Baseball pitching biomechanics in relation to pain, injury, and surgery: A systematic review.

OBJECTIVES: To investigate the relationship between baseball pitching biomechanics and pain, injury, or surgery, in pitchers of all ages and competition levels. DESIGN: Systematic review. METHODS: This study was registered on Prospero (CRD42019137462). Four online databases (MEDLINE, SPORTDiscus, CINAHL, and Embase) from inception to June 13, 2019 were systematically searched. Risk of bias was assessed through the modified Downs and Black. RESULTS: 967 titles/abstracts were screened with 11 studies (1376 pitchers) included. Four studies used 3D biomechanical analyses, five studies video analysis, and two studies evaluated EMG activity. Level 1b evidence suggests that injured pitchers had greater elbow valgus torque at late arm cocking (injured: 91.6Nm, non-injured: 74.7Nm, p=0.013) and early trunk rotation was predictive of increased upper extremity surgical risk (Hazard Ratio: 1.69 (95% CI 1.02-2.80)). Level 3b evidence observed pitchers with upper extremity surgical history had greater lateral trunk tilt at release (surgery: 29.3°, controls: 23.4°, p=0.035), and flexor carpi ulnaris EMG activity was decreased (injured: 68% MMT, controls: 103% MMT) in pitchers with elbow injury. CONCLUSIONS: Increased elbow valgus torque and early trunk rotation were injury risk factors, and elbow injured pitchers displayed diminished forearm muscle activity. Due to the low power of many of these studies, and the lack of prospective 3D biomechanical studies, other pitching biomechanical variables cannot be ascertained as injury risk factors. Future studies are needed to prospectively assess pitching injury risk through 3D biomechanical methods.

The Curse of the All-Star Team: A Single-Season Prospective Shoulder MRI Study of Little League Baseball Players.

BACKGROUND: Throwing guidelines have been implemented in Little League baseball in an attempt to minimize injuries in young baseball players. We hypothesized that playing pitcher or catcher and increased innings played during the season would result in dominant shoulder magnetic resonance imaging (MRI) abnormalities. METHODS: A prospective evaluation of Little League players aged 10 to 12 years was performed. Players recruited before the start of the season underwent bilateral preseason and dominant shoulder postseason MRI, physical examination, and questionnaires addressing their playing history and arm pain. Innings played, player position, pitch counts, and all-star team selection were recorded. RESULTS: In total, 23 players were enrolled. The majority (19/23, 82.6%) were right-handed and 16 of 23 (69.6%) played at least 10 innings as pitcher or catcher. Sixteen were selected for the all-star team. Fourteen players (60.9%) had positive dominant shoulder MRI findings not present in their nondominant shoulder. Eight players (34.8%) had new or worsening postseason MRI findings. Thirteen players (81.3%) selected to the all-star team had abnormal MRI findings whereas only one (14.3%) player not selected as an all-star had MRI abnormalities (P=0.005). Year-round play (P=0.016), innings pitched (P=0.046), innings catcher (P=0.039), and number of pitches (P=0.033) were associated with any postseason MRI abnormality, but not for new or worsening MRI changes. Single sport athletes and players playing for multiple teams were significantly more likely to have abnormal MRI findings (P=0.043 and 0.040, respectively) when compared with multisport athletes playing on a single team. CONCLUSIONS: MRI abnormalities involving the dominant shoulder are common in Little League baseball players and often develop or worsen during the season. Contrary to our hypothesis, MRI abnormalities were not associated with player position and pitch counts. Instead, they were most closely associated with year round play, single sports participation, and all-star team selection. The increased demands required for all-star selection comes at a price to the young athlete as the majority of players selected for this honor had abnormal MRI findings in their throwing shoulder while few non all-stars demonstrated such pathology. LEVEL OF EVIDENCE: Level II.

Humeral Retroversion and Participation Age in Professional Baseball Pitchers by Geographic Region.

