Athletic Injury Monitoring System

College Football – 1998

The following are preliminary observations based on the AIMS national college football injury data summary from the 1998 season. This prospective epidemiological study used a stratified sample (based on size of program and geographic region) of 33 college and university football teams, comprising a representative proportional sample of approximately five percent of football-playing institutions. These are preliminary observations based on the accompanying raw data summary.

The following observations can be made based on these data:

• There were 3,176 players on the 33 teams in the sample (average squad size = 96.2). Taking into account recurring injuries from this season and those who were injured more than once, approximately 1,007 individuals (31.7%) had at least one time-loss injury during the season.

• With 1,426 recorded injuries that kept a player out for one day or more, there were 44.9 injuries/100 players per season.

• There were 241,349 athlete-exposures recorded (one athlete-exposure is one player taking part in one game or practice where he is exposed to the possibility of being injured), with 222,011 athlete-exposures (92.0%) in practices and 19,338 athlete-exposures (8.0%) in games.

• While injuries in practices accounted for 54.8% of all recorded injuries, and 45.2% of the injuries occurred in games, the injury rate in games (JV and varsity combined) was 9.5 times as high in practices. In other words, an individual participating in a game is 9.5 times more likely to be injured during the game than while participating in practice.

• Each injury kept a player out for an average of slightly less than two weeks (13.4 days). This figure may be somewhat skewed by our practice of recording the number of days for a season-ending injury as a ‘99’ in the computer file. However, if it can be assumed that 14 weeks is a reasonable average for a season-ending injury, then this figure probably is not too far off. There were a total of 103 season-ending injuries recorded, or 7.2% of all injuries. In this case a better statistic to use is the median, which is 5 days per injury.

• While similar football injury data collection by the investigator during previous seasons has shown a consistently higher injury rate on artificial turf compared with natural grass, the total injury rate on artificial turf continued the downward trend toward matching the lower injury rate on natural grass surfaces, this year being essentially equal at the collegiate level of play. However, the injury rate during games, based on the amount of exposure for each type of surface, remained 10% higher for time-loss injuries on artificial turf compared with natural grass. Our working hypothesis has been that the age, and possibly the brand, of artificial turf has an impact on injury rates, with the newer turfs having better injury characteristics than older, worn turf. Detailed analyses of injury rates on various brands and ages of artificial turf are continuing.

• This year the injury rate on rushing plays was essentially the same as the rate on passing plays (1.90 and 1.99 per 1,000 athlete-exposures, respectively).

• As would be expected, most injuries occurred during blocking and tackling.

• Impact from another player’s hard-shell helmet caused a minimum of 13.8% of the recorded injuries. Impact from another player’s shoulder pads was a direct cause of a minimum of 7.9% of the recorded injuries.

• Injuries to offensive players accounted for 49.4% of the recorded injuries, 43.6% were to defensive players, and kickers and special teams accounted for the remaining 7.0% of the injuries.

• Taking into account the number of players on the field in the various positions (e.g., two offensive tackles, four defensive down linemen, three linebackers, etc.), the highest injury rates on the offensive side of the line appear to have occurred in flankers/wide receivers (0.54/1,000 A-E) and running backs (0.38/1,000 A-E). On the defense, all position categories had nearly the same injury rate: down linemen (0.24), backs (0.24), linebackers (0.24), and safeties (0.21/1,000 A-E).

• As expected, the body parts most frequently injured were knees and ankles, with sprains and strains the most common types of injuries. Of continuing concern is the fact that cerebral concussions are the fourth most common type of injury, following ligament sprains, muscle strains, and contusions. Exploring this data further shows that head concussions are the third most frequent injury in college football, following ankle sprains and knee ligament sprains and tears.

• A total of 7.6% of the injuries resulted in surgery.

• As has been the case during seven seasons of data collection now, the number of knee injuries to players wearing preventive knee braces was significantly higher than would be expected. These data do not indicate that the braces are reducing the number of knee injuries, since if that were the case we would expect to see significantly fewer knee injuries in braced players based on the proportion wearing braces. These results hold even when considering only MCL injuries. Analyses of these knee brace data are continuing. (A detailed analysis of this issue, based on previously collected AIMS data, appears in Sports Training, Medicine and Rehabilitation 1:287-296 (1990) and in Safety in American Football E.F. Hoerner (ed.) Philadelphia: American Society for Testing and Materials (in press).)