Sport specialization is associated with upper-extremity overuse injury in high school baseball players.

BACKGROUND AND HYPOTHESIS: Sport specialization is increasingly common in youth sports and is a risk factor for lower-extremity overuse injuries. However, limited data exist on whether specialization is associated with upper-extremity (UE) overuse injuries, specifically in youth baseball players. We hypothesized that specialization in baseball and being a pitcher would be associated with poorer arm health and UE overuse injury history in the previous year. METHODS: During the 2019 spring baseball season, 551 high school baseball athletes (aged 15.9 ± 1.3 years) from 3 states (Alabama, n = 200; California, n = 188; and Michigan, n = 163) completed an anonymous questionnaire. Athletes were recruited from 5 high schools in each state, with schools matched based on factors that influence specialization rates. The questionnaire consisted of (1) demographic characteristics, (2) baseball participation information (including sport specialization status), and (3) throwing-arm health and UE injury history in the previous 12 months. Throwing-arm health was assessed using the Youth Throwing Score (YTS), a validated and reliable outcome measure for youth baseball players. Multivariate regression analyses were used to examine the association between variables of interest and the YTS or UE overuse injury history, adjusting for covariates. RESULTS: After adjustment for covariates, highly specialized athletes were more likely to report a UE overuse injury in the previous year compared with low-specialization athletes (odds ratio [OR], 3.77; 95% confidence interval [CI], 1.39-10.2, P = .009). Both athletes who reported playing baseball for more than 8 months per year (OR, 2.03; 95% CI, 1.12-3.65; P = .019) and athletes who reported being a pitcher (OR, 2.11; 95% CI, 1.20-3.72; P = .010) were more likely to report a history of UE overuse injury. Highly specialized players reported lower (worse) YTS values compared with low-specialization players (least-squares mean estimate ± standard error, 56.5 ± 1.1 vs. 53.3 ± 0.7; P = .034). Players who reported pitching as one of their positions scored worse on the YTS than non-pitchers (least-squares mean estimate ± standard error, 51.6 ± 0.8 vs. 57.2 ± 0.6; P < .001). CONCLUSION: Although baseball recommendations that discourage sport specialization are widely available for parents, athletes, and coaches, high rates of sport specialization were reported in our sample. We found that being highly specialized in baseball was associated with UE overuse injury history and worse throwing-arm health in high school baseball athletes. Continued education for baseball parents, athletes, and coaches is necessary to raise awareness of the risks associated with high specialization.

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.

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.

Epidemiology of National Collegiate Athletic Association men's and women's swimming and diving injuries from 2009/2010 to 2013/2014.

BACKGROUND: Recent injury data for collegiate-level swimming and diving are limited. This study describes the epidemiology of men's and women's swimming and diving injuries reported by the National Collegiate Athletic Association (NCAA) Injury Surveillance Program (ISP) during the 2009/2010 to 2013/2014 academic years. METHODS: Injuries and athlete-exposure (AE) data reported within 9 men's and 13 women's swimming and diving programmes were analysed. Injury rates, injury rate ratios (IRR), and injury proportions by body site, diagnosis and mechanism were reported with 95% CIs. RESULTS: The ISP captured 149 and 208 injuries for men's and women's swimming and diving, respectively, leading to injury rates of 1.54/1000 and 1.71/1000 AEs. Among females, divers had a higher injury rate (2.49/1000 AEs) than swimmers (1.63/1000 AEs; IRR=1.53; 95% CI 1.07 to 2.19). Injury rates for male divers (1.94/1000 AEs) and swimmers (1.48/1000 AEs) did not differ (IRR=1.33; 95% CI 0.85 to 2.31). Most injuries occurred to the shoulder, resulted in strains and were classified as overuse or non-contact. Female swimmers had a higher overuse injury rate (1.04/1000 AEs) than male swimmers (0.66/1000 AEs; IRR=1.58; 95% CI 1.14 to 2.19). Overuse injury rates for female divers (0.54/1000 AEs) and male divers (0.46/1000 AEs) did not differ (IRR=1.16; 95% CI 0.40 to 3.34). Injury rates in 2012/2013-2013/2014 were lower than those in 2009/2010-2011/2012 for women's swimming (IRR=0.70; 95% CI 0.52 to 0.95) and diving (IRR=0.56; 95% CI 0.30 to 1.08), respectively. No time trends existed for men's swimmers or divers. CONCLUSIONS: Shoulder, strain and overuse injuries were common in collegiate men's and women's swimming and diving. Female swimmers were more likely to suffer an overuse injury than male swimmers. In addition, divers may have higher injury rates than swimmers, although small reported numbers warrant additional research.

