Julia Fink DO¹; Dylon Collins BS²; Ryan Geringer DO³; Brent Ponce MD³; Champ Baker III MD^3
1Nemours Children’s Health
²Nova Southeaster University, College of Osteopathic Medicine
³The Hughston Clinic

Background
There is scarce orthopaedic literature regarding prevalence of injuries and pitch counts in youth fastpitch softball pitchers. 

Objective
To evaluate the pitching regimens of youth fastpitch softball pitchers and prevalence of injuries reported. 

Study design
Retrospective Cross-sectional study 

Methods
One hundred and twenty youth fastpitch softball pitchers (ages 7-21 years) completed an electronic survey from February 1, 2020 to August 1, 2020 regarding demographics, pitching regimens and injuries during the previous season.  A univariable and multivariable regression analysis was performed comparing single variables (season, pitches per game, days rest, age group and aged started pitching) with the outcome of any type of injury.

Results
Over age 10, more than 90% of pitchers played on a travel softball team year-round and participated in private pitching lessons. There was an increased frequency of pitching appearances with increase in age and decrease days of rest with age. Risk of injury significantly increased with age. The most commonly injured joint was the shoulder (50%). Injuries resulting in missed playing time ranged from 37-41%. Of the 120 pitchers, 10 did not return to pitching following their injuries. 

Conclusion
Young female pitchers are experiencing injuries at a markedly increased rate with age. High school aged pitchers are experiencing injuries at rates similar to those at the collegiate level. Youth fastpitch softball pitchers have strenuous pitching regimens beginning at even the youngest age groups. Further prospective evaluation of pitch counts and associated injuries is necessary. 

Keywords: Softball, Female athlete, Pediatric sports medicine, Fastpitch, Windmill

INTRODUCTION

Women’s fastpitch softball has become one of the fastest growing female sports over the past two decades. Competition ranges from recreational teams to the Olympic and professional stage. Based on data from the National Federation of State High School Associations in 2018-2019, softball was the fifth most popular high school sport, with more than 1.2 million girls registered with the American Softball Association (3). As more young females have gained interest in the sport, it has also become increasingly competitive. The increase in competition is best seen with the evolution of fastpitch windmill pitchers. Athletes are throwing faster, utilizing different types of pitches, and throwing more often and at a younger age. There is the misconception that since the underhand windmill pitch is similar to the natural motion of the shoulder, pitchers are at decreased risk of injuries and overuse. However, there has been an increase in reported injuries in softball pitchers that is comparable or exceeds their baseball counterparts (14,11). Softball pitchers are at greater risk of injury compared to infield or outfield position players; due to their rigorous training schedules and high pitch counts per game and per season (3). Windmill pitchers may throw in back-to-back games in a single day over a 2 to 3-day tournament. Comparatively, baseball pitchers have 3 to 4 days of rest between games (2). Over a three-day tournament a starting softball pitcher can throw on average 1200 to 1500 pitches compared to 100 to 150 for baseball pitchers (10).  This constant overuse and repetitive microtrauma, continued throughout these young women’s pitching careers, can increase their risk for not only overuse but also acute injuries (5).

Although the windmill pitch seems very different from the overhand baseball pitch, there are similarities in joint forces about the shoulder and elbow (2). The biomechanical studies of the windmill pitch have demonstrated similar stress applied throughout the upper extremity compared to overhand baseball pitchers (2). Studies have also demonstrated peak distractive force of 80-95% bodyweight about the shoulder and 67-99% bodyweight about the elbow. These findings are similar to distractive forces found in baseball pitchers (2,1). A 1996 analysis of Olympic fastpitch softball pitchers demonstrated shoulder distractive forces of 80 +/- 22% bodyweight compared to 108 +/- 16% bodyweight in baseball counterparts. This further demonstrates the similarity of increased stress applied to the shoulder during fastpitch softball and overhand baseball pitches (2, 15).  Similarly, identification of muscle activation patterns has demonstrated forearm flexors can reach up to 500% maximal voluntary isometric contraction about the elbow during the later pitching phases (10). The windmill pitch does not only affect the upper extremity; but also relies on the energy generated by the legs, trunk, and hip rotation. This generates momentum and power to increase pitch velocity (2,7).  