CONTEXT: Baseball is played around the world, including in North America and Latin America. The repetitive and stressful act of throwing can lead to adaptations such as increased humeral retroversion (HR) in the throwing arm. This adaptation is often considered beneficial as it allows more glenohumeral external rotation during the cocking phase of pitching without soft tissue stretching. Therefore, it is speculated that throwing should be started at a young age to capitalize on this adaptation. Interestingly, athletes in different geographic regions of the world often begin organized baseball at different ages. However, range of motion (ROM), HR, and the starting age of baseball have never been examined based on geographic region. OBJECTIVE: To determine if ROM, HR, and the starting age of baseball players differed between professional baseball pitchers from North America and Latin America. DESIGN: Cross-sectional study. SETTING: Clinical setting. PATIENTS OR OTHER PARTICIPANTS: Thirty professional pitchers (North American = 19, Latin American = 11) with no current injury or surgery in the previous 6 months. MAIN OUTCOME MEASURE(S): Both ROM and HR were measured in the dominant and nondominant shoulder of each participant. The starting age for baseball was self-reported. RESULTS: The Latin American group had more dominant-arm HR (8.7°; P = .034), more nondominant-arm external rotation (5.3°; P = .049), and a trend toward more nondominant-arm HR (6.5°; P = .058), yet they started playing baseball at a later age (by 3.7 years; P = .021) compared with the North American group. CONCLUSIONS: Latin American players had greater HR but started playing baseball at an older age. These findings contradict current thinking that HR would be more pronounced if baseball was started at a younger age. Additional research is required to better understand HR and the genetic, environmental, and nutritional factors that contribute to its development.

Mortality Among Professional American-Style Football Players and Professional American Baseball Players.

Importance: Studies of American-style football players have suggested lower overall mortality rates compared with general populations, but with possibly increased neurodegenerative mortality. However, comparisons with general populations can introduce bias. This study compared mortality between US National Football League (NFL) and US Major League Baseball (MLB) players, a more appropriate comparison group of professional athletes. Objective: To compare all-cause and cause-specific mortality between NFL and MLB players. Design, Setting, and Participants: In this retrospective cohort study, the setting was US mortality from January 1, 1979, through December 31, 2013. The dates of analysis were January 2016 to April 2019. Participants were 3419 NFL and 2708 MLB players with at least 5 playing seasons. Exposures: Participation in the NFL compared with the MLB. Main Outcomes and Measures: Vital status and causes of death from the National Death Index from 1979 through 2013 were obtained. Cox proportional hazards regression models using age as the timescale were used to calculate hazard ratios (HRs) and 95% CIs to examine all-cause and cause-specific mortality among NFL players compared with MLB players, adjusted for race and decade of birth. Results: By the end of follow-up, there were 517 deaths (mean [SD] age, 59.6 [13.2] years) in the NFL cohort and 431 deaths (mean [SD] age, 66.7 [12.3] years) in the MLB cohort. Cardiovascular and neurodegenerative conditions, respectively, were noted as underlying or contributing causes in 498 and 39 deaths in the NFL and 225 and 16 deaths in the MLB. Compared with MLB players, NFL players had significantly elevated rates of all-cause (HR, 1.26; 95% CI, 1.10-1.44), cardiovascular disease (HR, 2.40; 95% CI, 2.03-2.84), and neurodegenerative disease (HR, 2.99; 95% CI, 1.64-5.45) mortality. Comparing hypothetical populations of 1000 NFL and 1000 MLB players followed up to age 75 years, there would be an excess 21 all-cause deaths among NFL players, as well as 77 and 11 more deaths with underlying or contributing causes that included cardiovascular and neurodegenerative conditions, respectively. Conclusions and Relevance: This study found that NFL players had elevated all-cause, cardiovascular, and neurodegenerative mortality rates compared with MLB players, although the absolute number of excess neurodegenerative deaths was still small. Factors that vary across these sports (eg, body habitus and head trauma) as opposed to those common across sports (eg, physical activity) could underlie the differences.

Relationship Between Physical Fitness at the End of Preseason and the Inseason Game Performance in Japanese Female Professional Baseball Players.

