{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T04:41:12Z","timestamp":1773290472992,"version":"3.50.1"},"reference-count":43,"publisher":"American Academy of Pediatrics (AAP)","issue":"5","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2022,11,1]]},"abstract":"<jats:sec><jats:title\/><\/jats:sec><jats:sec><jats:title>BACKGROUND AND OBJECTIVES<\/jats:title><jats:p>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 &amp;lt; bags &amp;lt; control &amp;lt; thud &amp;lt; live.<\/jats:p><\/jats:sec><jats:sec><jats:title>METHODS<\/jats:title><jats:p>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.<\/jats:p><\/jats:sec><jats:sec><jats:title>RESULTS<\/jats:title><jats:p>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 &amp;lt; bags = control &amp;lt; thud = live). Live drills had higher cumulative head-impact frequency (45.4 \u00b1 53.0 hits) and magnitude (PLA: 766.3 \u00b1 932.9 g; PRA: 48.9 \u00b1 61.3 kilorad\/s2) per player than other levels (P &amp;lt; .0001). In comparison, air drills had the lowest cumulative frequency (4.2 \u00b1 6.9 hits) and magnitude (PLA: 68.0 \u00b1 121.6 g; PRA: 6.4 \u00b1 13.2 kilorad\/s2).<\/jats:p><\/jats:sec><jats:sec><jats:title>CONCLUSIONS<\/jats:title><jats:p>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.<\/jats:p><\/jats:sec>","DOI":"10.1542\/peds.2022-057725","type":"journal-article","created":{"date-parts":[[2022,10,13]],"date-time":"2022-10-13T08:14:41Z","timestamp":1665648881000},"source":"Crossref","is-referenced-by-count":10,"title":["Drill Intensity and Head Impact Exposure in Adolescent Football"],"prefix":"10.1542","volume":"150","author":[{"given":"Kyle A.","family":"Kercher","sequence":"first","affiliation":[{"name":"aDepartments of Kinesiology"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jesse A.","family":"Steinfeldt","sequence":"additional","affiliation":[{"name":"cDepartment of Counseling and Educational Psychology, School of Education"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jonathan T.","family":"Macy","sequence":"additional","affiliation":[{"name":"bApplied Health Science, School of Public Health-Bloomington"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dong-Chul","family":"Seo","sequence":"additional","affiliation":[{"name":"bApplied Health Science, School of Public Health-Bloomington"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Keisuke","family":"Kawata","sequence":"additional","affiliation":[{"name":"aDepartments of Kinesiology"},{"name":"dProgram in Neuroscience, College of Arts and Sciences, Indiana University, Bloomington, Indiana"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"417","published-online":{"date-parts":[[2022,10,13]]},"reference":[{"key":"2023110816594040600_B1","unstructured":"National Federation of State High School Associations . 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