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Daniel Viggiani and Jack P. Callaghan

Viscoelastic creep generated in the lumbar spine following sustained spine flexion may affect the relationship between tissue damage and perceived pain. Two processes supporting this altered relationship include altered neural feedback and inflammatory processes. Our purpose was to determine how low back mechanical pain sensitivity changes following seated lumbar spine flexion using pressure algometry in a repeated-measures, cross-sectional laboratory design. Thirty-eight participants underwent a 10-minute sustained seated maximal flexion exposure with a 40-minute standing recovery period. Pressure algometry assessed pressure pain thresholds and the perceived intensity and unpleasantness of fixed pressures. Accelerometers measured spine flexion angles, and electromyography measured muscular activity during flexion. The flexion exposure produced 4.4° (2.7°) of creep that persisted throughout the entire recovery period. The perception of low back stimulus unpleasantness was elevated immediately following the exposure, 20 minutes before a delayed increase in lumbar erector spinae muscle activity. Women reported the fixed pressures to be more intense than men. Sustained flexion had immediate consequences to the quality of mechanical stimulus perceived but did not alter pressure pain thresholds. Neural feedback and inflammation seemed unlikely mechanisms for this given the time and direction of pain sensitivity changes, leaving a postulated cortical influence.

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Jeffrey S. Brooks, Kody R. Campbell, Wayne Allison, Andrew M. Johnson, and James P. Dickey

This study quantified head impact exposures for Canadian university football players over their varsity career. Participants included 63 players from one team that participated in a minimum of 3 seasons between 2013 and 2018. A total of 127,192 head impacts were recorded from 258 practices and 65 games. The mean (SD) number of career impacts across all positions was 2023.1 (1296.4), with an average of 37.1 (20.3) impacts per game and 7.4 (4.4) impacts per practice. The number of head impacts that players experienced during their careers increased proportionally to the number of athletic exposures (P < .001, r = .57). Linebackers and defensive and offensive linemen experienced significantly more head impacts than defensive backs, quarterbacks, and wide receivers (P ≤ .014). Seniority did not significantly affect the number of head impacts a player experienced. Mean linear acceleration increased with years of seniority within defensive backs and offensive linemen (P ≤ .01). Rotational velocity increased with years of seniority within defensive backs, defensive and offensive linemen, running backs, and wide receivers (P < .05). These data characterize career metrics of head impact exposure for Canadian university football players and provide insights to reduce head impacts through rule modifications and contact regulations.

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Sindhu Shanker and Balaram Pradhan

Yoga as a movement-based intervention is increasingly considered to improve the motor skills of children with autism spectrum disorder (ASD). However, there is little evidence of the effect of yoga on their motor skills. The current study aims to explore the effect of group yoga program on motor proficiency of children with ASD and feasibility of its inclusion in special schools. Forty-three children with ASD from four special schools were randomized into yoga (n = 23) and control (n = 20) group. A structured yoga program of 45 min for 12 weeks was delivered by trained yoga teachers who also tracked their daily responses. The Bruininks–Oseretsky Test of Motor Proficiency. Second Edition was used to assess both the groups pre- and postintervention. In conclusion, the study highlighted that yoga appears to have a positive impact on the gross motor rather than fine motor proficiency of children with ASD and is feasible to be delivered as group intervention in special schools.

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Allison L. Clouthier, Daniel Borschneck, Colin R. Smith, Michael F. Vignos, Darryl G. Thelen, Kevin J. Deluzio, and Michael J. Rainbow

Trochlear groove geometry and the location of the tibial tubercle, where the patellar tendon inserts, have both been associated with patellofemoral instability and can be modified surgically. Although their effects on patellofemoral biomechanics have been investigated individually, the interaction between the two is unclear. The authors’ aim was to use statistical shape modeling and musculoskeletal simulation to examine the effect of patellofemoral geometry on the relationship between tibial tubercle location and patellofemoral function. A statistical shape model was used to generate new knee geometries with trochlear grooves ranging from shallow to deep. A Monte Carlo approach was used to create 750 knee models by randomly selecting a geometry and randomly translating the tibial tubercle medially/laterally and anteriorly. Each knee model was incorporated into a musculoskeletal model, and an overground walking trial was simulated. Knees with shallow trochlear geometry were more sensitive to tubercle medialization with greater changes in lateral patella position (−3.0 mm/cm medialization shallow vs −0.6 mm/cm deep) and cartilage contact pressure (−0.51 MPa/cm medialization shallow vs 0.04 MPa/cm deep). However, knees with deep trochlear geometry experienced greater increases in medial cartilage contact pressure with medialization. This modeling framework has the potential to aid in surgical decision making.