In 2001, the American Academy of Pediatrics Committee on Sports Medicine and Fitness recommended restrictions in pitches thrown and instruction in proper mechanics for baseball and softball pitchers. However, there has been no implementation of regulations or rule changes within the USA Softball Association (13,9,16). In 2002, Dr. Lyman and colleagues, with the American Sports Medicine Institute and American Baseball Foundation, performed a prospective cohort study of 476 youth baseball pitchers through a single spring season to determine risk factors for elbow and shoulder pain. Their results and recommendations set forth safe pitch count restrictions which have been implemented into Little League Baseball (5).  There is scarce orthopaedic literature documenting incidence of injuries and pitching regimens for fastpitch softball pitchers. To properly implement injury prevention guidelines, we first need a better understanding of the population at risk as well as factors that influence injury (13). The purpose of our study is to perform an analysis of youth fastpitch windmill pitchers reported pitching regimens, levels of competition and reported injuries.

MATERIALS AND METHODS 

This was an Institutional review board approved survey study. A 2-part survey was created with the first part focused on pitching regimens while the second part focused on reported injuries sustained during pitching over the previous 12 months. The survey questions were designed through literature review and input of clinicians and coaches. The web-based survey was managed by an online survey software system (Version 1.0, 2021 SurveyPlanet, LLC). Surveys were distributed to coaches and USA softball state commissioners with available email addresses found on the USA Softball website (https://www.teamusa.org/usa-softball). They were then distributed to youth fastpitch softball pitchers aged 7 to 21 years old. Parents of participants under the age of 18 years-old were required to provide consent prior to beginning the survey and participants were encouraged to complete the surveys honestly without significant parental guidance. Surveys were unable to be distributed in person due to COVID-19 pandemic restrictions. 

The first section included demographics and questions regarding age, region, age started playing softball, age started pitching, participation in recreational teams, participation in travel team and attendance of private pitching lessons. Additional questions in this section were related to pitching regimens and included questions regarding participation (single season vs year-round), days pitched per week, innings pitched per game, pitches per game, games pitched per weekend, games pitched per season, days of rest per week, other sports played during and outside of softball season and types of pitches thrown. A complete game was defined as pitching 5 to 7 innings. Due to the retrospective nature of this study, pitch counts were evaluated based on previously reported game pitch count averages as an estimate of half game (30 to 50 pitches) vs full game (60 to 100 pitches) (13,14, 16). 

The second section of the survey contained 8 questions regarding injuries sustained from pitching over the past 12 months for each major joint of the upper and lower extremities to include the back. Questions were asked regarding injuries that did and did not require missed playing time. Examples of these injuries included tendonitis, bursitis, ligament sprain, pulled muscles, joint dislocations, ligament tears, broken bones, and stress fractures. However, we did not ask participants to specify exactly what injury they sustained. “Yes” or “No” responses were asked regarding injury occurring to pitching arms and if injury required evaluation by an athletic training or clinician. The final questions regarding injury asked at what level of competition the player returned to following conservative treatment (rest, ice, bracing or physical therapy) or surgical treatment; responses included “above previous level”, “same as previous level”, “below previous level”, and “did not return to pitching”. 

Data Analysis 
Responses were analyzed as a whole. Additionally, responses were separated into four age groups based on common categories for softball leagues: less than 10 years old (Group A), 10 to 13 years old (Group B), 14 to 17 years old (Group C) and 18 to 21 years old (Group D). Data was statistically analyzed using R Program 4.0.5 (The R Foundation, Vienna, Austria). A univariable and multivariable regression analysis was performed comparing single variables (season, pitches per game, days rest, age group and aged started pitching) with the outcome of any type of injury. The multivariable analysis also compared all variable together with the outcome of any type of injury. An odds ratio >1 was used to determine increased likelihood of injury. For all statistical comparisons with P <0.05, the finding was considered statistically significant. 

RESULTS

Demographics
A total of 140 surveys were completed between February 1, 2020 and August 1, 2020. Inclusion criteria for this study was any female fastpitch softball pitcher between age 7 to 21 years-old with or without prior injuries. Twenty surveys were excluded because they were either above or below our inclusion ages. Therefore, 120 surveys were included for review with inclusion rate of 86%. Of the 120 participants, 6 (5%) were in Group A, 35 (29%) in Group B, 56 (47%) in Group C, and 23 (19%) in Group D. The average age of participants was 14.7 years old (median 15, mode 14). The most common region represented was the south (45%). All participants confirmed they were fastpitch softball windmill pitchers. 

Approximately 90% of all participants were right hand dominant. The majority of participants over the age of 10 played on a travel softball team, attended private pitching lessons and played softball year-round (Table 1).