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.

Workplace-Related Factors Associated With Employees' Standing Time at Work: A Research Brief.

PURPOSE: The purpose of this study was to identify the relationship between work-related, individual, and environmental factors and self-reported standing time during the workday. DESIGN: Cross-sectional study design. SETTING: Participants were recruited from a large, public university in the southeastern United States. MEASURES: Data were collected through an 87-item online survey using previously validated scales that assessed workplace standing time, demographic variables, work-related psychosocial factors, and workplace environment factors. ANALYSIS: One-way analysis of variance, Pearson correlation coefficients, and nonparametric tests were used to determine univariate relationships between standing time and independent work-related variables and demographic factors. RESULTS: Mean standing time among the sample (n = 502) was 72.49 minutes (standard deviation = 73.48) daily. There was a significant relationship between standing time and barrier self-efficacy for standing at work, self-regulation strategies, social norms, local connectivity in the workplace, overall connectivity in the workplace, and proximity of coworkers. Standing time was significantly higher for men, employees with an advanced degree, employees with a standing desk, and faculty. CONCLUSION: Health promotion researchers and practitioners should consider factors at multiple levels of influence when designing studies to explore workplace sedentary behavior. The findings regarding variations in workplace behavior by employee subgroups should be taken into consideration when designing future studies in the workplace.

Worldwide measurements of bioturbation intensity, ventilation rate, and the mixing depth of marine sediments.

The activities of a diverse array of sediment-dwelling fauna are known to mediate carbon remineralisation, biogeochemical cycling and other important properties of marine ecosystems, but the contributions that different seabed communities make to the global inventory have not been established. Here we provide a comprehensive georeferenced database of measured values of bioturbation intensity (Db, n = 1281), burrow ventilation rate (q, n = 765, 47 species) and the mixing depth (L, n = 1780) of marine soft sediments compiled from the scientific literature (1864-2018). These data provide reference information that can be used to inform and parameterise global, habitat specific and/or species level biogeochemical models that will be of value within the fields of geochemistry, ecology, climate, and palaeobiology. We include metadata relating to the source, timing and location of each study, the methodology used, and environmental and experimental information. The dataset presents opportunity to interrogate current ecological theory, refine functional typologies, quantify uncertainty and/or test the relevance and robustness of models used to project ecosystem responses to change.

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.

Ecological Influences on Employees' Workplace Sedentary Behavior: A Cross-Sectional Study.

PURPOSE: The purpose of this study was to explore the relationship between ecological factors and occupational sedentary behavior (SB). DESIGN: Cross-sectional online survey. SETTING: Participants were employees recruited from a large, public university in the Southeastern United States from August to November 2016. PARTICIPANTS: The final sample included 527 (56% response rate) employees. MEASURES: Data were collected through an 87-item survey using previously validated scales that assessed occupational SB, perceived behavioral control, barrier self-efficacy, self-regulation strategies, organizational social norms, office environment, and worksite climate. ANALYSIS: One-way analysis of variance analyses were used to determine differences in occupational SB by demographic factors. A multivariate regression model was used to determine significant ecological determinants of occupational SB. RESULTS: Mean SB was 342.45 (standard deviation = 133.25) minutes. Significant differences in SB were found by gender, education, and employment classification. Barrier self-efficacy and workplace connectivity, which evaluates the spatial layout of the office setting that may impact mobility within the workplace, were significant predictors of SB in the multivariate model. CONCLUSION: Results from this study provide new information regarding the potential impact of workplace barriers and connectivity on occupational SB. The findings from this study support the inclusion of intervention modalities to minimize workplace barriers and increase workplace connectivity to increase workplace mobility and decrease SB.

The Epidemiology of Deltoid Ligament Sprains in 25 National Collegiate Athletic Association Sports, 2009-2010 Through 2014-2015 Academic Years.

