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Richard Greenwald

Richard Greenwald
Independent Researcher

PhD

About

136
Publications
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Introduction
Skills and Expertise

Publications

Publications (136)
Article
Full-text available
Sports concussions are a public health concern. Improving helmet performance to reduce concussion risk is a key part of the research and development community response. Direct and oblique head impacts with compliant surfaces that cause long-duration moderate or high linear and rotational accelerations are associated with a high rate of clinical dia...
Conference Paper
Injuries to the knee, in particular to the anterior cruciate ligament (ACL), continue to be the predominant injury in Alpine skiing, accounting for as many as 42% of all injuries[1]. Conversely, injuries to the tibia and ankle have decreased over the past two decades and now represent a very small fraction of the total injuries in skiing[2]. Ski eq...
Article
The relationship between head impact and subsequent brain injury for American football players is not well-defined, especially for youth. The objective of this study is to quantify and assess Head Impact Exposure (HIE) metrics among youth and collegiate football players. This multi-season study enrolled 639 unique athletes (354 collegiate; 285 yout...
Article
Full-text available
The long-term neurologic consequences of exposure to repetitive head impacts (RHI) are not well understood. This study used magnetic resonance spectroscopy (MRS) to examine later-life neurochemistry and its association with RHI and clinical function in former National Football League (NFL) players. The sample included 77 symptomatic former NFL play...
Article
Objectives Head impact exposure (HIE) in youth football is a public health concern. The objective of this study was to determine if one season of HIE in youth football was related to cognitive changes. Method Over 200 participants (ages 9–13) wore instrumented helmets for practices and games to measure the amount of HIE sustained over one season....
Article
The objective of this study was to determine the psychometrics (reliability, validity) of the original Standardized Assessment of Concussion (SAC) in a youth sample (ages 11 to 13). Demographic factors of race, level of vocabulary knowledge, mother’s level of education were also considered. Over 150 youth football athletes completed the SAC and a b...
Article
Background Concern for head injuries is widespread and has been reported by the media to be the number one cause of decreased participation in football among the American youth population. Identifying player mechanisms associated with intentional, or purposeful, head impacts should provide critical data for rule modifications, educational programs,...
Article
Objectives: The Ice Hockey Summit III provided updated scientific evidence on concussions in hockey to inform these 5 objectives: (1) describe sport related concussion (SRC) epidemiology; (2) classify prevention strategies; (3) define objective, diagnostic tests; (4) identify treatment; and (5) integrate science and clinical care into prioritized...
Article
Full-text available
Physical differences between youth and adults, which include incomplete myelination, limited neck muscle development, and a higher head-body ratio in the youth population, likely contribute towards the increased susceptibility of youth to concussion. Previous research efforts have considered the biomechanics of concussion for adult populations, but...
Article
Full-text available
Objectives The Ice Hockey Summit III provided updated scientific evidence on concussions in hockey to inform these five objectives: (1) describe sport related concussion (SRC) epidemiology, (2) classify prevention strategies, (3) define objective, diagnostic tests, (4) identify treatment and (5) integrate science and clinical care into prioritized...
Article
The Ice Hockey Summit III provided updated scientific evidence on concussions in hockey to inform these five objectives: 1) describe sport-related concussion (SRC) epidemiology, 2) classify prevention strategies, 3) define objective, diagnostic tests, 4) identify treatment, and 5) integrate science and clinical care into prioritized action plans an...
Article
Full-text available
This study aimed to compare head impact exposures between practices and games in football players ages 9 to 14, who account for approximately 70% of all football players in the US. Over a period of two seasons, 136 players were enrolled from three youth programs and 49,847 head impacts were recorded from 345 practices and 137 games. During the stud...
Article
Full-text available
Kinematic measurements of head impacts are sensitive to sports concussion, but not highly specific. One potential reason is these measures reflect input conditions only and may have varying degrees of correlation to regional brain tissue deformation. In this study, previously reported head impact data recorded in the field from high school and coll...
