Exposure to head impacts in youth football practice drills

September 12, 2017

Researchers at Wake Forest Baptist Medical Center examined differences in the number, location, and magnitude of head impacts sustained by young athletes during various youth football practice drills. Such information could lead to recommendations for football practices, including modification of some high-intensity drills in order to reduce players' exposure to head impacts and, consequently, lessen the risks of injury. Detailed information on the findings of this study can be found in the article, "Head impact exposure measured in a single youth football team during practice drills," by Mireille E. Kelley, MS (a graduate student in Biomedical Engineering at Wake Forest Baptist), et al., published today in the Journal of Neurosurgery: Pediatrics.

Much has been written about concussions sustained by youths engaged in . However, other less severe impacts are frequently experienced by young athletes throughout the football season. And, important to note, studies have shown that far more head impacts occur during football practice drills than during games.

Kelley and her colleagues collected biomechanical data and videos to evaluate the number, location, and magnitude of head impacts sustained by nine youths during football practice drills. All youths were members of the same team and were on average about 11 years of age. Inside each athlete's helmet was a Head Impact Telemetry (HIT) System, which measures head acceleration. This apparatus was worn for all football practices over an entire season of play, including preseason, regular season, and playoff practice drills. Every time the HIT System recorded a head impact greater than 10g, data collection was triggered and biomechanical data were transmitted to a sideline base unit for later analysis. Videos were recorded to ensure that helmets were worn at the time of impact and to pair videos of the drills with associated biomechanical data collected by the HIT System.

There were eleven types of practice drills: dummy/sled tackling, install, special teams, multiplayer tackle, Oklahoma, one-on-one, open-field tackling, passing, position skill work, scrimmage, and tackling drill stations. The authors provide descriptions and purposes of these drills in Table 1 in the paper (see attached).

The authors report that a total of 2,125 head impacts occurred while the nine young athletes participated in a total of 30 contact practices. The authors provide a summary of head impact exposure (HIE) data broken down by the eleven types of practice drills in Table 2 in their paper (see attached). The frequency of impacts was assessed by compiling the number of impacts per minute per player for each drill. The magnitudes of these impacts were determined on the basis of linear (g's) and rotational (radians per square second) head acceleration measured by the HIT System, which the authors report as means and 50th and 95th percentiles.

Kelley et al. used biomechanical data and videos not only to identify the number, magnitude, and location of head impacts, but also to interpret possible contributors to variations in these factors among different practice drills. A few interesting findings are listed below.

Head impacts occurred most frequently during contact drills involving multiple players, and higher-magnitude head impacts took place during tackling drills. Not all drills were practiced in each session. Open field tackling, for example, was only practiced in five of the 30 practice sessions. Although this drill was associated with relatively few head impacts (compared with other drills), the impacts tended to be of high magnitude. The authors point out that the high magnitude of head impacts associated with open field tackling is most likely caused by the fact that athletes build up speed as they move toward each other across distances greater than 3 yards. In one-on-one tackling, on the other hand, youth athletes cover less ground before reaching each other. The authors suggest that this may have contributed to the fact that the magnitude of head impacts for one-on-one tackling was lower than those for open field tackling.

The multiplayer tackle drill was associated with the highest rate of head impacts, but these impacts were relatively low-magnitude ones (compared with impacts in other tackling drills). The authors suggest that this may be due to the emphasis on blocking rather than tackling during this drill.

With the exception of the dummy/sled tackling drill, the most common location of impact was the front of the football helmet. However, when high-magnitude impacts (60g or greater) were evaluated, in some drills—namely, open-field tackling, Oklahoma, one-on-one, and position skill work—the most common impact location was the top of the helmet, which the authors suggest may represent improper tackling technique.

Thorough examination of variations among practice drills with respect to the number of head impacts, their magnitude, and the location on the head where they occur provides researchers with information on what drills are more likely to increase risks of injury. This provides valuable information to health professionals, coaches, and league officials for determining whether particular drills should be modified or eliminated from practice sessions.

The authors point out that this study is small—limited to only nine players of similar age in a single football team. The authors suggest that further studies should be conducted in larger numbers of players from different age groups to evaluate additional variations in biomechanical data across practice drills and assess risks of practice-related head injury.

In describing the study, lead investigator Jillian E. Urban, Ph.D. Assistant Professor of Biomedical Engineering at Wake Forest Baptist, said, "This study, along with future research, will help inform relevant evidence-based recommendations for youth football leagues to reduce head exposure and ultimately improve the safety of sport for our ."

Explore further: Head impact exposure increases as youth football players get older, bigger

More information: Journal of Neurosurgery: Pediatrics (2017). DOI: 10.3171/2017.5.PEDS16627

Related Stories

Head impact exposure increases as youth football players get older, bigger

June 21, 2017
Youth football players are exposed to more and more forceful head impacts as they move up in age- and weight-based levels of play, according to researchers at Wake Forest Baptist Medical Center.

Some youth football drills riskier than others

August 23, 2016
Nearly three quarters of the football players in the U.S. are less than 14 years old. But amid growing concern about concussion risk in football, the majority of the head-impact research has focused on college and professional ...

Study shows helmetless-tackling drills significantly reduce head impact

December 22, 2015
The national debate around football-related head impacts, and their relationship to concussions and spinal injuries, continues to raise concern in the United States. Sparked by efforts to help make the sport safer for players, ...

Study finds youth football players have significant differences in head impact exposure

June 7, 2017
A study of 97 youth football players ages 9-13 years who participated in different age- and weight- based levels over four seasons of play found that that youngsters experienced a total of 40,538 head impacts. Measures of ...

Head hits can be reduced in youth football

July 29, 2013
Less contact during practice could mean a lot less exposure to head injuries for young football players, according to researchers at Wake Forest Baptist Medical Center and Virginia Tech.

Scientists develop new way to measure cumulative effect of head hits in football

July 18, 2013
Scientists at Wake Forest Baptist Medical Center have developed a new way to measure the cumulative effect of impacts to the head incurred by football players.

Recommended for you

Molecules in spit may be able to diagnose and predict length of concussions

November 20, 2017
Diagnosing a concussion can sometimes be a guessing game, but clues taken from small molecules in saliva may be able to help diagnose and predict the duration of concussions in children, according to Penn State College of ...

Breastfed babies are less likely to have eczema as teenagers, study shows

November 13, 2017
Babies whose mothers had received support to breastfeed exclusively for a sustained period from birth have a 54% lower risk of eczema at the age of 16, a new study led by researchers from King's College London, Harvard University, ...

Obesity during pregnancy may lead directly to fetal overgrowth, study suggests

November 13, 2017
Obesity during pregnancy—independent of its health consequences such as diabetes—may account for the higher risk of giving birth to an atypically large infant, according to researchers at the National Institutes of Health. ...

Working to reduce brain injury in newborns

November 10, 2017
Research-clinicians at Children's National Health System led the first study to identify a promising treatment to reduce or prevent brain injury in newborns who have suffered hypoxia-ischemia, a serious complication in which ...

Why do some kids die under dental anesthesia?

November 9, 2017
Anesthesiologists call for more research into child deaths caused by dental anesthesia in an article published online by the journal Pediatrics.

Probability calculations—even babies can master it

November 3, 2017
One important feature of the brain is its ability to make generalisations based on sparse data. By learning regularities in our environment it can manage to guide our actions. As adults, we have therefore a vague understanding ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

shortwave02001
not rated yet Sep 13, 2017
It is the way they train. the practice has on long repetitions of repeated heading practice this needs to be reduced

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.