Overall Game and Practice Injury Rates
shows overall game and practice injury rates by division and season, combined across 15 sports. The seasonal injury rates in both games and practices show similar patterns across divisions. For games, preseason competition accounted for the lowest injury rate in all divisions (6.0 injuries per 1000 A-Es, 95% confidence interval [CI] = 5.7, 6.3), whereas the in season was associated with the highest game injury rates (14.5 per 1000 A-Es, 95% CI = 14.4, 14.6). Rates in the postseason were significantly higher than those in the preseason (8.7 versus 6.0 per 1000 A-Es) but significantly lower than those in the regular season (14.5 per 1000 A-Es). Division I had the highest rates and Division III the lowest, regardless of season; however, not all differences were statistically significant.
| Table 1Game and Practice Injury Rates, 15 Sports, National Collegiate Athletic Association, 1988–1989 through 2003–2004 |
For practices (
), preseason practices accounted for the highest injury rate (6.6 per 1000 A-Es, 95% CI = 6.6, 6.7) across all divisions, whereas the postseason had the lowest practice injury rates (rates ranged from 1.1 per 1000 A-Es in Division III to 1.6 per 1000 A-Es in Division I). Within each Division and overall, preseason practice injury rates were 2.5 to 3 times higher than in-season practice rates and 4.6 to 5.5 times higher than postseason practice rates. As was the case with game rates, practice injury rates were highest in Division I and lowest in Division III, regardless of season.
Across all divisions and seasons, the rate of game injuries (13.8 per 1000 A-Es, 95% CI = 13.7, 13.9) was 3.5 times higher than the rate of practice injuries (4.0 per 1000 A-Es, 95% CI = 3.9, 4.0). These rates equate to 1 injury every 2 games and 1 injury every 5 practices for a team of 50 participants.
Significant variability exists across sports for the “intensity” of both game activities and, particularly, practice activities. Quantifying this variable is an important research opportunity that could aid future injury prevention research. In general, the higher “intensity” of game activity, in nonquantifiable terms, is most likely an important contributor to the higher injury rates in games compared with practices.
A variety of reasons may explain why injury rates are higher during the preseason than during other parts of the sport season. Some athletes may come to the preseason poorly conditioned, and, thus, the stress of the high-intensity, high-load preseason training may result in an excess of injuries. Also, any given preseason practice often lasts longer than an in-season or postseason practice. Because an ISS exposure has no time component, an individual is at a higher risk of injury in a longer practice because of the extended exposure to athletic activity. Future authors who use a finer level of exposure measurement, such as player-minutes, may be better able to discriminate among these possible seasonal differences in injury rates. However, it should be noted that this more detailed exposure measurement (player-minutes) may be extremely difficult or impractical to obtain given the time and effort it would take to gather these data. Preseason practice also often includes multiple practices on the same day; this scenario may limit recovery for subsequent activities and pose a higher injury risk to players. Preseason practices also may have more less-skilled or “walk-on” persons trying out for the sport; such individuals may be more susceptible to injury. Preseason is also a time when all players may be competing for starting positions, thus creating a highly competitive atmosphere, which may increase injury rates. Many of the listed seasonal factors may be modifiable, so the potential is great for developing injury prevention interventions to address the high rates of preseason injuries. Preseason competition injury rates were lower than in-season or postseason competition rates. This finding is likely due to the fact that preseason competitions in most sports may be more like scrimmages or practice games. Coaches may be using players in different combinations than during the regular season, and the intensity of play may be somewhat mitigated compared with regular-season competitions.
Injury prevention strategies, such as phased-in, multiple-day practices; modifying practice times to accommodate environmental conditions; mandating appropriate recovery time; and preparticipation medical examinations, should be developed and implemented to reduce preseason injury rates. In 2003, the NCAA created legislation to address heat illness and general injury in preseason football practices. This policy mandated a 5-day acclimatization period and other practice time limitations during the preseason training session.