Article
Context: Despite the growing popularity of ice hockey among female youth and interest in the biomechanics of head impacts in sport, the head impacts sustained by this population have yet to be characterized. Objectives: To describe the number of, biomechanical characteristics of, and exposure to head impacts of female youth ice hockey players du...
Book
Full-text available
This book is open access under a CC BY-NC 2.5 license. This book covers the latest in snow sport epidemiology, snow sport injuries and treatment, and biomechanical/mechanical engineering related to snow sports injuries (mechanisms of injury, injury prevention by equipment design, injury prevention by design of resort features, and more). It brings...
Article
Epidemiological evidence suggests that female athletes may be at a greater risk of concussion than their male counterparts. The purpose of this study was to examine the biomechanics of head impacts associated with diagnosed concussions in a cohort of female collegiate ice hockey players. Instrumented helmets were worn by 58 female ice hockey player...
Article
To present currently known basic science and on-ice influences of sport related concussion (SRC) in hockey, building upon the Ice Hockey Summit I action plan (2011) to reduce SRC. The prior summit proceedings included an action plan intended to reduce SRC. As such, the proceedings from Summit I served as a point of departure, for the science and di...
Article
OBJECTIVE: To present currently known basic science and on-ice influences of sport-related concussion (SRC) in hockey, building on the Ice Hockey Summit I action plan (2011) to reduce SRC. METHODS: The prior summit proceedings included an action plan intended to reduce SRC. As such, the proceedings from Summit I served as a point of departure, for...
Article
Full-text available
Context: Concussion injury rates in men's and women's ice hockey are reported to be among the highest of all collegiate sports. Quantification of the frequency of head impacts and the magnitude of head acceleration as a function of the different impact mechanisms (eg, head contact with the ice) that occur in ice hockey could provide a better under...
Article
Full-text available
Sports-related concussion is a major public health problem in the United States and yet, its biomechanical mechanisms remain unclear. In vitro studies demonstrate axonal elongation as a potential injury mechanism; however, current response-based injury predictors (e.g., maximum principal strain, ε_ep) typically do not incorporate axonal orientation...
Article
S portS-related concussions were once believed to only result in transient symptoms and neurocogni-tive impairment. However, recent research has suggested potential links between repetitive concussions and neurodegenerative processes in some athletes. 6,12,13 This work has led to increased awareness and media attention on the possible long-term eff...
Article
Sports-related concussions result in 300,000 brain injuries in the United States each year. We conducted a study utilizing an in-helmet system that measures and records linear head accelerations to analyze head impacts in collegiate football. The Head Impact Telemetry (HIT) System is an in-helmet system with six spring-mounted accelerometers and an...
Article
Full-text available
Of all sports, football accounts for the highest incidence of concussion in the US due to the large number of athletes participating and the nature of the sport. While there is general agreement that concussion incidence can be reduced through rule changes and teaching proper tackling technique, there remains debate as to whether helmet design may...
Article
To determine whether exposure to repetitive head impacts over a single season affects white matter diffusion measures in collegiate contact sport athletes. A prospective cohort study at a Division I NCAA athletic program of 80 nonconcussed varsity football and ice hockey players who wore instrumented helmets that recorded the acceleration-time hist...
Article
Wrist injuries during snowboarding are very common. An instrumented snowboarding glove was developed to measure flexion/extension of the wrist in the sagittal plane, as well as forces and moments at the hand and wrist joint during snowboarding. On-slope data were analyzed from 128 falls resulting in hand impacts for 20 snowboarders. Impact forces a...
Article
The purpose of this study was to quantify head impact exposure (frequency, location and magnitude of head impacts) for individual male and female collegiate ice hockey players and to investigate differences in exposure by sex, player position, session type, and team. Ninety-nine (41 male, 58 female) players were enrolled and 37,411 impacts were rec...
Article
A number of human head finite element (FE) models have been developed from different research groups over the years to study the mechanisms of traumatic brain injury. These models can vary substantially in model features and parameters, making it important to evaluate whether simulation results from one model are readily comparable with another, an...
