Video Analysis Verification of Head Impact Events Measured by Wearable Sensors

Background: Wearable sensors are increasingly used to quantify the frequency and magnitude of head impact events in multiple sports. There is a paucity of evidence that verifies head impact events recorded by wearable sensors. Purpose: To utilize video analysis to verify head impact events recorded by wearable sensors and describe the respective frequency and magnitude. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Thirty male (mean age, 16.6 ± 1.2 years; mean height, 1.77 ± 0.06 m; mean weight, 73.4 ± 12.2 kg) and 35 female (mean age, 16.2 ± 1.3 years; mean height, 1.66 ± 0.05 m; mean weight, 61.2 ± 6.4 kg) players volunteered to participate in this study during the 2014 and 2015 lacrosse seasons. Participants were instrumented with GForceTracker (GFT; boys) and X-Patch sensors (girls). Simultaneous game video was recorded by a trained videographer using a single camera located at the highest midfield location. One-third of the field was framed and panned to follow the ball during games. Videographic and accelerometer data were time synchronized. Head impact counts were compared with video recordings and were deemed valid if (1) the linear acceleration was ≥20 g, (2) the player was identified on the field, (3) the player was in camera view, and (4) the head impact mechanism could be clearly identified. Descriptive statistics of peak linear acceleration (PLA) and peak rotational velocity (PRV) for all verified head impacts ≥20 g were calculated. Results: For the boys, a total recorded 1063 impacts (2014: n = 545; 2015: n = 518) were logged by the GFT between game start and end times (mean PLA, 46 ± 31 g; mean PRV, 1093 ± 661 deg/s) during 368 player-games. Of these impacts, 690 were verified via video analysis (65%; mean PLA, 48 ± 34 g; mean PRV, 1242 ± 617 deg/s). The X-Patch sensors, worn by the girls, recorded a total 180 impacts during the course of the games, and 58 (2014: n = 33; 2015: n = 25) were verified via video analysis (32%; mean PLA, 39 ± 21 g; mean PRV, 1664 ± 619 rad/s). Conclusion: The current data indicate that existing wearable sensor technologies may substantially overestimate head impact events. Further, while the wearable sensors always estimated a head impact location, only 48% of the impacts were a result of direct contact to the head as characterized on video. Using wearable sensors and video to verify head impacts may decrease the inclusion of false-positive impacts during game activity in the analysis.

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Game-Related Impacts in High School Boys’ Lacrosse

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967119835587 ◽

2019 ◽

Vol 7 (4) ◽

pp. 232596711983558 ◽

Cited By ~ 2

Author(s):

Shane V. Caswell ◽

Patricia Kelshaw ◽

Andrew E. Lincoln ◽

Lisa Hepburn ◽

Reginald Dunn ◽

...

Keyword(s):

High School ◽

Rotational Velocity ◽

Linear Acceleration ◽

The United States ◽

Head Impact ◽

Level Of Evidence ◽

Cross Sectional ◽

Head Impacts ◽

Direct Head ◽

The Impact

Background: The rate of concussions in boys’ lacrosse is reported to be the third highest among high school sports in the United States, but no studies have described game-related impacts among boys’ lacrosse players. Purpose: To characterize verified game-related impacts, both overall and those directly to the head, in boys’ varsity high school lacrosse. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 77 male participants (mean age, 16.6 ± 1.2 years; mean height, 1.77 ± 0.05 m; mean weight, 73.4 ± 12.2 kg) were instrumented with sensors and were videotaped during 39 games. All verified game-related impacts ≥20 g were summarized in terms of frequency, peak linear acceleration (PLA), and peak rotational velocity (PRV). Descriptive statistics and impact rates per player-game (PG) with corresponding 95% CIs were calculated. Results: Overall, 1100 verified game-related impacts were recorded (PLA: median, 33.5 g [interquartile range (IQR), 25.7-51.2]; PRV: median, 1135.5 deg/s [IQR, 790.0-1613.8]) during 795 PGs. The rate for all verified game-related impacts was 1.38 impacts per PG (95% CI, 1.30-1.47). Of these, 680 (61.8%) impacts (PLA: median, 35.9 g [IQR, 26.7-55.5]; PRV: 1170.5 deg/s [IQR, 803.2-1672.8]) were directly to the head (impact rate, 0.86 impacts/PG [95% CI, 0.79-0.92]). Overall, midfielders (n = 514; 46.7%) sustained the most impacts, followed by attackers (n = 332; 30.2%), defenders (n = 233; 21.2%), and goalies (n = 21; 1.9%). The most common mechanisms for overall impacts and direct head impacts were contact with player (overall: n = 706 [64.2%]; head: n = 397 [58.4%]) and stick (overall: n = 303 [27.5%]; head: n = 239 [35.1%]), followed by ground (overall: n = 73 [6.6%]; head: n = 26 [3.8%]) and ball (overall: n = 15 [1.4%]; head: n = 15 [2.2%]). Direct head impacts were associated with a helmet-to-helmet collision 31.2% of the time, and they were frequently (53.7%) sustained by the players delivering the impact. Nearly half (48.8%) of players delivering contact used their helmets to initiate contact that resulted in a helmet-to-helmet impact. Players receiving a head impact from player contact were most often unprepared (75.9%) for the collision. Conclusion: The helmet is commonly used to initiate contact in boys’ high school lacrosse, often targeting defenseless opponents. Interventions to reduce head impacts should address rules and coaching messages to discourage intentional use of the helmet and encourage protection of defenseless opponents.