CONTEXT: Deltoid ligament sprains among collegiate student-athletes have not been extensively investigated. Research regarding the mechanisms, participation-restriction time, and recurrence of deltoid ligament sprains in collegiate student-athletes is lacking. OBJECTIVE: To describe the epidemiology of deltoid ligament sprains in 25 National Collegiate Athletic Association championship sports. DESIGN: Descriptive epidemiology study. SETTING: National Collegiate Athletic Association Injury Surveillance Program. MAIN OUTCOME MEASURE(S): We analyzed deltoid ligament sprains recorded in the Injury Surveillance Program for the 2009-2010 through 2014-2015 academic years. Deltoid ligament sprain injury rates, rate ratios, and injury proportion ratios with 95% confidence intervals (CIs) were reported. RESULTS: During the study period, 380 deltoid ligament sprains were reported, resulting in a combined injury rate of 0.79/10 000 athlete-exposures (AEs; 95% CI = 0.71, 0.87). Most deltoid ligament sprains occurred in practices (54.2%, n = 206). However, the competition injury rate was higher than the practice injury rate (rate ratio = 3.74; 95% CI = 3.06, 4.57). The highest deltoid ligament sprain rates were in women's gymnastics (2.30/10 000 AEs; 95% CI = 1.05, 3.55), men's soccer (1.73/10 000 AEs; 95% CI = 1.14, 2.32), women's soccer (1.61/10 000 AEs; 95% CI = 1.13, 2.09), and men's football (1.40/10 000 AEs; 95% CI = 1.18, 1.62). Nearly half of all deltoid ligament sprains (49.7%, n = 189) were due to player contact, and 39.5% (n = 150) were non-time-loss injuries (ie, participation restricted for less than 24 hours). Only 8.2% (n = 31) of deltoid ligament sprains were recurrent. CONCLUSIONS: The highest deltoid ligament sprain rates were in women's gymnastics, men's and women's soccer, and men's football. However, the rate for women's gymnastics was imprecise (ie, the CI was wide), highlighting the need for further surveillance of deltoid ligament sprains in the sport. Most deltoid ligament sprains were due to player contact. Future researchers should assess interventions that may prevent deltoid ligament sprains.

Epidemiology of Acromioclavicular Joint Sprains in 25 National Collegiate Athletic Association Sports: 2009-2010 to 2014-2015 Academic Years.

BACKGROUND: No previous studies have described the incidence of acromioclavicular (AC) joint injuries in a large sample of National Collegiate Athletic Association (NCAA) student-athletes. Such data are needed to understand the injury prevalence, mechanisms of injury, and recovery patterns in NCAA student-athletes. PURPOSE: To describe the epidemiology of AC joint sprain injuries in 25 NCAA championship sports. STUDY DESIGN: Descriptive epidemiology study. METHODS: AC joint sprains were analyzed from the NCAA Injury Surveillance Program during the 2009-2010 to 2014-2015 academic years. AC joint sprain injury rates, rate ratios, and injury proportion ratios (IPRs) were reported with 95% CIs. RESULTS: In the 25 NCAA sports examined during the 2009-2010 to 2014-2015 academic years, a total of 844 AC joint sprains were reported, for a rate of 1.72 per 10,000 athlete-exposures (AEs). The majority of AC joint sprains were reported in football (50.4%, n = 425). Most AC joint sprains occurred in competitions (66.0%, n = 557), and the competition rate was 8.58 times the practice rate (95% CI, 7.44-9.89). In sex-comparable sports (ie, soccer, basketball, ice hockey, lacrosse, baseball/softball, indoor track, outdoor track, cross-country, tennis, and swimming and diving), the AC joint sprain rate in men was 4.67 times that of women (95% CI, 3.56-6.14). Most AC joint sprains were caused by player contact (54.7%, n = 462), followed by surface contact (29.0%, n = 245). Of all AC joint sprains, 47.5% resulted in a time loss of <24 hours, and 5.9% were severe. In addition, 9.7% were recurrent, and only 1.0% required surgery. In sex-comparable sports, male athletes had a larger proportion of injuries due to player contact than did female athletes (IPR, 1.50; 95% CI, 1.06-2.13); female athletes had a larger proportion of injuries due to surface contact than male athletes (IPR, 1.55; 95% CI, 1.01-2.38). Also, compared with women, men had a larger proportion of AC joint sprains that were recurrent (IPR, 10.29; 95% CI, 1.45-72.90). CONCLUSION: The highest rates of AC joint sprains occurred in men's football, ice hockey, and wrestling as well as women's ice hockey. Most AC joint sprains across all sports occurred because of a contact mechanism, particularly from player-player contact. Further research into the specific activities and exposures at the time of injury may lend a better understanding of the causation of these injuries and lead to appropriate interventions to decrease their incidence and severity.

