Injuries in a Japanese Division I Collegiate American Football Team: A 3-Season Prospective Study

Context:

Previous research on American football injuries in Japan has focused on incidence proportion in terms of the number of injuries divided by the number of players. This is the first study to examine injury rates over several seasons.

Objective:

To conduct a prospective study of injuries in a Japanese Division I collegiate American football team over the 2007 through 2009 seasons.

Design:

Cohort study.

Setting:

Collegiate football team at Doshisha University, Kyoto, Japan.

Patients or Other Participants:

All 289 athletes who played on the collegiate Division I football team during the 2007 through 2009 seasons.

Main Outcome Measure(s):

A certified athletic trainer kept a daily record of all practice and game injuries. Injury rates were calculated according to season, injury type, body part, severity, and mechanism. Injuries were also analyzed according to position of player, school year, and playing experience.

Results:

The game injury rate (GIR; 32.7 injuries/1000 athlete-exposures) was higher than the practice injury rate (PIR; 10.9 injuries/1000 athlete-exposures) over the 3 seasons (P < .05). The PIR was higher among Japanese players than the comparable United States collegiate football injury rates (5.8–7.0 injuries/1000 athlete-exposures). Ankle and foot injuries occurred more frequently during games, whereas thigh and gluteal injuries occurred more frequently during practices.

Conclusions:

Our data show differences between games and practices in terms of injury rates, body parts injured, and positions of players injured. The high PIR in Japan may be due to the increased contact during practices and length of practices compared with the United States. Further research involving multiple teams is recommended to validate the trends noted in this study. The expanded data set could assist in the development of safety regulations and preventive interventions for Japanese football.Key Words: Japanese football, American football, college football, injury rates

Key Points

• The practice injury rate for Japanese collegiate football players was higher than in the United States. This may be explained by the increased contact during practice and unregulated practice length in Japan.
• Ankle and foot injuries occurred more often during games, whereas thigh and gluteal injuries were more frequent during practices.

American football is 1 of the most popular sports in the United States, played by more than 60 000 college-level male athletes in 2008 and more than 1 million high school male athletes in 2009.^1,2 Football has a high injury risk,³ and as the number of players has grown, so has the number of injuries experienced.⁴ Previous researchers^3,5–13 have examined football injuries in a variety of conferences, divisions, and schools. Football had the highest number of reported injuries among the 5 fall collegiate sports.³ The National Collegiate Athletic Association (NCAA) reported 266 943 injuries during the 2004–2005 through 2008–2009 seasons. Hootman et al¹⁴ noted that football had the highest number of serious sport-related injuries (eg, anterior cruciate ligament injury, concussion) among the 15 collegiate sports. Ramirez et al¹³ found that the estimated cost per football injury increased by approximately 20% from 1977 to 1986. Injured athletes may also experience psychological trauma such as fear of reinjury or surgery.¹⁵ The NCAA has implemented measures to reduce injury risk. In 1998, limits were placed on the number of practices and the number of contacts allowed during spring football practices in an attempt to reduce the injury rate, which was twice as high during spring football practices as during fall practices.⁵Data released in 2008 by the Japanese Football Association¹⁶ indicated that approximately 20 000 football players participated on 402 teams, including 11 junior high school teams, 112 high school teams, 218 university teams, and 61 adult club teams. Despite the relatively large number of players, research regarding football injuries in Japan is limited.^17–21 Moreover, unlike in the United States, no evidence-based rule changes have been implemented to try to reduce injuries in Japanese football.Previous Japanese studies have focused on incidence proportion, calculated as the number of injuries divided by the number of players. Although incidence proportion can directly measure the risk of injury, which is useful information for the general public, this value is rarely used in the sport-injury literature and is difficult to compare among different sports.²² Injury rate is easier to compare among different sports and permits comparisons within the sport, both nationally and internationally.Only 1 Japanese study²⁰ has examined injury rates according to athlete-exposures (AEs). However, that study was conducted during a single season, and no studies have followed a team over several seasons. In comparison, research in the United States has examined injury rates based on multiple-year records.^{5,7,10,11,13,14} We aimed to examine practice and game injury rates according to season, injury type, body part, severity, and mechanism in a Japanese Division I collegiate football team over 3 consecutive seasons. Injuries were also analyzed according to position of player, school year, and playing experience.