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Head Kinematics by Contact Scenarios in Youth Ice Hockey

Neurology ◽

10.1212/wnl.0000000000011045 ◽

2020 ◽

Vol 95 (20 Supplement 1) ◽

pp. S1.1-S1

Author(s):

Abigail Swenson ◽

Logan Miller ◽

Jillian Urban ◽

Joel Stitzel

Keyword(s):

Rotational Velocity ◽

Angular Acceleration ◽

Linear Acceleration ◽

Head Impact ◽

Ice Hockey ◽

Contact Sports ◽

Head Impacts ◽

Rigorous Study ◽

Improving Accuracy ◽

Impact Events

ObjectiveThe objective of this pilot study was to characterize head impact exposure in a sample of youth boys' ice hockey using a novel instrumented mouthpiece, improving accuracy.BackgroundFrom 2010 to 2018 youth ice hockey saw a 15% increase in participation, despite growing concerns for concussion risk in contact sports. While contact sports with similar rates of concussion have been subjected to rigorous study, head impact exposure in youth ice hockey has been largely underexplored. Existing youth studies have utilized helmet-mounted sensors, which are associated with error due to poor coupling with the skull.Design/MethodsCustom mouthpieces containing a tri-axial accelerometer and gyroscope were fit to seven enrolled athletes, and monitored during practices and games throughout the season. Linear acceleration and rotational velocity of the head were recorded for 60 ms when 5 g was exceeded on any axis for at least 3 ms. Time-synchronized film was reviewed to identify the contact scenario and head contact. Summary statistics of kinematics were calculated by scenario and presence of head contact.ResultsA total of 465 events were recorded over 25 weeks. Of these events 25% involved head contact; 92% of all contact scenarios were board checks, falls, or ice checks. Events involving head contact (i.e., head impacts) had median [95th percentile] peak linear acceleration, rotational velocity, and angular acceleration of 8.1 [30.9] g, 7.9 [20.2] rad/s, and 614 [2673] rad/s2, respectively. Events not involving head contact had median [95th percentile] peak linear acceleration, rotational velocity, and angular acceleration of 6.6 [43.8] g, 6.5 [17.5] rad/s, and 455 [4115] rad/s2, respectively.ConclusionsThe majority of the recorded events could be classified as board checks, falls, or ice checks. Median peak kinematics were higher for head impacts than non-head impact events. In contrast, 95th percentile linear and angular accelerations were greater for impacts not involving head contact.

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Biomechanical head impact characteristics during sparring practice sessions in high school taekwondo athletes

Journal of Neurosurgery Pediatrics ◽

10.3171/2017.1.peds16432 ◽

2017 ◽

Vol 19 (6) ◽

pp. 662-667 ◽

Cited By ~ 3

Author(s):

David M. O'Sullivan ◽

Gabriel P. Fife

Keyword(s):