Watanabe, Y, Yamada, Y, Yoshida, T, Matsui, T, Seo, K, Azuma, Y, Hiramoto, M, Miura, Y, Fukushima, H, Shimazu, A, Eto, T, Saotome, H, Kida, N, and Morihara, T. Relationship between physical fitness at the end of preseason and the inseason game performance in Japanese female professional baseball players. J Strength Cond Res 33(6): 1580-1588, 2019-This study examined anthropometric and fitness profiles of Japanese female professional baseball players and investigated the relationship between players' physical fitness and inseason game performance. Fifty-seven players who were registered in the Japan Women's Baseball League (JWBL) participated. Height, body mass, grip strength, back strength, knee extension and flexion strength, hamstring extensibility, vertical jump height, and horizontal jump distance were measured at preseason (February and March) in 2013. Game performance during the 2013 season (March-November) was obtained from official JWBL statistics. Vertical jump height showed significant positive correlations with individual performance records (e.g., total bases [r = 0.551], slugging percentage [r = 0.459], and stolen bases [r = 0.442]). Similar relationships were observed between horizontal jump distance and performance statistics in most cases. By contrast, grip, back, and lower-limb strength, as well as hamstring extensibility were not significantly correlated with game performance. Stepwise regression analysis selected vertical jump height as an independent variable, significantly correlating with several game performance measures (e.g., total bases: adjusted R = 0.257). Also, vertical jump height and body mass index were identified as independent variables significantly associated with stolen bases (adjusted R = 0.251). Maximal jump performance, rather than simple isometric muscle strength or flexibility, is a good performance test that can be used at the end of preseason to predict inseason batting and stolen base performance. Our findings demonstrate the importance of constructing preseason training programs to enhance lower-limb muscular power that is linked to successful inseason performance in female baseball players.

Pitching Performance After Ulnar Collateral Ligament Reconstruction at a Single Institution in Major League Baseball Pitchers.

BACKGROUND: Ulnar collateral ligament (UCL) reconstruction (UCLR) has shown reliable rates of return to play, with conflicting results on pitching performance after players' return. PURPOSE: To evaluate Major League Baseball (MLB) pitching performance before and after UCLR performed at a single institution. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: MLB pitchers (minor league players were excluded) who underwent UCLR at our institution between 2002 and 2016 were identified. Player information and return to play were determined including pitching level (MLB vs minor league) and total number of years played after surgery. Pitching performance statistics were evaluated for 3 years before surgery and for 3 years after returning to play including earned run average (ERA), walks plus hits per inning pitched (WHIP), innings pitched, wins above replacement, runs above replacement, and pitch velocity. RESULTS: A total of 54 MLB pitchers were identified, with 46 primary and 8 revision reconstructions. The mean time to return to play was 13.8 months (primary reconstruction: 13.7 months). The majority returned to play with a 94% return rate (primary reconstruction: 96%), and 80% returned to MLB play (primary reconstruction: 82%). Three primary reconstructions required revision surgery. Pitchers played a mean of 3.2 years in MLB and 4.6 years total after surgery (39% still playing). Pitching workload and performance were maintained or improved after surgery. The preoperative ERA was 4.63 versus 4.13 after returning to play ( P = .268). Fastball velocity ( P = .032), ERA ( P = .003), and WHIP ( P = .001) worsened the first year after surgery and then improved the second year (ERA: 4.63 to 4.06 [ P = .380]; WHIP: 1.35 to 1.32 [ P = .221]; fastball velocity: 91.3 to 91.9 mph [ P = .097]). Compared with a matched control group, pitchers who had UCLR showed improvements or maintained performance after reconstruction including improved ERA ( P = .007), WHIP ( P = .025), and fastball velocity ( P = .006). CONCLUSION: MLB players experienced a high rate of return to play and previous level of play after UCLR. Pitching workload was maintained after returning to play. Pitching performance initially decreased the first year after returning and then improved or reverted to previous levels after the first year from UCLR.

Youth Baseball Coach Awareness of Pitch Count Guidelines and Overuse Throwing Injuries Remains Deficient.

