Risk assessment in different Judo techniques for children and adolescent athletes

2020 ◽  
Vol 234 (7) ◽  
pp. 686-696
Author(s):  
Luca Vacca ◽  
Valeria Rosso ◽  
Laura Gastaldi
Keyword(s):  
Head Injury ◽  
Injury Risk ◽  
Inertial Sensors ◽  
Angular Acceleration ◽  
Linear Acceleration ◽  
Severity Index ◽  
Time Duration ◽  
Neck Extension ◽  
Children And Adolescent ◽  
Experience Levels

Judo is a combat sport that involves throwing the opponent onto the back. When being thrown, head biomechanics may be related to head injury risk. This study aimed to assess head injury risks associated with four Judo techniques in children and adolescents with different experience levels. Twenty children (<12 years) and 20 adolescents (≥ 12 years) judoka were recruited. Each group was divided into non-expert and expert. Two inertial sensors were fixed on fallers’ head and torso. Two backward ( o-soto-gari and o-uchi-gari) and two forward ( ippon-seoi-nage and tai-otoshi) techniques were performed. Peak of linear and angular head acceleration magnitude, impact time duration, neck angle, and the Gadd Severity Index were assessed. Children did not show differences between techniques or experience levels. In contrast, adolescents showed greater linear acceleration peak in o-soto-gari than tai-otoshi (p = 0.03), greater angular acceleration peak in o-soto-gari and o-uchi-gari than ippon-seoi-nage (p < 0.05), and greater neck flexion in o-uchi-gari than ippon-seoi-nage (p = 0.004). Compared to expert adolescents, non-expert adolescents showed greater angular acceleration peak, impact duration, and the Gadd Severity Index in o-soto-gari (p < 0.05) and greater neck extension in o-uchi-gari (p = 0.02). Current results pointed out higher risks for adolescents judoka while being thrown with backward techniques, especially for non-expert participants. This study highlights the need of training athletes in controlling head and neck during back falls from a young age to become expert judoka in adulthood.

scholarly journals Impact test comparisons of 20th and 21st century American football helmets

2012 ◽  
Vol 116 (1) ◽  
pp. 222-233 ◽  
Author(s):  
Adam Bartsch ◽  
Edward Benzel ◽  
Vincent Miele ◽  
Vikas Prakash
Keyword(s):  
Head Injury ◽  
21St Century ◽  
Injury Risk ◽  
Diffuse Axonal Injury ◽  
Angular Acceleration ◽  
Linear Acceleration ◽  
Severity Index ◽  
Head Impact ◽  
American Football ◽  
Acute Subdural Hematoma

Object Concussion is the signature American football injury of the 21st century. Modern varsity helmets, as compared with vintage leather helmets, or “leatherheads,” are widely believed to universally improve protection by reducing head impact doses and head injury risk for the 3 million young football players in the US. The object of this study was to compare the head impact doses and injury risks with 11 widely used 21st century varsity helmets and 2 early 20th century leatherheads and to hypothesize what the results might mean for children wearing similar varsity helmets. Methods In an injury biomechanics laboratory, the authors conducted front, oblique front, lateral, oblique rear, and rear head impact tests at 5.0 m/second using helmeted headforms, inducing near- and subconcussive head impact doses on par with approximately the 95th percentile of on-field collision severity. They also calculated impact dose injury risk parameters common to laboratory and on-field traumatic neuromechanics: linear acceleration, angular acceleration, angular velocity, Gadd Severity Index, diffuse axonal injury, acute subdural hematoma, and brain contusion. Results In many instances the head impact doses and head injury risks while wearing vintage leatherheads were comparable to or better than those while wearing several widely used 21st century varsity helmets. Conclusions The authors do not advocate reverting to leather headgear, but they do strongly recommend, especially for young players, instituting helmet safety designs and testing standards, which encourage the minimization of linear and angular impact doses and injury risks in near- and subconcussive head impacts.

