The Influence of Sport-Related Concussion on Lower Extremity Injury Risk: A Review of Current Return-to-Play Practices and Clinical Implications

International Journal of Exercise Science 13(3): 873-889, 2020. Sport-related concussions (SRCs) are now classified as a major health concern affecting athletes across all sporting levels, with recent evidence suggesting upwards of 3.8 million SRCs occur each year. Multiple injury surveillance datasets have recently determined that athletes post-SRC, compared to non-concussed counterparts, are at greater risk for lower extremity (LE) injury beyond the resolution of traditional SRC assessment batteries. However, it is presently uncertain if common clinical practices (symptom reporting, neuropsychological (NP) examination, and static postural control analysis) can determine athletes at risk for LE injury following an SRC. A comprehensive review of the literature determined that these tools may not reveal subtle cognitive and neuromuscular deficits that lead to subsequent LE injury during dynamic sporting tasks. Current return-to-play (RTP) protocols should consider clarifying the addition of specific objective locomotor analysis, such as gait tasks and sport-specific maneuvers, to determine the risk of LE injury after an athlete has sustained an SRC

The Relationship Between Concussion History and Sex on Lower Extremity Biomechanics During a Cutting Task

Athletes with a history of sports related concussion (SRC) have been shown to exhibit lower extremity (LE) mechanics during high impact landing tasks that are conducive to increased injury risk. The underlying cause, and extent of this phenomena is currently unknown. PURPOSE: The purpose of this study was to analyze the relationship between SRC history and sex on LE biomechanics during a land-and-cut task. METHODS: College athletes with a history of SRC and a control group of healthy athletes matched by sport, position, sex, and age were recruited for this study. Both groups were comprised of 9 males and 11 females. Athletes performed an unanticipated land-and-cut task. The task consisted of each athlete standing on a 60 cm box with a visual stimulus positioned three meters away from the athlete. Various colors (green, pink, blue, and red) were presented as the visual stimulus. Athletes were instructed to only respond to a green or red light. When a red or green light was shown, athletes were instructed to step off the box, land on both limbs and perform a 45-degree cutting movement to the left or right, respectively. Two separate point biserial correlations were conducted (one for each sex) correlating group (0 = control, 1 = SRC) with the following dependent variables: vertical ground reaction force (vGRF), peak knee extensor moment (pKEM), peak knee abduction moment (pKAM), peak ankle dorsiflexion angle (pDF), peak knee flexion angle (pKFA), and peak knee abduction angle (pKA). A linear regression equation was obtained for significant correlations. RESULTS: There was a significant negative moderate correlation between group and KF in males (r = -.69, p \u3c .01). There were no other significant correlations between group and LE biomechanical variables in either males or females (p \u3e .05). A linear regression analysis showed SRC history was a significant predictor of KF (KF = 63.71 – 12.43(group); R2 = .473, p = .002) CONCLUSION: Males in the SRC group were associated with lower KF. Specifically, the regression analysis indicated that males with an SRC history had a predicted 12.4 degree decrease in KF during the land-and-cut task. This suggests previously concussed males may be at increased risk for LE injury

The Relationship Between Concussion History And Lower Extremity Biomechanics During A Land And Cut Task

In high impact landing tasks, athletes with a history of sports related concussion (SRC) have been found to demonstrate lower extremity (LE) biomechanics that are associated with elevated injury risk. However, the exact relationships between SRC history and LE biomechanics are inconclusive. PURPOSE: The purpose of this study was to investigate the relationship between SRC history and LE biomechanics during a cutting task. METHODS: A cohort of athletes with a history of SRC (n=20) and a control group of healthy athletes (n=20) were recruited for this study. The control group were matched by age, sex, and sport. Athletes performed an unanticipated land and cut task. Athletes stood on a 60 cm box and focused on a visual light positioned three meters away from them. The light displayed green, pink, blue, or red. Athletes were instructed to step off the box, land on both limbs, and perform a 45-degree cutting maneuver to left or right when they saw red or green light respectively. A point biserial correlation was conducted correlating group (0 = control, 1 = SRC) with the following dependent variables: dominant limb ground reaction force (D_GRF), dominant limb ankle dorsiflexion angle (D_DF), dominant limb knee flexion angle (D_KFA), dominant limb knee flexion moment (D_KFM), dominant limb knee abduction angle (D_KAA), and dominant limb knee abduction moment (D_KAM). A linear regression equation was obtained for any significant correlations. RESULTS: There was a small significant negative correlation between group and KFA (r = -.342, p \u3c .01). There were no other significant correlations between group and LE biomechanical variables (p \u3e .05). A linear regression analysis showed SRC history as a significant predictor of KFA (KFA = 60.24 - 6.16(group); R2 = 0.117, p = .03). CONCLUSION: The SRC group was associated with lower KFA. According to our regression analysis, athletes with an SRC history had predicted a 6.2 degree decrease in KFA compared to the control group during the land and cut task. Furthermore, approximately 12% of the variance in KFA can be explained by SRC. This suggests that previously concussed athletes may be at a higher risk for LE injury. Further research in this area is needed to confirm this relationship

Impaired Self-Other Distinction and Subcortical Gray-Matter Alterations Characterize Socio-Cognitive Disturbances in Multiple Sclerosis

