Altered Cervical Spine Position Results in Decreased Eccentric Shoulder Rotation Strength.

Overhead athletes require strenuous shoulder activity in nonneutral cervical spine positions to eccentrically decelerate the throwing/striking arm following ball release/contact. We therefore aimed to compare eccentric shoulder rotation strength through a 90° arc between neutral and rotated positions. Fifty-two participants (19 M, 34 F 170±10 cm; 73±18 kg, 21.9±2.9 years) without shoulder or cervical spine pathology participated. Isokinetic eccentric shoulder rotation strength was measured through a 90° arc with the shoulder elevated 90° in frontal plane (frontal plane), and 45° anterior to the frontal plane (scapular plane) in neutral and rotated cervical spine positions. Cervical spine position was obtained by instructing participants to maximally rotate their respective side. Frontal plane eccentric external rotated strength differed between neutral and contralaterally positions in the first 10° of the motion, near forearm vertical (p+=+0.029). Internal rotation strength differed between neutral and contralaterally rotated positions from 55-60° external rotation (p+=+0.004). Scapular plane eccentric external rotation differed between cervical positions between 21-67° shoulder external rotation (p<0.001). Scapular plane internal rotation strength differed between cervical positions between 22-60° shoulder external rotation (p<0.001). In populations requiring strenuous use of their shoulders in altered cervical spine positions, sports medicine clinicians should consider including strength testing that reflects the functional positions of their patients during an orthopedic examination.

Kinematics of Hitting in Youth Baseball: Implications for Skill Development.

This study compared lower extremity, trunk, and upper extremity kinematics between tee and front toss hitting in youth baseball athletes. Twenty youth baseball athletes (14.3±2.9 yrs) performed three maximal effort swings off front toss and tee. Kinematic data were collected during the preparatory and acceleration phases. Lower extremity, trunk, and upper extremity kinematics were compared between tee and front toss hitting using 1-dimensional statistical parametric mapping (SPM). There was a significant difference in trunk kinematics between tee and front toss during the preparatory phase (p=.001); the trunk rotated more toward the back side when hitting off a tee compared to front toss (p<0.001). There was also a significant difference in trunk kinematics between tee and front toss for 67% of the acceleration phase; the trunk rotated more towards the back side from 0 to 67% when hitting off the tee (p<0.001). Significant differences were found in trunk kinematics between tee and front toss hitting in youth baseball players, where the trunk is less rotated toward the pitcher in the tee than in the front toss. Coaches utilize various training modalities to enhance hitting performance; however, differences in trunk kinematics should be considered between modalities when developing fundamental hitting techiques in youth baseball athletes.

A Model for Causality of Pitching-related Overuse Injuries in Women's Fastpitch Softball.

Fastpitch softball is a popular women's sport, and athletes, particularly pitchers, are at high risk for overuse injury. Softball-related injury rates are low; however, the prevalence of overuse injuries is high. Injuries at the high school and collegiate levels occur early in the season, and approximately 50% of shoulder and elbow injuries in softball are attributable to overuse. Survey research showed 77% of high school pitchers pitch with pain, and 73% of collegiate pitchers reported an overuse injury in the previous season. Modifiable and non-modifiable intrinsic and extrinsic risk factors contribute to injury risk in a model that can be used in history taking, clinical examination, and management of softball-related injuries. In this manuscript, we present a scoping review of fastpitch softball injury research by competitive levels from 1990 to present. We also introduce a model for overuse injury causality in this athlete population. With this information, clinicians will be able to identify risk factors related to injury in softball pitchers. More research is needed to make evidence-based recommendations for injury prevention in this athlete population.

Evaluation of Hip Characteristics in Baseball and Softball Athletes with and Without Throwing Arm Pain.

During throwing, the lower extremity assists in the generation and transfer of momentum. Lower extremity stability assists in this transfer by providing a base for distal mobility of the arm segments. This study aimed to determine differences between hip rotational range of motion and strength based on the presence of throwing-arm pain (yes/no) and throwing sport (baseball/softball). We hypothesized those experiencing pain would display decreases in hip range of motion and strength, and that softball players would display greater range of motion than baseball, but less strength based on sex-specific characteristics. Forty-four baseball (13±2 years, 165.2±13.0 cm, 58.5±13.4 kg) and 50 softball players (13±2 years, 160.9±11.2 cm, 62.7±17.9 kg) participated. Multivariate analysis of variance tests (2×2) determined differences in bilateral hip range of motion, total arc of motion, and strength between pain status and sport. There were no significant interactions (>0.05) for pain status and sport on hip range of motion, total arc of motion, and strength. Furthermore, no significant main effects (>0.05) were found for pain status or sport alone on range of motion or strength. Future work should be directed at explaining the effects of hip characteristics on the throwing motion and how it equates to throwing-arm health.