Conference Paper
Periodic assessments of motor function in children with Cerebral Palsy can enable clinicians to make more informed decisions about the type and timing of treatment interventions. Current clinical practice is limited to sporadic assessments performed in a clinical environment and hence, not suitable for capturing small changes that occur longitudina...
Article
Full-text available
The wrist is the most frequently injured body region among snowboarders. Studies have shown that the risk of sustaining a wrist injury can be reduced by wearing wrist protection. Currently, there are a wide variety of wrist protection products for snowboarding on the market that offer a range of protective features. However, there are no minimum pe...
Article
Full-text available
In a previous analysis of ImPACT scores relative to traditional neuropsychological tests (NP) and experimental tasks (Maerlender et al., 2010 ) we demonstrated convergent construct validity for the primary ImPACT test-score composites. A complete analysis of discriminant validity was not undertaken at that time. Here, test scores from the 54 colleg...
Article
Purpose: This study compares the frequency and severity of head impacts sustained by football players on days with and without diagnosed concussion and to identify the sensitivity and specificity of single-impact severity measures to diagnosed injury. Methods: One thousand two hundred eight players from eight collegiate football teams and six hi...
Article
Purpose: Concussions are commonly undiagnosed in an athletic environment because the postinjury signs and symptoms may be mild, masked by the subject, or unrecognized. This study compares measures of head impact frequency, location, and kinematic response before cases of immediate and delayed concussion diagnosis. Methods: Football players from...
Article
Full-text available
Object: Concussive head injuries have received much attention in the medical and public arenas, as concerns have been raised about the potential short- and long-term consequences of injuries sustained in sports and other activities. While many student athletes have required evaluation after concussion, the exact definition of concussion has varied...
Article
Full-text available
Recent research has suggested a possible link between sports-related concussions and neurodegenerative processes, highlighting the importance of developing methods to accurately quantify head impact tolerance. The use of kinematic parameters of the head to predict brain injury has been suggested because they are indicative of the inertial response...
Article
The clinical management of children with Cerebral Palsy (CP) relies upon periodic assessments of changes in the severity of gait deviations in response to clinical interventions. Current clinical practice is limited to sporadic assessments in a clinical environment and hence it is limited in its ability to estimate the impact of CP-related gait dev...
Article
To determine whether exposure to repetitive head impacts over a single season negatively affects cognitive performance in collegiate contact sport athletes. This is a prospective cohort study at 3 Division I National Collegiate Athletic Association athletic programs. Participants were 214 Division I college varsity football and ice hockey players w...
Article
Full-text available
The purpose of this study was to quantify the severity of head impacts sustained by individual collegiate football players and to investigate differences between impacts sustained during practice and game sessions, as well as by player position and impact location. Head impacts (N = 184,358) were analyzed for 254 collegiate players at three collegi...
Article
Full-text available
On-field monitoring of head impacts, combined with finite element (FE) biomechanical simulation, allow for predictions of regional strain associated with a diagnosed concussion. However, attempts to correlate these predictions with in vivo measures of brain injury have not been published. This article reports an approach to and preliminary results...
Article
It is estimated that 10-20% of United States soldiers returning from Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF) have suffered at least one instance of blast-induced traumatic brain injury (bTBI) with many reporting persistent symptomology and long-term effects. This variation in blast response may be related to the complexit...
Article
Full-text available
Over the last decade, advances in technology have enabled researchers to evaluate concussion biomechanics through measurement of head impacts sustained during play using two primary methods: (1) laboratory reconstruction of open-field head contact, and (2) instrumented helmets. The purpose of this study was to correlate measures of head kinematics...
Article
The age at which young hockey players should safely body check is unknown. We sought to determine if playing position (defensemen vs. forwards), event type (practice vs. game), or head impact location (top vs. back vs. front vs. sides) had an effect on head impact biomechanics in youth hockey. A total of 52 Bantam (13-14 years old) and Midget (15-1...
Article
The paper reports on a symposium on sports helmets and presents a synthesis of information and opinion from a range of presenters and disciplines. A review of the literature shows that helmets play an important role in head injury prevention and control. Helmets have been shown to be very efficacious and effective in a range of sports and in preven...