High School ◽

Rotational Velocity ◽

Linear Acceleration ◽

Head Impact ◽

Rotational Acceleration ◽

Head Impacts ◽

Head Injury Criterion ◽

Impact Location ◽

Male High School ◽

Impact Characteristics

OBJECTIVEThe purpose of this study was to monitor head impact magnitude and characteristics, such as impact location and frequency, at high school taekwondo sparring sessions.METHODSEight male high school taekwondo athletes participated in this study. The head impact characteristics were recorded by X-Patch, a wireless accelerometer and gyroscope, during 6 taekwondo sparring sessions. The outcome measures were the peak linear acceleration (g = 9.81 msec2), peak rotational acceleration, rotational velocity, and Head Injury Criterion.RESULTSA total of 689 impacts occurred over 6 sessions involving the 8 athletes. There was an average of 24 impacts per 100 minutes, and there were significant differences in the frequency of impacts among both the sessions and individual athletes. In order of frequency, the most commonly hit locations were the side (38.2%), back (35.7%), and front (23.8%) of the head.CONCLUSIONSThe data indicate that there is a relatively high number of head impacts experienced by taekwondo athletes during sparring practice. According to the rotational acceleration predicting impact severity published in previous research, 17.1% of the impacts were deemed to be a moderate and 15.5% were deemed to be severe.

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Video Confirmation of Head Impact Sensor Data From High School Soccer Players

The American Journal of Sports Medicine ◽

10.1177/0363546520906406 ◽

2020 ◽

Vol 48 (5) ◽

pp. 1246-1253 ◽

Cited By ~ 5

Author(s):

Declan A. Patton ◽

Colin M. Huber ◽

Catherine C. McDonald ◽

Susan S. Margulies ◽

Christina L. Master ◽

...

Keyword(s):

High School ◽

Video Analysis ◽

Female Athletes ◽

Head Impact ◽

Field Of View ◽

Sensor Data ◽

Lower Percentage ◽

Level Of Evidence ◽

Filtering Algorithms ◽

Impact Events

Background: Recent advances in technology have enabled the development of head impact sensors, which provide a unique opportunity for sports medicine researchers to study head kinematics in contact sports. Studies have suggested that video or observer confirmation of head impact sensor data is required to remove false positives. In addition, manufacturer filtering algorithms may be ineffective in identifying true positives and removing true negatives. Purpose: To (1) identify the percentage of video-confirmed events recorded by headband-mounted sensors in high school soccer through video analysis, overall and by sex; (2) compare video-confirmed events with the classification by the manufacturer filtering algorithms; and (3) quantify and compare the kinematics of true- and false-positive events. Study Design: Cohort study; Level of evidence, 2. Methods: Adolescent female and male soccer teams were instrumented with headband-mounted impact sensors (SIM-G; Triax Technologies) during games over 2 seasons of suburban high school competition. Sensor data were sequentially reduced to remove events recorded outside of game times, associated with players not on the pitch (ie, field) and players outside the field of view of the camera. With video analysis, the remaining sensor-recorded events were identified as an impact event, trivial event, or nonevent. The mechanisms of impact events were identified. The classifications of sensor-recorded events by the SIM-G algorithm were analyzed. Results: A total of 6796 sensor events were recorded during scheduled varsity game times, of which 1893 (20%) were sensor-recorded events associated with players on the pitch in the field of view of the camera during verified game times. Most video-confirmed events were impact events (n = 1316, 70%), followed by trivial events (n = 396, 21%) and nonevents (n = 181, 10%). Female athletes had a significantly higher percentage of trivial events and nonevents with a significantly lower percentage of impact events. Most impact events were head-to-ball impacts (n = 1032, 78%), followed by player contact (n = 144, 11%) and falls (n = 129, 10%) with no significant differences between male and female teams. The SIM-G algorithm correctly identified 70%, 52%, and 66% of video-confirmed impact events, trivial events, and nonevents, respectively. Conclusion: Video confirmation is critical to the processing of head impact sensor data. Percentages of video-confirmed impact events, trivial events, and nonevents vary by sex in high school soccer. Current manufacturer filtering algorithms and magnitude thresholds are ineffective at correctly classifying sensor-recorded events and should be used with caution.

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Validation of a Custom Instrumented Retainer Form Factor for Measuring Linear and Angular Head Impact Kinematics

Journal of Biomechanical Engineering ◽

10.1115/1.4039165 ◽

2018 ◽

Vol 140 (5) ◽

Cited By ~ 7

Author(s):

Logan E. Miller ◽

Calvin Kuo ◽

Lyndia C. Wu ◽

Jillian E. Urban ◽

David B. Camarillo ◽

...

