Epidemiology of Injuries in National Collegiate Athletic Association Men's Cross-Country: 2014–2015 Through 2018–2019

Men's cross-country exposure and injury data collected in the NCAA ISP during the 2014–2015 through 2018–2019 athletic 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. The methods of the surveillance program are described in detail in separately within this special issue.⁶  Briefly, ATs at participating institutions contributed exposure and injury data using their clinical electronic medical record systems. A reportable injury (or illness, inclusive of heat illnesses and respiratory conditions) was one that occurred due to participation in an organized intercollegiate practice or competition and required medical attention by a team certified AT or physician (regardless of time loss [TL]). Scheduled team practices and competitions were considered reportable exposures for this analysis. Data from 13 (1% of membership) participating cross-country programs in 2014–2015, 6 (∼1% of membership) in 2015–2016, 14 (1% of membership) in 2016–2017, 19 (2% of membership) in 2017–2018, and 36 (4% of membership) in 2018–2019 qualified for inclusion in the analyses. Qualification criteria are detailed further in the methods manuscript.⁶ 

Injury counts and rates per 1000 AEs (for which 1 AE was defined as 1 athlete participating in 1 exposure event) were assessed by event type (practice or competition), competition level (Division I, Division II, or Division III), season segment (preseason, regular season, or postseason), and TL (TL or non-TL [NTL]). Weighted and unweighted rates were estimated, and results are presented in terms of unweighted rates (due to low frequencies of injury observations across levels of certain covariates) unless otherwise specified. Temporal trends in injury rates across the study period were evaluated using stratified (by levels of abovementioned variables) rate profile plots. Injury counts and proportions were examined by TL, body part injured, mechanism of injury, injury diagnosis, and activity at the time of injury. Injury rate ratios (IRRs) were used to evaluate differential injury rates across event types, competition levels, and season segments. IRRs with associated 95% confidence intervals (CIs) excluding 1.00 were considered statistically significant, and all analyses were conducted using SAS (version 9.4; SAS Institute).

A total of 364 men's cross-country injuries were reported to the NCAA ISP from 90 723 AEs during 2014–2015 through 2018–2019 (rate = 4.01 per 1000 AEs). This equated to a national estimate of 22 056 injuries overall (Table 1). A relatively small number of competition-related injuries (55 injuries) were reported during the study period, although the competition injury rate was higher than the practice rate (IRR = 2.11; 95% CI = 1.59, 2.82). Competition injury rates decreased notably between 2014–2015 and 2015–2016, remained relatively stable thereafter until 2017–2018, and increased drastically between 2017–2018 and 2018–2019 (Figure A). In comparison, practice injury rates remained relatively stable across the study period (Figure A). The overall Division III injury rate (rate = 5.48 per 1000 AEs) was higher than Division I (3.86 per 1000 AEs), and Division II (3.14 per 1000 AEs) injury rates; statistically significant differences were observed between Division I and Division III rates (IRR = 0.70; 95% CI = 0.55, 0.89), as well as between Division II and Division III rates (IRR = 0.57; 95% CI = 0.44, 0.75).

Overall, 99 preseason injuries (national estimate: 5504), 212 regular season injuries (national estimate: 13 856), and 53 postseason injuries (national estimate: 2696) were reported during 2014–2015 through 2018–2019 (Table 2). The preseason injury rate was higher than the regular season (IRR = 1.45; 95% CI = 1.14, 1.84) and postseason (IRR = 2.69; 95% CI = 1.92, 3.75) injury rates. Regular and postseason injury rates remained relatively stable across the study period, whereas preseason injury rates were notably more variable (Figure B). The preseason injury rate decreased considerably between 2014–2015 and 2015–2016 and then increased between 2016–2017 and 2018–2019 (Figure B). The most notable increase in the preseason injury rate was between 2017–2018 and 2018–2019.

