Pool-Based Surfboard Elicits Activation of Posterior Shoulder Muscles During a Surfing Stroke.

ABSTRACT: Pexa, BS, Johnston, CD, Elder, EE, Ford, KR, Patterson, MQ, and Myers, JB. Pool-based surfboard elicits activation of posterior shoulder muscles during a surfing stroke. J Strength Cond Res 38(7): 1300-1304, 2024-Surfboard paddling may activate posterior shoulder muscles, which are critical to baseball pitchers' injury risk and performance. The purpose of this study was to measure posterior shoulder muscle activation during different phases of the surf stroke (propulsion vs. recovery) on a pool-based surfboard. Twenty healthy active adult subjects completed a familiarization and testing session with the pool-based surfboard. During the testing session, electromyography (EMG) sensors were placed on 6 posterior shoulder muscles: latissimus dorsi, infraspinatus, posterior deltoid, upper trapezius, middle trapezius, and lower trapezius. Subjects completed 4 laps in a pool at 3 separate resistances (low, moderate, and heavy) in a randomized order. The peak EMG signal during each phase (propulsion and recovery) was recorded. A 2-way within subject ANOVA (resistance-by-phase) with post hoc Bonferroni's corrections was used to identify differences in EMG activation. There was a significant main effect of phase for the latissimus dorsi (F = 91.3, p < 0.001), upper trapezius (F = 36.5, p < 0.001), middle trapezius (F = 33.8, p < 0.001), and lower trapezius (F = 21.6, p < 0.001). The latissimus dorsi demonstrated higher activation during the propulsion phase (p < 0.001), and all trapezius muscles demonstrated higher activation during the recovery phase (p < 0.001). There was a significant main effect of resistance for the posterior deltoid (F = 3.4, p = 0.043), with higher muscle activation in the low resistance trials compared with the heavy resistance trials (p = 0.036). Recreationally active individuals demonstrate activation of the posterior shoulder when using a pool-based surfboard. This pool-based surfboard may be beneficial to activate the posterior musculature and may be more accessible than standard surfing to baseball athletes.

Infraspinatus Cross-Sectional Area and Shoulder Range of Motion Change Following Live-Game Baseball Pitching.

CONTEXT: Following a baseball pitching bout, changes can occur to glenohumeral range of motion that could be linked to injury. These effects are in part due to the posterior shoulder's eccentric muscle activity, which can disrupt muscle contractile elements and lead to changes in muscle cross-sectional area (CSA), as measured by ultrasound. OBJECTIVE: To assess changes in muscle CSA, and range of motion immediately before and after pitching, and days 1 to 5 following pitching. DESIGN: Repeated measures. SETTING: Satellite athletic training room. PATIENTS: Ten elite college baseball pitchers participating in the fall season (age: 18.8 [1.2] y, height: 189.2 [7.3] cm, mass: 93.1 [15.3] kg, 8 starters, 2 long relievers). INTERVENTION: A pitching bout of at least 25 pitches (63.82 [17.42] pitches). MAIN OUTCOME MEASURES: Dominant and nondominant infraspinatus CSA, as measured by ultrasound, and glenohumeral range of motion including internal rotation (IRROM), external rotation (ERROM), and total rotation range of motion (TROM) before pitching, after pitching, and days 1 to 5 following the pitching bout. RESULTS: Dominant limb CSA significantly increased day 1 after pitching, and returned to baseline on day 2 (P < .001). Dominant and nondominant TROM did not change until day 5 (4.4°, P < .001) and day 3 (4.5°, P < .001), respectively, where they increased. Dominant IRROM was significantly decreased for 3 days (day 1: 1.9°, P < .001; day 2: 3.1°, P < .001; day 3: 0.3°, P < .001) following pitching and returned to baseline on day 4, with no such changes in the nondominant limb. Dominant external rotation significantly increased immediately post pitching (4.4°, P < .001) but returned to baseline by day 1. CONCLUSIONS: The results of the study demonstrate that infraspinatus CSA does not recover until 2 days following pitching, and IRROM does not recover until 4 days following pitching. Baseball pitching elicits damage to the posterior shoulder muscle architecture, resulting in changes to physical characteristics that last up to 4 days following pitching.