Keyword(s):

Form Factor ◽

Degrees Of Freedom ◽

Rotational Velocity ◽

Linear Acceleration ◽

Head Impact ◽

Contact Sports ◽

Head Impacts ◽

Sensing Technology ◽

The One ◽

Impact Data

Head impact exposure in popular contact sports is not well understood, especially in the youth population, despite recent advances in impact-sensing technology which has allowed widespread collection of real-time head impact data. Previous studies indicate that a custom-instrumented mouthpiece is a superior method for collecting accurate head acceleration data. The objective of this study was to evaluate the efficacy of mounting a sensor device inside an acrylic retainer form factor to measure six-degrees-of-freedom (6DOF) head kinematic response. This study compares 6DOF mouthpiece kinematics at the head center of gravity (CG) to kinematics measured by an anthropomorphic test device (ATD). This study found that when instrumentation is mounted in the rigid retainer form factor, there is good coupling with the upper dentition and highly accurate kinematic results compared to the ATD. Peak head kinematics were correlated with r2 > 0.98 for both rotational velocity and linear acceleration and r2 = 0.93 for rotational acceleration. These results indicate that a rigid retainer-based form factor is an accurate and promising method of collecting head impact data. This device can be used to study head impacts in helmeted contact sports such as football, hockey, and lacrosse as well as nonhelmeted sports such as soccer and basketball. Understanding the magnitude and frequency of impacts sustained in various sports using an accurate head impact sensor, such as the one presented in this study, will improve our understanding of head impact exposure and sports-related concussion.

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The Effect of Protective Headgear on Frequency and Magnitude of Impacts in Girls’ High School Varsity Lacrosse

Archives of Clinical Neuropsychology ◽

10.1093/arclin/acz026.12 ◽

2019 ◽

Vol 34 (5) ◽

pp. 742-742

Author(s):

P M Kelshaw ◽

A E Lincoln ◽

L H Hepburn ◽

D C Herman ◽

H K Vincent ◽

...

Keyword(s):

High School ◽

Video Analysis ◽

Injury Risk ◽

Rotational Velocity ◽

Wearable Sensors ◽

Linear Acceleration ◽

Game Play ◽

Team Game ◽

Larger Sample ◽

Different Levels

Abstract Purpose In an effort to reduce head and facial injuries in girls’ lacrosse, ASTM F3137-approved headgear for girls’ lacrosse was developed. However, the effect of wearing headgear on impacts during girls’ lacrosse game play is unknown. This study aimed to evaluate differences in impact rates and magnitudes across two conditions (No Headgear, and Headgear) during girls’ lacrosse games. Methods Thirty-five female participants (16.2±1.2years, 1.66±0.05m, 61.2±6.4kg) volunteered for this study during 18 games in the 2016 (No Headgear), and 15 games in the 2017 (Headgear) lacrosse seasons. All participants were instrumented with wearable sensors (X2 Biosystems) prior to each game paired with video verification. Results There were a total of 700 sensor-instrumented player-games. A total of 204 impacts ≥ 20g recorded by the wearable sensors were verified using video analysis (102 No Headgear; 102 Headgear). Impact rates did not vary between the No Headgear and Headgear conditions (0.27 vs 0.31 AEs/per team game, IRR=0.87, 95% CI=0.66, 1.14). The No Headgear condition experienced higher magnitudes (median peak linear acceleration (PLA)=26.9g and peak rotational velocity (PRV)=1578.6 deg/s) than the Headgear conditions (median PLA=24.7g; Z= –2.6, P<. 0.01 and PRV=1304.2 deg/s; Z = –2.6, P<. 0.01). No game-related concussions were reported during this two-year study. Conclusion There were no meaningful differences between impact rates and only slight differences in impact magnitudes in the No Headgear and Headgear groups. Further research should be conducted with a larger sample and different levels of play to evaluate the consequences of ASTM F3137-approved headgear on impacts, injury risk, and game play.

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Head Impact Biomechanics in Youth Flag Football: A Prospective Cohort Study

The American Journal of Sports Medicine ◽

10.1177/03635465211026643 ◽

2021 ◽

pp. 036354652110266

Author(s):

Landon B. Lempke ◽

Rachel S. Johnson ◽

Rachel K. Le ◽

Melissa N. Anderson ◽

Julianne D. Schmidt ◽

...

