Epidemiology of Injuries in National Collegiate Athletic Association Women's Softball: 2014–2015 Through 2018–2019

Women's softball exposure and injury data collected in the NCAA ISP during the 2014–2015 through 2018–2019 competitive seasons were analyzed in this study. The methods of the NCAA ISP have been reviewed and approved as an exempt study by the NCAA Research Review Board. Briefly, athletic trainers at participating institutions contributed exposure and injury data using their clinical electronic medical record systems. A reportable injury was one that occurred due to participation in an organized intercollegiate practice or competition, and required medical attention by a team certified athletic trainer or physician (regardless of time loss). Scheduled team practices and competitions were considered reportable exposures for this analysis. Data from 24 (2% of membership) participating programs in 2014–2015, 18 (2% of membership) in 2015–2016, 24 (2% of membership) in 2016–2017, 28 (3% of membership) in 2017–2018, and 101 (10% of membership) in 2018–2019 qualified for inclusion in analyses. Qualification criteria are detailed further in the methods article within this special issue.⁹ 

A total of 1511 women's softball injuries from 385 922 AEs were reported to the NCAA ISP during the 2014–2015 through 2018–2019 athletic seasons (3.92 per 1000 AEs). This equated to a national estimate of 40 433 injuries overall (Table 1). The competition and practice injury rates were comparable across the study period (Table 1). Competition injury rates remained relatively stable between 2014–2015 and 2016–2017 before decreasing sharply between 2016–2017 and 2017–2018 (Figure A). In comparison, practice injury rates increased moderately between 2015–2016 and 2017–2018, before sharply increasing during the final year of the study period (Figure A). The overall Division I injury rate (3.48 per 1000 AEs) was lower than Division II (3.85 per 1000 AEs) and Division III (4.61 per 1000 AEs) injury rates. The Division III injury rate was significantly higher than the Division I (IRR = 1.33; 95% CI = 1.17, 1.50) and Division II (IRR = 1.20; 95% CI = 1.06, 1.36) injury rates.

A total of 529 preseason injuries (national estimate = 14 078), 945 regular season injuries (national estimate = 25 217), and 37 postseason injuries (national estimate = 1138) were reported from 2014–2015 through 2018–2019 (Table 2). The preseason injury rate (5.23 per 1000 AEs) was higher than the regular season (3.49 per 1000 AEs) and postseason (2.58 per 1000 AEs) rates; statistically significant differences were observed when comparing preseason rates with regular season rates (IRR = 1.50; 95% CI = 1.35, 1.67) and when comparing preseason rates with postseason rates (IRR = 2.03; 95% CI = 1.45, 2.83). Preseason injury rates decreased between 2014–2015 and 2015–2016, then increased steadily thereafter (Figure B). In comparison, regular season injury rates remained stable during the early years of the study before decreasing between 2016–2017 and 2017–2018 and then increasing sharply during the final year of the study (Figure B). Temporal patterns in postseason injury incidence were not examined due to low frequencies of postseason injuries observed during certain years of the study period.

Approximately one-third (31.9%) of all reported injuries during the study period resulted in time loss (time loss was not recorded in 31.0% of all reported injuries). Time-loss injuries accounted for comparable proportions of reported competition (34.2%) and practice (30.2%) injuries. Rates of competition-related time-loss injuries followed an increasing trajectory between 2014–2015 and 2016–2017 before fluctuating drastically during the final years of the study (Figure C). In contrast, rates of practice-related time-loss injuries followed a decreasing trajectory between 2014–2015 and 2016–2017 and steadily increased thereafter (Figure C).

Shoulder (15.2%), hand/wrist (11.8%), knee (11.2%), and head/face (11.2%) injuries accounted for the largest proportions of all injuries reported during the study. Knee injuries accounted for comparable proportions of practice- and competition-related injuries (Table 3). Conversely, shoulder injuries (61% of which were attributed to throwing or pitching activities) accounted for a larger proportion of practice injuries (17.3%) than competition injuries (12.2%), and head/face injuries accounted for a larger proportion of competition injuries (14.3%) than practice injuries (8.9%). About one-quarter of all reported injuries were accredited to noncontact mechanisms (25.0%), and noncontact injuries accounted for comparable proportions of practice (26.7%) and competition (22.6%) injuries (Table 3).Overuse mechanism injuries also accounted for a notable proportion (21.4%) of all reported injuries. Overuse injuries accounted for a larger proportion of reported practice injuries (29.4%) than competition injuries (10.4%).