The Relationship Between the Push Off Ground Reaction Force and Ball Speed in High School Baseball Pitchers.

Oyama, S and Myers, JB. The relationship between the push off ground reaction force and ball speed in high school baseball pitchers. J Strength Cond Res 32(5): 1324-1328, 2018-Baseball pitching is a sequential movement that requires transfer of momentum from the lower extremity to the throwing arm. Therefore, the ground reaction force (GRF) during push off is suggested to play a role in production of ball speed. The purpose of this study was to investigate the correlation between GRF characteristics during push off and ball speed in high school baseball pitchers. A total of 52 pitchers performed fast pitches from an indoor pitching mound. A force plate embedded in an indoor mound was used to capture the push off GRF. The GRF characteristics (peak anterior, vertical, and resultant forces, vertical and resultant forces at the time of peak anterior GRF, and impulse produced by the anterior GRF) from the 3 fastest strike pitches from each pitcher were used for analyses. Spearman's rank correlation coefficients were used to describe the relationships between ball speed and the GRF characteristics. Ball speed was only weakly correlated with peak resultant force (ρ = 0.32, p = 0.02) and vertical (ρ = 0.45, p < 0.001) and resultant (ρ = 0.42, p = 0.002) forces at the time of peak anterior force. The ball speed was not correlated with other variables. The correlation between ball speed and push off force in high school pitchers was weak, especially when compared with what was reported for adult pitchers in other studies. Unlike for adult pitchers, higher push off force is only weakly correlated with ball velocity in high school pitchers, which suggests that training to better use body momentum may help high school pitchers improve ball speed.

The Influence of Verbal and Tactile Feedback on Electromyographic Amplitude of the Shoulder Musculature During Common Therapeutic Exercises.

CONTEXT: Verbal and tactile feedback (VTF) during rehabilitation exercises can increase muscle activation, thus improving the therapeutic benefits. However, it is unclear which feedback method elicits the greatest electromyographic (EMG) amplitude. OBJECTIVE: To determine if the addition of tactile to verbal feedback (VF) increases EMG amplitude of selected shoulder musculature during scapular plane elevation (Ys), shoulder horizontal abduction with external rotation (Ts), and scapular retraction with external rotation (Ws). DESIGN: Repeated-measures cross-over design. SETTING: Biomechanics laboratory. PARTICIPANTS: A total of 30 physically active adults volunteered for this study-age = 20.23 (1.25) years; height = 1.71 (0.073) m; and mass = 70.11 (15.14) kg. INTERVENTIONS: Electromyography of the serratus anterior; upper, middle, and lower trapezii; and anterior and posterior deltoids was recorded during Ys, Ts, and Ws with VTF and VF alone during separate testing sessions. Participants completed baseline trials without feedback, then received VTF and VF across 2 counterbalanced sessions. MAIN OUTCOME MEASURES: Difference scores were calculated between prefeedback and postfeedback interventions, and the difference score between baseline measurements was used as a control. One-way analysis of variance of the difference scores was used to evaluate the influence of VTF and VF on EMG amplitude during Ys, Ts, and Ws. RESULTS: There was a significant difference between conditions for EMG amplitude of the middle trapezius (F2,28 = 4.09, P = .02) and serratus anterior (F2,28 = 3.91, P = .03) during Ys, the middle trapezius (F2,28 = 7.82, P = .001) during Ws, and the upper (F2,28 = 3.61, P = .03) and middle trapezii (F2,28 = 5.81, P = .01) during Ts. Post hoc testing revealed that both feedback conditions elicited greater EMG amplitude compared with no feedback, but there were no significant differences between the feedback conditions. CONCLUSIONS: The addition of tactile feedback to VF does not increase EMG amplitude compared with VF alone. This study indicates that feedback, regardless of type, is more beneficial than providing no feedback, for increasing EMG amplitude.

Preseason screening of shoulder range of motion and humeral retrotorsion does not predict injury in high school baseball players.