Pitching Regimens 
Pitching regimens were compared among all four age groups (Table 2), However with only six participants in group A, these were not included in analysis. Overall, there was an increased frequency of pitching appearances with increased age. Most participants over 14 years old were throwing with the frequency comparable to a starting pitcher position (21 to 30+ games per season). Participants over the age of 10 more commonly threw complete games with approximately 60 to 100 pitches (Grp B/C/D >65%). There was also a decrease in number of rest days from pitching with increasing age groups, with most participants under the age of 18 having 2 to 3 days of rest per week (83%, 63%, 68%), while 70% of participants in Group D had 0 to 1 days of rest per week.  Participants also became more sport specialized over 14 years-old (54% vs 38%). Basketball and volleyball were the most commonly played sports outside of softball. Additional pitching regimen details can be found in Table 2.

Injuries 
There were no injuries reported in Group A and were not included in analysis. There was a substantial increase in participants with injuries (Grp B 51%, Grp C 80%, Grp D 91%) and number of reported injuries (Grp B 49 vs Grp C 134 vs Grp D 86) with increasing age. Within Group B, the average number of years pitching were similar between the injured and uninjured participants (5.9 years vs 5.8 years). However, on average injured pitchers in Group C had been pitching for 1.5 years longer than their uninjured counterparts (6.6 years vs 5.1 years). The most commonly injured joint was the shoulder with reported injuries in nearly 50% of participants in each group (Fig. 1), with the highest number of injuries reported in the 14- to 17-year-old group. The percentage of injuries with missed playing time was between 37 to 41% (Fig 2). 

Group A
There were no injuries reported from participants in group A.

Group B 
Of the reported shoulder injuries (n=12), 25% resulted in missed playing time. Most of these participants returned to their previous level of competition following conservative treatment (78%). The other commonly injured joints included the foot and ankle (39%), back (33%) and elbow (22%). There were no surgeries reported for this age group. 

When comparing injured and uninjured participants in Group B, there was a small trend of an increase in injuries reported for participants who played on a travel softball team (45% vs 55%), took private pitching lessons (47% vs 53%) and played softball year-round (45% vs 55%) (Fig. 3). An increase in reported injuries was also seen in pitchers with higher cumulative pitch counts per game/season as well as decreased days of rest (Fig 4). 

Group C
Of the reported shoulder injuries (n=37), 41% resulted in missed playing time. Other reported injuries about the foot and ankle (n=23), back (n=19) and knee (n=19), were similar with missed playing time ranging from 37 to 43%. Of the elbow injuries reported (n=15), approximately 50% resulted in missed playing time. There were three reported surgeries in this age group (2 shoulder, 1 elbow). Of all injuries reported, approximately 50% of participants returned to their previous level of competition.  Seven participants did not return to pitching following their injury (3 shoulder, 2 back, 1 knee, 1 elbow). 

When comparing injured and uninjured participants in Group C, there was a much larger trend towards injuries reported in participants who played on a travel softball team (22% vs 78%), took private pitching lessons (22% vs 78%) and played softball year-round (18% vs 82%) (Fig. 5). An increase in reported injuries was also seen in pitchers with higher cumulative pitch counts per game and season as well as decreased days of rest (Fig 6).

Group D
Of the reported shoulder injuries (n=20), 45% resulted in missed playing time. Other frequently reported injuries were about the back (n=16), knee (n=13) and elbow (n=13), with 38% of injuries resulting in missed playing time. There were six reported surgeries in this age group (2 shoulder, 4 knee). Following surgery, 3 out of the 4 participants with knee injuries returned below their previous level of competition and one participant with a shoulder injury did not return to pitching. On average 56% of participants with non-operative injury returned to their previous level of competition. Three participants did not return to pitching following their injury (2 shoulder, 1 elbow). 

Statistical Analysis 
When analyzing all injured players together, pitchers were approximately two times more likely to have an injury if they threw a full game (60-100 pitches) (p 0.16, p 0.25). As a single variable, participants who began pitching at less than or equal to 9 years old were twice as likely to have an injury than participants beginning over 10 years old (p= 0.14). However, both results did not reach statistical significance. There was no significant increased risk of injury when comparing single season vs year-round pitching (p 0.03).  However, pitchers aged 14 to 17 were 5-6 times more likely to have an injury than younger groups (P <0.001) and pitchers aged 18 to 21 were 28-30 times more likely to have an injury than younger groups (P 0.002).  (Table 3). 