3 Initial feedback from both coaches and players was generally favorable, although it is too early to quantify the effect on preseason heat or general injury rates. The American College of Sports Medicine has followed up on this NCAA policy with a 2004 expert panel roundtable, “Youth football: heat stress and injury risk,”
4 expanding the conversation to youth sports and setting the stage for discussions across multiple sports. Minimizing preseason injury rates in all sports through basic concepts of recovery and hydration, as well as through more innovative ideas, represents an important area in which certified athletic trainers can make a difference.
Time Trends in Game and Practice Injury Rates
shows time trends in game and practice injury rates from 1988–1989 to 2003–2004 for all the 15 sports combined. Time trends show that game injury rates varied somewhat from 1988–1989 through 1995–1996 and leveled out for the remaining years, while practice injury rates demonstrated a more stable course. No statistically significant increases or decreases in game (
P = .78) or practice (
P = .70) injury rates occurred over the 16-year sample period.
Although not statistically significant, visual trends indicate decreasing game injury rates over the 16 years, particularly in the last 2 academic years. This finding may be related to the modifications associated with NCAA policy and general sports medicine practice discussed in the “Introduction and Methods” article.
1 In particular, many of the specific NCAA rules modifications made over this time period were specifically focused on game situations (eg, clipping in football, hitting from behind in ice hockey). If such policies achieved some level of success in the applicable sport, the resulting injury trends may eventually be reflected in these data. It also is possible that the steady increase in the number of schools participating in the ISS over the sample period has contributed to a stabilization of game injury rates by effectively increasing the sample size over time.
Injury Mechanism
shows practice and game injury mechanisms for the 15 sports combined across years. For both practices and games, player contact accounted for the majority of injuries (58.0% in games, 41.6% in practices). In practices, noncontact injury mechanisms account for 36.8% of all injuries, compared with only 17.7% in games.
Player contact is a normal part of some sports, such as football, men's ice hockey, men's lacrosse, and wrestling. However, as noted earlier, although the percentages of player contact injuries may be somewhat similar between practices and games, the overall practice injury rate in these contact sports may be significantly lower because of the judicious use of player contact in practice. Sport rules and policies that promote safer forms of player contact can be instituted and enforced. For example, the no-spearing and no-clipping rules were instituted in an effort to reduce contact-related injury rates (specifically head and neck injuries and knee injuries) in football. The no-spearing rule was thought to be such an important part of the game that the
2006 NCAA Football Division I Manual
3 listed it in the opening “Points of Emphasis” section, as well as under the code of ethics for coaches. Protective equipment, such as face guards in men's ice hockey and protective devices for injured body parts, also can be effective in minimizing player and apparatus contact injuries. Athletic trainers continue to play a leading role in creating innovative protection for susceptible body parts that allow players to participate with a reduced risk of injury from a direct blow.
Sports that limit or restrict player contact, such as soccer, basketball, and women's ice hockey, still have a majority of their game injuries associated with player contact. A review of playing rules in these sports to determine the effectiveness of the noncontact emphasis seems warranted.
The high percentage of practice noncontact injuries primarily reflects muscle strains and joint sprains that, for the most part, cannot be effectively addressed by formal NCAA legislation. Most of these noncontact practice injuries would best be addressed by identification and modification of risk factors. Just by being present and observing practices, athletic trainers may be able to identify and remedy potential injury-causing situations (eg, wet floors, environmental conditions). Future researchers should investigate the circumstances and characteristics of these noncontact practice injuries in more detail to identify possible injury prevention initiatives.
Distribution of Injuries by Body Part
shows the distribution of injuries by body part for practice and games, for 15 sports, combined across years. The distribution of injuries by body part was similar for both practices and games. More than 50% of all reported injuries were to the lower extremity in both practices and games, with knee and ankle injuries accounting for most of the lower extremity injuries (data not shown). Injuries to the upper extremity accounted for 18.3% and 21.4% of game and practice injuries, respectively.
