Adam W. Kiefer

• PhD
• Professor (Assistant) at University of North Carolina at Chapel Hill

This commentary focuses on a complementary theoretical–experimental approach to the target article by Hill, Den Hartigh, Meijer, De Jonge, and Van Yperen (2018). In the target article, the authors develop an initial roadmap for identifying persistent behavioral patterns (i.e., athletic resilience) through measurements to identify specific attractor...

Biomechanical analysis has typically been confined to a laboratory setting. While attempts have been made to take laboratory testing into the field, this study was designed to assess whether augmented reality (AR) could be used to bring the field into the laboratory. This study aimed to measure knee load in volleyball players through a jump task in...

The best predictor of future injury is previous injury and this has not changed in a quarter century despite the introduction of evidence-based medicine and associated revisions to post-injury treatment and care. Nearly nine million sports-related injuries occur annually, and the majority of these require medical intervention prior to clearance for...

Methodologies in applied sport science have predominantly driven a reductionist grounding to component-specific mechanisms to drive athlete training and care. While linear mechanistic approaches provide useful insights, they have impeded progress in the development of more complex network physiology models that consider the temporal and spatial int...

Background: Teens with attention deficit-hyperactivity disorder (ADHD) are at increased risk for motor vehicle collisions. A computerized skills-training program to reduce long glances away from the roadway, a contributor to collision risk, may ameliorate driving risks among teens with ADHD. Methods: We evaluated a computerized skills-training p...

Background: Despite evidence suggesting perceived stress negatively impacts post-concussion outcomes and that mindfulness may improve that relationship, research has not investigated those connections. Methods: This cross-sectional, observational study included 80 young adults with a concussion history who completed a single study visit includin...

Context Postoperative muscle weakness contributes to the development of aberrant gait biomechanics that persist following traditional anterior cruciate ligament reconstruction (ACLR). However, it is unknown if quadriceps weakness impedes the ability of ACLR patients to modify gait biomechanics using a real-time gait biofeedback (RTGBF) intervention...

The current literature on resilience shows a trend toward a dynamic process conceptualization, moving away from the previous trait-approach. However, the term “dynamic” is increasingly treated as a buzzword and is thereby oversimplified in the literature. The aim of this article is to develop a unified language pertaining to resilience as a dynamic...

(1) Background: As digital health technology evolves, the role of accurate medical-gloved hand tracking is becoming more important for the assessment and training of practitioners to reduce procedural errors in clinical settings. (2) Method: This study utilized computer vision for hand pose estimation to model skeletal hand movements during in situ...

Quiet eye (QE), the visual fixation on a target before initiation of a critical action, is associated with improved performance. While QE is trainable, it is unclear whether QE can directly predict performance, which has implications for training interventions. This study predicted basketball shot outcome (make or miss) from visuomotor control vari...

Background Changes in lower limb joint coordination have been shown to increase localized stress on knee joint soft tissue—a known precursor of osteoarthritis. While 50% of individuals who undergo anterior cruciate ligament reconstruction (ACLR) develop radiographic osteoarthritis, it is unclear how underlying joint coordination during gait changes...

Context: Mindfulness interventions (yoga, meditation) in traumatic brain injury populations show promising improvements in injury outcomes. However, most studies include all injury severities and use in-person, general programming lacking accessibility and specificity to the nuance of concussion. Therefore, this study investigated the feasibility...

Knee osteoarthritis is a major cause of global disability and is a major cost for the healthcare system. Lower extremity loading is a determinant of knee osteoarthritis onset and progression; however, technology that assists rehabilitative clinicians in optimizing key metrics of lower extremity loading is significantly limited. The peak vertical co...

Introduction Higher perceived stress negatively impacts concussion recovery, but there are limited data examining connections between perceived stress and concussion. Additionally, higher mindfulness is associated with lower perceived stress, but there is limited research on how mindfulness impacts concussion outcomes. Therefore, this study aimed t...

Purpose of Review To provide an overview of common injuries experienced by esports players and factors that contribute to injury development with the goal of helping clinicians feel more prepared to care for this new patient population and bring attention to the need for more interventional research focusing on esports players’ health. Recent Find...

Objective Examine patterns and predictors of skill learning during multisession Enhanced FOrward Concentration and Attention Learning (FOCAL+) training. Background FOCAL+ teaches teens to reduce the duration of off-road glances using real-time error learning. In a randomized controlled trial, teens with ADHD received five sessions of FOCAL+ traini...

Mobile eye tracking technology enables the objective evaluation of what, when, and how athletes use visual information from the environment to control action in service of skilled performance. This review highlights the strengths, weaknesses, opportunities, and threats (SWOT) to consider before adopting this technology to evaluate visual–motor cont...