BACKGROUND: Shoulder and elbow injuries are commonplace in high school baseball. Although altered shoulder range of motion (ROM) and humeral retrotorsion angles have been associated with injuries, the efficacy of preseason screening of these characteristics remains controversial. METHODS: We conducted preseason screenings for shoulder internal and external rotation ROM and humeral retrotorsion on 832 high school baseball players and tracked their exposure and incidence on throwing-related shoulder and elbow injuries during a subsequent season. Poisson regression with robust error variance was used to determine whether preseason screening could identify injury risk in baseball players and whether the injury risk was higher for pitchers compared with players who do not pitch. RESULTS: Shoulder rotation ROM or humeral retrotorsion at preseason did not predict the risk of throwing-related upper extremity injury (P = .15-.89). Injury risk was 3.84 higher for baseball players who pitched compared with those who did not (95% confidence interval, 1.72-8.56; P = .001). DISCUSSION: Preseason measures of shoulder ROM and humeral retrotorsion may not be effective in identifying players who are at increased injury risk. Because shoulder ROM is a measure that fluctuates under a variety of influences, future study should investigate whether taking multiple measurements during a season can identify at-risk players. The usefulness of preseason screening may also depend on rigor of participation in sports. Future studies should investigate how preseason shoulder characteristics and participation factors (ie, pitch count and frequency, competitive level, pitching in multiple leagues) interact to predict injury risk in baseball players.

Practice habits and attitudes and behaviors concerning shoulder pain in high school competitive club swimmers.

OBJECTIVE: The objective of this study is to describe the practice habits, injury frequency, and attitudes and behaviors concerning shoulder pain in high school-aged competitive swimmers and describe the relationship between attitudes and behaviors. DESIGN: Cross-sectional research design. SETTING: Local swimming clubs. PARTICIPANTS: One hundred two swimmers, aged 13-18 years, at the top training level of their club team were included in the study. ASSESSMENT OF RISK FACTORS: Participants were given a survey with questions regarding swimming practice and attitudes and behaviors concerning shoulder pain. MAIN OUTCOME MEASURES: Practice habits (yards/week, practice/week, dry-land and weight/week, and months swimming/year) and attitudes and behaviors concerning shoulder pain. RESULTS: Subjects completed an average of 6.89 ± 1.41 swimming practices/wk of 6000 to 7000 yd/practice. The majority of swimmers believe that mild and moderate shoulder pain is normal in swimming and should be tolerated to complete practice, while a majority responded that they swim with shoulder pain. Seventy-three percent of swimmers reported using pain medication to manage their shoulder pain. There was a significant correlation between attitude and behaviors of moderate and severe shoulder pain. CONCLUSIONS: Club swimmers have a high frequency of practices, comparable to collegiate and professional swimmers. They believe that shoulder pain is normal and should be tolerated to complete practice. The association between the swimmers' attitudes and behaviors indicates that the interventions that educate the swimmers, coaches, and parents may be effective in changing their attitudes and ultimately their behaviors, decreasing the number of athletes who train with shoulder pain.

Scapular dysfunction in high school baseball players sustaining throwing-related upper extremity injury: a prospective study.

HYPOTHESIS AND BACKGROUND: Though commonly suggested as an injury risk factor, scapular dysfunction has not been established as a prospective cause of throwing-related upper extremity injury in baseball players. The purpose is to determine whether scapular dysfunction identified during preseason screening is predictive of increased risk of throwing-related shoulder and elbow injuries in high school baseball players. MATERIALS AND METHODS: The presence or absence of scapular dysfunction was obtained prospectively during preseason screenings in 246 high school baseball players over the 2010 and 2011 seasons. Exposure and injury surveillance data were then obtained weekly over the course of each season to determine whether scapular dysfunction was predictive of subsequent throwing-related upper extremities sustained. RESULTS: There were 12 throwing-related upper extremity injuries sustained in the 246 participants, yielding an injury rate of 1.0 per 1,000 athlete exposures. There were no significant differences in injury rates between the participants with normal scapular function versus subtle scapular dysfunction (P = .62), normal scapular function versus obvious scapular dysfunction (P = .26), or subtle versus obvious scapular dysfunction (P = .45). CONCLUSION: This study showed that scapular dysfunction identified during preseason screenings is not associated with subsequent throwing-related upper extremity injury.

Effect of a 6-week strengthening program on shoulder and scapular-stabilizer strength and scapular kinematics in division I collegiate swimmers.

