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

Women's swimming and diving exposure and injury data collected in the NCAA ISP during the 2014–2015 through 2018–2019 athletic seasons were analyzed in this study. The ISP has been reviewed and approved as an exempt study by the NCAA Research Review Board. The methods of the surveillance program are described in detail in a separate manuscript within this special issue.⁶  Briefly, athletic trainers (ATs) at participating institutions contributed exposure and injury data by 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 AT or physician, regardless of time loss (TL). Scheduled team practices and competitions were considered reportable exposures for this analysis. Data from 8 (2% of membership with sponsored programs) participating programs in 2014–2015, 7 (1% of membership with sponsored programs) in 2015–2016, 10 (2% of membership with sponsored programs) in 2016–2017, 15 (3% of membership with sponsored programs) in 2017–2018, and 36 (6% of membership with sponsored programs) in 2018–2019 qualified for inclusion in analyses. Qualification criteria are detailed further in the aforementioned methods manuscript.⁶ 

Injured athletes were identified as either swimmers or divers when injury records were submitted by the AT. For injury records with an unknown athlete type, the injured athlete was assumed to be a swimmer if the corresponding activity at the time of injury was reported as backstroke, breaststroke, butterfly, freestyle, or medley; and the athlete was assumed a diver if the corresponding activity was reported as 1.0-m board, 1.0-m platform, 3.0-m board, 3.0-m platform, 5.0-m platform, 7.5-m platform, or 10.0-m platform. Records for which athlete type was not identifiable (either by AT report or activity, as noted above) were not retained in the analysis (n = 10). Combined AEs were collected for swimming and diving teams in the NCAA ISP. Previous researchers in this population determined that, on average, 87% of athletes on swimming and diving team rosters are swimmers, whereas 13% are divers.⁵  Injury rates were calculated using the appropriate distribution of AEs for each athlete type.

Injury counts and rates per 1000 AEs for each athlete type (swimmers or divers) were examined by event type (practice or competition) and TL (TL or non-TL [NTL]). An AE was defined as 1 athlete participating in 1 exposure event. Weighted and unweighted rates were estimated; however, results were presented in terms of unweighted rates (unless otherwise specified) due to low frequencies of injury observations across levels of certain explanatory variables. Temporal trends in injury rates (pooled for practices and competitions) across the study period were described using rate profile plots stratified by athlete type. Injury counts and proportions were examined by body part injured, mechanism of injury, injury diagnosis, and activity at the time of injury. Respiratory infections (n = 41) were not included in analyses due to reporting inconsistencies across the study period. Injury rate ratios (IRRs) were used to examine differential injury rates across event types. IRRs with associated 95% confidence intervals (CIs) excluding 1.00 were considered statistically significant. All analyses were conducted using SAS 9.4 (SAS Institute).

A total of 630 women's swimming and diving injuries (swimmers: 521; divers: 109) from 336851 AEs (swimmers: 293060; divers: 43,791) were reported to the NCAA ISP during the 2014–2015 through 2018–2019 athletic seasons (rate: swimmers = 1.78 per 1000 AEs; divers = 2.49 per 1000 AEs). This equated to a national estimate of 23 281 injuries overall (swimmers: 19 734; divers: 3548; Table 1). Practice and competition injury rates did not significantly differ in both swimming and diving. Injury rates in women's swimming remained relatively stable between 2014–2015 and 2015–2016, then increased through 2017–2018 before decreasing in the final year of the study (Figure). Injury rates in women's diving decreased notably between 2014–2015 and 2015–2016, and then steadily increased through 2017–2018 before decreasing in the final year of the study (Figure). Similarly, by inspecting injury incidence in diving, we found that the injury rate decreased notably between 2014–2015 and 2015–2016 and then steadily increased through 2017–2018 before decreasing in the final year of the study (Figure).

Original sentence: In both women's swimming and diving, NTL injuries represented a larger proportion of reported injuries than TL injuries (swimmers: NTL- 49.9%; TL- 28.6%; missing- 21.5%; divers: NTL- 45.0%; TL- 40.4%; missing- 14.7%). TL injuries accounted for a greater proportion of reported competition (43.1%) injuries than practice (27.0%) injuries in women's swimming. Conversely, TL injuries accounted for a greater proportion of reported practice (41.0%) injuries than competition (33.3%) injuries in women's diving.

Injuries to the shoulder (33.0%) and trunk (15.6%) accounted for the largest proportions of all injuries reported in women's swimming during the study period (Table 2). Most swimming injuries were attributed to overuse (51.3%) and noncontact (18.0%) mechanisms. Overuse injuries accounted for a larger proportion of practice-related (52.6%) than competition-related (39.2%) women's swimming injuries. Noncontact injuries accounted for comparable proportions of practice- and competition-related injuries (Table 2). Most women's swimming injuries reported during 2014–2015 through 2018–2019 were categorized as inflammatory conditions (23.8%) and strains (12.9%). The most commonly reported specific injury diagnoses during the study period were shoulder impingement (8.6%; rate = 1.54 per 10 000 AEs), biceps tendonitis (shoulder) (7.9%; rate = 1.40 per 10 000 AEs), and rotator cuff tendonitis (5.4%; rate = 0.96 per 10 000 AEs).

