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Multicenter Study
. 2022 Nov 1;150(5):e2022057725.
doi: 10.1542/peds.2022-057725.

Drill Intensity and Head Impact Exposure in Adolescent Football

Kyle A Kercher  1 , Jesse A Steinfeldt  2 , Jonathan T Macy  3 , Dong-Chul Seo  3 , Keisuke Kawata  1   4
Affiliations
Multicenter Study

Drill Intensity and Head Impact Exposure in Adolescent Football

Kyle A Kercher et al. Pediatrics. .

Abstract

Background and objectives: The objective of this study was to examine head-impact exposure by intensity level and position group, and to test the hypothesis that there would be an increase in cumulative head-impact exposure between drill intensities after controlling for duration in each level with air recording the lowest frequency and magnitude and live recording the highest: air < bags < control < thud < live.

Methods: We conducted a prospective, multisite study in 1 season with players from 3 high school football teams (n = 74). Each player wore a sensor-installed mouthguard, which monitored head-impact frequency, peak linear acceleration (PLA), and peak rotational acceleration (PRA). Practice drills and games were categorized by level of contact.

Results: A total of 7312 impacts were recorded with a median of 67 (interquartile range:128) impacts per player. After controlling for duration, increases in head-impact outcomes by level of contact were observed (air < bags = control < thud = live). Live drills had higher cumulative head-impact frequency (45.4 ± 53.0 hits) and magnitude (PLA: 766.3 ± 932.9 g; PRA: 48.9 ± 61.3 kilorad/s2) per player than other levels (P < .0001). In comparison, air drills had the lowest cumulative frequency (4.2 ± 6.9 hits) and magnitude (PLA: 68.0 ± 121.6 g; PRA: 6.4 ± 13.2 kilorad/s2).

Conclusions: These data support the levels-of-contact system as a practical approach to limiting head-impact exposure in tackle football. Our findings are clinically important, because data have begun to suggest the relationship between chronic head-impact exposure and decline in brain health. Since head-impact exposure was influenced by levels of contact, regulation of the duration of certain drill intensities (eg, thud, live) may associate with reduced head-impact exposure in high school football.

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Conflict of interest statement

CONFLICT OF INTEREST DISCLAIMER: The authors have indicated they have no conflicts of interest relevant to this article to disclose.

Figures

FIGURE 1
FIGURE 1
Cumulative head-impact kinematics between levels of contact. Cumulative (A) head impact count, (B) PLA, and (C) PRA per player were influenced by the level of contact in an incremental manner, with air being the lowest and live being the highest. Data are presented as mean ± SD.
FIGURE 2
FIGURE 2
Cumulative head-impact kinematics between levels of contact after controlling for duration in each level. Cumulative (A) head-impact count, (B) PLA, and (C) PRA per player were influenced by the level of contact. Data are presented as mean ± SD.
FIGURE 3
FIGURE 3
Group-dependent cumulative head-impact exposure between levels of contact. All 3 groups shared a similar incrementally increasing pattern in cumulative head-impact kinematic outcomes per player, with air being the lowest and live being the highest. Data are presented as mean ± SD.
FIGURE 4
FIGURE 4
Average head impact magnitude per impact between levels of contact and group. Average PLA per head impact (A) was influenced by the level of contact (P < .001), whereas average PRA per head impact (B) was not (P = .219) across levels of contact and position groups. Data are presented as mean ± SD.
FIGURE 5
FIGURE 5
Frequency of head impacts within various magnitude ranges. A total number of head impacts was categorized into PLA (A) 10 to 20 g, (B) 20 to 60 g, and (C) >60 g. The incrementally increasing pattern of greater head-impact exposure was observed in (A) and (B).
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References

    1. National Federation of State High School Associations. Participation in high school sports registers first decline in 30 years. Available at: https://www.nfhs.org/articles/participation-in-high-school-sports-regist.... Accessed March 1, 2021
    1. Veliz P, Eckner JT, Zdroik J, Schulenberg JE. Lifetime prevalence of self-reported concussion among adolescents involved in competitive sports: a national U.S. study. J Adolesc Health. 2019;64(2):272–275 - PMC - PubMed
    1. Sarmiento K, Hoffman R, Dmitrovsky Z, Lee R. A 10-year review of the Centers for Disease Control and Prevention’s Heads Up initiatives: bringing concussion awareness to the forefront. J Safety Res. 2014;50:143–147 - PMC - PubMed
    1. McCrory P, Meeuwisse W, Dvořák J, et al. Consensus statement on concussion in sport-the 5th international conference on concussion in sport held in Berlin, October 2016. Br J Sports Med. 2017;51(11):838–847 - PubMed
    1. Bahrami N, Sharma D, Rosenthal S, et al. Subconcussive head impact exposure and white matter tract changes over a single season of youth football. Radiology. 2016;281(3):919–926 - PMC - PubMed

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