Many models of motor performance acknowledge that adapting to stressors plays a major role in how we move. However, most models lack a precise conceptualization of the way in which stress-response dynamics unfold. To fill this void, we first present popular models from the domain of biology and psychology which argue that the impact of a stressor d...

Objective The present study examined the association between executive functioning (EF) and risky driving behaviors in teens with ADHD. Method Teens diagnosed with ADHD (n = 179; Mage = 17.4 years) completed two 15-min drives in a fixed-base driving simulator. EF was assessed using parent- and self-report Behavior Rating Inventory of Executive Fun...

Knee osteoarthritis is a major cause of global disability and is a major cost for the healthcare system. Lower extremity loading is a determinant of knee osteoarthritis onset and progression; however, technology that assists rehabilitative clinicians in optimizing key metrics of lower extremity loading is significantly limited. The peak vertical co...

Introduction: Aberrant gait variability has been observed following anterior cruciate ligament reconstruction (ACLR), yet it remains unknown if gait variability associates with early changes in cartilage composition linked to osteoarthritis development. Our purpose was to determine the association between femoral articular cartilage T1ρ magnetic r...

Factors associated with continued driving during shelter in place orders have been examined in a community sample of typically developing teen drivers, but not in teens diagnosed with Attention/Deficit-Hyperactivity Disorder (ADHD). Our objective was to examine psychosocial factors that predicted risky driving during shelter in place orders in teen...

The practice of early sport specialization, defined as intense year-round training in a single sport at the exclusion of others, is increasing in youth athletics. Despite potential benefits, sport specialization may be detrimental to the health of young athletes, as specialization may increase the risk of musculoskeletal injuries—particularly overu...

Background: Young athletes who specialize early in a single sport may subsequently be at increased risk of injury. While heightened injury risk has been theorized to be related to volume or length of exposure to a single sport, the development of unhealthy, homogenous movement patterns, and rigid neuromuscular control strategies may also be indict...

Head impacts and physical exertion are ubiquitous in American football, but the relationship between these factors is poorly understood across a competitive season or even within an individual session. Gameplay characteristics, including player position and session type, may contribute to these relationships but have not been prospectively examined...

Purpose: The present study investigated Special Operations Forces (SOF) combat Servicemember mental health at different SOF career stages in association with resilience. Methods: Fifty-eight SOF combat Service Members either entering SOF (career start; n=38) or multiple years with their SOF organization (mid-career; n=20) self-reported mild trau...

Purpose: Our aim in this study was to psychometrically test resilience assessments (Ego Resiliency Scale [ER89], Connor-Davidson Resilience Scale [CD-RISC 25], Responses to Stressful Experiences Scale [RSES short-form]) and describe resilience levels in a Special Operations Forces (SOF) combat sample. Methods: Fifty-eight SOF combat Servicemembe...

Context Neuromuscular training (NMT) facilitates the acquisition of new movement patterns that reduce ACL injury risk; however, the neural mechanisms underlying these changes are unknown. Objective Determine the relationship between brain activation and biomechanical changes following NMT with biofeedback. Study Design Controlled Laboratory Study...

Markerless motion capture systems are promising for the assessment of movement in more real world research and clinical settings. While the technology has come a long way in the last 20 years, it is important for researchers and clinicians to understand the capacities and considerations for implementing these types of systems. The current review pr...

Athletes commonly make decisions about the passability of closing gaps when navigating sport environments. This study examined whether increased temporal pressure to arrive at a desired location modifies these decisions. Thirty participants navigated toward a waypoint in a virtual, sport-inspired environment. To do so, they had to decide whether th...

PURPOSE: New methods are needed to identify those at risk of developing posttraumatic osteoarthritis (PTOA). We employed a novel e X plainable machine learning (X-ML) approach to predict PTOA-related symptoms and identify differentiating markers post-anterior cruciate ligament reconstruction (ACLR) via serum biomarkers and patient demographics. MET...

Background Anterior cruciate ligament (ACL) injury is secondary to a multifactorial etiology encompassing anatomical, biological, mechanical, and neurological factors. The nature of the injury being primarily due to non-contact mechanics further implicates neural control as a key injury-risk factor, though it has received considerably less study....

(1) Background: Biomechanics during landing tasks, such as the kinematics and kinetics of the knee, are altered following anterior cruciate ligament (ACL) injury and reconstruction. These variables are recommended to assess prior to clearance for return to sport, but clinicians lack access to the current gold-standard laboratory-based assessment. I...

s Biofeedback has been effectively implemented to improve the mediation and distribution of joint loads during gait, however, the inability to effectively coordinate lower limb movement by altering loading patterns may increase pathological stress and risk of injury and deleterious joint changes. This study examined the influence cueing an increase...

