Rotational Acceleration

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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Rotational Acceleration Measurements - Evaluating Helmet Protection

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/s031716710000370x ◽

2004 ◽

Vol 31 (4) ◽

pp. 499-503 ◽

Cited By ~ 8

Author(s):

M. Kis ◽

F. Saunders ◽

M.W. ten Hove ◽

J.R. Leslie

Keyword(s):

Horizontal Plane ◽

Rotational Acceleration ◽

Testing Device ◽

Cerebral Concussion ◽

Impact Simulation ◽

Head Protection ◽

Rotational Components ◽

Protection Devices ◽

Testing Standards ◽

Testing Paradigm

Purpose:Current helmet testing standards do not address the rotational components of an impact to the head. We describe a new testing paradigm used to measure the rotational acceleration of a headform and a protective helmet following an impact to the head in the horizontal plane. This impact simulation allows for the testing of currently available head protection devices in conditions thought to be important for the generation of cerebral concussion. The degree to which a particular helmet dampens rotational acceleration, and thus protects against concussion, can be assessed.Methods:Our testing device consists of a pneumatic piston that provides a measured impact to a standard headform. Four different helmets were tested using the described paradigm.Results:Acceleration curves for each helmet and the corresponding headform are presented.Conclusion:Clear differences in rotational acceleration were demonstrated. Possible avenues of further investigation are discussed.

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The Effect of Shoulder Pad Design on Reducing Peak Resultant Linear and Rotational Acceleration in Shoulder-to-Head Impacts

Mechanism of Concussion in Sports ◽

10.1520/stp155220120150 ◽

2014 ◽

pp. 142-152 ◽

Cited By ~ 4

Author(s):

Marshall Kendall ◽

Andrew Post ◽

Philippe Rousseau ◽

T. Blaine Hoshizaki

Keyword(s):

Rotational Acceleration ◽

Head Impacts

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New generation of headgear for rugby: impact reduction of linear and rotational forces by a viscoelastic material-based rugby head guard

BMJ Open Sport & Exercise Medicine ◽

10.1136/bmjsem-2018-000464 ◽

2018 ◽

Vol 4 (1) ◽

pp. e000464 ◽

Cited By ~ 2

Author(s):

Mark Ganly ◽

Jill Mary McMahon

Keyword(s):

Impact Energy ◽

Impact Test ◽

Linear Acceleration ◽

Rotational Acceleration ◽

Impact Reduction ◽

Subconcussive Injury ◽

Drop Tests ◽

Repeated Use ◽

Repeated Impacts ◽

New Generation

ObjectivesIn the aim to develop a usable and wearable head guard for rugby that could reduce impact energy and lessen the likelihood of concussive and subconcussive injury during play, a combination of viscoelastic materials was employed to develop a guard with similar dimensions to those currently used in international rugby.MethodsThe head guard was tested for impact energy reduction following linear acceleration, using drop tests, as required by World Rugby. The head guard was also subjected to pendulum tests, allowing acceleration to be simultaneously measured on two headforms, as well as repeated impacts to mimic ageing and repeated use. Impact following rotational acceleration was determined at two impact locations and at three impact velocities.ResultsThe viscoelastic head guard (N-Pro) was shown to reduce linear impacts by up to 75% in comparison to the use of a commercially available rugby head guard and repeated impacts did not impair the attenuation of impact energy. Rotational impact energy was also reduced by an average of 34% across three speeds and two sites of impact test sites, in comparison to tested bare headforms.ConclusionsThis heralds a new generation of soft-shelled headgear that could help reduce two primary risk factors in sports-induced mild traumatic brain injury: linear and rotational impacts to the head.

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Detection of Rotational Acceleration of Bennu Using HST Light Curve Observations

Geophysical Research Letters ◽

10.1029/2018gl080658 ◽

2019 ◽

Vol 46 (4) ◽

pp. 1956-1962 ◽

Cited By ~ 12

Author(s):

M. C. Nolan ◽

E. S. Howell ◽

D. J. Scheeres ◽

J. W. McMahon ◽

O. Golubov ◽

...

