Preliminary Analysis of Closed Kinetic Chain Upper Extremity Stability Test Differences Between Healthy and Previously Injured/In-Pain Baseball Pitchers

BACKGROUND

A comprehensive examination of the kinetic chain during an overhead athlete's upper extremity assessment, such as the closed kinetic chain upper extremity stability test (CKCUEST), may help clinicians identify potential upper extremity dysfunction.

HYPOTHESIS

Body position observed on dominant and nondominant hand touch during a CKCUEST trial differs between players with previous injury/pain history compared with healthy counterparts.

STUDY DESIGN

Descriptive laboratory study.

LEVEL OF EVIDENCE

Level 5.

METHODS

Seventeen baseball pitchers were recruited to participate (18.03 ± 2.01 years; 185.40 ± 6.57 cm; 83.92 ± 13.87 kg). A medical history questionnaire was used to separate participants into groups, either previous injury/pain or healthy. Kinematic and kinetic data were collected on the participants performing the CKCUEST with an electromagnetic tracking system. Kinematics were analyzed using a pair of 1-way multivariate analyses of variance (MANOVAs).

RESULTS

The MANOVA for nondominant hand touch in the CKCUEST revealed a significant difference in lumbopelvic-hip complex (LPHC) kinematics between previously injured/pain group and healthy group (Λ = 0.37; F_4,12 = 5.12; P = 0.01).

CONCLUSIONS

The previously injured/pain group displayed less pelvic axial rotation and dominant hip abduction during the nondominant touch indicating more LPHC stability during the nondominant touch. In conclusion, differences were observed in LPHC kinematics during the CKCUEST nondominant touch between a healthy and previously injured/pain group perhaps due to the increased awareness provided through rehabilitative programs for the previously injured/pain group.

CLINICAL RELEVANCE

Clinicians can use this information to help address kinetic chain movement efficiency within baseball pitchers. This study provides evidence of LPHC kinematic differences during the nondominant touch of baseball pitchers and may enhance the use of the CKCUEST as a return-to-play assessment.

Increased Upper Arm Length and Loading Rate Identified as Potential Risk Factors for Injury in Youth Baseball Pitchers

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.

DESIGN

Descriptive laboratory study.

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.

Energy generation, absorption, and transfer at the shoulder and elbow in youth baseball pitchers

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.

Relationship Between Humeral Energy Flow During the Baseball Pitch and Glenohumeral Stability

Researchers suggest that motion deriving energy from the more proximal segments of the body is important to reduce injury susceptibility. However, limited clinical assessments have been associated with efficient energy flow within a complex movement such as the baseball pitch. This research aimed to determine the relationship between glenohumeral stability as determined by the closed kinetic chain upper extremity stability test and energy transfer into and out of the humerus during the baseball pitching motion. Kinematic and kinetic data were collected at 240 Hz on twenty-four baseball pitchers. Participants performed the closed kinetic chain upper extremity stability test prior to throwing three fastballs at game speed to a catcher with the fastest fastball used for analysis. Spearman's Rho were used to examine relationships between energy flow in and out of the humerus with glenohumeral stability as determined by the average score and normalized stance width during the closed kinetic chain upper extremity stability test. There was a significant negative correlation between the average score and normalized peak power leaving the humerus (r _s[22]=-0.42, p=0.04). This result provides preliminary support for the use of the closed kinetic chain upper extremity stability test as a clinical assessment of a pitcher's ability to efficiently transfer energy within the upper extremity during the pitch.

Lower Extremity Pain and Pitching Kinematics and Kinetics in Collegiate Softball Pitchers

The primary aims of the study were (1) to examine kinematics and kinetics of those pitching with and without lower extremity pain in collegiate softball pitchers, and (2) to determine if there was an association between the lower extremity pain and lower extremity kinematics, trunk kinematics, and shoulder kinetics in collegiate softball pitchers. Thirty-seven NCAA Division I female collegiate softball pitchers (19.8±1.3 yrs,173.7±7.7 cm, 79.0±12.4 kg) participated. Participants were divided into two groups, those who were currently experiencing lower extremity pain and those who were not. Participants threw three rise ball pitches. Kinematic data were collected at 100 Hz using an electromagnetic tracking system. Mann-Whitney U tests revealed no significant kinematic or kinetic differences between pitchers with and without lower extremity pain. Additionally, there were no significant correlations between pain and recorded kinematic and kinetic variables. Considering there were no biomechanical differences observed between pitchers, coaches and athletic trainers should take caution with athlete assessment since athletes may not display altered biomechanics. Further examination into the duration and degree of pain is needed in an attempt to fully understand the implication of pain and pitching mechanics.

Sport Specialization and Single-Legged-Squat Performance Among Youth Baseball and Softball Athletes

CONTEXT

Previous research has indicated that throwing sports expose athletes to overuse injuries and that specialization in sport is linked to injury. However, the effect of overexposure to a throwing sport on a dynamic movement task is unknown.

