their age at the time of data collection (35 youth [mean age, 11 ± 1 years]; 55 collegiate [mean age, 20 ± 2 years]). We compared between-group differences in pelvic posterior tilt, lateral tilt, axial rotation, and axial rotation velocity as well as trunk extension, lateral flexion, axial rotation, and axial rotation velocity during the pitching phase between start of pitch and ball release (BR) using 1-dimensional statistical parametric mapping. Statistical significance was determined using Holmes-Šidák stepdown correction–adjusted P values (P ′).
Results: Compared with youth pitchers, collegiate pitchers exhibited a more posteriorly tilted pelvis from the moment of start of pitch until 94% of the way between start of pitch and BR (P ′ = .002) and a more laterally flexed trunk toward the glove side from the moment of start of pitch until 71% of the way between start of pitch and BR (P ′ = .010).
Conclusion: Collegiate pitchers displayed a more posteriorly tilted pelvis and more laterally flexed trunk toward the glove side during the windmill pitching motion when compared with youth pitchers.
Clinical Relevance: These findings add to the growing body of softball research and help elucidate mechanical differences between youth and collegiate softball pitchers
The full manuscript is available at: https://journals.sagepub.com/doi/abs/10.1177/23259671211021826
Energy generation, absorption, and transfer at the shoulder and elbow in youth baseball pitchers
Kyle Wasserberger, Kevin Giordano, Anne de Swart, Jeff Barfield, Gretchen Oliver
Performance during the baseball pitch is dependent on the flow of mechanical energy through the kinetic chain. Little is known about energy flow during the pitching motion and it is not known whether patterns of energy flow are related to pitching performance and injury risk. Therefore, the purpose of this study was to quantify energy generation, absorption, and transfer across the shoulder and elbow during the baseball pitch and explore the associations between these energetic measures, pitch speed, and traditional measures of upper extremity joint loading. The kinematics of 40 youth baseball pitchers were measured in a controlled laboratory setting. Energy flow between the thorax, humerus, and forearm was calculated using a segmental power analysis. Regression analyses revealed that pitch speed was best predicted by arm cocking phase shoulder energy transfer to the humerus and peak elbow valgus torque was best predicted by arm acceleration-phase elbow energy transfer to the forearm. Additionally, energy transfer across the shoulder and elbow generally exhibited the strongest correlations to pitch speed and upper extremity joint loads. These data reinforce the importance of energy transfer through the kinetic chain for producing high pitch speeds and provide descriptive data for energy flow during baseball pitching not previously found in the literature.
The full manuscript is available at: https://www.tandfonline.com/doi/abs/10.1080/14763141.2021.1933158
Knee Kinetics in Baseball Hitting and Return to Play after ACL Reconstruction
Kevin Giordano, Meredith Chaput, Adam Anz, Jeremy Braziel, James Andrews, Gretchen D. Oliver
The purpose of this study was to describe the knee kinetics of baseball hitting, develop a tool to predict knee kinetics from easily obtainable measures, and to compare knee kinetics to other exercises along the rehabilitation continuum to determine a timeline for when hitting may resume after ACL reconstruction. Nineteen high school baseball athletes (16.3±0.8 yrs, 180.6±5.7 cm, 78.4±10.8 kg) participated. Participants took ten swings off a tee. Kinetic data were recorded using an electromagnetic tracking system. Data from swings with the top three exit velocities were averaged for analysis. Linear regressions were used to determine if predictors of height, mass, age and exit velocity could predict the following torques: bilateral knee net, extension, internal and external rotation, valgus and varus torque; and anterior force. Backwards regression models revealed independent variables could significantly predict front knee net, internal and external rotation, extension, and varus torque, and anterior force; and back knee net and valgus torque. Based on the kinetics of baseball hitting compared to those of rehabilitation exercises, if the involved knee is the front, we suggest tee hitting may be initiated at 13 weeks after ACL reconstruction. If the involved knee is the back, we suggest tee hitting may initiated at 17 weeks after ACL reconstruction.
The full manuscript is available at: https://www.thieme-connect.com/products/ejournals/abstract/10.1055/a-1236-4102
Electromyographic Analysis of Shoulder Rotation Strength Testing Positions
Molly Cassidy, Nicole Bordelon, Kyle Wasserberger, Kevin Giordano, Gretchen Oliver
Auburn University Journal of Undergraduate Scholarship. Article is available at: http://our.auburn.edu/wp-content/uploads/2021/10/Cassidy-pdf.pdf