Keyword(s):

Light Curve ◽

Rotational Acceleration

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Neck Flexion Induces Larger Deformation of the Brain Than Extension at a Rotational Acceleration, Closed Head Trauma

Advances in Neuroscience ◽

10.1155/2014/945869 ◽

2014 ◽

Vol 2014 ◽

pp. 1-13 ◽

Cited By ~ 1

Author(s):

Hans-Arne Hansson ◽

Ulrika Krave ◽

Svante Höjer ◽

Johan Davidsson

Keyword(s):

Head Trauma ◽

Sagittal Plane ◽

Positive Pressure ◽

High Time Resolution ◽

Rotational Acceleration ◽

Brain Deformation ◽

Closed Head ◽

Negative Pressures ◽

Closed Head Trauma ◽

The Brain

A closed head trauma induces incompletely characterized temporary movement and deformation of the brain, contributing to the primary traumatic brain injury. We used the pressure patterns recorded with light-operated miniature sensors in anaesthetized adult rabbits exposed to a sagittal plane rotational acceleration of the head, lasting 1 ms, as a measure of brain deformation. Two exposure levels were used and scaled to correspond to force levels reported to cause mild and moderate diffuse injury in an adult man, respectively. Flexion induced transient, strong, extended, and predominantly negative pressures while extension generated a short positive pressure peak followed by a minor negative peak. Low level flexion caused as strong, extended negative pressures as did high level extension. Time differences were demonstrated between the deformation of the cerebrum, brainstem, and cerebellum. Available X-ray and MRI techniques do not have as high time resolution as pressure recordings in demonstrating complex, sequential compression and stretching of the brain during a trauma. The exposure to flexion caused more protracted and extensive deformation of the brain than extension, in agreement with a published histopathological report. The severity and extent of the brain deformation generated at a head trauma thus related to the direction at equal force.

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An examination of the current National Operating Committee on Standards for Athletic Equipment system and a new pneumatic ram method for evaluating American football helmet performance to reduce risk of concussion

Proceedings of the Institution of Mechanical Engineers Part P Journal of Sports Engineering and Technology ◽

10.1177/1754337116633376 ◽

2016 ◽

Vol 231 (2) ◽

pp. 83-90 ◽

Cited By ~ 3

Author(s):

Thomas Blaine Hoshizaki ◽

Clara Karton ◽

R. Anna Oeur ◽

Marshall Kendall ◽

Lauren Dawson ◽

...

Keyword(s):

Traumatic Brain Injury ◽

Brain Injury ◽

Significant Risk ◽

Standard Test ◽

American Football ◽

New Method ◽

Rotational Acceleration ◽

Football Helmets ◽

Athletic Equipment ◽

New System

Brain injuries are prevalent in the sport of American football. Helmets have been used which effectively have reduced the incidence of traumatic brain injury, but have had a limited effect on concussion rates. In an effort to improve the protective capacity of American football helmets, a standard has been proposed by National Operating Committee on Standards for Athletic Equipment that may better represent helmet-to-helmet impacts common to football concussions. The purpose of this research was to examine the National Operating Committee on Standards for Athletic Equipment standard and a new impact method similar to the proposed National Operating Committee on Standards for Athletic Equipment standard to examine the information these methods provide on helmet performance. Five National Operating Committee on Standards for Athletic Equipment–certified American football helmets were impacted according to the National Operating Committee on Standards for Athletic Equipment standard test and a new method based on the proposed standard test. The results demonstrated that the National Operating Committee on Standards for Athletic Equipment test produced larger linear accelerations than the new method, which were a reflection of the stiffer compliance of the standard meant to replicate traumatic brain injury mechanisms of injury. When the helmets were impacted using a new helmet-to-helmet method, the results reflected significant risk of concussive injury but showed differences in rotational acceleration responses between different helmet models. This suggests that the new system is sensitive enough to detect the effect of different design changes on rotational acceleration, a metric more closely associated with risk of concussion. As only one helmet produced magnitudes of response lower than the National Operating Committee on Standards for Athletic Equipment pass/fail using the new system, and all helmets passed the National Operating Committee on Standards for Athletic Equipment standard, these results suggest that further development of helmet technologies must be undertaken to reduce this risk in the future. Finally, these results show that it would be prudent to use both standards together to address risk of injury from traumatic brain injury and concussion.

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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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