Overall, women's softball injuries reported between 2014–2015 and 2018–2019 were most commonly classified as strains (19.3%).Contusions (14.2%), sprains (14.1%), and inflammatory conditions (14.1%) also accounted for considerable proportions of all reported injuries. Strains accounted for comparable proportions of competition (18.5%) and practice (19.9%) injuries. Contusions and sprains accounted for larger proportions of competition injuries than practice injuries, while inflammatory conditions were more prevalent among reported practice injuries than competition injuries (Table 3). The most commonly reported specific injuries during the study period were concussion (6.8%), lateral ligament complex tears (ankle sprains; 5.5%), and hamstring tears (3.6%). Concussions were most often attributed to equipment contact (59.2%) and player contact (20.4%). Rates of lateral ligament complex tears were stable for most of the study period (Figure D). Rates of hamstring tears followed a decreasing trajectory between 2014–2015 and 2016–2017 and remained stable thereafter, while concussion rates fluctuated across the study period (Figure D).

Women's softball injuries reported during the study period were comparably distributed among several activities, including throwing, fielding, batting, general play, and pitching (Table 4). Throwing and general play accounted for larger proportions of practice injuries than competition injuries, while batting and pitching injuries accounted for larger proportions of competition injuries than practice injuries (Table 4). Most women's softball injuries during the study period were reported among outfielders (Table 4).

This study aimed to describe the epidemiology of NCAA women's softball-related injuries during the 2014–2015 through 2018–2019 athletic seasons. Across the study period, the overall practice and competition injury rates were comparable, although a larger proportion of all reported injuries were practice related (∼58%). In the present study, we did not observe a difference between competition and practice injury rates. Conversely, previous studies (albeit including only TL injuries in analyses) have reported higher competition injury rates than practice injury rates in this population (1988–1989 through 2003–2004: IRR = 1.60; 95% CI = 1.50, 1.70; 2004–2005 through 2013–2014: IRR = 1.39; 95% CI = 1.27, 1.52).^7,8  Notably, the competition injury rate decreased sharply between 2016–2017 and 2017–2018, and although it increased thereafter during the final year of the study, the practice injury rate also rose considerably during the same time period. Consequently, the practice injury rate was markedly higher than the competition injury rate during the final year of the study, and it is reasonable to suggest that the overall comparability of practice- and competition-related injury rates is attributable to the aforementioned changes observed between 2016–2017 and 2018–2019. Further, preseason injury rates steadily increased during the majority of the study period. Given this result, it may be important to assess preseason training routines, particularly the abrupt change in workload between offseason and preseason, to better understand preseason injury risk in this population. The NCAA ISP does not collect detailed information on training activities (specific drills or exercises) and is therefore unable to support such assessments. Future studies should specifically target preseason training routines, including the rapid return to play and high repetitions of throwing in softball (which may be activity with the greatest change in frequency/repetition between offseason and preseason). Given that athletes are at greater risk of injury after rapid return to activity without adequate rest,^10,11  implementing workload monitoring and subsequent workload management may form parts of effective injury prevention programs throughout the softball season.¹²  Nonetheless, based on the results observed in this study, it remains vital to continue monitoring practice-related and preseason injury incidence beyond 2018–2019. This may be particularly important considering the marked increase in NCAA ISP participation among women's softball programs during the final year of the study, which is largely attributable to revised recruitment strategies (eg, support and communication from the NCAA Sport Science Institute). Although the external validity of the findings presented here may be limited by low ISP participation during the earlier years of the study period, it is reasonable to suggest that the estimates associated with 2018–2019 are a more appropriate representation of the injury burden in this population compared with the earlier years. Close monitoring of the incidence trajectories of practice-related and preseason injuries will elucidate whether the patterns observed here are maintained, and will inform the direction of specific injury prevention efforts.