BACKGROUND: Baseball is one of the most popular youth sporting activities. Youth pitchers remain at high risk for shoulder and elbow overuse injuries despite well-established recommendations on pitch count limits. The purpose of this investigation was to conduct surveys of youth baseball coaches evaluating the current state of understanding and compliance with youth pitch count guidelines and risk factors for overuse injuries. METHODS: A total of 82 youth baseball coaches in surrounding suburban areas outside 2 separate Midwestern metropolitan cities were asked to answer an anonymous 13-question survey. Survey questions solicited demographic information of youth athletes coached, while assessing for incidence, knowledge of, and compliance with established recommendations on pitch count limits and upper extremity overuse injuries in youth pitchers. RESULTS: In total, 61 of 82 (74%) coaches returned surveys. The majority of coaches reported coaching male athletes (89%, n=54) primarily between the ages of 11 to 12 years (51%, n=31). A total of 56% (n=34) of coaches reported "always" keeping track of pitch counts; however, 92% (n=56) reporting not keeping track of pitches based on established recommendations by the American Sports Medicine Institute, whereas 56% were noncompliant with age appropriate pitch count recommendations as established by the 2006 US Baseball Medical and Safety Advisory Committee. Only 13% (n=8) of coaches were able to correctly identify risk factors for overuse injuries while acknowledging the necessity of off-season strengthening. Thirty-eight percent (n=23) of coaches reported sitting out an athlete because of overuse injury, with the highest rates found in those coaching the youngest (≤8 and younger) and oldest (≥17 and older) age groups. Meanwhile, 15% (n=9) of coaches were noncompliant with age-based recommendations against throwing breaking pitches. CONCLUSIONS: Knowledge regarding pitch count guidelines established to prevent overuse injuries to the shoulder and elbow in youth pitchers remains deficient in the cohort of coaches surveyed. LEVEL OF EVIDENCE: Level IV-Case Series.

Sports-Related Concussion Occurrence at Various Time Points During High School Athletic Events: Part 2.

BACKGROUND: Sports-related concussion (SRC) injury rates, and identifying those athletes at the highest risk, have been a primary research focus. However, no studies have evaluated at which time point during an athletic event athletes are most susceptible to SRCs. PURPOSE: To determine the clinical incidence of SRCs during the start, middle, and end of practice and competition among high school male and female athletes in the state of Michigan. STUDY DESIGN: Descriptive epidemiological study. METHODS: There were 110,774 male and 71,945 female student-athletes in grades 9 through 12 (mean time in high school, 2.32 ± 1.1 years) who participated in sponsored athletic activities (13 sports) during the 2015-2016 academic year. An SRC was diagnosed and managed by a medical professional (ie, MD, DO, PA, NP). SRC injuries were reported by certified athletic trainers, athletic administrators, and coaches using the Michigan High School Athletic Association Head Injury Reporting System. Time of SRC was defined as the beginning, middle, or end of practice/competition. Clinical incidence was calculated by dividing the number of SRCs in a time point (eg, beginning) by the total number of participants in a sport per 100 student-athletes (95% CI). Risk ratios were calculated by dividing one time point by another time point. RESULTS: There were 4314 SRCs reported, with the highest in football, women's basketball, and women's soccer. The total clinical incidence for all sports was 2.36 (95% CI, 2.29-2.43) per 100 student-athletes. The most common time for SRCs was the middle, followed by the end of all events. Athletes had a 4.90 (95% CI, 4.44-5.41) and 1.50 (95% CI, 1.40-1.60) times greater risk during the middle of all events when compared with the beginning and end, respectively. There was a 3.28 (95% CI, 2.96-3.63) times greater risk at the end of all events when compared with the beginning. CONCLUSION: Athletes were at the greatest risk for SRCs at the middle of practice and competition when compared with the beginning and end. CLINICAL RELEVANCE: The current study suggests that medical attention is particularly important during the middle of all athletic events. Intervention measures to limit SRCs may be most beneficial during the middle of athletic events.

Sex Differences in the Clinical Incidence of Concussions, Missed School Days, and Time Loss in High School Student-Athletes: Part 1.