Keyword(s):

Mixed Model ◽

Linear Acceleration ◽

Cross Sectional Study ◽

Head Impact ◽

Rotational Acceleration ◽

Event Type ◽

Level Of Evidence ◽

Cross Sectional ◽

Head Impact Biomechanics ◽

Impact Biomechanics

Background: Youth flag football participation has rapidly grown and is a potentially safer alternative to tackle football. However, limited research has quantitatively assessed youth flag football head impact biomechanics. Purpose: To describe head impact biomechanics outcomes in youth flag football and explore factors associated with head impact magnitudes. Study Design: Cross-sectional study; Level of evidence, 3. Methods: We monitored 52 player-seasons among 48 male flag football players (mean ± SD; age, 9.4 ± 1.1 years; height, 138.6 ± 9.5 cm; mass, 34.7 ± 9.2 kg) across 3 seasons using head impact sensors during practices and games. Sensors recorded head impact frequencies, peak linear ( g) and rotational (rad/s2) acceleration, and estimated impact location. Impact rates (IRs) were calculated as 1 impact per 10 player-exposures; IR ratios (IRRs) were used to compare season, event type, and age group IRs; and 95% CIs were calculated for IRs and IRRs. Weekly and seasonal cumulative head impact frequencies and magnitudes were calculated. Mixed-model regression models examined the association between player characteristics, event type, and seasons and peak linear and rotational accelerations. Results: A total of 429 head impacts from 604 exposures occurred across the study period (IR, 7.10; 95% CI, 4.81-10.50). Weekly and seasonal cumulative median head impact frequencies were 1.00 (range, 0-2.63) and 7.50 (range, 0-21.00), respectively. The most frequent estimated head impact locations were the skull base (n = 96; 22.4%), top of the head (n = 74; 17.2%), and back of the head (n = 66; 15.4%). The combined event type IRs differed among the 3 seasons (IRR range, 1.45-2.68). Games produced greater IRs (IRR, 1.24; 95% CI, 1.01-1.53) and peak linear acceleration (mean difference, 5.69 g; P = .008) than did practices. Older players demonstrated greater combined event–type IRs (IRR, 1.46; 95% CI, 1.12-1.90) and increased head impact magnitudes than did younger players, with every 1-year age increase associated with a 3.78 g and 602.81-rad/s2 increase in peak linear and rotational acceleration magnitude, respectively ( P≤ .005). Conclusion: Head IRs and magnitudes varied across seasons, thus highlighting multiple season and cohort data are valuable when providing estimates. Head IRs were relatively low across seasons, while linear and rotational acceleration magnitudes were relatively high.

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Football concussion case series using biomechanical and video analysis

Neurology ◽

10.1212/01.wnl.0000550623.36010.20 ◽

2018 ◽

Vol 91 (23 Supplement 1) ◽

pp. S2.2-S2

Author(s):

Mirellie Kelley ◽

Jillian Urban ◽

Derek Jones ◽

Alexander Powers ◽

Christopher T. Whitlow ◽

...

Keyword(s):

Video Analysis ◽

Case Series ◽

Linear Acceleration ◽

The United States ◽

Head Impact ◽

Rotational Acceleration ◽

Impact Location ◽

Injury Mechanisms ◽

The Mean ◽

Impact Data

Approximately 1.1–1.9 million sport-related concussions among athletes ≤18 years of age occur annually in the United States, but there is limited understanding of the biomechanics and injury mechanisms associated with concussions among lower level football athletes. Therefore, the objective of this study was to combine biomechanical head impact data with video analysis to characterize youth and HS football concussion injury mechanisms. Head impact data were collected from athletes participating on 22 youth and 6 HS football teams between 2012 and 2017. Video was recorded, and head impact data were collected during all practices and games by instrumenting players with the Head Impact Telemetry (HIT) System. For each clinically diagnosed concussion, a video abstraction form was completed, which included questions concerning the context in which the injury occurred. Linear acceleration, rotational acceleration, and impact location were used to characterize the concussive event and each injured athlete's head impact exposure on the day of the concussion. A total of 9 (5 HS and 4 youth) concussions with biomechanics and video of the event were included in this study. The mean [range] linear and rotational acceleration of the concussive impacts were 62.9 [29.3–118.4] g and 3,056.7 [1,046.8–6,954.6] rad/s2, respectively. Concussive impacts were the highest magnitude impacts for 6 players and in the top quartile of impacts for 3 players on the day of injury. Concussions occurred in both practices (N = 4) and games (N = 5). The most common injury contact surface was helmet-to-helmet (N = 5), followed by helmet-to-ground (N = 3) and helmet-to-body (N = 1). All injuries occurred during player-to-player contact scenarios, including tackling (N = 4), blocking (N = 4), and collision with other players (N = 1). The biomechanics and injury mechanisms of concussions varied among athletes in our study; however, concussive impacts were among the highest severity for each player and all concussions occurred as a result of player-to-player contact.