CONTEXT: Shoulder injuries are common in swimmers because of the demands of the sport. Muscle imbalances frequently exist due to the biomechanics of the sport, which predispose swimmers to injury. To date, an effective shoulder-injury-prevention program for competitive swimmers has not been established. OBJECTIVE: To assess the effectiveness of a 6-wk strengthening and stretching intervention program on improving glenohumeral and scapular muscle strength and scapular kinematics in collegiate swimmers. DESIGN: Randomized control trial. SETTING: University biomechanics research laboratory. PARTICIPANTS: Forty-four Division I collegiate swimmers. INTERVENTIONS: The intervention program was completed 3 times per week for 6 wk. The program included strengthening exercises completed using resistance tubing-scapular retraction (Ts), scapular retraction with upward rotation (Ys), scapular retraction with downward rotation (Ws), shoulder flexion, low rows, throwing acceleration and deceleration, scapular punches, shoulder internal rotation at 90° abduction, and external rotation at 90° abduction-and 2 stretching exercises: corner stretch and sleeper stretch. MAIN OUTCOME MEASUREMENTS: Scapular kinematics and glenohumeral and scapular muscle strength assessed preintervention and postintervention. RESULTS: There were no significant between-groups differences in strength variables at pre/post tests, although shoulder-extension and internal-rotation strength significantly increased in all subjects regardless of group assignment. Scapular kinematic data revealed increased scapular internal rotation, protraction, and elevation in all subjects at posttesting but no significant effect of group on the individual kinematic variables. CONCLUSIONS: The current strengthening and stretching program was not effective in altering strength and scapular kinematic variables but may serve as a framework for future programs. Adding more stretching exercises, eliminating exercises that overlap with weight-room training and swim training, and timing of implementation may yield a more beneficial program for collegiate swimmers.

Scapulohumeral kinematic assessment of the forward kayak stroke in experienced whitewater kayakers.

By understanding the normal humeral and scapular kinematics during the kayak stroke, inferences about the relationship of kayaking technique and shoulder injury may be established. The purpose of this study was to describe scapular and humeral kinematics and to compare dominant versus nondominant symmetry in healthy whitewater kayakers performing the forward stroke. Twenty-five competent whitewater kayakers (mean age: 34.1 +/- 9.4 years, mean height: 1.768 +/- 0.093m, mean mass: 78.2 +/- 13.0 kg) underwent humeral and scapular kinematic assessment, using an electromagnetic tracking device, while kayaking on a kayak ergometer. Paired t-tests were used to determine symmetry. Scapular and humeral kinematic means and standard deviations at six time points during the kayak stroke were described. Scapular and humeral kinematics were shown to be similar upon bilateral comparison. The greatest potential for injury during the forward stroke may be at thrust paddle shaft vertical when the humerus is maximally elevated in internal rotation and adduction as subacromial structures may be mechanically impinged. The relationship between scapulohumeral kinematics related to injury at other time points are also described.

Three-dimensional scapular and clavicular kinematics and scapular muscle activity during retraction exercises.

STUDY DESIGN: Controlled laboratory study. OBJECTIVES: To describe and compare scapular and clavicular kinematics and muscle activity during 6 retraction exercises in young healthy adults (mean +/- SD age, 23.2 +/- 2.4 years). BACKGROUND: Based on the association between shoulder injuries and scapular/clavicular movement, muscle activity during various exercises that target muscles surrounding the scapula have been investigated. However, the scapular and clavicular movements occurring during these exercises remain uninvestigated. Evaluation of the scapular and clavicular kinematics in addition to muscle activity provides additional information that allow clinicians to select exercises that best meet the patient's needs. METHODS: Three-dimensional scapular and clavicular kinematics and scapular muscle activity data were collected while the participants performed 6 scapular retraction exercises. One-way repeated-measures ANOVA and post hoc analyses were used to determine differences in scapular/clavicular kinematics and activation levels of the upper, middle, and lower trapezius and serratus anterior muscles occurring during the exercises. RESULTS: The general pattern of the kinematics observed during all retraction exercises was scapular external rotation, scapular upward rotation, scapular posterior tilting, clavicular retraction, and clavicular depression. However, the exercises resulted in varying amounts of scapular movement and muscle activity. CONCLUSION: Clinicians can select appropriate exercises for their patients based on their need to strengthen specific retractor muscles and to improve specific scapular and clavicular movement patterns, pre-existing conditions, and available range of motion.

