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Understanding How Athlete Classification Is Supported by Administrators Within National Sport Organizations

Janet A. Lawson and Amy E. Latimer-Cheung

Classification is an essential aspect of parasport. However, the exact roles and responsibilities of parasport administrators related to classification have not yet been fully explored. This study aimed to understand how administrators in national sport organizations support classification. Six administrators participated in semistructured interviews. Critical realist analysis generated three themes: knowledge of classification, classification context, and administrators’ roles related to classification. Knowledge of classification speaks to the importance of administrators’ understanding classification, as well as their reliance on experiential learning and mentorship to understand the classification system and their role within it. Classification context refers to the tension within parasport resulting from competing uses of classification: Some organizations use classification to facilitate participation, while others reserve classification for high-performance athletes. Resultingly, administrators’ roles are responsive to the unique needs of their organization. Altogether, this work describes how administrators may act as knowledge brokers in the parasport context.

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Lower Limb Stiffness During a Loaded Walk and Run Over Different Surfaces

Tyler N. Brown, Eric B. Francis, and Abigail C. Aultz

This study quantified vertical ground reaction forces (vGRFs) and lower limb stiffness for both sexes walking and running with body-borne load over 2 surfaces. Nine males and 9 females had lower limb biomechanics quantified during a walk (1.3 m/s) and run (4.5 m/s) with (15 kg) and without (0 kg) body-borne load over a firm and soft foam surface. vGRF measures, and leg and lower limb joint stiffness were submitted to a linear mixed model. Loaded walking increased very GRF and stiffness measure (all: P < .016). Loaded running increased every GRF measure and knee stiffness (all: P < .033). The foam surface increased peak vGRF (P = .002, P = .010) and knee stiffness (P < .001, P = .004) during the walk and run, and leg (P < .001) and ankle (P = .025) stiffness during the run. Males walked with greater peak vGRF (P = .012), and stiffer hip and ankle (P = .026; P = .012), but ran with a stiffer knee on the foam (P = .041) and stiffer hip on the firm (P = .005) surface than females. Loaded walking and running may elevate injury risk by increasing vertical GRFs and lower limb stiffness. Injury risk may also increase for locomotion over a foam surface, especially for males.

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A 40-Year Contemporary Evolution of Gait and Posture Mechanics in the Journal of Applied Biomechanics

Jason R. Franz, Christopher McCrum, and Tanvi S. Bhatt

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Applied Aspects of Contemporary Motor Control Theories: A Natural Science Perspective

Mark L. Latash

The review is based on theoretical advances in the field of motor control that view the neural control of movements as a subfield of natural science. We accept the theory of hierarchical control of movements with basic commands, reciprocal, and coactivation, at different levels of the hierarchy, from the control of whole-body actions to the control of individual joints and digits. The principle of abundance views the numerous elements participating in all actions as an important feature that allows movements to combine dynamical stability with adaptability. This principle is readily compatible with the uncontrolled manifold hypothesis. These concepts have been applied to analysis of consequences of fatigue, natural aging, and a range of neurological disorders, from large-fiber peripheral neuropathy to brain disorders. Mechanisms of rehabilitation of movement disorders and improvement of motor performance are discussed. Important pieces of information are missing in the described theoretical frameworks in particular those related to mapping between the theoretical levels of control and coordination and neurophysiological circuitry. New directions of studies are sketched that may lead to progress in understanding applied aspects of motor control.

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Shaping the Future of JSR: Efficiency, Visibility, Excellence, and Community

Danilo De Oliveira Silva

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Acute Effects of High-Intensity Interval Running on Plantar Fascia Thickness and Stiffness in Healthy Adults

Lukas Krumpl, Nathan R. Schiele, Dale Cannavan, Lindsay W. Larkins, Ann F. Brown, and Joshua P. Bailey

Plantar fascia (PF) thickness and stiffness have been linked diagnostically to plantar fasciitis. Acute changes to these properties in response to submaximal running have been noted but not yet tested in maximal effort bouts. This study assessed the acute effects of high-intensity interval running on PF thickness and stiffness in healthy adults. Sixteen participants completed 5 maximal effort 400-m sprints with a 1:1 work-to-rest ratio, followed by additional maximal effort trials until fatigue. Thickness and stiffness at the calcaneal origin were measured prerun, postrun, and 30 minutes postrun via ultrasonography and shear wave elastography, respectively. PF thickness and stiffness did not differ between right and left foot (P > .05) and between males and females (P = .067). Thickness and stiffness decreased postrun (0.43 mm, P < .001; 1.54 m·s−1, P < .001) and increased 30 minutes postrun (0.28 mm, P < .002; 1.0 m·s−1, P < .001). No significant difference was found between prerun and 30 minutes postrun thickness (P = .134), but prerun stiffness was higher than 30 minutes postrun (P = .031). These findings indicate that although high-intensity interval running altered both PF thickness and stiffness, 30 minutes of rest allowed some level of recovery in the noninjured PF tissue.

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Hip Muscle Activity and Frontal Plane Lower Extremity Kinematics in Long-Distance Runners With Plantar Fasciitis

Worapong Kongtong and Surasa Khongprasert

Proximal control and lower extremity (LE) movement related to foot function may be an important factor for plantar fasciitis (PF) during running. This study aimed to investigate hip muscle activity and frontal plane LE kinematics during running between long-distance runners with and without PF. The electromyographic amplitude of the hip muscles (tensor fascia latae, gluteus medius, gluteus maximus) and frontal plane LE joint angles (ankle, knee, and hip range of motion during stance phase) of 30 habitually shod long-distance runners (15 with acute PF and 15 healthy controls) were simultaneously recorded using surface electromyography, 8 infrared cameras, and force plates while they ran barefoot at a speed of 3 to 3.67 m·s−1. Independent t test and 2-way analysis of variance were used to analyze the differences for dependent variables. The PF group had significantly lower tensor fascia latae (P = .040, effect size = 0.259) and gluteus medius (P = .014, effect size = 0.197) activation during the swing phase and gluteus maximus (P = .012, effect size = 0.207) activation during the stance phase compared with the control group. Moreover, the PF group showed significantly greater joint angular excursions of the contralateral pelvic drop (P = .049, effect size = 0.75), hip adduction (P = .019, effect size = 0.91), knee abduction (P = .040, effect size = 0.79), and rearfoot eversion (P = .004, effect size = 1.14) during the stance phase than the control group. Adding assessment of hip muscle activity and LE joint angles during running would be beneficial for evaluating runners with PF.