In terms of total burden in the athletic population, the preponderance of injuries to the lower extremity justifies particular emphasis in athletic training education and prevention efforts in this area. Although studies targeted to minimize injury to particular joints (ankles) or structures (ACLs) have merit, more attention should be directed to injury prevention research that is applicable to all types of lower extremity injuries. Identifying modifiable risk factors that are common to the majority of lower extremity injuries and targeting injury prevention interventions to the populations that have the greatest need (eg, highest incidence or prevalence, those who are disproportionately affected) should result in noticeable reductions in injury rates and, possibly, reductions in related medical costs over time. This approach also may be scientifically stronger, because it is extremely difficult and expensive (since very large sample sizes and long follow-up times are needed) to conduct randomized controlled trials of injury prevention interventions for conditions that are relatively rare (eg, noncontact ACL injuries). For example, much of the research on neuromuscular exercise training programs for ACL injury prevention may have applicability to other conditions, such as ankle ligament sprains,
5,
6 hamstring injuries,
7 and lower extremity injuries in general.
8–10 There is a critical need to train researchers in the appropriate methods and to increase funding for injury prevention research in the United States. The NCAA ISS is an ongoing, flexible, and standardized injury surveillance tool that can be a valuable resource for such studies.
Rates of Select Injuries (Ankle Ligament Sprains, Anterior Cruciate Ligament Injuries, and Concussions) by Sport
shows the frequency, distribution, and rates of select injuries (ankle ligament sprains, ACL injuries, and concussions), broken out by the 16 sports, combined across years. More than 27
000 ankle ligament sprains were reported over the 16 academic years, yielding an average of approximately 1700 per year. Assuming the sample represents approximately 15% of the total population of NCAA institutions, this equates to an annual average of more than 11
000 ankle sprains in these 15 activities. These injuries accounted for approximately one quarter of all injuries in men's and women's basketball and women's volleyball. However, spring football (1.34 per 1000 A-Es) and men's basketball (1.30 per 1000 A-Es) had the highest rates of ankle ligament sprains.
| Table 2Frequency, Distribution, and Rates of Select Injuries (Ankle Ligament Sprains, Anterior Cruciate Ligament Injuries, and Concussions) for Games and Practices Combined for 15 Sports, 1988–1989 to 2003–2004 |
Approximately 5000 ACL injuries were reported over the 16 years, an average of 313 per year in this sample. Assuming the sample represents approximately 15% of the total population, this equates to an annual average of more than 2000 ACL injuries in these 15 activities. Football had the highest number of reported ACL knee injuries (2159 in fall and 379 in spring, 53% of all recorded ACL injuries), but women's gymnastics had the highest rate (0.33 per 1000 A-Es), equal to the rate for spring football (0.33 per 1000 A-Es). Three of the 4 sports with the highest rates were women's sports (gymnastics, basketball, and soccer), and, along with spring football, all had significantly higher ACL injury rates than any other sport.
More than 9000 concussions were reported over the 16 years, an average of 563 per year in this sample. Assuming the sample represents approximately 15% of the total population, this equates to an annual average of about 3753 concussions in these 15 activities. Football had the highest number of reported concussions (fall and spring combined, n = 5016, 55% of all concussions recorded), but women's ice hockey had the highest rate (0.91 injuries per 1000 A-Es, 95% CI = 0.71, 1.11; significantly higher than for all other sports). However, we caution that the ISS has collected data from women's ice hockey for only 4 years, and therefore data must interpreted with caution. Women's soccer, traditionally a noncontact sport, also had a relatively high rate of concussions (0.41 per 1000 A-Es, 95% CI = 0.38, 0.44).