Less than one-half (40.7%) of all reported injuries resulted in TL of greater than or equal to 1 day (TL was not reported in ∼23% of all reported injuries). TL injuries accounted for a larger proportion of reported competition injuries (49.1%) than practice injuries (39.2%). Notably, competition-related TL injury rates consistently decreased between 2014–2015 and 2017–2018 and then increased slightly between 2017–2018 and 2018–2019 (Figure C). Rates of practice-related TL injuries remained relatively stable throughout the study period (Figure C).

Lower leg injuries (29.1%) accounted for the largest proportion of all injuries reported during the study period. Knee injuries (14.6%), ankle injuries (12.1%), and foot injuries (12.1%) were also common overall. Although knee injuries and foot injuries accounted for notably larger proportions of practice injuries than competition injuries, ankle injuries accounted for comparable proportions of both practice and competition injuries (Table 3). Overuse (38.5%) and noncontact (32.1%) injuries accounted for most of all reported injuries; surface contact injuries also accounted for approximately 12% of all reported injuries (Table 3). Noncontact injuries accounted for comparable proportions of practice (32.4%) and competition injuries (30.9%), whereas overuse injuries accounted for a notably larger proportion of practice injuries (41.4%) than competition injuries (21.8%).

During the 2014–2015 through 2018–2019 academic years, inflammatory conditions (musculoskeletal pathologies with degenerative characteristics to the corresponding tissue, such as bursitis, capsulitis, osteochondritis, and tendinitis; 30.2%), strains (18.7%), and sprains (11.5%) accounted for most reported men's cross-country injuries. Inflammatory conditions (most commonly reported in the lower leg or Achilles, knee, and foot or toes) accounted for a larger proportion of practice injuries (33.3%) than competition injuries (12.7%). Inflammatory conditions also occurred at a markedly higher rate in preseason (rate = 2.07 per 1000 AEs) than in the regular season (rate = 1.20 per 1000 AEs) and postseason (rate = 0.64 per 1000 AEs). Conversely, strains (29.1%) accounted for larger proportions of competition injuries than practice injuries (16.8%). The most commonly reported injuries during the study period were partial or complete lateral ligament complex tears (ankle sprains) (8.2%) and medial tibial stress syndrome (shin splints) (6.6%). During the study period, the overall rate of lateral ligament complex tears was 3.31 per 10 000 AEs (95% CI = 2.12, 4.49), and the overall rate of medial tibial stress syndrome was 2.65 per 10 000 AEs (95% CI = 1.59, 3.70).

Most injuries in men's cross-country between 2014–2015 and 2018–2019 occurred during 800-m to 10 000-m distance running (70.3%). Fitness or conditioning and running 10 000-m (6 mile) events were other notable activities to which injuries were attributed (Table 4).

We aimed to describe the epidemiology of NCAA men's cross-country injuries during the 2014–2015 through 2018–2019 athletic seasons. Across the study period, the competition injury rate was higher than the practice injury rate. Importantly, this result had not been observed previously in NCAA men's cross-country athletes; and particularly, the competition injury rate observed in this study was notably higher than the competition rates previously reported in this population.⁵  Given the trajectory of competition injury rates during the final years of this study, it may be important to closely monitor the incidence of competition injuries after 2018–2019 to better understand the burden of such injuries to this population. Similar results were observed when we examined injury rates by season segment. The overall preseason injury rate was higher than regular and postseason injury rates across the study period. However, the preseason injury rate was notably more variable than the regular and postseason rates. Although preseason and regular season rates were comparable between 2015–2016 and 2017–2018, the preseason injury rate increased sharply between 2017–2018 and 2018–2019. Much akin to competition injuries, this trajectory of preseason injury rates indicates the need to closely monitor preseason injury incidence and outcomes after 2018–2019. This may be particularly important given the notable increase in ISP participation observed during 2018–2019. NCAA ISP recruitment tactics have evolved over time, and the improvements in participation during 2018–2019 in particular reflects the success of recently used recruitment strategies (for instance, support and communication from the NCAA Sport Science Institute). Consequently, although it is reasonable to suggest that the injury rates and characteristics reported during the latter years of the study period more closely represent the larger population of interest (as compared with the earlier years) due to greater participation in the ISP, continued monitoring during sustained periods of healthy participation is needed. Closer monitoring of offseason and preseason training routines may be warranted if comparable preseason injury rates are observed beyond 2018–2019.