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Effect of Head Impact Exposures on Changes in Cognitive Testing

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967118761031 ◽

2018 ◽

Vol 6 (3) ◽

pp. 232596711876103 ◽

Cited By ~ 2

Author(s):

Eleni Diakogeorgiou ◽

Theresa L. Miyashita

Keyword(s):

Reaction Time ◽

National Collegiate Athletic Association ◽

Assessment Tool ◽

Vital Signs ◽

Head Impact ◽

Cognitive Testing ◽

Repeated Impact ◽

Level Of Evidence ◽

Head Impacts ◽

Significant Difference

Background: Gaining a better understanding of head impact exposures may lead to better comprehension of the possible effects of repeated impact exposures not associated with clinical concussion. Purpose: To assess the correlation between head impacts and any differences associated with cognitive testing measurements pre- and postseason. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 34 National Collegiate Athletic Association Division I men’s lacrosse players wore lacrosse helmets instrumented with an accelerometer during the 2014 competitive season and were tested pre- and postseason with the Sport Concussion Assessment Tool (SCAT 3) and Concussion Vital Signs (CVS) computer-based neurocognitive tests. The number of head impacts >20 g and results from the 2 cognitive tests were analyzed for differences and correlation. Results: There was no significant difference between pre- and postseason SCAT 3 scores, although a significant correlation between pre- and postseason cognitive scores on the SCAT 3 and total number of impacts sustained was noted ( r = –0.362, P = .035). Statistically significant improvements on half of the CVS testing components included visual reaction time ( P = .037, d = 0.37), reaction time ( P = .001, d = 0.65), and simple reaction time ( P = .043, d = 0.37), but no correlation with head impacts was noted. Conclusion: This study did not find declines in SCAT 3 or CVS scores over the course of a season among athletes who sustained multiple head impacts but no clinical concussion. Thus, it could not be determined whether there was no cognitive decline among these athletes or whether there may have been subtle declines that could not be measured by the SCAT 3 or CVS.

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Video Analysis and Verification of Direct Head Impacts Recorded by Wearable Sensors in Junior Rugby League Players

10.21203/rs.3.rs-52754/v1 ◽

2020 ◽

Author(s):

Lauchlan John Carey ◽

Douglas P Terry ◽

Andrew McIntosh ◽

Peter Stanwell ◽

Grant L Iverson ◽

...

Keyword(s):

Video Analysis ◽

Wearable Sensors ◽

Case Series ◽

Rugby League ◽

Secondary Source ◽

Head Impacts ◽

Youth Athletes ◽

Video Review ◽

Direct Head ◽

Elite Level

Abstract Background: Rugby League is a high-intensity collision sport that carries a risk of concussion. Youth athletes are considered to be more vulnerable and take longer to recover from concussion than adult athletes. Purpose: To review head impact events in elite level junior representative rugby league and to verify and analyze x-patchTM recorded impacts via video analysis.Study Design: Observational case series.Methods: The x-patchTM was used on twenty-one adolescent players (thirteen forwards and eight backs) during a 2017 junior representative rugby league competition. Game day footage, recorded by a trained videographer from a single camera, was synchronized with accelerometer timestamps. Impacts were double verified by video review. Impact rates, playing characteristics, and game play situations were described.Results: The x-patchTM recorded 624 impacts 20g between game start and finish, of which 564 (90.4%) were verified on video. Upon video review, 413 (73.2%) of all verified impacts 20g where determined to be direct head impacts. Direct head impacts 20g occurred at a rate of 5.2 impacts per game hour; 7.6 for forwards and 3.0 for backs (range=0-18.2). A defender’s arm directly impacting the head of the ball carrier was the most common event, accounting for 21.3% (n=120) of all impacts, and 46.7% of all “hit-up” impacts. There were no medically diagnosed concussions during the competition.Conclusion: The majority (90.4%) of impacts 20g recorded by the x-patchTM sensor were verified by video. Double verification of direct head impacts in addition to cross-verification of sensor recorded impacts using a secondary source such as synchronized video review can be used to ensure accuracy and validation of data.

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