DISCUSSION

Our study found that even in the youngest age group, youth pitchers are frequently pitching on travel softball teams at least 3 to 4 days per week on a year-round basis. As to be expected, the frequency of pitching increased with age. Considering the pitches thrown during games, practice and private lessons, youth softball pitchers have high cumulative pitch counts with few days of rest. About half of these youth pitchers played other sports throughout different seasons especially under the age of 13. However, in the high school age group (14 to 17 years old) these pitchers became more sports specialized. 

There has been a marked increase in reported injuries among pitchers between the ages of 10-21. With increasing age, youth pitchers had a statistically significantly increased risk of injury. In our cohort, the high school aged group (14 to 17 years old) had the highest reported injuries. Similar to previous studies, 52% of these injuries were about the shoulder (12, 14). Young women in this age group are experiencing changes physiologically while still developing their core and lower extremity strength and balance. This can cause young pitchers to rely more on their upper extremity strength to increase pitch velocity, which may further predispose them to early injury (8). 

While most injuries reported did not require time off, there was still an increasing percentage of pitchers whose injuries resulted in missed playing time (B 37%, C 41%, D 40%).  More concerning was the number of players that did not return to pitching post injury (B 6%, C 16%, D 14%). Furthermore, softball pitchers experience a similar number of injuries as high-level baseball pitchers due to the cumulative microtrauma sustained at younger ages (5). The most susceptible age group for injury was the 14 to 17-year-olds (Group C). These high school aged pitchers had the highest reported injuries, missed playing time and number of pitchers who did not return to pitching following their injury. 

Nearly one third of injuries reported among all age groups were about the lower extremity and back. This further reinforces that the windmill pitch is a full body motion that involves synchronized activation and energy transfer from the lower extremity to the upper extremity. A breakdown in this kinetic chain can cause injury to not only the shoulder and elbow, but also the lower extremity (7). Most injuries were resolved following conservative treatment with only 9 total surgeries reported in pitchers over 14 years old. 

To our knowledge, this is the largest study that has used a detailed survey to evaluate pitching regimens and reported injuries from ages 7 to 21. In 2004, Hill and colleagues conducted a survey of collegiate fastpitch softball pitchers with regards to pitching regimens and injuries. They found 70% of reported injuries were classified as chronic or overuse, with 41% of injuries occurring about the shoulder (4). The result of our study demonstrates similar injury rates in youth fastpitch softball pitchers compared to collegiate level pitchers. Youth softball pitchers also have rigorous year-round pitching regimens starting at the youngest age groups. These pitchers are at a significantly increased risk of injury with increasing age and starting to pitch at very young ages. Based on our findings, 80% of high school pitchers reported injuries and almost 50% of injuries resulted in missed playing.  

There were several limitations to our study. This study was retrospective and relied upon young girls and young women to recall injuries. Some of the younger participants may have had larger influences from parents to complete the survey which can confound our results. This was an online only survey which may have allowed for influence of answers by parents or coaches. Our geographic distribution was skewed and had the most participants from the Midwest and South regions. This is likely due to the author’s location and previous knowledge of coaches in these regions. Due to the COVID-19 pandemic we were unable to distribute surveys in person. Although this was a large study of youth softball pitchers compared to previous literature, our sample was still small compared to the number of youth pitchers in the country. Also, most of our participants played on a travel softball team which may make them more competitive than players who play only in a single season. However, softball pitchers who play in multiple types of leagues may be at a higher risk for injury. These competitive softball pitchers are ideal to study and more importantly protect (6).

In conclusion, our study demonstrated the windmill motion of fastpitch softball pitch is not as benign as once believed (1,2). Young female pitchers are experiencing injuries at a markedly increased rate.  The injury rates are comparable to collegiate softball pitchers (Group D). Young female athletes are not only going through physiologic changes that affect their bones, ligaments, and muscles; they are also facing higher demands to increase competition through faster pitching speeds and more types of movement pitches. These athletes are pitching frequently at younger ages, on year-round travel teams, without pitch count restrictions or mandated time for rest and recovery. As softball continues to grow in popularity and participation, the focus needs to turn to protecting youth pitchers. A prospective study following regimens and pitch counts, as well as injuries, will help to identify risk factors for injury and provide guidelines for youth softball pitchers and coaches. 

Figure 1 | Figure 2 | Figure 3 | Figure 4 | Figure 5 | Figure 6 | Table 1 | Table 2 | Table 3

Required Disclosures and Declaration

Copyright Information: No Copyright Information Added
IRB Approval Information: Yes
Disclosure Information: No known conflicts of interest

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