Most women's softball injuries reported were attributed to the shoulder, hand/wrist, knee, and head/face. Most shoulder injuries occurred during pitching or throwing activities. Similar distributions of injuries by body part have also been previously reported in men's baseball.¹³  It has been previously suggested that softball (windmill) and baseball (overhead) pitching create a similar joint distraction moment in the shoulder,^12,14,15  and it is further estimated that the maximum weight force produced on the shoulder, during windmill pitching motion in particular, is ∼70% to 80% of the pitcher's body weight.¹⁴  Despite these biomechanical similarities, our results, coupled with findings from previous studies of NCAA baseball and softball, highlight differences in the prevalence of injury associated with the pitching activity, with much higher proportions of practice and competition pitching injuries being sustained by baseball pitchers than softball pitchers.^7,13  An additional point to consider when comparing the injury epidemiology across NCAA baseball and softball is the difference in proportion of pitchers within a softball or baseball roster (ie, softball teams on average may carry comparatively fewer pitchers, subsequently resulting in a greater volume of exposures among softball pitchers). It may therefore be important to particularly assess the accumulation of concentrated workload (in the shoulder) among pitchers to better reconcile the observed findings and inform future injury prevention efforts. That said, workload monitoring (ie, pitch count, pitch type, pitch speed),^10,16,17  which has been used across overhead-throwing–dominant sports, may also be effectively leveraged to better assess injury risk and prevent injuries in women's softball.¹⁸  Such investigations may be used to better understand the etiology of shoulder injuries in this population and prompt interventions aimed at managing training workloads during practice and pitcher recovery status. The NCAA ISP in its current form is not equipped to accommodate workload monitoring. As such, targeted studies may be needed to better understand the relationship between workload accumulation and overuse injury risk among NCAA women's softball athletes. Further, the overhead throw, which is a common activity among infield players and an activity in which injuries were prevalent, is biomechanically distinct from windmill pitching. Therefore, injuries attributed to throwing and pitching should be examined separately. There is a paucity of data examining the overhead throw among softball players. However, the relationship between hip, trunk, shoulder, and elbow muscle activation has been identified to be critical for a biomechanically efficient throw.¹⁹  Softball players use a larger and heavier ball than baseball players, potentially influencing the nature and etiology of (overhead) throwing injuries. In its current form, the NCAA ISP does not collect nuanced athlete-level information that could identify a connection between the injuries observed in the present study and biomechanical differences that may result from a larger and heavier ball (compared with baseball). As such, future research efforts should also be directed toward investigating the complex neuromusculoskeletal movements associated with the overhead throw in softball by specifically capturing and analyzing biomechanical (throwing) information, including athlete-specific workload metrics/indices. Together with sports injury surveillance, these efforts are likely to better characterize the scientific understanding of overhead movements and risk of injury.

The most commonly reported specific injuries were concussions, lateral ligament complex (partial or complete) tears of the ankle, and hamstring tears (partial or complete). The incidence of lateral ligament complex tears and hamstring tears remained relatively stable during much of the study period. Conversely, concussion rates fluctuated throughout the study period and increased drastically between 2017–2018 and 2018–2019. In juxtaposition to the stability in rates of lateral ligament complex tears and hamstring tears, the marked increase in concussion rates that accompanied improved participation in the ISP is noteworthy. While it is reasonable to suggest that the observed concussion rate in 2018–2019 may be attributable to greater awareness and diagnostic sensitivity, it is likely that there are also other contributing factors.^20,21  Given the limited contact nature of the sport,²²  it may be particularly important for future studies to specifically examine the dynamics of equipment/apparatus contact-resultant concussions in this population while continuing to monitor concussion incidence after 2018–2019. This is particularly salient given that concussions were most prevalently attributed to equipment contact mechanisms in the present study. Further investigation of inciting mechanisms and antecedent events surrounding concussions in women's softball is needed to truly appraise the burden of concussions to NCAA women's softball athletes.

The results of this study were in alignment with existing research in this population, though the observed trajectories of practice injury rates and preseason injury rates are noteworthy and warrant further attention. Future research may also target concussion incidence, overuse injury etiology, and the relationship between workload accumulation and shoulder injury risk in this population. While surveillance-based studies are important in identifying salient patterns in injury incidence, small-scale studies are needed to expand on the observed results to better understand the underlying etiologic frameworks.

The NCAA Injury Surveillance Program was funded by the NCAA. The Datalys Center is an independent nonprofit organization that manages the operations of the NCAA ISP. The content of this report is solely the responsibility of the authors and does not necessarily represent the official views of the funding organization. We thank the many ATs who have volunteered their time and efforts to submit data to the NCAA-ISP. Their efforts are greatly appreciated and have had a tremendously positive effect on the safety of collegiate student-athletes.