Comparison of Upper Extremity Physical Characteristics Between Adolescent Competitive Swimmers and Nonoverhead Athletes.

CONTEXT: Alterations to upper extremity physical characteristics of competitive swimmers (posture, range of motion [ROM], and subacromial-space distance) are commonly attributed to cumulative training load during a swimmer's competitive career. However, this accepted clinical belief has not been established in the literature. It is important to understand whether alterations in posture and associated physical characteristics occur as a result of sport training or factors other than swimming participation to better understand injury risk and possible interventions. OBJECTIVE: To compare posture, subacromial-space distance, and glenohumeral external-rotation, internal-rotation, and horizontal-adduction ROM between adolescent competitive swimmers and nonoverhead athletes. DESIGN: Cross-sectional study. SETTING: Local swimming pools and high school athletic training rooms. PATIENTS OR OTHER PARTICIPANTS: Forty-four competitive adolescent swimmers and 31 nonoverhead athletes who were not currently experiencing any elbow, shoulder, neck, or back pain that limited their sport activity. INTERVENTION(S): Posture, subacromial-space distance, and glenohumeral ROM were measured using photography, diagnostic ultrasound, and a digital inclinometer, respectively. MAIN OUTCOME MEASURE(S): Forward shoulder posture, forward head posture, normalized subacromial-space distance, internal-rotation ROM, and external-rotation ROM. RESULTS: No clinically significant differences existed between swimmers and nonoverhead athletes for posture, normalized subacromial-space distance, or external- or internal-rotation ROM. Swimmers presented with less horizontal-adduction ROM than nonoverhead athletes. CONCLUSIONS: Factors other than swimming participation, such as school and technology use, play important roles in the adaptation of physical characteristics in adolescents. Adolescents, regardless of swimming participation, presented with postural deviations. It is important to consider factors other than swimming participation that contribute to alterations in physical characteristics to understand injury risk and injury-prevention strategies in competitive adolescent swimmers.

Effect of Swim Training on the Physical Characteristics of Competitive Adolescent Swimmers.

BACKGROUND: Subacromial space distance and forward head and shoulder posture are common characteristics resulting from swim training. These alterations can cause abnormal scapular kinematics and positioning, potentially increasing compression of structures in the subacromial space and increasing the risk for the development of swimmer's shoulder. PURPOSE: To evaluate the effect of the swim training season on subacromial space distance and forward head and forward shoulder posture as well as to determine the relationship between these variables. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Included in the study were 43 competitive adolescent swimmers and 29 nonoverhead adolescent athletes (controls) who were not currently experiencing any shoulder, neck, or back pain that limited their participation in sports activity. All participants were evaluated 3 times: once before the start of the swim training season and then at 2 follow-up sessions 6 and 12 weeks after the initial testing session. At each testing session, each participant completed a physical examination that included evaluation of posture and subacromial space distance. RESULTS: Swimmers had significantly greater decreases in subacromial space distance during the training season compared with nonoverhead athletes. Swimmers also demonstrated significantly greater increases in forward shoulder posture compared with nonoverhead athletes. A significant relationship was noted between changes in forward shoulder posture and changes in subacromial space distance from the baseline testing session to the assessment 6 weeks after baseline assessment. As forward shoulder posture increased, subacromial space significantly decreased. CONCLUSION: Because of their training load, swimmers experience a decrease in subacromial space distance and an increase in forward shoulder posture over the course of 12 weeks of training, potentially making these athletes more vulnerable to the development of shoulder pain and injury.