A comparison of physical characteristics and swing mechanics between golfers with and without a history of low back pain.

STUDY DESIGN: Controlled laboratory study using a cross-sectional design. OBJECTIVES: To examine the kinematics and kinetics of the trunk and the physical characteristics of trunk and hip in golfers with and without a history of low back pain (LBP). BACKGROUND: Modified swing patterns and general exercises have been suggested for golfers with back pain. Yet we do not know what contributes to LBP in golfers. To create and validate a low back-specific exercise program to help prevent and improve back injuries in golfers, it may be valuable to understand the differences in biomechanical and physical characteristics of golfers with and without a history of LBP. METHODS: Sixteen male golfers with a history of LBP were matched by age and handicap with 16 male golfers without a history of LBP. All golfers underwent a biomechanical swing analysis, trunk and hip strength and flexibility assessment, spinal proprioception testing, and postural stability testing. RESULTS: The group with a history of LBP demonstrated significantly less trunk extension strength at 60 degrees/s and left hip adduction strength, as well as limited trunk rotation angle toward the nonlead side. No significant differences were found in postural stability, trunk kinematics, and maximum spinal moments during the golf swing. CONCLUSION: Deficits observed in this study may affect a golfer's ability to overcome the spinal loads generated during the golf swing over time. Exercises for improving these physical deficits can be considered, although the cause-effect of LBP in golfers still cannot be determined.

Influence of Baseball Training Load on Clinical Reach Tests and Grip Strength in Collegiate Baseball Players.

CONTEXT: A baseball-specific training load may influence strength or glenohumeral range of motion, which are related to baseball injuries. Glenohumeral reach tests and grip strength are clinical assessments of shoulder range of motion and upper extremity strength, respectively. OBJECTIVE: To examine changes in glenohumeral reach test performance and grip strength between dominant and nondominant limbs and high, moderate, and low baseball-specific training-load groups. DESIGN: Repeated-measures study. SETTING: University laboratory and satellite clinic. PATIENTS OR OTHER PARTICIPANTS: Collegiate baseball athletes (n = 18, age = 20.1 ± 1.3 years, height = 185.0 ± 6.5 cm, mass = 90.9 ± 10.2 kg). MAIN OUTCOME MEASURE(S): Participants performed overhead reach tests (OHRTs), behind-the-back reach tests (BBRTs), and grip strength assessments using the dominant and nondominant limbs every 4 weeks for 16 weeks. Percentage change scores were calculated between testing times. After each training session, participants provided their duration of baseball activity, throw count, and body-specific and arm-specific ratings of perceived exertion. We classified them in the high, moderate, or low training-load group based on each training-load variable: body-specific acute:chronic workload ratio (ACWR), arm-specific ACWR, body-specific cumulative load, and arm-specific cumulative load. Mixed models were used to compare training-load groups and limbs. RESULTS: The arm-specific ACWR group demonstrated as main effect for OHRT (F = 7.70, P = .001), BBRT (F = 4.01, P = .029), and grip strength (F = 8.89, P < .001). For the OHRT, the moderate training-load group demonstrated a 10.8% greater increase than the high group (P = .004) and a 13.2% greater increase than the low group (P < .001). For the BBRT, the low training-load group had a 10.1% greater increase than the moderate group (P = .011). For grip strength, the low training-load group demonstrated a 12.1% greater increase than the high group (P = .006) and a 17.7% greater increase than the moderate group (P < .001). CONCLUSIONS: Arm-specific ACWR was related to changes in clinical assessments of range of motion and strength. Clinicians may use arm-specific ACWR to indicate when a baseball athlete's physical health is changing.

Influence of humeral torsion on interpretation of posterior shoulder tightness measures in overhead athletes.