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Michael A. Samaan, Valentina Pedoia, Matthew S. Tanaka, Richard B. Souza, C. Benjamin Ma, and Xiaojuan Li

Joint coordination variability during walking that is associated with patellofemoral joint cartilage degeneration after anterior cruciate ligament reconstruction are not well understood. The purpose of this study was to assess between-limb differences in joint coordination variability and to determine the relationship of coordination variability with postoperative patellofemoral joint cartilage composition. Thirty-five patients underwent bilateral gait analysis and a magnetic resonance exam of the reconstructed knee joint at 6 months post anterior cruciate ligament reconstruction. Vector coding was used to assess coordination variability during the early (1%–33%), mid (34%–66%), and late (67%–100%) stance phase. The T1ρ/T2 mapping was used to evaluate the glycosaminoglycan–collagen matrix of the patellar and femoral trochlear cartilage. Compared with the uninjured limb, the reconstructed limb exhibited higher hip sagittal/knee sagittal plane coordination variability during midstance as well as higher knee sagittal/ankle sagittal plane coordination variability during both mid and late stance. The hip sagittal/knee sagittal plane coordination variability during midstance predicted 14.6% of the variance in patellar cartilage T1ρ values within the reconstructed limb. In addition, sex of participants was able to predict 32.4% and 13.7% of the variance in femoral trochlea T1ρ and T2 values, respectively. The study results demonstrate that a multijoint mechanism may be associated with early patellofemoral joint cartilage degeneration at 6 months after anterior cruciate ligament reconstruction.

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Jaehun Jung, Layne Case, Samuel W. Logan, and Joonkoo Yun

The purposes of this study were (a) to investigate the prevalence of physical educators who report delivering high-quality instructional practices to students with disabilities and (b) to examine the relationships between teachers’ qualifications and the delivery of high-quality instructional practices. A secondary analysis using data from the School Health Policy and Practice Study 2014 data set was employed. The analytic sample included 256 physical educators who taught students with disabilities. Prevalence estimates of physical educators who reported using high-quality instructional practices were calculated. Two separate binary logistic regressions using weighted data were conducted to evaluate the relative contribution of (a) teacher qualifications and (b) educational degrees in accounting for differences in the use of high-quality instructional practices. Less than half of the sample reported using high-quality instructional practices. Considering the increasing prevalence of students with disabilities in general education classrooms, teacher education programs should prioritize providing teacher candidates with coursework that aligns with the expectations of physical educators who teach students with disabilities.

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Steven M. Hirsch, Christopher J. Chapman, David M. Frost, and Tyson A.C. Beach

Ratio scaling is the most common magnitude normalization approach for net joint moment (NJM) data. Generally, researchers compute a ratio between NJM and (some combination of) physical body characteristics (eg, mass, height, limb length, etc). However, 3 assumptions must be verified when normalizing NJM data this way. First, the regression line between NJM and the characteristic(s) used passes through the origin. Second, normalizing NJM eliminates its correlation with the characteristic(s). Third, the statistical interpretations following normalization are consistent with adjusted linear models. The study purpose was to assess these assumptions using data collected from 16 males and 16 females who performed a single-leg squat. Standard inverse dynamics analyses were conducted, and ratios were computed between the mediolateral and anteroposterior components of the knee NJM and participant mass, height, leg length, mass × height, and mass × leg length. Normalizing NJM-mediolateral by mass × height and mass × leg length satisfied all 3 assumptions. Normalizing NJM-anteroposterior by height and leg length satisfied all 3 assumptions. Therefore, if normalization of the knee NJM is deemed necessary to address a given research question, it can neither be assumed that using (any combination of) participant mass, height, or leg length as the denominator is appropriate nor consistent across joint axes.

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Chia-Cheng Lin, Sunghan Kim, Paul DeVita, Matt Becker, and Stacey Meardon

This study aimed to examine the feasibility of using time-to-contact measures during the perturbation protocol in people with diabetes mellitus. Three-dimension motion capture and force data were collected during 0.5-s perturbations in four directions (forward, backward, right, and left) and at two accelerations (20 and 40 cm/s2) to compute the time-to-contact. Time-to-contact analysis was divided into three phases: perturbation, initial recovery, and final recovery. The statistical analysis showed the main effects of Direction and Phase (p < .01) as well as a Direction by Phase interaction (p < .01). Backward perturbation with lower acceleration and backward/forward perturbation with higher acceleration had deleterious effects on postural stability in people with diabetes mellitus.

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Jason Kostrna and Aaron D’Addario

The mindful sport performance enhancement (MSPE) protocol is designed to enhance mindfulness, emotional regulation, and attentional awareness and control. The MSPE consists of trainer led group sessions teaching the concepts of mindfulness through discussion and meditation practice. However, little research has tested the MSPE protocol’s adaptability and generalizability to National Collegiate Athletic Association (NCAA) Division-I teams and practitioners independent of the MSPE protocol’s creators. Therefore, the aim of the present study was to test the efficacy of an adapted MSPE protocol. The adapted MSPE protocol was delivered to a NCAA Division I team while a second team participated as a potentially equivalent control group. Both teams completed measures of attentional control, flow, rumination, and mindful attention as primary outcome variables. Results revealed significant decreases in rumination and trait anxiety, as well as improvements in concentration control and focusing ability compared with the control group. Findings support the external validity of the MSPE protocol to adapt to independent practitioners and a previously unstudied combination of sport and level of competition.