BACKGROUND: Sports-related concussion (SRC) injury rates are well established in collegiate athletics through epidemiological studies using the National Collegiate Athletic Association Injury Surveillance System. However, few studies have examined sex differences, time loss, and missed school days in high school athletes, especially at the state level. PURPOSE: To identify sex differences in the clinical incidence of SRCs, missed school days, and time loss in high school student-athletes. STUDY DESIGN: Descriptive epidemiological study. METHODS: A total of 193,757 (116,434 male and 77,323 female) student-athletes (10th grade ± 1.1) participating in Michigan High School Athletic Association (MHSAA)-sponsored athletic activities were recorded in the Head Injury Reporting System. Certified athletic trainers, school athletic administrators, and coaches from MHSAA high schools reported SRC data and overall participation for the 2015-2016 academic year. Total concussive injuries, as well as missed school days and time loss for each concussive injury, were reported. The clinical incidence was calculated by dividing the number of SRCs in a particular category by the number of participants in that category and presented with 95% CIs. Relative risk ratios (RRs) were determined for sex-comparable sports. RESULTS: The overall clinical incidence for all sports was 1.7 per 100 player-seasons (95% CI, 1.6-1.8) and 1.9 (95% CI, 1.8-2.0) for male sports and 1.5 (95% CI, 1.4-1.6) for female sports. Female athletes were at a 1.9 (95% CI, 1.8-2.2) times greater risk for enduring SRCs than male athletes in sex-comparable sports, with a greater risk in baseball/softball (RR, 2.7 [95% CI, 1.9-3.8]), basketball (RR, 2.5 [95% CI, 2.1-2.9]), and soccer (RR, 1.6 [95% CI, 1.4-1.9]). Female student-athletes had significantly longer time loss than male student-athletes ( P < .001). The mean number of missed school days did not differ between sexes ( P = .70). CONCLUSION: High school female student-athletes have a higher risk for an SRC in all sex-comparable sports except lacrosse. This may be because of biomechanical differences of the head-neck segment, hormonal differences, and the fact that female athletes are more likely to report symptoms after a suspected SRC. CLINICAL RELEVANCE: Despite sex differences in the clinical incidence of SRCs and time loss from participation in high school sports, the numbers of missed school days are relatively similar between sexes.

Forearm Flexor Injuries Among Major League Baseball Players: Epidemiology, Performance, and Associated Injuries.

BACKGROUND: Despite evidence highlighting the importance of the forearm flexor muscles of elite baseball players, no studies have reported on the epidemiology of flexor strains and their associated outcomes. PURPOSE: To examine the incidence, associated injuries, and outcomes associated with forearm flexor injuries among major and minor league baseball players. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Injury data attributed to forearm flexor injuries among Major League Baseball (MLB) and minor league teams between 2010 and 2014 were obtained from the professional baseball Health and Injury Tracking System. This analysis included the number of players injured, seasonal timing of injury, days spent on the disabled list (DL), preinjury performance data, and subsequent injuries. RESULTS: A total of 134 and 629 forearm flexor injuries occurred in MLB and the minor leagues, respectively. The mean player age was 28.6 and 22.8 years in the MLB and minor leagues, respectively. The mean time spent on the DL for MLB players was 117.0 days, as opposed to 93.9 days in the minor leagues ( P = .272). Interestingly, pitcher performance declined in all categories examined leading up to the season of injury, with significant differences in walks plus hits per inning pitched ( P = .04) and strike percentage ( P = .036). Of MLB players with a forearm injury, subsequent injuries included 50 (37.3%) shoulder, 48 (35.8%) elbow, and 24 (17.9%) forearm injuries. Among injured minor league players, subsequent injuries included 170 (27.0%) shoulder, 156 (24.8%) elbow, and 83 (13.2%) forearm injuries. These rates of subsequent injuries were significantly higher compared with the rates of injuries sustained among players without forearm injuries in both leagues ( P < .001). Finally, 26 (19.4%) MLB and 56 (8.9%) minor league players required an ulnar collateral ligament reconstruction, rates that were significantly higher compared with players without a flexor strain ( P < .001). CONCLUSION: Flexor-pronator injuries are responsible for considerable time spent on the DL for elite players in MLB and the minor leagues. The most significant findings of this investigation illustrate that a flexor strain may be a significant risk factor for subsequent upper extremity injuries, including an ulnar collateral ligament tear.