Time Trends in Injury Rates for Select Injuries
shows time trends in injury rates for select conditions (ankle ligament sprains, ACL knee injuries, and concussions), combined across the 15 sports and combined across years. Time trends in the rates of reported ankle ligament sprains across sports appear relatively stable, with a nonsignificant decrease (−0.1%,
P = .68) noted over 16 years. Rates of ACL injuries and concussions both demonstrated significant increases (ACL: 1.3% average annual increase,
P = .02; concussion: 7.0% average annual increase,
P < .01) over time. The rates of concussions doubled from 0.17 per 1000 A-Es in 1988–1989 to 0.34 per 1000 A-Es in 2003–2004. The observed upward trend in the concussion rate undoubtedly reflects improvements in the detection and management of concussion over the 16-year study period (especially in football) but may also represent some true increases in concussion rates over time.
Ligamentous injuries to the ankle are the most common injury occurring, regardless of sport or exposure type (game or practice), a fact supported in the literature.
11 In this sample, ankle ligament injuries represented 14.8% of all reported injuries (range = 3% [women's ice hockey] to 26% [men's basketball]). Marchi et al
12 reported in 1999 that 23% of ankle sprains in their study of moderate to severe sports injuries among children aged 6 to 15 years resulted in permanent sequelae over 12 years of follow-up. Although only 1 in 5 ISS ankle ligament injuries resulted in 10+ days of time loss (a marker of injury severity), if even a small proportion of these injuries result in long-term morbidity or disability, then they represent a large potential burden in the population.
Effective interventions exist that can reduce the incidence of ankle injury without critically impairing performance.
5,
13,
14 Prophylactic bracing or taping and neuromuscular/balance exercise programs can reduce the rate of lower extremity injuries by as much as 50%.
5 These interventions are particularly efficacious among athletes with a prior history of ankle injury. Specifically looking at the sport of volleyball, ankle sprain prevention programs have been proven efficacious and cost effective.
6,
15,
16 Because the majority of lower extremity sports injuries occur to the ankle, it is reasonable to think that these interventions, if broadly implemented, could reduce the incidence of ankle injury and/or reinjury. Despite this likelihood, no existing “best practice” or clinical practice guidelines direct the broad uptake of these interventions in the sports medicine community.
Overall, ACL injuries, regardless of mechanism, only accounted for approximately 3% of all injuries (range: 0.7% [women's ice hockey, men's baseball] to 5% [women's gymnastics, women's basketball]), but 88% of these injuries resulted in 10+ days of time loss. The rate of ACL injury increased 1.3% per year on average over the sample period. Evaluation of this injury trend over time also must include consideration of the significant changes in conditioning, bracing, and medical technology and diagnosis discussed earlier. The intense interest focused on ACL injuries—in particular, the noncontact ACL sex differences reported previously,
17,
18 which continue to be substantiated in this sample period—may have contributed to increased detection of these injuries. In conjunction with the increased clinical awareness of these injuries is the increased use and sensitivity of adjunct diagnostic tools such as arthrograms and magnetic resonance imaging. Although serious (as measured by time loss, pain, disability, and costs) in terms of both frequency and rates, ACL injuries are not “epidemic.” In fact, using the standard of <.05 as rare, the actual probability of ACL injury would be considered a rare event. For example, in 2003 Uhorchak et al
19 reported the probability of noncontact ACL injury during club and varsity sports at the US Military Academy to be 1 in 25
782 hours of exposure (probability, <.0001). The ACL injury rates in these NCAA data range from 0.02 to 0.33 per 1000 A-Es, depending upon the sport, which also indicates that ACL injuries are relatively rare. Contrast this with the ankle ligament sprain rates discussed above (range: 0.14 to 1.34 per 1000 A-Es); all but 4 sports (men's ice hockey, women's ice hockey, men's baseball, and women's softball) had ankle ligament sprain rates that were higher than that associated with the sports with the highest ACL injury rate (women's gymnastics and men's spring football). One interpretation of these data, as noted previously, is that injury prevention research should focus more on lower extremity injuries in general and not just on injuries to specific anatomical structures. This approach would require, however, that we establish risk factors that are common to all (or most) lower extremity injuries and develop interventions to address these factors.