Length-Tension Differences Between Concentric and Eccentric Shoulder Rotation Strength.

ABSTRACT: Giordano, KA, Cassidy, MM, and Oliver, GD. Length-tension differences between concentric and eccentric shoulder rotation strength. J Strength Cond Res 38(2): 253-258, 2024-Eccentric contractions generally produce more force than concentric contractions. However, if length-tension relationships affect both contractions equally remains unknown. Therefore, our purpose was to compare concentric versus eccentric shoulder external and internal rotation strength across a continuous 90° arc. Fifty-two physically active individuals performed isokinetic concentric and eccentric shoulder external rotation and internal rotation through a 90° arc (forearm horizontal to forearm vertical) with the shoulder elevated in both the frontal and scapular planes. Statistical parametric mapping analysis compared concentric and eccentric trials within subjects. Frontal plane eccentric external rotation torque was greater than concentric 30°-90° (p < 0.01) external rotation, and concentric external rotation torque was greater 5°-15° external rotation (p = 0.01). Frontal plane, eccentric internal rotation torque was greater than concentric 15°-55° external rotation (p < 0.01), and concentric torque was greater at forearm horizontal (p = 0.05) and 70°-90° external rotation (p < 0.01). Scapular plane eccentric external rotation torque was greater than concentric 30°-90° external rotation (p < 0.01) and concentric external rotation torque was greater 5°-20° external rotation (p < 0.01). Scapular plane eccentric internal rotation torque was greater than concentric 15°-60° external rotation (p < 0.01), and concentric torque was greater at forearm horizontal (p = 0.05) and 78°-90° external rotation (p = 0.02). Coaches, clinicians, and researchers should interpret data from studies reporting isokinetic data with the understanding that isokinetic peak strength values are not comparing the same muscle length and are not an appropriate measure for all muscle lengths. Furthermore, shoulder stability is affected through decreased eccentric force production at end ranges of shoulder rotation.

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.

Kinetic chain revisited: consensus expert opinion on terminology, clinical reasoning, examination, and treatment in people with shoulder pain.

BACKGROUND: The purpose of this study was to reach consensus on the most appropriate terminology and issues related to clinical reasoning, examination, and treatment of the kinetic chain (KC) in people with shoulder pain among an international panel of experts. METHODS: A 3-round Delphi study that involved an international panel of experts with extensive clinical, teaching, and research experience in the study topic was conducted. A search equation of terms related to the KC in Web of Science and a manual search were used to find the experts. Participants were asked to rate items across 5 different domains (terminology, clinical reasoning, subjective examination, physical examination, and treatment) using a 5-point Likert-type scale. An Aiken coefficient of validity (V) ≥0.7 was considered indicative of group consensus. RESULTS: The participation rate was 30.2% (n = 16), whereas the retention rate was high throughout the 3 rounds (100%, 93.8%, and 100%). A total of 15 experts from different fields and countries completed the study. After the 3 rounds, consensus was reached on 102 items: 3 items were included in the "terminology" domain; 17 items, in the "rationale and clinical reasoning" domain; 11 items, in the "subjective examination" domain; 44 items, in the "physical examination" domain; and 27 items, in the "treatment" domain. Terminology was the domain with the highest level of agreement, with 2 items achieving an Aiken V of 0.93, whereas the domains of physical examination and treatment of the KC were the 2 areas with less consensus. Together with the terminology items, 1 item from the treatment domain and 2 items from the rationale and clinical reasoning domain reached the highest level of agreement (V = 0.93 and V = 0.92, respectively). CONCLUSION: This study defined a list of 102 items across 5 different domains (terminology, rationale and clinical reasoning, subjective examination, physical examination, and treatment) regarding the KC in people with shoulder pain. The term "KC" was preferred and a agreement on a definition of this concept was reached. Dysfunction of a segment in the chain (ie, weak link) was agreed to result in altered performance or injury to distal segments. Experts considered it important to assess and treat the KC in particular in throwing or overhead athletes and agreed that no one-size-fits-all approach exists when implementing shoulder KC exercises within the rehabilitation process. Further research is now required to determine the validity of the identified items.