Epidemiology, Workload, and Performance of Major League Baseball Pitchers Placed on the Disabled List.

There is limited information on the effect of pitcher workload, pitch type, and performance of Major League Baseball pitchers placed on the disabled list (DL). This study evaluated demographic, performance, workload, and injury data of 330 Major League Baseball pitchers with 454 injuries who were placed on the DL during the 2014 and 2015 seasons. Upper extremity, lower extremity, core, hip/groin, and other injuries were analyzed, and injury year data were compared with career data as well as against other injury groups. Upper extremity injuries represented 60% of injuries and a mean of 61.4 (SE, 2.6) days on the DL, while lower extremity and core injuries each represented 14% of all injuries. Players with upper extremity injuries returned to play the same season at the lowest rate (67.3%). Starters pitched more mean innings per game (5.31 vs 5.14 innings, P=.012) and threw more mean pitches per game (85.9 vs 82.4 pitches, P=.003) the year of injury compared with their career. There was a decrease in mean fastball velocity (92.2 vs 91.6 mph, P<.001) and percentage of fastballs thrown (60.3% vs 58.5%, P<.001) the year of injury for all injuries. The authors found that upper extremity injuries are the most common, require the most time on the DL, and have the lowest same season return to play rate. Starters pitched significantly more innings and threw more pitches during the year of injury. Pitchers were found to have a decrease in fastball velocity and percentage of fastballs thrown during the year of injury. [Orthopedics. 2018; 41(3):178-183.].

Epidemiology of Elbow Ulnar Collateral Ligament Injuries Among Baseball Players: National Collegiate Athletic Association Injury Surveillance Program, 2009-2010 Through 2013-2014.

BACKGROUND: Injuries to the ulnar collateral ligament (UCL) of the elbow are of major concern in baseball; however, the epidemiology of these injuries among National Collegiate Athletic Association (NCAA) athletes is poorly described. PURPOSE: To determine the incidence of UCL injuries in NCAA baseball and investigate the risk factors involved. STUDY DESIGN: Descriptive epidemiology study. METHODS: All UCL injuries for academic years 2009-2010 through 2013-2014 were extracted from the NCAA Injury Surveillance Program database. The incidence was calculated for different positions, activity, time in game, competition status, and injury characteristics and compared via injury risk ratios to determine risk factors for injury occurrence. The NCAA provides sampling weights based on division and year. For all other injury characteristic analysis, unweighted data were used. RESULTS: Over the course of the 2009-2010 to 2013-2014, 20 UCL injuries were reported in the NCAA Injury Surveillance Program over 177,992 athletic exposures (AEs) for an overall incidence of 1.12 per 10,000 AEs (95% CI, 0.63-1.62). Eighty-five percent occurred during throwing, and 100% were new injuries. Of the injuries sustained during games, 28.6% occurred early (warm-up through third inning) and 71.4% late (fourth inning or later), with a risk ratio of 1.3 for late-game injuries (95% CI, 0.24-6.44). Of those injured, 45.0% were able to return to play by the next season, while the remainder were out for at least 7 days. Injury was season ending for 15% of athletes (0.17 per 10,000 AEs), and 15% of athletes required surgery. CONCLUSION: UCL injury is a potentially season-ending, even career-ending, injury among NCAA baseball players. Additionally, while more injuries occurred later in games, the current study revealed no significant difference in injury rates with respect to time in game. Last, the authors found a higher reported rate of extensive time away from sport after UCL injury than previously published studies on this patient population.

Implications of Core and Hip Injuries on Major League Baseball Pitchers on the Disabled List.