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Synthesizing Research in Sport and Exercise: Transitioning to Real-World Data and Data Science

Jocelyn F. Hafer, David Whiteside, Kenneth M. Kozloff, and Ronald F. Zernicke

The American Society of Biomechanics (ASB) Jim Hay Memorial Award recognizes individuals for their original long-term contributions to the field of biomechanics. The recipient’s work is highlighted at the Jim Hay Symposium held during the ASB annual meeting each year. This paper summarizes the 2024 Jim Hay Symposium, Biomechanics of Exercise and Sport, at the 2024 ASB Annual Meeting in Madison, WI. The symposium was thematically framed around the evolution of integrative, multidisciplinary research in the biomechanical study of human activity and behavior. With the foundations of biomechanical research being laid in controlled laboratory settings, advancements in wearable sensor technology have allowed investigators to capture increasingly sophisticated real-world activity and behavior and physiological data (eg, physical activity, sleep, and heart rate) that may be linked to biomechanical processes (eg, gait biomechanics), which are integral to optimizing health and wellness in the context of human performance, physical activity, exercise, and sport. Wearable sensors enable the collection of unprecedented amounts of meaningful data that can be used to make previously unknown associations among behavior, biomechanics, physiology, and health outcomes that may lead to new and useful scientific insights. These unique discoveries are propelled by multidisciplinary and integrative collaborations in technology, biomechanics, physiology, artificial intelligence, and data science. Human performance, exercise, and sport science inspire and drive integrated new approaches that can reveal how biomechanical data and discoveries may be harnessed to benefit individuals of all abilities across their lifespan.

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Toe Grip Functionality as a Prerequisite of Vertical Jumping Skills in Children: A Longitudinal Study of Preschool Motor Development

Aileen Kotzsch, Andy Papke, and Angela Heine

The capacity to execute vertical jumps is an important motor skill that constitutes a basic requirement not only for many athletic activities but also for coping with everyday demands. As a relatively complex motor pattern, jumping develops considerably during the preschool years. Interestingly, the available literature on prerequisites for the vertical jump to develop is scarce, with only a few studies investigating the role of foot development in children’s changing jumping skills. The present study aims to shed light on the role of foot development in vertical jumping skills of preschoolers. The assessment of relevant aspects of motor development in a group of 463 children at four annual measurement points (mean age at first measurement, t1: 3.49 ± 0.26 years) provided the basis for the present longitudinal study of toe grip functionality in relation to the capacity to execute vertical jumps. A series of multilevel models were fitted to the data to predict children’s jumping skills as measured by means of a standardized motor development test at each time point. Independent of the influences of age and body mass index, toe grip functionality as a proxy for the strength and fine motor capacities of the toes was demonstrated to be a significant predictor, both longitudinally and concurrently, of children’s jumping skills at each of four measurement points. Establishing toe grip functionality at an early age in childhood as a predictor of children’s later jumping skills paves the way for the design and development of intervention approaches targeting these domains of motor development.

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The Utilization of the Landing Error Scoring System in Patients’ Postanterior Cruciate Ligament Reconstruction: An Exploratory Factor Analysis

Amelia S. Bruce Leicht, Xavier D. Thompson, Robin M. Queen, Jordan Rodu, Michael J. Higgins, Kevin M. Cross, Brian C. Werner, Jacob E. Resch, and Joe M. Hart

Context: The landing error scoring system (LESS) was developed to screen healthy individuals for anterior cruciate ligament  (ACL) injury risk factors using a jump landing task. The purpose of this study was to evaluate unique landing error components of a modified LESS scoring criteria to determine its clinical utility in patients following ACL reconstruction (ACLR). Design: An observational cross-sectional study design was implemented to determine if each individual error component of the modified LESS provided unique information in an ACLR patient population. Methods: Post-ACLR patients (N = 194 [47.9% female]) completed the LESS 7.91 (1.80) months after surgery. To complete the LESS, patients stood on a 30-cm plyometric box and jumped down to a ground target, at 50% of their height in front of the box, then completed a maximal vertical jump. The LESS was repeated 3 times. Two video cameras positioned 3 m from the landing area at a height of 1 m above the floor (frontal and sagittal) recorded all trials. Video analysis of landing kinematics was performed to determine scores for each error item using the modified LESS. Itemized error scores for each patient were evaluated using an exploratory factor analysis, and factors were retained if eigenvalues were greater than 1. Results: Our exploratory factor analysis yielded 2 factor groupings. The first factor (λ = 1.61) was comprised of 4 biplanar error items (ie, errors that occur in both the frontal and sagittal plane) that evaluated body segment positioning (eg, hip and knee flexion during landing). The second factor (λ = 1.02) was comprised of 2 errors occurring in the frontal plane that evaluated knee valgus and the overall impression of their landing strategy. Conclusions: Reducing the modified LESS errors to 6-items could improve the efficiency and clinical utilization of the LESS in ACLR patients. An abbreviated version of the modified LESS may guide clinicians’ decision making in gauging patients’ readiness to return to play after ACLR.