Article
Generating subject-specific, all-hexahedral meshes for finite element analysis continues to be of significant interest in biomechanical research communities. To date, most automated methods "morph" an existing atlas mesh to match with a subject anatomy, which usually result in degradation in mesh quality because of mesh distortion. We present an au...
Article
To evaluate the effect of cervical muscle strength on head impact biomechanics. Prospective cohort. Field setting. Thirty-seven volunteer ice hockey players (age = 15.0 ± 1.0 years, height = 173.5 ± 6.2 cm, mass = 66.6 ± 9.0 kg, playing experience = 2.9 ± 3.7 years). Participants were equipped with accelerometer-instrumented helmets to collect head...
Article
Full-text available
In American football, impacts to the helmet and the resulting head accelerations are the primary cause of concussion injury and potentially chronic brain injury. The purpose of this study was to quantify exposures to impacts to the head (frequency, location and magnitude) for individual collegiate football players and to investigate differences in...
Article
Passive-elastic foot prostheses cannot produce net work. Consequently, passive-elastic foot prostheses are limited in their ability to enable a biologically-realistic gait pattern in transtibial amputees. This shortcoming results in difficulties in balance and walking and leads to high levels of oxygen consumption during locomotion. A powered prost...
Article
The objective of this proceedings is to integrate the concussion in sport literature and sport science research on safety in ice hockey to develop an action plan to reduce the risk, incidence, severity, and consequences of concussion in ice hockey. A rationale paper outlining a collaborative action plan to address concussions in hockey was posted f...
Article
Full-text available
The results of a comparative study of five aluminum and one wood baseball bats are presented. The study includes an analysis of field data, high-speed laboratory testing, and modal analysis. It is found that field performance is strongly correlated with the ball–bat coefficient of restitution (BBCOR) and only weakly correlated with other parameters...
Article
The objective of this proceeding is to integrate the concussion in sport literature and sport science research on safety in ice hockey to develop an action plan to reduce the risk, incidence,severity, and consequences of concussion in ice hockey. methods: A rationale paper outlining a collaborative action plan to address concussions in hockey was p...
Article
This study aimed to quantify the frequency, magnitude, and location of head impacts sustained by male and female collegiate ice hockey players during two seasons of play. During two seasons, 88 collegiate athletes (51 females, 37 males) on two female and male National Collegiate Athletic Association varsity ice hockey teams wore instrumented helmet...
Article
The high incidence rate of concussions in football provides a unique opportunity to collect biomechanical data to characterize mild traumatic brain injury. The goal of this study was to validate a six degree of freedom (6DOF) measurement device with 12 single-axis accelerometers that uses a novel algorithm to compute linear and angular head acceler...
Article
Sports-related brain injuries rapidly are reaching epidemic levels, with an estimated incidence range of 1.6 to 3.8 million in the United States per year (7,17). These values likely underestimate the true incidence because of underreporting by athletes (18), and the limitations of current national injury databases (7,17) have prompted Congress to m...
Article
Full-text available
Measuring head impact exposure is a critical step toward understanding the mechanism and prevention of sport-related mild traumatic brain (concussion) injury, as well as the possible effects of repeated subconcussive impacts. To quantify the frequency and location of head impacts that individual players received in 1 season among 3 collegiate teams...
Article
Full-text available
Although computerized neuropsychological screening is becoming a standard for sports concussion identification and management, convergent validity studies are limited. Such studies are important for several reasons: reference to established measures is needed to establish validity; examination of the computerized battery relative to a more traditio...
Article
The objective was to determine how body collision type and player anticipation affected the severity of head impacts sustained by young athletes. For anticipated collisions, we sought to evaluate different body position descriptors during delivery and receipt of body collisions and their effects on head impact severity. We hypothesized that head im...
Article
Full-text available
The performance characteristics of football helmets are currently evaluated by simulating head impacts in the laboratory using a linear drop test method. To encourage development of helmets designed to protect against concussion, the National Operating Committee for Standards in Athletic Equipment recently proposed a new headgear testing methodolog...