Injuries to the head or face (29.4%) and trunk (20.2%) accounted for the largest proportions of all women's diving injuries reported during the study period (Table 3). Injuries were most commonly attributed to surface contact (31.2%) and overuse (23.9%) mechanisms. Women's diving injuries reported during the study period were distributed across several diagnostic classifications (Table 3). Concussions accounted for 13.8% of all reported injuries in diving, although this result should be interpreted with caution given the low number of diving injuries reported across the study period.

Most women's swimming injuries from 2014–2015 through 2018–2019 occurred during freestyle stroke (47.2%) and conditioning (14.4%; Table 4). Freestyle stroke in particular accounted for 60.9% of all reported shoulder injuries and 44.4% of all trunk injuries in swimming. Most women's diving injuries during the study period occurred in unspecified diving activities (30.3%) and 3.0-m board (24.8%).

We aimed to describe the epidemiology of NCAA women's swimming- and diving-related injuries reported to the NCAA ISP during the 2014–2015 through 2018–2019 academic years. Injury rates in women's swimming remained relatively low during 2014–2015 to 2015–2016, as compared with the latter years of the study period. The overall women's swimming injury rate observed in the present study was consistent with previous findings in this population.⁵  Furthermore, there were no differences between practice- and competition-related injury rates in women's swimming, a finding also consistent with previous reports.⁵  Although these findings appear to indicate stability in injury incidence among NCAA women's swimming athletes across 2 time periods, it is necessary to note that in the context of injury surveillance, these inferences are drawn on the basis of relatively small numbers of injury observations. Furthermore, we only examined temporal trends in overall injury incidence (and not by event type), which was also the case in previous reports. Given that competition exposures account for a smaller proportion of all reported exposures than practice exposures, it is perhaps unsurprising that few competition injuries were captured during the present study period. The low number of observed competition injuries also precluded juxtapositions of differential injury distributions between event types for several explanatory variables of interest (eg, comparisons of injury distributions by activity across event types). As such, future researchers may not only examine temporal patterns in injury incidence with more granularity (by event type, for instance), but also target the distribution of competition-related injuries for further attention. Such examinations will not only help elucidate factors in the sport that contributed to the burden of injury among NCAA women's swimming athletes, but also highlight areas for directing injury prevention efforts in this population.

Nearly one-half of all reported injuries in women's swimming were NTL injuries. Notably, the prevalence of TL injuries was higher among reported competition injuries than practice injuries. Furthermore, more than 60% of competition injuries were attributed to noncontact and overuse mechanisms. Although the low number of competition injuries reported across the study period restrict the inferential capacity of these injury distributions (ie, the extent to which these findings represent true distributions), it is important to consider that overuse and noncontact injuries also accounted for a large proportion (∼70%) of all reported practice injuries. Together, with these findings, we indicate the need to further examine the complex injury etiology associated with muscular and connective tissue breakdown during high-intensity repetitive movements inherent to swimming,⁷  which occur similarly during practice and competition events and may not be attributed to a discrete point in time. It is reasonable to suggest that injury prevention efforts in women's swimming may target commonly injured body parts, such as the shoulder and trunk, for further attention and targeted care in protecting against chronic workloads that may contribute to overuse injuries.^8,9  Future researchers may also aim to better understand the etiology of workload accumulation in women's swimming athletes that may be unspecific to a particular event type and rather inherent to the sport. The physiologic strain on the shoulder during all swimming motions requires muscular endurance, excellent technique, and a large range of motion.^10,11  This may be particularly salient with regard to injuries attributed to the freestyle stroke, which was most prevalently associated with reported injuries in the present study, and also accounted for large proportions of shoulder and trunk injuries. With that said, the observed prevalence of injuries attributed to freestyle stroke may be unsurprising given the frequent use of the freestyle stroke among practices and competitions.¹²  The freestyle stroke consists of a complex series of muscle activation with antagonistic activity in the biceps and triceps brachii to maintain joint stability during the early pull-through phase, the pectoralis major and latissimus dorsi during the underwater phase, and the rotator cuff throughout the stroke.^13,14  The trunk also serves an integral role as a stable base that allows for a transfer of force from the core to the extremities.^15–17  A breakdown in this force transfer has been previously shown to predispose overhead athletes to shoulder injury.¹⁸  Such findings suggesting a related injury risk in these body parts in other overhead-concentrated sports indicate that this kinetic link warrants further attention in women's swimming athletes.