Optimal management of ulnar collateral ligament injury in baseball pitchers.

The ulnar collateral ligament stabilizes the elbow joint from valgus stress associated with the throwing motion. During baseball pitching, this ligament is subjected to tremendous stress and injury if the force on the ulnar collateral ligament during pitching exceeds the physiological limits of the ligament. Injuries to the throwing elbow in baseball pitchers result in significant time loss and typically surgical intervention. The purpose of this paper is to provide a review of current information to sports medicine clinicians on injury epidemiology, injury mechanics, injury risk factors, injury prevention, surgical interventions, nonsurgical interventions, rehabilitation, and return to play outcomes in baseball pitchers of all levels.

Assessing biological maturity: chronological age and the pubertal development scale predict free testosterone in adolescent males.

BACKGROUND: Pubertal development status has implications for development of physical characteristics, performance, and injury risk in school-aged athletes. OBJECTIVE: The objective of this study was to evaluate the ability of non-invasive measures of biological maturity to predict salivary free testosterone. PARTICIPANTS: A total of 61 physically active males (ages 6-16) participated in this study. METHODS: Participants had their anthropometrics measured, completed the Pubertal Development Scale (PDS), and reported their birthdays and the heights of their biological parents. Exact chronological age and percent of predicted height were calculated. Resting salivary samples were collected and assessed for free testosterone levels using enzyme-linked immunosorbent assay procedures. Variables were entered into a stepwise linear regression to predict free testosterone. RESULTS: The regression model was statistically significant (R²=0.716, F2,61=74.2, p<0.005) with chronological age (ß=0.66, t60=7.587, p<0.005) and PDS (ß=0.26, t60=3.02, p=0.004) remaining as significant predictors of free testosterone. CONCLUSIONS: Chronological age and PDS adequately predict salivary free testosterone levels in school-aged males and may be an appropriate tool to evaluate physical maturity in school-aged males quickly, cheaply, and accurately.

Increase in humeral retrotorsion accounts for age-related increase in glenohumeral internal rotation deficit in youth and adolescent baseball players.

BACKGROUND: Glenohumeral internal rotation deficit (GIRD) is the difference in internal rotation range of motion (IRROM) between the dominant and nondominant limbs. Pathological GIRD of greater than 15° to 25° has previously been linked to shoulder and elbow injuries in baseball players. Because of its relationship to shoulder and elbow disorders, research has focused on understanding the underlying factors that contribute to changes in IRROM and ultimately GIRD. The rotation deficit reportedly increases during adolescence, but it remains unclear whether this change is caused by changes in osseous properties or soft tissue tightness. PURPOSE: To evaluate the influence of age group on GIRD, humeral retrotorsion, retrotorsion-adjusted GIRD, and total range of motion (TROM) in healthy baseball players. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Four groups of healthy baseball players participated in the study: 52 youth (aged 6-10 years), 52 junior high school (JH) (aged 11-13 years), 70 junior varsity (JV) (aged 14-15 years), and 113 varsity (aged 16-18 years) players. Internal rotation range of motion, external rotation range of motion (ERROM), and humeral retrotorsion were measured bilaterally using a digital inclinometer and diagnostic ultrasound. Retrotorsion-adjusted IRROM was calculated as the available IRROM from the humeral retrotorsion position; TROM was calculated as the sum of IRROM and ERROM; and GIRD, the difference in humeral retrotorsion between limbs, adjusted GIRD, and the difference in TROM between limbs were calculated as the difference between the dominant and nondominant sides. Four separate analyses of variance were used to compare these variables between age groups. RESULTS: There was a significant group difference in GIRD (F3,284 = 8.957; P < .001) and a difference in humeral retrotorsion between limbs (F3,284 = 9.688; P < .001). Also, GIRD was greater in varsity participants compared with youth (mean difference [MD], 5.05°) and JH (MD, 4.95°) participants and in JV participants compared with JH (MD, 5.36°) and youth (MD, 5.47°) participants. The difference in humeral retrotorsion between limbs was greater in varsity participants compared with youth (MD, 8.79°) and JH (MD, 5.52°) participants and in JV participants compared with youth participants (MD, 7.88°). There were no significant differences in adjusted GIRD (F3,284 = 1.136; P = .335) or TROM (F3,284 = 1.214; P = .305). CONCLUSION: Glenohumeral internal rotation deficit and humeral retrotorsion increased with age in youth/adolescent baseball players, while retrotorsion-adjusted GIRD and TROM remained unchanged. An age-related increase in GIRD is primarily attributed to humeral retrotorsion rather than soft tissue tightness. CLINICAL RELEVANCE: While there was an increase in GIRD from youth league to high school participants, TROM and retrotorsion-adjusted GIRD remained constant across the age groups, indicating that this increase between the age groups is not pathological GIRD and may not contribute to an increased injury risk.