Altered Cervical Spine Position Results in Decreased Shoulder Rotation Strength.

BACKGROUND: Strength testing of shoulder rotation is commonly used in clinical examinations of the shoulder. People prone to shoulder injury, such as overhead athletes and manual trade workers, place their shoulders under tremendous amounts of stress when the cervical spine is in nonneutral positions. If these nonneutral cervical spine positions result in decreased shoulder strength, it may help explain the etiology of the high prevalence of shoulder injuries in these populations. Given standard clinical strength assessments are performed with a neutral cervical spine, an investigation into the effects of cervical spine rotation is warranted. QUESTIONS/PURPOSES: We sought to compare isokinetic shoulder rotation strength while in a neutral position with rotated cervical spine positions, specifically (1) with the cervical spine rotated contralaterally with the shoulder elevated in the frontal plane and (2) with the cervical spine rotated ipsilaterally and the shoulder elevated in the scapular plane. METHODS: A convenience sample of 52 individuals (height 170 ± 10 cm; weight 73 ± 18 kg, age 21 ± 2 years; 18 males, 34 females), without shoulder or cervical spine pathology participated in this study. Participants were screened for eligibility via questionnaire. Concentric shoulder internal and external rotation torque was measured through a 90° arc on an isokinetic dynamometer with the shoulder elevated 90° in the frontal plane, and again 45° anterior to the frontal plane (scapular plane). Two repetitions were performed in a single testing session with the participant's cervical spine in neutral in both planes, maximally rotated contralaterally in the frontal plane, and maximally rotated ipsilaterally with the shoulder in the scapular plane; the second repetition was used for analysis. The testing order was randomized. Data were imported into a platform for statistical parametric mapping analysis (a technique that allows data from the entire arc of motion to be compared with data from another arc to identify differences in the wave form) to compare strength between positions throughout 90° arc of motion. RESULTS: Rotating the cervical spine contralaterally with the shoulder in the frontal plane resulted in a decrease in external (2.24 Nm or 12% average difference; p < 0.001) and internal (2.22 Nm or a 6% average difference; p = 0.02) rotation strength with the forearm within 15° and 20° of the vertical position. Rotating the cervical spine ipsilaterally with the shoulder in the scapular plane resulted in a decrease in external rotation strength (1.27 Nm or a 6% average difference; p < 0.001) throughout nearly all the motion, with peaks approximately 20° and 60° from the horizontal position, and internal rotation strength (1.78 Nm or 5% average difference; p < 0.001) the last 60° towards the horizontal position. CONCLUSION: Patient populations who require strenuous use of their shoulders in altered cervical spine positions may be at increased risk for injury from decreased shoulder rotator strength. CLINICAL RELEVANCE: Clinicians should assess shoulder strength in the position the patient requires to use their shoulder because cervical spine position may cause weakness that would be missed in standard testing positions.

Characteristics of Injury in Collegiate Rodeo.

OBJECTIVE: The purpose of this study was to investigate injury occurrence sustained by collegiate rodeo athletes during practice and competition. DESIGN: Descriptive epidemiology. SETTING: Eleven National Intercollegiate Rodeo Association member institutions across the United States. PARTICIPANTS: Participants included 264 male and female college rodeo athletes. Athletic trainers (ATs) from each institution reported injury and exposure data using the National Collegiate Athletic Association Injury Surveillance Program. INTERVENTIONS: Institutional ATs reported athlete exposures (AEs) and injuries that occurred from collegiate rodeo practices and competitions. MAIN OUTCOME MEASURE: Injury and AEs from practices and competitions for one college rodeo season were analyzed. Injury rates and ratios were calculated for non-time loss (NTL) and time loss (TL) with 95% confidence intervals (CI). RESULTS: Data revealed a higher proportion of TL than NTL injuries [2.47 vs 1.77 per 1000 AE; injury rate ratios (IRRs) = 1.39; 95% CI: 0.93-2.08]. There was a higher injury rate during competition as compared with practice (10.98 vs 3.09 per 1000 AE; IRR = 3.56; 95% CI: 2.36-5.35), but more injuries were reported in practice (62.2%). CONCLUSIONS: Although the injury rate during rodeo competition was significantly higher than during practice in this study, a greater number of injuries were reported during practice. This indicates all college rodeo athletes can potentially benefit from available medical care.