OBJECTIVE: To measure the influence of humeral torsion on interpretation of clinical indicators of posterior shoulder tightness in overhead athletes. DESIGN: Cross-sectional control group comparison. SETTING: A university-based sports medicine research laboratory. PARTICIPANTS: Twenty-nine healthy intercollegiate baseball players and 25 college-aged control individuals with no history of participation in overhead athletics were enrolled. INTERVENTION: In all participants, bilateral humeral rotation and humeral horizontal adduction variables were measured with a digital inclinometry. Bilateral humeral torsion was measured with ultrasonography. MAIN OUTCOME MEASURES: Group and limb comparisons were made for clinical indicators of posterior shoulder tightness (humeral rotation and horizontal adduction variables) and humeral torsion variables. The relationship between humeral torsion and clinical indicators of posterior shoulder tightness were established. RESULTS: The dominant limb of the baseball players demonstrated greater humeral torsion, and less internal rotation and total rotation range of motion, compared with control participants and the nondominant limb in both groups. Once corrected for torsion, no group or limb differences in internal rotation were present. Statistically significant relationships existed between the amount of humeral torsion and measures of posterior shoulder tightness. CONCLUSIONS: Although limb differences in clinical indicators of posterior tightness exist in healthy overhead athletes, these measures appear to be influenced by humeral torsion rather than soft tissue tightness. Once torsion is accounted for, the limb differences observed clinically were minimal in healthy overhead athletes. When possible, accounting for humeral torsion when interpreting clinical measures of posterior shoulder tightness may aid in treatment decisions.

Effects of spinal manipulation on trunk proprioception in subjects with chronic low back pain during symptom remission.

OBJECTIVE: The purpose of this study was to examine the immediate effects of spinal manipulative therapy (SMT) on trunk proprioception in subjects with asymptomatic chronic low back pain (CLBP) and determine if those effects lasted 1 week. METHODS: This unbalanced randomized controlled crossover design examined 33 subjects with CLBP. Proprioception was tested via joint position sense, threshold to detect passive motion (TTDPM), direction of motion (DM), and force reproduction. Each subject received lumbar manipulation or a sham procedure followed by proprioception retest. This procedure was repeated 1 week later using the opposing treatment. Subjects receiving SMT in the second session returned a third time receiving the sham procedure again. RESULTS: Spinal manipulative therapy produced an effect for TTDPM in the manipulation first group (P = .008), the sham procedure produced an effect for joint position sense in the sham first group (P = .005). Spinal manipulative therapy had a 1-week effect for the manipulation first group (P = .006). No effect was noted for either DM or force reproduction. CONCLUSIONS: Results suggest SMT had minimal immediate effect on trunk proprioception. The effects noted occurred in session 1, implicating learning as a potential source. Learning, from repetitive proprioception training, may enhance neuromuscular control in subjects with CLBP before the use of therapeutic exercise. Subjects showed smaller deficits than previously reported for TTDPM or DM, suggesting proprioception deficits may correlate with pain level.

Variability in the identification and reporting of overuse injuries among sports injury surveillance data collectors.

PURPOSE: This study examined variability in identifying and reporting overuse injuries among Certified Athletic Trainers (ATs). METHODS: This cross-sectional study of ATs participating in the National Collegiate Athletic Association's Injury Surveillance Program, utilized a novel online-only survey, consisting of seven hypothetical clinical scenarios representing various clinical presentations including overuse and acute elements. Participants reported clinical opinions regarding the role overuse played in each scenario (major contributor, not a major contributor, not enough information) and probability (0-100%) of classifying each scenario as having an overuse injury mechanism, then completed open-ended questions addressing their decision-making process. RESULTS: 74 ATs (25%) completed the survey. Six of the seven scenarios generated discordance in responses among the participating ATs. Variability in AT decisions involved: the progression of injury, duration of symptoms, and activity at time of injury. CONCLUSION: Developing a formalized definition of overuse injury may improve consistency and standardize methods for identifying and reporting overuse injuries within injury research.

Rate of Upper Extremity Injury in High School Baseball Pitchers Who Played Catcher as a Secondary Position.