Article
Full-text available
Although injury risk factors can be described In biomechanical terms, previous research has not described the relationship between style of play and the frequency and magnitude of head impacts. This paper is focused on the analysis of head impact profiles and safe hockey behaviors demonstrated during contact situations in a cohort of 13 Bantam-aged...
Article
Spinal cord injury involves three phases. In the first, trauma events deliver direct pressure to the cervical spine, which may compress, dislocate, or fracture the spine, and in turn compress, crush, or transect the spinal cord. In the process, local neurons are destroyed and sensory and motor pathways can be severed. In the second phase, acute tis...
Article
Full-text available
It is common for athlete exposure (AE) and body contact (BC) to be incorrectly estimated in epidemiologic research due to the technical challenges associated with field-based research in ice hockey. Time-on-task technology has shown promise in accurately quantifying AE and BC using computer technology through direct measurement during real time gam...
Article
Full-text available
The clinical management of children with cerebral palsy (CP) relies on monitoring changes in the severity of gait abnormalities and on planning appropriate clinical interventions. Currently available technology does not make it possible to perform clinical gait evaluations as often as it would be desirable from a clinical standpoint. The use of wea...
Article
In spite of the broad popularity of ice hockey, little has been done to characterize the performance of pucks or sticks used in play. Data representative of play conditions is particularly lacking. A high speed impact test was developed to measure the puck impact force and coefficient of restitution. Puck brand, temperature, and speed were all show...
Article
Full-text available
There is increasing concern among parents, coaches, and officials about injury risk in youth ice hockey, particularly in light of recent evidence suggesting that incidence of serious injury is considerably under reported. However, an adequate method for ascertaining injury risk for concussion does not yet exist. The purpose of this study was to exa...
Article
Full-text available
A pilot study was performed to measure head impact accelerations in collegiate men's ice hockey during the 2005–2007 seasons using helmets instrumented with Head Impact Telemetry System technology to monitor and record linear head accelerations and impact locations in situ. The objectives of this study were 1 to quantify the relationship between re...
Article
Several randomly selected models of three types of protective equipment for ice hockey, protective cups, shoulder pads, and shin pads, were tested according to CEN/TS 15256. Three of the nine models of genital protectors, three of the four models of shoulder pads, and four of the fifteen models of shin pads exceeded the threshold limits defined in...
Article
Following the death of a youth hockey coach in a fight with a parent in 2000, the Mayo Clinic Sports Medicine Center and Minnesota Hockey collaborated to implement a three-component Hockey Education Program (HEP). HEP was initiated in 2003 to ensure youth players develop sportsmanship, skills, and a Fair Play approach to the game. Another goal was...
Article
This paper reports on the results of a study to determine the protective characteristics of ice hockey helmets when tested using two different methodologies. The first methodology involved a traditional monorail drop impact test commonly used In North American ice hockey helmet standards (i.e., ASTM F1045, CSA Z262.1 ). This involves a guided freef...
Article
Ice hockey ranks among the highest of all sports for rates of concussion, and estimates from youth hockey appear ominously close to estimates from the NHL (23.15 and 29.59 per 1000 player-hours, respectively), yet concussion is seldom studied in the youth setting, particularly in a way that accounts for under-reporting. To maximize the capture of c...
Article
This paper will discuss the duties facility owners and operators owe participants and spectators in the ice skating and ice hockey environment. These duties have been established by case law, standards in the industry, and the safety and risk management literature in sports and recreation. There will also be a discussion of court cases that illustr...
Article
Full-text available
Physical conditioning, technical ability, contact, and protective equipment have been identified through research as factors that can potentially contribute to the incidence of injuries in ice hockey players. One safety-related factor often overlooked Is the interaction between the skate blade and the Ice. Skating Is one of the fundamental skills o...
Article
In this study, the relationship between flagrant impacts to the head and peaktranslational and rotational accelerations in reconstructed Ice hockey impacts was examined. A Hybrid III head-neck complex attached to a sliding table and equipped with nine accelerometers was fitted with an ice hockey helmet and impacted under various striking conditions...