Softball Pitching Propulsion and Performance Differences According to Body Fat Percentage.

Softball pitchers with a high body-fat percentage (bf%) can often be successful, despite the heightened risk of injury associated with high bf%. Given the importance of propulsion during pitching, those with high bf% may have an advantage performance-wise. Therefore, the purpose of this study was to examine the differences in ground reaction force (GRF) development between two groups of pitchers: those with a high-fat percentage (≥32 bf%) and a healthy-fat percentage (<32 bf%). Thirty-two female high-school softball pitchers (1.70±.06 m, 76.09±17.50 kg, 15±1 yrs) completed dual-energy x-ray absorptiometry (DEXA) scans. GRF data were collected during pitch propulsion via a force plate, pitch speed was captured using a radar gun, BMI was calculated from pitcher height and mass, and fat free mass index (FFMI) and fat mass index (FMI) were calculated using DEXA data and pitcher height. Multivariate analysis of variance revealed pitcher group GRFs differed significantly (F3,30=3.45, p=.030). Univariate follow-up analyses showed healthy bf% pitchers presented greater weight-normalized peak medial GRF (F1,30=7.17, p=.012). BMI and FFMI were positively associated with pitch speed while bf% and FMI were negatively associated with pitch speed. While pitchers can be successful and carry excess bf%, results indicate potential performance disadvantages associated with having an increased bf%.

Flexibility, Position, and Strength of the Shoulder Complex in Pediatric and Adult Amateur Tennis Athletes.

CONTEXT: Understanding the musculoskeletal adaptations in the shoulder complex of varying ages of tennis athletes may suggest preventive protocols and conditioning and rehabilitation programs to this population. This study aimed to generate a bilateral descriptive profile of shoulder flexibility, scapular and clavicular position, and muscle strength in pediatric and adult amateur tennis athletes. The outcome measures were compared between groups and sides. The number and percentage of athletes "at risk" according to cutoff values for shoulder range of motion (ROM) were also analyzed. DESIGN: Cross-sectional study. METHODS: 36 pediatric and 28 adult amateur tennis athletes were tested. Outcome measures were ROM of shoulder flexion, abduction, internal and external rotation, posterior capsule tightness, pectoralis minor index (PMI), scapular upward rotation, clavicular elevation, and strength of the external rotators, serratus anterior, and lower trapezius of the dominant/nondominant sides. RESULTS: Pediatric athletes had greater dominant side external rotation (P = .01) and total ROM (P = .04), increased Low Flexion test (P = .01), and decreased PMI (P = .01) compared with the adults. Bilaterally, the pediatric athletes had greater dominant side external rotation ROM (P < .01) and decreased PMI (P = .002) as compared with their nondominant side, whereas the adults displayed lower values on posterior capsule tightness (P = .01) and decreased PMI (P = .02) on their dominant side compared with their nondominant side. For the remaining outcomes, no interaction effects were observed. The cutoff values for shoulder ROM showed that several athletes were "at risk" of shoulder problems. CONCLUSION: Upper extremity adaptations at the shoulder are present in both pediatric and adult tennis athletes. These data can assist clinicians in better understanding the biomechanical adaptations in the shoulder of amateur tennis athletes in different age groups.

Influence of a Pre-throwing Protocol on Range of Motion and Strength in Baseball Athletes.

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. Therefore, 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. 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. 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. Practitioners should use the results of this study and consider incorporating exercises that target lumbopelvic-hip complex musculature into their current training program.

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.

Knee Kinetics in Baseball Hitting and Return to Play after ACL Reconstruction.

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.

Biceps Tendon Changes and Pitching Mechanics in Youth Softball Pitchers.