CONTEXT: Many high school pitchers play another position after they have finished pitching for the day or on their rest days from pitching. Because of the cumulative demands on the arm, pitchers who also play catcher may have a greater risk of developing a throwing-related shoulder or elbow injury. OBJECTIVE: To compare the rate of throwing-related upper extremity injuries between high school baseball pitchers who also played catcher as a secondary position and those who did not play catcher. DESIGN: Prospective cohort study. SETTING: Field laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 384 male high school baseball pitchers were recruited from 51 high school teams. Pitchers who reported their secondary position as catcher were classified into the pitcher/catcher group and those who did not report playing catcher as a secondary position were classified into the other group. MAIN OUTCOME MEASURE(S): Participants completed a demographic questionnaire preseason and then athlete participation and injury status were tracked during the subsequent season. Athlete-exposures were monitored and the shoulder and elbow injury proportion rates were calculated. RESULTS: Athlete-exposures did not differ between groups ( P = .488). The pitcher/catcher group's risk of shoulder or elbow injury was 2.9 times greater than that of the other pitchers (15% versus 5%; injury proportion rate = 2.9; 95% confidence interval = 1.03, 8.12). CONCLUSIONS: Pitchers who reported also playing catcher were at a greater risk of sustaining a throwing-related shoulder or elbow injury than the other pitchers. These findings suggest that pitchers should consider not playing catcher as their secondary position in order to allow adequate time for recovery and to decrease their overall throwing load. Serial physical examinations of pitchers/catchers during the season may be useful in determining if their physical characteristics are changing during the season because of the cumulative throwing load.

Medial Elbow Joint Space Increases With Valgus Stress and Decreases When Cued to Perform A Maximal Grip Contraction.

BACKGROUND: Previous research indicates that the amount of valgus torque placed on the elbow joint during overhead throwing is higher than the medial ulnar collateral ligament (UCL) can tolerate. Wrist and finger flexor muscle activity is hypothesized to make up for this difference, and in vitro studies that simulated activity of upper extremity musculature, specifically the flexor digitorum superficialis and flexor carpi ulnaris, support this hypothesis. PURPOSE: To assess the medial elbow joint space at rest, under valgus stress, and under valgus stress with finger and forearm flexor contraction by use of ultrasonography in vivo. STUDY DESIGN: Controlled laboratory study. METHODS: Participants were 22 healthy males with no history of elbow dislocation or UCL injury (age, 21.25 ± 1.58 years; height, 1.80 ± 0.08 m; weight, 79.43 ± 18.50 kg). Medial elbow joint space was measured by use of ultrasonography during 3 separate conditions: at rest (unloaded), under valgus load (loaded), and with a maximal grip contraction under a valgus load (loaded-contracted) in both limbs. Participants lay supine with their arm abducted 90° and elbow flexed 30° with the forearm in full supination. A handgrip dynamometer was placed in the participants' hand to grip against during the contracted condition. Images were reduced in ImageJ to assess medial elbow joint space. A 2-way (condition × limb) repeated-measures analysis of variance and Cohen's d effect sizes were used to assess changes in medial elbow joint space. Post hoc testing was performed with a Bonferroni adjustment to assess changes within limb and condition. RESULTS: The medial elbow joint space was significantly larger in the loaded condition (4.91 ± 1.16 mm) compared with the unloaded condition (4.26 ± 1.23 mm, P < .001, d = 0.712) and the loaded-contracted condition (3.88 ± 0.94 mm, P < .001, d = 1.149). No significant change was found between the unloaded and loaded-contracted conditions ( P = .137). CONCLUSION: Medial elbow joint space increases under a valgus load and then decreases when a maximal grip contraction is performed. This indicates that wrist and finger flexor muscle contraction may assist in limiting medial elbow joint space, a result similar to findings of previous research in vitro. CLINICAL RELEVANCE: Muscle activation of the upper extremity limits the medial elbow joint space, suggesting that injury prevention programs for throwing athletes should incorporate exercises for the elbow, wrist, and hand to limit excessive medial elbow joint space gapping during activities that create high valgus load.

Capture of Time-Loss Overuse Soccer Injuries in the National Collegiate Athletic Association's Injury Surveillance System, 2005-2006 Through 2007-2008.