The influence of deflection and neck compliance on the impact dynamics of a Hybrid III headform

2009 ◽  
Vol 223 (3) ◽  
pp. 89-97 ◽  
Author(s):  
P Rousseau ◽  
T B Hoshizaki
Keyword(s):  
Angular Acceleration ◽  
Linear Acceleration ◽  
Severity Index ◽  
Impact Dynamics ◽  
Risk Of Injury ◽  
Lateral Translation ◽  
Hybrid Iii ◽  
Front Impact ◽  
The Impact

The objective of this study was to determine the influence of impact deflection and neck compliance on the Gadd severity index (GSI), peak linear acceleration, and peak angular acceleration during a front impact to a Hybrid III head using a pneumatic linear impactor. Impact deflection was performed by translating the headform laterally and was shown to be effective at reducing the linear and angular accelerations as well as the GSI. Neck compliance was altered using one Hybrid III 50th percentile neck and two modified Hybrid III necks. A less compliant neck increased linear acceleration but decreased angular acceleration and GSI. When compared with estimated injury thresholds, the results demonstrated that an increase in the lateral translation or a decrease in the neck compliance resulted in a significant decrease in the risk of injury as reflected by peak linear and angular accelerations and the GSI.

Child ATD Reconstruction of a Fatal Pediatric Fall

2009 ◽  
Author(s):  
Chris Van Ee ◽  
David Raymond ◽  
Kirk Thibault ◽  
Warren Hardy ◽  
John Plunkett
Keyword(s):  
Head Injury ◽  
Additional Data ◽  
Skull Fracture ◽  
Angular Acceleration ◽  
Linear Acceleration ◽  
Test Device ◽  
Critical Data ◽  
Animal Data ◽  
Injury Assessment ◽  
Accident Scenarios

The current head Injury Assessment Reference Values (IARVs) for the child dummies are based in part on scaling adult and animal data and on reconstructions of real world accident scenarios. Reconstruction of well-documented accident scenarios provides critical data in the evaluation of proposed IARV values, but relatively few accidents are sufficiently documented to allow for accurate reconstructions. This reconstruction of a well documented fatal-fall involving a 23-month old child supplies additional data for IARV assessment. The videotaped fatal-fall resulted in a frontal head impact onto a carpet-covered cement floor. The child suffered an acute right temporal parietal subdural hematoma without skull fracture. The fall dynamics were reconstructed in the laboratory and the head linear and angular accelerations were quantified using the CRABI-18 Anthropomorphic Test Device (ATD). Peak linear acceleration was 125 ± 7 g (range 114–139), HIC15 was 335 ± 115 (Range 257–616), peak angular velocity was 57± 16 (Range 26–74), and peak angular acceleration was 32 ± 12 krad/s2 (Range 15–56). The results of the CRABI-18 fatal fall reconstruction were consistent with the linear and rotational tolerances reported in the literature. This study investigates the usefulness of the CRABI-18 anthropomorphic testing device in forensic investigations of child head injury and aids in the evaluation of proposed IARVs for head injury.

Vulnerable Locations on the Head to Brain Injury and Implications for Helmet Design

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Michael Fanton ◽  
Jake Sganga ◽  
David B. Camarillo
Keyword(s):  
Brain Injury ◽  
Injury Risk ◽  
Contact Point ◽  
Angular Acceleration ◽  
Linear Acceleration ◽  
Input Force ◽  
Contact Points ◽  
Impact Location ◽  
Tissue Strain ◽  
The Relationship

Abstract In studying traumatic brain injury (TBI), it has been long hypothesized that the head is more vulnerable to injury from impacts in certain directions or locations, as the relationship between impact force and the resulting neurological outcome is complex and can vary significantly between individual cases. Many studies have identified head angular acceleration to be the putative cause of brain trauma, but it is not well understood how impact location can affect the resulting head kinematics and tissue strain. Here, we identify the susceptibility of the head to accelerations and brain strain from normal forces at contact points across the surface of the skull and jaw using a three-dimensional, 20-degree-of-freedom rigid-body head and cervical spine model. We find that head angular acceleration and brain tissue strain resulting from an input force can vary by orders of magnitude based on impact location on the skull, with the mandible as the most vulnerable region. Conversely, head linear acceleration is not sensitive to contact location. Using these analyses, we present an optimization scheme to distribute helmet padding thickness to minimize angular acceleration, resulting in a reduction of angular acceleration by an estimated 25% at the most vulnerable contact point compared to uniform thickness padding. This work gives intuition behind the relationship between input force and resulting brain injury risk, and presents a framework for developing and evaluating novel head protection gear.