With the lack of pitch count regulation, youth softball pitchers are experiencing unremitting high stresses on the anterior shoulder. The purpose of this study was to examine the association of acute changes in the long head of the biceps tendon with pitching kinematics and kinetics in youth softball pitchers following an acute bout of pitching. Twenty-three softball pitchers (12.17±1.50 yrs.; 160.32±9.41 cm; 60.40±15.97 kg) participated. To investigate the association between biceps tendon changes and kinematic and kinetic changes from pre- to post-simulated game, each biceps tendon measure was split into those whose biceps tendon thickness, width, and/or area increased pre- to post-simulated game, and those whose did not. There were significant differences in biceps tendon longitudinal thickness (Z=- 2.739, p=0.006) and pitch speed; as well as a difference between groups in biceps tendon transverse thickness and the amount of change in trunk rotation at the start of the pitching motion (p=0.017) and the amount of change in trunk flexion at ball release (p=0.030). This study illustrates the association of trunk and lower extremity kinematics and shoulder kinetics with morphologic changes in the biceps tendon with an acute bout of windmill softball pitching.

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.

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

ABSTRACT: 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 35(11): 3145-3150, 2021-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. R2 = 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.

Preliminary Evaluation of Knee Kinetics in Female Athletes on Hormonal Contraceptives.

Recently, an emphasis has been placed on understanding how ovarian sex hormones and hormonal contraceptives affect risk for anterior cruciate ligament (ACL) injury. The literature presents large discrepancies in whether or not hormonal contraceptives affect ACL injury risk; therefore, the purpose of this study was to evaluate whether vertical ground reaction force (GRF) and knee valgus force are different between athletes who do and do not use hormonal contraceptives. Twenty-two female athletes volunteered to participate and were divided into two groups based on their answers to a health history questionnaire: those who use hormonal contraceptives and those who do not. Participants performed a drop vertical jump (DVJ) and single leg crossover dropdown (SCD) at two different time points in their menstrual cycle (pre-ovulatory phase and mid-luteal phase). Kinetic data were collected at 1000 Hz. Independent samples t-tests revealed no significant differences between groups in vertical GRF and knee valgus force at both time points. Findings from this study suggest that hormonal contraceptives do not elicit detectable changes in vertical GRF and knee valgus force. Ultimately, this calls for further studies on the relationship between hormones and ACL injury risk and physicians to consider hormonal screening in addition to neuromuscular and biomechanical screening.

The Relationship between Serum Relaxin Concentrations and Knee Valgus.

Female athletes are at an elevated risk for tearing their anterior cruciate ligament, compared to their male counterparts. Though injury screening clinical tests and neuromuscular training programs have been widely implemented, injury rates remain high among female athletes. The purpose of this study was to examine the relationship between serum relaxin concentrations and knee valgus during three clinical tests (single leg squat, drop vertical jump, and single leg crossover dropdown). Twenty-two female athletes volunteered. Participants were scheduled for collection during the mid-luteal phase, when serum relaxin concentrations are known to be measurable. Blood samples were collected, and serum relaxin concentrations were quantified. Kinematic data were collected while participants performed the three clinical tests. Regression analyses revealed statistically significant relationships between serum relaxin concentrations and knee valgus throughout all tests. These findings suggest that serum relaxin concentrations and knee valgus are not independent of each other and more holistic approaches may be necessary to truly map out the risk for injury and ultimately reduce the rate of anterior cruciate ligament injuries. Thus, concluding that knee valgus, a highly utilized modifiable biomechanical risk factor, and relaxin, a hormone that has been associated with anterior cruciate ligament injury in female athletes, are related to each other.

Glenohumeral and Hip Range of Motion in Youth Softball Athletes.

The purpose of this study was to compare measures of bilateral shoulder and hip range of motion (ROM) between youth softball pitchers and position players. Fifty-two youth softball athletes (12.7±2.1 yrs.; 160.28±10.98 cm; 59.31±15.07 kg) participated. Bilateral hip and shoulder ROM were measured among pitchers (n=29) and position players (n=23). A 2 (pitcher/position player) × 2 (dominant/non-dominant) ANOVA was performed for both internal and external rotation ROM for the shoulder and hip. Paired sample t-tests were also conducted to examine side-to-side differences in total ROM. Data revealed a significant interaction between position and side dominance. Specifically, position players have significantly more non-dominant shoulder external rotation ROM (106.92°± 9.14°) than pitchers (100.12°± 11.21°). There were no significant differences between throwing and non-throwing sides. It is important that coaches and clinicians are aware of these adaptations between overhand and underhand throwing in order to properly develop conditioning and rehabilitation programs to alleviate injury susceptibility and cater to position-specific demands. Additionally, the current data suggest many of the functional adaptations seen within older populations are not fully developed until after youth.