Background: Carotid to femoral pulse wave velocity (cfPWV), the gold-standard measure of aortic stiffness, is associated with the incidence of cardiovascular disease (CVD) events. Most cfPWV measurements depend on technical proficiency, which limit broader implementation in clinical settings. Recently, an estimated pulse wave velocity (ePWV) measur...

presents a novel technology platform for assessing quiet eye performance during esports.

Background The development of stable postural control is characterized by changes in sway variability and periods of rapid reorganization of motor system components. Research question The current study examined whether changing biomechanical and perceptual demands influences the postural control behavior during development. Method The center of p...

Military resilience research is increasing due to the growing literature associating resilience with stress adaptation. This study aimed to investigate which physiological stress adaptation components were associated with resilience in Special Operations Forces combat service members. Special Operations Forces combat service members (n = 117) self‐...

Heart rate variability (HRV) provides insight into the dynamic ways in which individuals adapt to changing environments, reflecting the interaction between parasympathetic and sympathetic systems. For trauma survivors, studies have suggested that survivors may experience inflexible physiological adaptation (e.g., low HRV) or over-responding (e.g.,...

In the past decades, much research has examined the negative effects of stressors on the performance of athletes. However, according to evolutionary biology, organisms may exhibit growth under stress, a phenomenon called antifragility. For both coaches and their athletes, a key question is how to design training conditions to help athletes develop...

This technical report describes the design and implementation of a novel biofeedback system to reduce biomechanical risk factors associated with anterior cruciate ligament (ACL) injuries. The system provided objective real-time biofeedback driven by biomechanical variables associated with increased ACL injury risk without the need of a present expe...

Background: Improving the assessment and training of tracheal intubation is hindered by the lack of a sufficiently validated profile of expertise. Although several studies have examined biomechanics of tracheal intubation, there are significant gaps in the literature. We used 3-dimensional motion capture to study pediatric providers performing sim...

Prospective evidence indicates that functional biomechanics and brain connectivity may predispose an athlete to an anterior cruciate ligament injury, revealing novel neural linkages for targeted neuromuscular training interventions. The purpose of this study was to determine the efficacy of a real‐time biofeedback system for altering knee biomechan...

Anterior cruciate ligament (ACL) injuries are physically and emotionally debilitating for athletes,while motor and biomechanical deficits that contribute to ACL injury have been identified, limited knowledge about the relationship between the central nervous system (CNS) and biomechanical patterns of motion has impeded approaches to optimize ACL in...

Mistaken beliefs pose a barrier to science learning. For this reason, it is important to understand the circumstances in which they emerge and change. In the current paper, we apply complexity theory to shed light on the nature of mistaken beliefs. The strength of this approach lies in conceptualizing beliefs as dynamic stabilities, a well-defined...

Biomechanical analysis can effectively identify factors associated with task performance and injury risk, but often does not account for the interaction among the components that underlie task execution. Uncontrolled manifold (UCM) analyses were applied to data from 38 female, adolescent athletes performing single-leg drop landings and were used to...

Intercepting and impeding an opponent is a fairly common behavior in contact and collision sports such as soccer, football, lacrosse or basketball. In soccer, for example, the main objective of a defender is to intercept and impede an attacking opponent as he or she navigates toward the goal. These athlete vs. athlete interactions often lead to col...

Background Anterior cruciate ligament (ACL) injury is associated with alterations in the central nervous system and resultant sensorimotor control (Courtney et al., 2005; Grooms et al., 2017). Our prospective data indicates that altered knee-motor functional brain connectivity is associated with increased risk for ACL injury (Diekfuss et al., revis...

Context: Existing anterior cruciate ligament (ACL) injury prevention programs have failed to reverse the high rate of ACL injuries in adolescent female athletes. Objective: This investigation attempts to overcome factors that limit efficacy with existing injury prevention programs through the use of a novel, objective, and real-time interactive...

Context: Laboratory-based biomechanical analyses of sport-relevant movements such as landing and cutting have classically been used to quantify kinematic and kinetic factors in the context of injury risk, which are then used to inform targeted interventions designed to improve risky movement patterns during sport. However, the noncontextual nature...

Human motion is highly variable due to the effects of interaction with the environment and the intentionality of movement. Current assistive device control systems struggle to support this variable human motion as they restrict typically uncontrolled degrees of freedom resulting in unnatural, mechanistic and highly repetitive (i.e., artificially in...

The first systematic collaboration between cognitive scientists and sports psychologists considers the mind–body relationship from the perspective of athletic skill and sports practice. This landmark work is the first systematic collaboration between cognitive scientists and sports psychologists that considers the mind–body relationship from the pe...

Exposure to explosive blasts places one at risk for traumatic brain injury, especially for special weapons and tactics (SWAT) and military personnel, who may be repeatedly exposed to blasts. In the current study, the effectiveness of a jugular vein compression collar to prevent alterations in resting-state electrocortical activity following a singl...