Dominant-limb range-of-motion and humeral-retrotorsion adaptation in collegiate baseball and softball position players.

CONTEXT: Biomechanically, the motions used by baseball and softball pitchers differ greatly; however, the throwing motions of position players in both sports are strikingly similar. Although the adaptations to the dominant limb from overhead throwing have been well documented in baseball athletes, these adaptations have not been clearly identified in softball players. This information is important in order to develop and implement injury-prevention programs specific to decreasing the risk of upper extremity injury in softball athletes. OBJECTIVE: To compare range-of-motion and humeral-retrotorsion characteristics of collegiate baseball and softball position players and of baseball and softball players to sex-matched controls. DESIGN: Cross-sectional study. SETTING: Research laboratories and athletic training rooms at the University of North Carolina at Chapel Hill. PATIENTS OR OTHER PARTICIPANTS: Fifty-three collegiate baseball players, 35 collegiate softball players, 25 male controls (nonoverhead athletes), and 19 female controls (nonoverhead athletes). INTERVENTION(S): Range of motion and humeral retrotorsion were measured using a digital inclinometer and diagnostic ultrasound. MAIN OUTCOME MEASURE(S): Glenohumeral internal-rotation deficit, external-rotation gain, total glenohumeral range of motion, and humeral retrotorsion. RESULTS: Baseball players had greater glenohumeral internal-rotation deficit, total-range-of-motion, and humeral-retrotorsion difference than softball players and male controls. There were no differences between glenohumeral internal-rotation deficit, total-range-of-motion, and humeral-retrotorsion difference in softball players and female controls. CONCLUSIONS: Few differences were evident between softball players and female control participants, although range-of-motion and humeral-retrotorsion adaptations were significantly different than baseball players. The throwing motions are similar between softball and baseball, but the athletes adapt to the demands of the sport differently; thus, stretching/strengthening programs designed for baseball may not be the most effective programs for softball athletes.

Prevalence of freestyle biomechanical errors in elite competitive swimmers.

BACKGROUND: Poor freestyle stroke biomechanics is a suggested risk factor for shoulder pain and pathology, but this has not been proven in biomechanical or clinical studies. Furthermore, the prevalence of these theoretical errors has not been identified, which would help coaches, athletic trainers, and researchers determine the most appropriate errors to focus on and develop interventions. HYPOTHESIS: The majority of swimmers will present with at least 1 freestyle stroke error. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 4. METHODS: Stroke biomechanics for 31 swimmers from a collegiate swimming team were captured using underwater/above-water cameras. Each video was evaluated for biomechanical errors: a dropped elbow during the pull-through phase, a dropped elbow during the recovery phase, an eyes-forward head-carrying angle, incorrect hand position during hand entry, incorrect hand entry angle, incorrect pull-through pattern, and inadequate body roll. Error prevalence was calculated, and relationships among the errors were evaluated using chi-square statistics. RESULTS: A dropped elbow during the pull-through phase (61.3%) and a dropped elbow during the recovery phase (53.2%) had the highest prevalence. A dropped elbow during the recovery phase was significantly associated with a thumb-first hand entry angle (P = 0.027) and incorrect hand entry position (P = 0.009). An eyes-forward head-carrying angle was associated with an incorrect pull-through pattern (P = 0.047). CONCLUSION: Biomechanical errors potentially detrimental to the shoulder are prevalent among swimmers. Many of the errors were interrelated, suggesting that one error may lead to other errors. CLINICAL RELEVANCE: These errors highlight the need for proper stroke instruction and evaluation to decrease the risk of shoulder injury in competitive swimmers.