OBJECTIVE

To determine if sport specialization in youth throwing athletes affected performance on the single-legged squat (SLS).

DESIGN

Descriptive laboratory study.

SETTING

University research laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 49 youth baseball and softball athletes (23 baseball, 26 softball; age = 12.96 ± 2.32 years, height = 165.01 ± 13.05 cm, mass = 61.42 ± 13.04 kg) were recruited.

MAIN OUTCOME MEASURE(S)

Participants were grouped into 3 categories based on specialization definitions: (1) 8 months or longer in season, (2) 8 months or longer in training, or (3) 8 months or longer in season and previously quit another sport. We measured SLS kinematics and used a set of 1-way multivariate analyses of variances to determine if trunk kinematics differed by group.

RESULTS

Athletes who spent 8 months or more in sport-specific training exhibited significantly more trunk control, revealed by less trunk lateral flexion (Λ = 0.69, F_6,38 = 2.89, P = .020) and less trunk flexion (Λ = 0.69, F_6,38 = 2.88, P = .021) throughout an SLS.

CONCLUSIONS

These results agree with the principle of specific adaptation to imposed demands. Surprisingly, athletes who spent 8 months or more playing a unilateral sport showed no differences in SLS performance. Clinicians should emphasize that neuromuscular adaptations of the lumbopelvic-hip complex for dynamic movement, such as an SLS, may be achieved through training instead of strict sport participation. Future researchers should consider how much of the training protocol is actually specialized for sport training.

Association of Upper Extremity Pain With Softball Pitching Kinematics and Kinetics

Background:

There is a paucity of research regarding the relationship between fastpitch softball pitching mechanics and reported pain. Thus, understanding the pitching mechanics of athletes pitching with upper extremity pain and those pain free is paramount.

Purpose:

To examine lower extremity pitching mechanics, upper extremity kinetics, and upper extremity pain in National Collegiate Athletic Association (NCAA) Division I female softball pitchers.

Study Design:

Descriptive laboratory study.

Methods:

A total of 37 NCAA Division I female softball pitchers (mean age, 19.84 ± 1.28 years; mean height, 173.67 ± 7.77 cm; mean weight, 78.98 ± 12.40 kg) from across the United States were recruited to participate. Participants were divided into 2 groups: upper extremity pain (n = 13; mean age, 19.69 ± 1.18 years; mean height, 172.60 ± 11.49 cm; mean weight, 86.75 ± 13.02 kg) and pain free (n = 24; mean age, 19.91 ± 1.35 years; mean height, 174.26 ± 4.96 cm; mean weight, 74.78 ± 9.97 kg). An electromagnetic tracking system was used to obtain kinematic and kinetic data during the riseball softball pitch.

Results:

At foot contact (F_3,33 = 7.01, P = .001), backward elimination regression revealed that stride length, trunk rotation, and center of mass (COM) significantly explained about 33% of variance with softball pitchers experiencing upper extremity pain (adjusted R² = 0.33).

Conclusion:

At foot contact, the kinematic variables of increased trunk rotation toward the pitching arm side, increased stride length, and a posteriorly shifted COM were associated with upper extremity pain in collegiate softball pitchers. Variables early in the pitching motion that do not set a working and constructive proximal kinetic chain foundation for the rest of the pitch to follow could be associated with breakdowns more distal in the kinetic chain, possibly increasing the susceptibility to upper extremity pain.

Clinical Relevance:

The identification of pitching mechanics associated with pain allows clinicians to develop exercises to avoid such mechanics. Avoiding mechanics associated with pain may help reduce the prevalence of pain in windmill softball pitchers as well as help coaches incorporate quantitative biomechanics into their instruction.

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.

Differences in trunk and upper extremity kinematics and segmental velocities during the offside forehand polo swing between male and female athletes

Although polo is a well-known equestrian sport, it is fundamentally misunderstood. The purpose of this study was to examine trunk and upper extremity kinematics and segmental velocities during the offside forehand polo swing between male and female athletes. Ten female and 17 male professional polo athletes volunteered. An electromagnetic tracking system collected kinematic data at 100 Hz while participants performed three offside forehand polo swings from a stationary wooden horse. One-way ANOVAs revealed statistically significant differences (p<0.05) in all kinematic variables and segmental velocities. Specifically, males exhibited a greater mean difference (MD=23°) of trunk flexion at take away (TA) and top of backswing (TOB)(MD=29°) trunk lateral flexion at ball contact (BC)(MD=23°), trunk rotation at TA(MD=97°) and TOB(MD=118°), shoulder abduction at TOB(MD=64°), and shoulder elevation at TOB(MD=13°) and BC(MD=40°). Females displayed greater trunk rotation at BC(MD=91°), shoulder elevation at TA(MD=19°), and elbow flexion at TA(MD=90°). Additionally, females generated greater segmental velocities early in the swing, while the males generated velocity later. The movement patterns observed amongst the males suggest energy is being transferred more efficiently along the kinetic chain, thus more efficient swing mechanics, but further investigation into the role of the trunk and lumbopelvic-hip complex in reference to the polo swing is warranted.