scholarly journals The Head AIS 4+ Injury Thresholds for the Elderly Vulnerable Road User Based on Detailed Accident Reconstructions

2021 ◽  
Vol 9 ◽  
Author(s):  
He Wu ◽  
Yong Han ◽  
Di Pan ◽  
Bingyu Wang ◽  
Hongwu Huang ◽  
...  
Keyword(s):  
Head Injury ◽  
Brain Tissue ◽  
Injury Risk ◽  
Tissue Injury ◽  
Angular Acceleration ◽  
The Elderly ◽  
Road User ◽  
Injury Criteria ◽  
Cumulative Strain ◽  
Head Injury Criteria

Compared with the young, the elderly (age greater than or equal to 60 years old) vulnerable road users (VRUs) face a greater risk of injury or death in a traffic accident. A contributing vulnerability is the aging processes that affect their brain structure. The purpose of this study was to investigate the injury mechanisms and establish head AIS 4+ injury tolerances for the elderly VRUs based on various head injury criteria. A total of 30 elderly VRUs accidents with detailed injury records and video information were selected and the VRUs’ kinematics and head injuries were reconstructed by combining a multi-body system model (PC-Crash and MADYMO) and the THUMS (Ver. 4.0.2) FE models. Four head kinematic-based injury predictors (linear acceleration, angular velocity, angular acceleration, and head injury criteria) and three brain tissue injury criteria (coup pressure, maximum principal strain, and cumulative strain damage measure) were studied. The correlation between injury predictors and injury risk was developed using logistical regression models for each criterion. The results show that the calculated thresholds for head injury for the kinematic criteria were lower than those reported in previous literature studies. For the brain tissue level criteria, the thresholds calculated in this study were generally similar to those of previous studies except for the coup pressure. The models had higher (&gt;0.8) area under curve values for receiver operator characteristics, indicating good predictive power. This study could provide additional support for understanding brain injury thresholds in elderly people.

scholarly journals Is Acceleration a Valid Proxy for Injury Risk in Minimal Damage Traffic Crashes? A Comparative Review of Volunteer, ADL and Real-World Studies

2021 ◽  
Vol 18 (6) ◽  
pp. 2901
Author(s):  
Paul S. Nolet ◽  
Larry Nordhoff ◽  
Vicki L. Kristman ◽  
Arthur C. Croft ◽  
Maurice P. Zeegers ◽  
...  
Keyword(s):  
Real World ◽  
Injury Risk ◽  
Angular Acceleration ◽  
Traffic Crashes ◽  
Rear Impact ◽  
Comparative Review ◽  
Minimal Damage ◽  
Injury Causation ◽  
Crash Tests ◽  
Biomechanical Approach

Injury claims associated with minimal damage rear impact traffic crashes are often defended using a “biomechanical approach,” in which the occupant forces of the crash are compared to the forces of activities of daily living (ADLs), resulting in the conclusion that the risk of injury from the crash is the same as for ADLs. The purpose of the present investigation is to evaluate the scientific validity of the central operating premise of the biomechanical approach to injury causation; that occupant acceleration is a scientifically valid proxy for injury risk. Data were abstracted, pooled, and compared from three categories of published literature: (1) volunteer rear impact crash testing studies, (2) ADL studies, and (3) observational studies of real-world rear impacts. We compared the occupant accelerations of minimal or no damage (i.e., 3 to 11 kph speed change or “delta V”) rear impact crash tests to the accelerations described in 6 of the most commonly reported ADLs in the reviewed studies. As a final step, the injury risk observed in real world crashes was compared to the results of the pooled crash test and ADL analyses, controlling for delta V. The results of the analyses indicated that average peak linear and angular acceleration forces observed at the head during rear impact crash tests were typically at least several times greater than average forces observed during ADLs. In contrast, the injury risk of real-world minimal damage rear impact crashes was estimated to be at least 2000 times greater than for any ADL. The results of our analysis indicate that the principle underlying the biomechanical injury causation approach, that occupant acceleration is a proxy for injury risk, is scientifically invalid. The biomechanical approach to injury causation in minimal damage crashes invariably results in the vast underestimation of the actual risk of such crashes, and should be discontinued as it is a scientifically invalid practice.