Introduction: Recent studies of patients with multiple sclerosis (MS) have revealed disturbances in distinct components of social cognition, such as impaired mentalizing and empathy. The present study investigated this socio-cognitive profile in MS patients in more detail, by examining their performance on tasks measuring more fundamental components of social cognition and any associated disruptions to gray-matter volume (GMV). Methods: We compared 43 patients with relapse-remitting MS with 43 age- and sex-matched healthy controls (HCs) on clinical characteristics (depression, fatigue), cognitive processing speed, and three aspects of low-level social cognition; specifically, imitative tendencies, visual perspective taking, and emotion recognition. Using voxel-based morphometry, we then explored relationships between GMV and these clinical and behavioral measures. Results: Patients exhibited significantly slower processing speed, poorer perspective taking, and less imitation compared with HCs. These impairments were related to reduced GMV throughout the putamen, thalami, and anterior insula, predominantly in the left hemisphere. Surprisingly, differences between the groups in emotion recognition were not significant. Conclusion: Less imitation and poorer perspective taking indicate a cognitive self-bias when faced with conflicting self- and other-representations. This suggests that impaired self-other distinction, and an associated subcortical pattern of GM atrophy, might underlie the socio-cognitive disturbances observed in MS

Influence of Cognitive Performance on Musculoskeletal Injury Risk: A Systematic Review

Background: While a large number of studies have investigated the anatomic, hormonal, and biomechanical risk factors related to musculoskeletal (MSK) injury risk, there is growing evidence to suggest that cognition is an important injury contributor in the athletic population. A systematic review of the available evidence regarding the influence of cognitive performance on MSK injury risk has yet to be published in the sports medicine literature. Purpose/Hypothesis: The purpose was to determine the effects of cognition on (1) MSK biomechanics during sports-specific tasks and (2) MSK injury occurrence in the athletic population. It was hypothesized that athletes with lower cognitive performance would demonstrate biomechanical patterns suggestive of MSK injury risk and that injured athletes would perform worse on baseline measures of cognition as compared with their noninjured counterparts. Study Design: Systematic review. Methods: PubMed and SPORTDiscus were searched from January 2000 to January 2020. Manual searches were performed on the reference lists of the included studies. A search of the literature was performed for studies published in English that reported MSK biomechanics as a function of cognitive performance and MSK injury occurrence after baseline measures of cognition. Two independent reviewers extracted pertinent study data in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2009 guidelines and assessed study quality using the Quality Assessment Tool for Observational Cohort and Cross-sectional Studies from the National Institutes of Health. A meta-analysis was not performed, owing to the heterogeneous nature of the study designs. Results: Ten studies met inclusion criteria: 4 cognition–MSK biomechanics studies and 6 cognition–MSK injury studies. All 4 cognition–MSK biomechanics studies demonstrated that worse performance on measures of cognition was associated with lower extremity MSK biomechanical patterns suggestive of greater risk for MSK injury. The majority of the cognition–MSK injury studies demonstrated that injured athletes significantly differed on baseline cognition measures versus matched controls or that cognitive performance was a significant predictor for subsequent MSK injury. Conclusion: Although the literature exploring cognitive contributions to MSK injury risk is still in its infancy, it is suggested that sports medicine personnel conduct baseline assessments of cognition—in particular, reaction time and working memory—to identify which athletes may be at elevated risk for future MSK injury

Structural, Electronic, and Magnetic Properties of MnO

We calculate the structural, electronic, and magnetic properties of MnO from first principles, using the full-potential linearized augmented planewave method, with both local-density and generalized-gradient approximations to exchange and correlation. We find the ground state to be of rhombohedrally distorted B1 structure with compression along the [111] direction, antiferromagnetic with type-II ordering, and insulating, consistent with experiment. We show that the distortion can be understood in terms of a Heisenberg model with distance dependent nearest-neighbor and next-nearest-neighbor couplings determined from first principles. Finally, we show that magnetic ordering can induce significant charge anisotropy, and give predictions for electric field gradients in the ground-state rhombohedrally distorted structure.Comment: Submitted to Physical Review B. Replaced: regenerated figures to resolve font problems in automatically generated pd

Weak ferromagnetism with very large canting in a chiral lattice: (pyrimidine)2FeCl2

The transition metal coordination compound (pyrimidine)2FeCl2 crystallizes in a chiral lattice, space group I 4_1 2 2 (or I4_3 2 2). Combined magnetization, Mossbauer spectroscopy and powder neutron diffraction studies reveal that it is a canted antiferromagnet below T_N = 6.4 K with an unusually large canting of the magnetic moments of 14 deg. from their general antiferromagnetic alignment, one of the largest reported to date. This results in weak ferromagnetism with a ferromagnetic component of 1 mu_B. The large canting is due to the interplay between the antiferromagnetic exchange interaction and the local single-ion anisotropy in the chiral lattice. The magnetically ordered structure of (pyrimidine)2FeCl2, however, is not chiral. The implications of these findings for the search of molecule based materials exhibiting chiral magnetic ordering is discussed.Comment: 6 pages, 5 figure

Valency of rare earths in RIn3 and RSn3: Ab initio analysis of electric-field gradients

In RIn3 and RSn3 the rare earth (R) is trivalent, except for Eu and Yb, which are divalent. This was experimentally determined in 1977 by perturbed angular correlation measurements of the electric-field gradient on a 111Cd impurity. At that time, the data were interpreted using a point charge model, which is now known to be unphysical and unreliable. This makes the valency determination potentially questionable. We revisit these data, and analyze them using ab initio calculations of the electric-field gradient. From these calculations, the physical mechanism that is responsible for the influence of the valency on the electric-field gradient is derived. A generally applicable scheme to interpret electric-field gradients is used, which in a transparent way correlates the size of the field gradient with chemical properties of the system.Comment: 10 page