Most injuries reported among men's NCAA cross-country athletes during 2014–2015 through 2018–2019 were inflammatory conditions, sprains, and strains. The prevalence of inflammatory conditions (delineated as musculoskeletal pathologies with degenerative characteristics to the tissue involved) is particularly noteworthy, and the relatively higher rate of such injuries in preseason (as compared with regular and postseason) suggests that inflammatory-related injuries, especially in preseason, warrant further attention in this population. In a sport in which the body's largest muscle groups are recruited to perform at maximal exertion for long periods of time, exercise-induced muscle damage (nonpathophysiological) is arguably expected given the physiological mechanisms involved in the recovery process.^7,8  This suggested trend may be attributable to the nature of the sport, as athletes are required to undergo repetitive movements for long periods of time. These movements cause the body's largest muscle groups to perform in a high intensity capacity for long periods of time. This exercise-induced muscle damage is arguably expected given the physiological mechanism involved in the recovery process^7,8  but may become pathological if appropriate recovery is not allowed.⁹  The current trend observed may suggest that cross-country athletes may not always be implementing the requisite recovery practices to prevent these conditions. Given the higher injury incidence during the preseason and time constraints that may hamper the athlete's ability to fully recover, implementation of preventative programs before athletic participation may serve as an effective intervention strategy and is an important avenue for future researchers.¹⁰  Furthermore, it is important to note that given the nature of sports injury surveillance, inflammatory conditions are made up of several potential injury diagnoses in the ISP (such as bursitis, capsulitis, osteochondritis, and tendinitis). As such, it is difficult to discuss these records in greater detail than in terms of commonly reported body parts or rates by season segment (as noted above) in this context. In future studies directed toward studying inflammatory conditions in this population, researchers may not only target specific types of inflammatory conditions but also capture physiological characteristics of athletes at various times during the season to expand the understanding of such injuries among NCAA men's cross-country athletes. Future study of training and recovery practices that are associated with a higher prevalence of such conditions may also be important.

The most commonly reported specific injuries were (partial or complete) lateral ligament complex tears (ankle sprains) and medial tibial stress syndrome (shin splints). Particularly with regards to medial tibial stress syndrome, prior research in collegiate athletes has suggested that potential etiological elements of this injury include weak hip abductors, restrictive hip musculature, and long durations of rearfoot eversion during stance.¹¹  In addition, it has also been noted that greater hip external rotation (in males), prior orthotic use, fewer years of running experience, increased body mass index, navicular drop, and navicular drop greater than 10 millimeters are all factors associated with a higher risk of medial tibial stress syndrome.¹²  Importantly, we did not examine temporal patterns in rates of commonly observed injuries due to low injury frequencies (of both lateral ligament complex tears and medial tibial stress syndrome) observed per year. The observed frequencies are at least partially attributable to low ISP participation among men's cross-country programs, particularly during the earlier years of this study. Therefore, continued monitoring of commonly reported injuries is needed through a period of healthy and stable ISP participation among NCAA men's cross-country programs. Given the results observed here, it may be important to discuss the development injury prevention strategies for commonly observed injuries, while continuing to closely monitor the incidence (and associated outcomes) of such injuries after 2018–2019.

The juxtaposition of the results we observed here to those reported by previous researchers examining this population reveal stark differences, particularly with regard to competition injury incidence. With that said, it is important to acknowledge the rapid growth in the number of NCAA men's cross-country athletes nationwide, as well as the growth in ISP participation among men's cross-country programs during 2016–2017 through 2018–2019. Taking such factors into consideration, continuous and routine monitoring of NCAA men's cross-country injuries is critical for providing insight into injury incidence and outcomes within 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.