Athletic Injury Monitoring System
College Football – 1997
The following are preliminary observations based on the AIMS national
college football injury data summary from the 1997 season. This prospective
epidemiological study used a stratified sample (based on size of program and
geographic region) of 46 college and university football teams, comprising a
representative proportional sample of approximately seven 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 4,471 players on
the 46 teams in the sample (average squad size = 97.2). Taking into
account recurring injuries from this season and those who were injured
more than once, approximately 1,360 individuals (30.4%) had at least one
time-loss injury during the season.
- With 1,863 recorded injuries
that kept a player out for one day or more, there were 41.7 injuries/100
players per season.
- There were 315,137
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 289,440 athlete-exposures (91.8%) in practices and 25,697
athlete-exposures (8.2%) in games.
- While injuries in practices
accounted for 59.5% of all recorded injuries, and 40.5% of the injuries
occurred in games, the injury rate in games (JV and varsity
combined) was 7.7 times as high in practices. In other words, an
individual participating in a game is 7.7 times as
likely to be injured during the game than he is while participating
- Each injury kept a player out
for an average of slightly less than two weeks (12.5 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 114 season-ending injuries recorded, or 6.2% of all injuries. In this
case a better statistic to use is the median, which is 4 days per injury.
- As was the case during
similar football injury data collection the investigator did during the
1986-90 seasons, the total injury rate on artificial turf was higher (by
nearly 20%) than on natural grass, although the general trend has been a
narrowing of this difference over the years. Our working hypothesis has
been that the age, and possibly the brand, of artificial turf has an
impact on injury rates, with the newer generation of turfs having better
injury characteristics than older, worn turf. Detailed analyses of injury
rates on various brands and ages of artificial turf are continuing.
- The injury rate on rushing
plays was about three-fourths the rate on passing plays (1.65 and 2.29 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 13.1% of the recorded injuries.
Impact from another player’s shoulder pads was a direct cause of a minimum
of 7.3% of the recorded injuries.
- Injuries to offensive players
accounted for 49.3% of the recorded injuries, 44.8 % were to defensive
players, and kickers and special teams accounted for the remaining 5.9% of
- 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 (0.63/1,000 A-E) and running backs
(0.37/1,000 A-E). On the defense, down linemen (0.24), backs (0.26) and
linebackers (0.28) had nearly the same injury rate. Safeties maintained a
rate of 0.17/1,000 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 injury. This is higher
than the fifth most common injury that concussions were ranked during the
- A total of 6.1% of the
injuries resulted in surgery.
- As was the case during the
1986-90 seasons, 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).)
Eric D. Zemper,