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

The purpose of this study was to determine whether glove arm kinematics during a windmill softball pitch impact pelvic and trunk kinematics as well as pitching arm shoulder kinetics. Thirty-Nine college softball pitchers (20.0±1.4 yrs.; 174.7±6.1 cm; 82.0±13.0 kg; 10.7±2.7 yrs. of experience) threw 3 pitches to a catcher while kinematic and kinetic data were collected. Pearson product moment correlations were run, and significant correlations found with glove arm kinematics, occurring before pelvis kinematics, trunk kinematics, and shoulder kinetics, were then put through a linear regression to identify whether there was any potential cause and effect. Results revealed that glove arm elbow flexion during phase 1 significantly predicted normalized shoulder rotation moment during phase 4 (t=2.60, p=0.013). Additionally, glove arm shoulder horizontal abduction during phase 1 significantly predicted normalized shoulder moment in phase 3 (t=- 2.40, p=0.021) and pelvic angular velocity during phase 3 (t=-  3.20, p=0.003). In conclusion, an active glove arm was predictive of a more efficient kinetic chain later in the windmill pitching motion and could possibly play a role in preventing injury by lessening pitching shoulder joint loads.

Tuck Jump Assessment as an Indicator for Upper Extremity Injury

The purpose of this study was to determine if tuck jumps can be used as a dynamic movement assessment to ascertain a previous history of upper extremity injury in an overhead throwing sport. Seventy-one youth baseball and softball athletes (28 baseball/43 softball; 12.41±2.22 yrs.; 161.98±13.65 cm; 59.17 ± 14.90 kg) were recruited to participate and were placed in either the previous injury (N=18) or no previous injury (N=53) groups. Kinematic data were collected from jumps 4 through 8 during a trial of 10 tuck jumps performed at 100 Hz using an electromagnetic tracking system (trakSTAR ^TM , Ascension Technologies, Inc., Burlington, VT, USA) synced with the MotionMonitor ^® (Innovative Sports Training, Chicago, IL, USA). A logistic regression showed no significance in trunk flexion or upper leg elevation in the ability to determine upper extremity injury ( χ ² (1, N =71)=3.55, p =0.315). In conclusion, examining only trunk flexion and upper leg elevation during the tuck jump assessment (TJA) is not enough for clinicians to recognize previous upper extremity injury. Even though the body behaves as a kinetic chain, simplifying the dynamic movement assessment while not specifying the type of upper extremity injury is not favorable for the clinician to identify previous injury.

Relationship of Glove Arm Kinematics With Established Pitching Kinematic and Kinetic Variables Among Youth Baseball Pitchers

Background:

While the kinematics of the pitching arm, trunk, and pelvis have been described and studied, glove arm kinematics remain an understudied portion of the pitching motion. Baseball pitchers seek to achieve maximum ball velocity in a fashion that does not place the arm at risk of injury.

Purpose:

To assess the relationship between glove arm shoulder horizontal abduction and elbow flexion and pitching arm kinematics and kinetics among youth pitchers to determine whether recommendations can be made toward a safer pitching motion.

Study Design:

Descriptive laboratory study.

Methods:

Thirty-three right-handed youth male baseball pitchers (mean ± SD: age, 13.6 ± 2.0 years; height, 169.4 ± 14.3 cm; weight, 63.5 ± 13.0 kg; experience, 7.3 ± 3.0 years) threw 3 fastballs to a catcher while kinematic data were collected with an electromagnetic tracking system. The Spearman rank-order test was used to identify relationships between glove arm horizontal abduction and glove arm elbow flexion and various kinematics and kinetics found at maximum shoulder external rotation (MER) and ball release for the fastest fastball delivered by each participant.

Results:

At MER, there were significant relationships found between a more flexed glove arm elbow and increased pitching arm elbow valgus force (r_s[31] = –0.52, P = .002), increased pitching arm shoulder anterior force (r_s = –0.39, P = .024), and decreased hip velocity (r_s[31] = –0.45, P = .009). Additionally, there were significant relationships between greater glove arm horizontal abduction at MER and increased pitching arm humeral velocity (r_s[31] = 0.52, P = .002) and increased trunk rotational velocity (r_s[31] = 0.40, P = .022) at MER.

Conclusion:

A more extended glove arm elbow and more horizontally abducted glove arm shoulder at MER could prove to be more advantageous for performance and possibly be a safer motion for the baseball thrower.

Clinical Relevance:

The orthopaedic community can dictate safer biomechanics when communicating with pitchers, trainers, and pitching coaches.