PURPOSE: To investigate the frequency of core and hip injuries in Major League Baseball (MLB) pitchers and their impact on performance, workload, and pitch type. METHODS: Demographic, performance data, and injury data were acquired for 330 MLB pitchers with 454 injuries placed on the disabled list (DL) from 2014 to 2015 seasons. Core and hip/groin injuries were analyzed in which injury year data were compared with career data and against other injury groups. RESULTS: Core injuries represented 14% of all injuries and hip/groin injuries represented 7%. Average days on the DL for core injuries were 47.0 (standard deviation 5.6) days and 37.7 (standard deviation 8.1) days for hip/groin injuries. Return from the DL the same season for core injuries was 78% and 73% for hip/groin injuries. Core injuries returned to the DL 46% of the time (73% for noncore injuries) and hip/groin returned 56% of the time (60% for nonhip/groin injuries). No changes in workload were noted except starters with core injuries pitched less innings/game (5.3 vs 4.9 innings/game, P = .031) and more pitches/game (85.5 vs 78.4 pitches, P = .026). Fastball velocity decreased in the core injury group the year of injury (91.6 vs 92.2 mph, P = .001). Core injuries had slightly fewer home runs/9 innings and fewer strikeouts/9 innings; hip/groin injuries had slightly more strikeouts/9 innings, with all other performance statistics no different between the groups including earned run average and wins above replacement. CONCLUSIONS: Core and hip injuries in MLB pitchers result in similar time on the DL compared with other injuries. Pitching workload during the year of injury does not seem to have a significant impact on sustaining a core or hip injury. Although there is a high rate of return to play from the DL, there is a high rate of reinjury in these pitchers more often for other injuries. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Elbow Injuries in Professional Baseball: Epidemiological Findings From the Major League Baseball Injury Surveillance System.

BACKGROUND: Elbow injuries cause significant disability for the throwing athlete. Scant data are available on the distribution and characteristics of these injuries in elite baseball players. No study exists that focuses solely on the epidemiological characteristics of elbow injuries in professional baseball players using a comprehensive injury surveillance system. HYPOTHESIS: Professional baseball players have a high occurrence of elbow injuries influenced by factors including length of time playing, time period within the annual baseball season, and specific position played. STUDY DESIGN: Descriptive epidemiological study. METHODS: Data on elbow injuries occurring during the 2011-2014 seasons were collected from Major League Baseball's Health Injury and Tracking System, a comprehensive injury surveillance system. Each specific type of elbow injury was evaluated with respect to overall injury rate, years as a professional player, mechanism of injury, treatment, average time lost, and return to play. RESULTS: During the study period, 3185 elbow injuries (n = 430 Major League; n = 2755 Minor League) occurred. The mean number of days missed and percentage requiring surgery were similar between Major and Minor League players. Overall, 20.0% (650/3185) of the injuries required surgical treatment. Pitchers were the most likely to incur an elbow injury (40.0% of injured athletes were pitchers), were the most likely to require surgery (34.2% of injured pitchers required surgery), and had the greatest mean number of days missed when treated nonsurgically (33.2 days). Medial injuries composed 42.1% (1342/3185) of all elbow injuries. Of all elbow surgeries performed during the study period, the highest percentage involved ligaments (372/650; 57.2%). CONCLUSION: Elbow injuries are a considerable source of disability in professional baseball players. Pitchers are most likely to incur these injuries, are most likely to require surgery, and have the highest mean number of days missed when treated nonsurgically. The most common injuries involve the medial elbow, with ligament injuries most often requiring surgery. This study represents the only investigation to date using a comprehensive injury surveillance system to examine elbow injuries in professional baseball players. It provides a basis for injury prevention and treatment recommendations, establishes the most thorough framework for determining elbow injury risk, and focuses continued research on elbow injury prevention in the elite baseball player.

The Epidemiology and Effect of Sliding Injuries in Major and Minor League Baseball Players.