Concussions represented 5% (women's volleyball) to 18% (women's ice hockey) of reported injuries, 14% of which restricted participation for 10 days or more (range: 2%). The rate of concussion increased significantly by 7% on average over the 16 years covered in this report, despite sport-specific efforts (eg, in ice hockey and men's lacrosse) to address the rising risk. This trend may reflect an actual increase in the numbers of concussions per unit of exposure, but it is also attributable, at least in part, to improvements in the identification of concussion (better awareness and diagnosis) in recent years. Even mild traumatic brain injuries may have long-term effects; therefore, it is critically important to identify potential prevention interventions for this injury. Promising areas of research include baseline neuropsychological testing for identification and helmet and mouthguard design for prevention. Collins et al
20 recently reported that newer models of football helmets (eg, the Riddell Revolution, Elyria, OH) may protect players from concussion. More research is needed in these areas, as well as in the area of injury biomechanics in ice hockey and lacrosse, to maximize the potential beneficial effect of concussion identification and prevention in all sports. Sex differences in the susceptibility to concussions in similar sports (such as soccer and basketball in this issue) may be another area for future research and prevention.
Game and Practice Injury Rates, by Sport
shows game and practice injury rates for 15 sports (fall and spring football are listed separately for practices; only fall football is listed for games) combined across years.
For games, football had the highest rate of injury in games (35.9 per 1000 A-Es), followed by wrestling (26.4 per 1000 A-Es). Baseball had the lowest game injury rate (5.8 per 1000 A-Es) among men's sports. Among women's sports, soccer (16.4 per 1000 A-Es) had the highest game injury rate (fourth highest overall) and women's softball the lowest (4.3 per 1000 A-Es).
For practices, spring football had the highest rate of practice injuries (9.6 per 1000 A-Es), followed by women's gymnastics (6.1 per 1000 A-Es), wrestling (5.7 per 1000 A-Es), and women's soccer (5.2 per 1000 A-Es). The sports with the lowest rates of practice injuries were men's ice hockey (2.0 per 1000 A-Es), women's ice hockey (2.5 per 1000 A-Es), and men's baseball (1.9 per 1000 A-Es).
In sports traditionally associated with player contact, such as football, men's ice hockey, men's lacrosse, and even wrestling, the dramatic difference in the practice injury rate versus the game injury rate may be a reflection of curtailed contact in practice activities. In particular, men's ice hockey has the same sharp skates, wooden sticks, and high-speed pucks flying around during both practices and games; however, the player contact is reduced, contributing to a practice injury rate (2.0 injuries per 1000 A-Es) more than 8 times lower than the game injury rate (16.3 injuries per 1000 A-Es). The sports that are not traditionally associated with significant player contact do not have such dramatic differences between practice and game injury rates (eg, women's volleyball, baseball, and softball). The limiting of player contact with teammates in practice may be an important modifiable factor that, along with the concept of effectively quantifying the intensity variables, as noted above, warrants more research. Two typically noncontact sports, women's soccer and women's gymnastics, had injury rates in the range reported for contact sports such as wrestling (practices) and men's ice hockey (games). These data indicate that identifying risk factors for injury and implementing injury prevention interventions should be a high priority in these activities.
The ISS data also provide a foundation for informed institutional decision making with regard to staffing activities. Although individual school injury rates are the optimal resource, these national data can allow a sports medicine professional to make decisions regarding where to place limited staff during simultaneous events based on the risk of injury, a basic foundation of the NATA guidelines discussed previously.
2 By virtue of its limited and defined practice period, spring football was the only “nontraditional season” activity monitored in this sample. However, the finding of a spring practice injury rate that is almost 3 times higher than the fall football practice injury rate raises concern about why student-athletes appear to be at significantly higher risk for injury in “nontraditional” activities compared with in-season activities. Future research and prevention efforts should be directed to out-of-season activities in all sports.
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