Background: Female athletes are at an increased risk of developing patellofemoral pain (PFP) relative to male athletes. The unique effects of maturation may compound that risk. Hypothesis/Purpose: The purpose was to evaluate the neuromuscular control mechanisms that are adaptive to pubertal maturation and determine their relative contribution to P...

Dyslexia, or reading difficulty (RD), is characterized by slow, inaccurate reading and accompanied by deficit in executive functions (EF) and altered functional connectivity (FC) in the related networks (i.e., cingulo‐opercular). Individuals with RD also present with altered oculomotor gaze patterns that include longer fixation times. The researche...

Objective To estimate the incidence proportion (IP) and incidence rate (IR) of ACL injury in football players. Design Systematic review with meta-analysis. Data sources PubMed, CINAHL and SPORTDiscus electronic databases were searched from inception to 20 January 2017. Eligibility criteria for selecting study Studies that reported the total numb...

Context: A limiting factor for reducing anterior cruciate ligament (ACL) injury risk is ensuring that the movement adaptions made during the prevention program transfer to sport-specific activity. Virtual reality provides a mechanism to assess transferability and neuroimaging provides a means to assay the neural processes allowing for such skill t...

Lack of adequate physical activity in children is an epidemic that can result in obesity and other poor health outcomes across the lifespan. Physical activity interventions focused on motor skill competence continue to be developed, but some interventions, such as neuromuscular training (NMT), may be limited in how early they can be implemented due...

The recent debunking by Brown, Sokal, and Friedman of some high-profile results applying chaos theory to positive psychology creates the opportunity to shed light on the quality work that has been done by others in this area. Too many humanists may be unaware of the large volume of legitimate work that exists in the literature apart from Fredrickso...

Approximately 1.5 million senior citizens live under nursing supervision, and most require assistance with at least one or more Activities of Daily Living (ADL). These include transferring in and out of chairs, beds and toilets, which necessitates the ability to perform sit-to-stand transitions. The sit-to-stand transition is a complex full-body ac...

Two conference abstracts from our symposium titled, "Developing Resilience in Athletes and Teams".

Objectives: To evaluate associations between pre-season oculomotor performance on visual tracking tasks and in-season head impact incidence during high school boys ice hockey. Design: Prospective observational study design. Methods: Fifteen healthy high school aged male hockey athletes (M=16.50±1.17years) performed two 30s blocks each of a pro...

Coherent collective behavior emerges from local interactions between individuals that generate group dynamics. An outstanding question is how to quantify group coordination of non-rhythmic behavior, in order to understand the nature of these dynamics at both a local and global level. We investigate this problem in the context of a small group of fo...

Successfully meeting a shared goal usually requires co-actors to adopt complementary roles. However, in many cases, who adopts what role is not explicitly predetermined, but instead emerges as a consequence of the differences in the individual abilities and constraints imposed upon each actor. Perhaps the most basic of roles are leader and follower...

Emerging evidence indicates that repetitive head impacts, even at a sub-concussive level, may result in exacerbated or prolonged neurologic deficits in athletes. This study aimed to: 1) quantify the effect of repetitive head impacts on the alteration of neuronal activity based on fMRI of working memory after a high school football season; and 2) de...

Resistance training often is not an inherent component of current dance training for pediatric female dancers. Reasons for this include concerns surrounding injury to the immature skeleton and diminishing dancer aesthetic appearance, as well as questions related to the effectiveness of such training for increasing dancer strength and muscle enduran...

Background Historical approaches to protect the brain from outside the skull (eg, helmets and mouthpieces) have been ineffective in reducing internal injury to the brain that arises from energy absorption during sports-related collisions. We aimed to evaluate the effects of a neck collar, which applies gentle bilateral jugular vein compression, res...

Objectives Utilize a prospective in vivo clinical trial to evaluate the potential for mild neck compression applied during head impact exposure to reduce anatomical and physiological biomarkers of brain injury. Methods This project utilized a prospective randomized controlled trial to evaluate effects of mild jugular vein (neck) compression (colla...

PART I OF THIS REVIEW DESCRIBES THE MOST IMPORTANT NEUROMUSCULAR SPORTS INJURY RISK FACTORS IN YOUTH ATHLETES: MUSCLE FATIGUE, ALTERED TIMING AND MAGNITUDE OF MUSCLE ACTIVATION, STRENGTH DEFICITS, PREDOMINANCE OF FRONTAL PLANE CONTROL STRATEGIES, NEUROMUSCULAR IMBALANCES BETWEEN LIMBS, INADEQUATE MUSCLE STIFFNESS, DEFICITS IN POSTURAL STABILITY, AL...

Background: Anterior cruciate ligament (ACL) injuries are physically and financially devastating but affect a relatively small percentage of the population. Prospective identification of risk factors for ACL injury necessitates a large sample size; therefore, study of this injury would benefit from a multicenter approach. Purpose: To determine t...