The overall women's diving injury rate in the present study was comparable to that in previous reports in this population.⁵  Due to the limitations in stratifying diving injuries by explanatory variables of interest, it is difficult to contextualize these findings for the reasons described in subsequent sections. Most women's diving injuries occurred to the head/face and trunk. Coupled with the observed prevalence of knee and shoulder injuries, these findings are arguably consistent with expectations given the nature of the sport. For instance, head/face injuries were most often attributed to surface contact mechanisms (particularly with water) in the present study; this result is unsurprising given that diving athletes often break the surface tension of water at high velocities.^19,20  Furthermore, the biomechanical nuances of diving align with the prevalence of trunk, shoulder, and knee injuries observed in the present study. The sequence of diving begins with “take-off” from a stable (or unstable) surface in the form of a handstand or jump that requires considerable neuromuscular control of the lower extremity and trunk, followed by flight and entry, for which athletes perform complex maneuvers that demand precise proprioception.²¹  The entry has been measured at 7.58 m/s on average in the 1.0-m (springboard) dive and 9.54 m/s on average in the 3.0-m (springboard) dive into the water, which may particularly affect the hand or wrist, arm or elbow, shoulder, trunk, and head or face.^20–22  Each phase of a dive predisposes the athlete to various risks of injury across the kinetic chain that may be accumulated over a series of dives that may vary in difficulty as athletes work to develop new skills. With the findings of the present study (in particular, the observed prevalence of shoulder, trunk, and knee injuries), we indicate that injuries in women's diving are distributed across the kinetic chain²³  and suggest that future researchers may leverage this rationale in directing research efforts. However, given the low number of diving injuries observed in this study, it is important not only to exercise caution in drawing inferences from the observed results but also to acknowledge that future studies regarding the etiology of injuries across the kinetic chain in this population are needed to inform injury prevention efforts.

Although the results of the present study extend the existing literature surrounding injury incidence in NCAA women's swimming and diving, it is important to consider the limitations that warrant further attention in examining these results. To begin with, participation in the NCAA ISP among women's swimming and diving programs was low across the study period, which limited the analytical scope of the present study, as well as the overall external validity of findings. More specifically, and as alluded to above, low participation precluded several cross-tabulations in this particular analysis. As a corollary to this point, sports injury surveillance is often leveraged to closely monitor temporal patterns in injury incidence; however, robust participation in surveillance is also critical for securing the requisite volume of data to support such investigations. Therefore, as future researchers consider studying this population, it is concurrently important to emphasize the continued surveillance and strong participation in surveillance programs. Furthermore, while considering the estimates of injury incidence presented here, it is important to acknowledge that there exist 2 fundamental compromises involved in their estimation. First, the representation of at-risk exposure time by using AEs may be particularly imprecise for swimming and diving. Given the individualized nature of swimming and diving activities, at-risk exposure time captured as AEs may not appropriately represent true differences in exposure time between athletes irrespective of their position or event (swimming or diving). Second, although swimming and diving are typically unified as a single sport within member institutions, swimming and diving exposures, including the likelihood and nature of contact, are inherently different due to the differences in activities and training routines between swimming and diving athletes.²⁴  Swimmers typically repeat comparable movements at high volumes, whereas divers perform highly technical maneuvers at comparatively lower volumes. The consolidation of swimming and diving as a single sport, coupled with the current structure of the NCAA ISP, precludes precise estimations of position-specific at-risk exposure time. Although separating exposure time on the basis of roster size (as seen here) is a practical solution, this strategy is understandably not ideal. As such, it is critical that future researchers studying this population not only consider methods for more precisely capturing at-risk exposure time in swimming and diving athletes but also measure exposure time for swimming and diving separately. Athlete-level measurements using dedicated data recorders or wearable technology may be effective alternative strategies for exposure time ascertainment in this population.^19,25,26  Such strategies may also allow researchers to capture more detailed exposure data, such as swim distance, type and number of dives, and exertional metrics, in this group. Although the NCAA ISP is unable to accommodate all of these measurement advancements in its current form, researchers may conduct targeted studies to pilot their feasibility and ultimately refine them for large-scale implementation.

Injury surveillance in NCAA women's swimming and diving facilitates the identification of emerging injury-related patterns in this population, and healthy participation in surveillance programs is critical to support meaningful inferences. With the findings of the present study, we direct attention toward potential areas for further monitoring in this athlete population, such as the incidence of shoulder and trunk injuries, as well as overuse injuries. We also highlight meaningful differences in injury incidence between swimming and diving athletes. In addition, in the discussions above, we offer important study design considerations for future research in this population. Together, the findings and discussions presented here will be critical for informing future work that will profoundly affect injury prevention in this population.

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.