CONTEXT: Overuse injuries are reported to account for nearly 50% of sports injuries and, due to their progressive nature and the uncertainty regarding date of onset, are difficult to define and categorize. Comparing the capture rates of overuse injuries between injury-surveillance systems and medical records can clarify completeness and determinants of how overuse injuries are represented in injury-surveillance data. OBJECTIVE: To estimate the capture rate of time-loss medical-attention overuse injuries in men's and women's soccer in the National Collegiate Athletic Association Injury Surveillance System (NCAA ISS) compared with medical records maintained by certified athletic trainers and assess the differences in completeness of capture and factors contributing to those differences. DESIGN: Capture-recapture study. SETTING: Fifteen NCAA institutions provided NCAA ISS and medical record data from men's and women's soccer programs from 2005-2006 through 2007-2008. PATIENTS OR OTHER PARTICIPANTS: National Collegiate Athletic Association men's and women's soccer players. MAIN OUTCOME MEASURE(S): Time-loss medical-attention overuse injuries were defined as injuries with an overuse mechanism of injury in the NCAA ISS or medical records. Capture rates were calculated as the proportion of total overuse injuries classified as having overuse mechanisms in the NCAA ISS and the NCAA ISS and medical records combined. RESULTS: The NCAA ISS captured 63.7% of the total estimated overuse mechanisms of injury in men's and women's soccer players. The estimated proportion of overuse injury mechanisms captured by both the NCAA ISS and medical records was 37.1%. The NCAA ISS captured more overuse injury mechanisms in men's soccer than in women's soccer (79.2% versus 45.0%, χ2 = 9.60; P = .002) athletes. CONCLUSIONS: From 2005-2006 through 2007-2008, the NCAA ISS captured only two thirds of time-loss medical-attention overuse mechanisms of injury in men's and women's soccer players. Future researchers should consider supplementing injury-surveillance data with a clinical record review to capture the burden of these injuries.

Strength, flexibility, and balance characteristics of highly proficient golfers.

Despite the emergence of golf-specific training programs and training aids, relatively little research has been conducted examining the physical characteristics that are important to golf performance. We studied the strength, flexibility, and balance characteristics of golfers across 3 proficiency levels based on handicap index (HCP) (<0, 1-9, and 10-20) to determine the physical characteristics unique to highly proficient golfers. A total of 257 (age: 45.5 +/- 12.8 years, height: 180.6 +/- 6.5 cm, weight: 87.9 +/- 12.6 kg) healthy, male golfers participated in the study. Testing included an assessment of strength (torso, shoulder, and hip), flexibility (torso, shoulder, and hip), and single-leg balance. Golfers in the highest proficiency group (HCP < 0) had significantly (p < 0.05) greater hip strength, torso strength, shoulder strength, shoulder flexibility, hip flexibility, torso flexibility, and balance (eyes open) than golfers in the lowest proficiency group (HCP 10-20). The results of this study demonstrate that better golfers possess unique physical characteristics that are important to greater proficiency. These characteristics have also been demonstrated to be modifiable through golf-specific training programs.

Glenohumeral range of motion deficits and posterior shoulder tightness in throwers with pathologic internal impingement.

BACKGROUND: Alterations in glenohumeral range of motion, including increased posterior shoulder tightness and glenohumeral internal rotation deficit that exceeds the accompanying external rotation gain, are suggested contributors to throwing-related shoulder injuries such as pathologic internal impingement. Yet these contributors have not been identified in throwers with internal impingement. HYPOTHESIS: Throwers with pathologic internal impingement will exhibit significantly increased posterior shoulder tightness and glenohumeral internal rotation deficit without significantly increased external rotation gain. STUDY DESIGN: Case control study; Level of evidence, 3. METHODS: Eleven throwing athletes with pathologic internal impingement diagnosed using both clinical examination and a magnetic resonance arthrogram were demographically matched with 11 control throwers who had no history of upper extremity injury. Passive glenohumeral internal and external rotation were measured bilaterally with standard goniometry at 90 degrees of humeral abduction and elbow flexion. Bilateral differences in glenohumeral range of motion were used to calculate glenohumeral internal rotation deficit and external rotation gain. Posterior shoulder tightness was quantified as the bilateral difference in passive shoulder horizontal adduction with the scapula retracted and the shoulder at 90 degrees of elevation. Comparisons were made between groups with dependent t tests (P < .05). RESULTS: The throwing athletes with internal impingement demonstrated significantly greater glenohumeral internal rotation deficit (P = .03) and posterior shoulder tightness (P = .03) compared with the control subjects. No significant differences were observed in external rotation gain between groups (P = .16). CLINICAL RELEVANCE: These findings could indicate that a tightening of the posterior elements of the shoulder (capsule, rotator cuff) may contribute to impingement. The results suggest that management should include stretching to restore flexibility to the posterior shoulder.