Laboratory and field evaluation of a small form factor head impact sensor in un-helmeted play

2017 ◽  
Vol 232 (3) ◽  
pp. 242-254 ◽  
Author(s):  
Derek Nevins ◽  
Kasee Hildenbrand ◽  
Jeff Kensrud ◽  
Anita Vasavada ◽  
Lloyd Smith
Keyword(s):  
Form Factor ◽  
Center Of Mass ◽  
False Negative ◽  
Angular Acceleration ◽  
Linear Acceleration ◽  
Field Evaluation ◽  
Head Impact ◽  
Sensor Data ◽  
Small Form ◽  
Small Form Factor

Head impact sensors are increasingly used to quantify the frequency and magnitude of head impacts in sports. A dearth of information exists regarding head impact in un-helmeted sport, despite the substantial number of concussions experienced in these sports. This study evaluated the performance of one small form factor head impact sensor in both laboratory and field environments. In laboratory tests, sensor performance was assessed using a Hybrid III headform and neck. The headform assembly was mounted on a low-friction sled and impacted with three sports balls over a range of velocities (10–31 m/s) at two locations and from three directions. Measures of linear and angular acceleration obtained from the small form factor wireless sensor were compared to measures of linear and angular acceleration obtained by wired sensors mounted at the headform center of mass. Accuracy of the sensor varied inversely with impact magnitude, with relative differences across test conditions ranging from 0.1% to 266.0% for peak linear acceleration and 4.7% to 94.6% for peak angular acceleration when compared to a wired reference system. In the field evaluation, eight male high school soccer players were instrumented with the head impact sensor in seven games. Video of the games was synchronized with sensor data and reviewed to determine the number of false positive and false negative head acceleration event classifications. Of the 98 events classified as valid by the sensor, 20.5% (20 impacts) did not result from contact with the ball, another player, the ground or player motion and were therefore considered false positives. Video review of events classified as invalid or spurious by the sensor found 77.8% (14 of 18 impacts) to be due to contact with the ball, another player or player motion and were considered false negatives.

scholarly journals The assessment of pedestrian`s head injury risk at the contact with the vehicle`s hood

2019 ◽  
Vol Volume XXIX (XIX), 2019/3 (3) ◽  
Author(s):  
H Beles ◽  
B A Tolea ◽  
G F Crisan ◽  
C A Dogar ◽  
V V Ciotachiev
Keyword(s):  
Head Injury ◽  
Injury Risk

Gyroscope-Free Link Parameter Measurement Using Accelerometers and Magnetometer

2014 ◽  
Author(s):  
Vishesh Vikas ◽  
Carl D. Crane
Keyword(s):  
Angular Velocity ◽  
Joint Angle ◽  
Inertial Sensors ◽  
Angular Acceleration ◽  
Parameter Measurement ◽  
Joint Angles ◽  
Symmetry Constraint ◽  
Estimation Techniques ◽  
Angular Velocities ◽  
Joint Parameters

Knowledge of joint angles, angular velocities is essential for control of link mechanisms and robots. The estimation of joint angles and angular velocity is performed using combination of inertial sensors (accelerometers and gyroscopes) which are contactless and flexible at point of application. Different estimation techniques are used to fuse data from different inertial sensors. Bio-inspired sensors using symmetrically placed multiple inertial sensors are capable of instantaneously measuring joint parameters (joint angle, angular velocities and angular acceleration) without use of any estimation techniques. Calibration of inertial sensors is easier and more reliable for accelerometers as compared to gyroscopes. The research presents gyroscope-less, multiple accelerometer and magnetometer based sensors capable of measuring (not estimating) joint parameters. The contribution of the improved sensor are four-fold. Firstly, the inertial sensors are devoid of symmetry constraint unlike the previously researched bio-inspired sensors. However, the accelerometer are non-coplanarly placed. Secondly, the accelerometer-magnetometer combination sensor allows for calculation of a unique rotation matrix between two link joined by any kind of joint. Thirdly, the sensors are easier to calibrate as they consist only of accelerometers. Finally, the sensors allow for calculation of angular velocity and angular acceleration without use of gyroscopes.

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