BACKGROUND: Although sliding occurs frequently in professional baseball, little is known about the epidemiology and effect of injuries that occur during sliding in this population of elite athletes. PURPOSE: To describe the incidence and characteristics of sliding injuries, determine their effect in terms of time out of play, and identify common injury patterns that may represent appropriate targets for injury prevention programs in the future. STUDY DESIGN: Descriptive epidemiologic study. METHODS: All offensive sliding injuries occurring in Major League Baseball (MLB) and Minor League Baseball (MLB) that resulted in time out of play during a span of 5 seasons (2011-2015) were identified. In addition to player demographics, data extracted included time out of play, location on field where injury occurred, level of play, treatment (surgical vs nonsurgical), direction of slide (head vs feet first), body region injured, and diagnosis. Descriptive statistics were used to describe the distribution of these injuries, and injury rates were calculated per slide. RESULTS: From 2011 to 2015, 1633 injuries occurred as a result of a slide. The total number of days missed per season was 4263. Surgical intervention was required for 134 (8.2%) injuries, and the mean days missed was 66.5 for players treated surgically and 12.3 days for players treated nonoperatively ( P < .001). MLB players were more likely than MiLB players to require surgical intervention (12.3% vs 7.5%, P = .019). Injuries to the hands/fingers represented 25.3% of all injuries and 31.3% of those requiring surgery. Although the majority of injuries occurred at second base (57%), the per-slide injury rate was similar across all bases ( P = .991). The estimated overall frequency of injury in MLB was once per every 336 slides, and the rate of injury for head- and feet-first slides was 1 in 249 and 413 slides, respectively ( P = .119). CONCLUSION: Injuries occurring while sliding in professional baseball result in a significant amount of time out of play for these elite athletes. Injuries occurring at second base and those occurring to the hands and fingers were most prevalent and may be an appropriate target for future injury prevention programs.

How jet lag impairs Major League Baseball performance.

Laboratory studies have demonstrated that circadian clocks align physiology and behavior to 24-h environmental cycles. Examination of athletic performance has been used to discern the functions of these clocks in humans outside of controlled settings. Here, we examined the effects of jet lag, that is, travel that shifts the alignment of 24-h environmental cycles relative to the endogenous circadian clock, on specific performance metrics in Major League Baseball. Accounting for potential differences in home and away performance, travel direction, and team confounding variables, we observed that jet-lag effects were largely evident after eastward travel with very limited effects after westward travel, consistent with the >24-h period length of the human circadian clock. Surprisingly, we found that jet lag impaired major parameters of home-team offensive performance, for example, slugging percentage, but did not similarly affect away-team offensive performance. On the other hand, jet lag impacted both home and away defensive performance. Remarkably, the vast majority of these effects for both home and away teams could be explained by a single measure, home runs allowed. Rather than uniform effects, these results reveal surprisingly specific effects of circadian misalignment on athletic performance under natural conditions.

Determinants of Major League Baseball Pitchers' Career Length.

PURPOSE: To investigate variables (injury, position, performance, and pitching volume) that affect the career longevity of Major League Baseball pitchers. METHODS: To be eligible, pitchers must have entered Major League Baseball between 1989 and 1992 without missing information for the variables on the website http://www.baseball-reference.com. The variables assessed were average innings pitched per year before and after age 25 years, earned run average, walks and hits divided by innings pitched, strikeout to walk ratio, pitching position, time on the disabled list, length of career, and starting and retirement age. We used analysis of variance to compare the differences between groups and a regression model to assess the relationship between variables before age 25 years and career length. RESULTS: Mean retirement age for the group was 31.74 (95% confidence interval 30.83-32.65) and mean career length was 10.97 (95% confidence interval, 10.02-11.92) years. Innings pitched after age 25 years increased slightly, but not significantly, from the number of innings pitched before age 25 years, 85.35 versus 74.25, P = .5063. Career earned run average was not significantly different after age 25 years compared with before age 25 years, 4.83 versus 5.58, respectively, P = .8834. Both strikeout to walk ratio, 1.55 to 1.77, P = .0022, and walks and hits divided by innings pitched, 1.63 to 1.50, P = .0339, improved significantly after age 25 years compared with before age 25 years. The position the player started and ended his career (starter or reliever) did not influence career length. Multiple regression analysis comparing the variables from before age 25 revealed only the number of innings pitched before age 25 were positively related to career length, R2 = 0.1408, P < .0001. All other variables analyzed before age 25 years were not significantly related to career length. CONCLUSIONS: The only studied variable that had significant relationship, which was weak to low, with career length was innings pitched per year before age 25 years. All other variables analyzed before age 25 years were not significantly related to career length. LEVEL OF EVIDENCE: Level IV, case series.