Background There is a current need to produce a simple, yet effective method for screening and targeting possible deficiencies related to increased anterior cruciate ligament (ACL) injury risk. Hypothesis Frontal plane knee angle (FPKA) during a drop vertical jump will decrease upon implementing augmented feedback into a standardized sport training program. Study Design Controlled laboratory study. Methods Thirty-seven female participants (mean ± SD: age, 14.7 ±1.5 years; height, 160.9 ± 6.8 cm; weight, 54.5 ± 7.2 kg) were trained over 8 weeks. During each session, each participant received standardized training consisting of strength training, plyometrics, and conditioning. They were also videotaped running on a treadmill at a standardized speed and performing a repeated tuck jump for 10 seconds. Study participants were randomized into 2 groups and received augmented feedback on either their jumping (AF) or sprinting (CTRL) form. Average (mean of 3 trials) and most extreme (trial with greatest knee abduction) FPKA were calculated from 2-dimensional video captured during performance of the drop vertical jump. Results After testing, a main effect of time was noted, with the AF group reducing their FPKA average by 37.9% over the 3 trials while the CTRL group demonstrated a 26.7% reduction average across the 3 trials (P < .05). Conversely, in the most extreme drop vertical jump trial, a significant time-by-group interaction was noted (P < .05). The AF group reduced their most extreme FPKA by 6.9° (pretest, 18.4° ± 12.3°; posttest, 11.4° ± 10.1°) on their right leg and 6.5° (pretest, 16.3° ± 14.5°; posttest, 9.8° ± 10.7°) on their left leg, which represented a 37.7% and 40.1 % reduction in FPKA, respectively. In the CTRL group, no similar changes were noted in the right (pretest, 16.9° ± 14.3°; posttest, 14.0° ± 12.3°) or left leg (pretest, 9.8° ± 11.1°; posttest, 7.2° ± 9.2°) after training. Conclusion Providing athletes with augmented feedback on deficits identified by the tuck jump assessment has a positive effect on their biomechanics during a different drop vertical jump task that is related to increased ACL injury risk. The ability of the augmented feedback to support the transfer of skills and injury risk factor reductions across different tasks provides exciting new evidence related to how neuromuscular training may ultimately cross over into retained biomechanics that reduce ACL injuries during sport. Clinical Relevance The tuck jump assessment’s ease of use makes it a timely and economically favorable method to support ACL prevention strategies in young girls.

Context Early sport specialization, or the participation in 1 sport year-round to the exclusion of all others, is a growing concern in youth athletics because of its possible association with musculoskeletal injury. The underlying injury risk may be the result of coordination differences that sport-specialized athletes have been speculated to exhibit relative to multisport athletes; however, little evidence exists to support or refute this notion. Objective To examine relative hip- and knee-joint angular-motion variability among adolescent sport-specialized and multisport female adolescent athletes to determine how sport specialization may affect coordination. Design Cohort study. Setting Research laboratory. Patients or Other Participants A total of 366 sport-specialized and 366 multisport adolescent female basketball, soccer, and volleyball players. Intervention(s) Drop–vertical-jump (DVJ) assessment. Main Outcome Measure(s) Average coupling-angle variability (CAV) for hip flexion and knee flexion, knee flexion and ankle flexion, hip flexion and knee abduction, knee flexion and knee abduction, knee flexion and knee internal rotation, and knee abduction and knee internal rotation. Results The sport-specialized group exhibited increased coupling variability in dominant-limb hip flexion and knee flexion (P = .015), knee flexion and knee abduction (P = .014), and knee flexion and knee internal rotation (P = .048) while landing during the DVJ, although they had small effect sizes (η2 = 0.010, 0.010, and 0.007, respectively). No differences were present between groups for any of the other CAV measures of the dominant limb, and no differences were found for any CAV measures of the nondominant limb (all P values &gt; .05). Conclusions Sport specialization was associated with increased variability of critical hip- and knee-joint couplings responsible for effective landing during the DVJ. Altered coordination strategies that involve the hip and knee joints may underlie unstable landings, inefficient force-absorption strategies, or greater contact forces that can place the lower extremities at risk for injury (or a combination of these).

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Sport specialization is a growing trend in youth athletes and may contribute to increased injury risk. The neuromuscular deficits that often manifest during maturation in young, female athletes may be exacerbated in athletes who specialize in a single sport. The purpose of this study was to investigate if sport specialization is associated with increased lower extremity biomechanical deficits pre- to post-puberty in adolescent female athletes. Seventy-nine sport-specialized female adolescent (Mean ± SD age = 13.4 ± 1.8 years) basketball, soccer, and volleyball athletes were identified and matched with seventy-nine multi-sport (soccer, basketball, and volleyball) female athletes from a database of 1,116 female adolescent basketball, soccer, and volleyball athletes who were enrolled in one of two large prospective, longitudinal studies. The athletes were assessed over two visits (Mean ± SD time = 724.5 ± 388.7 days) in which they were classified as pre-pubertal and post-pubertal, respectively. Separate 2 × 2 analyses of covariance were used to compare sport-specialized and multi-sport groups and dominant/non-dominant limbs with respect to pubertal changes in peak knee sagittal, frontal, and transverse plane joint angular measures and moments of force recorded while performing a drop vertical jump task. The sport-specialized group were found to exhibit significantly larger post-pubertal increases in peak knee abduction angle ( p = 0.005) and knee abduction moment ( p = 0.006), as well as a smaller increase in peak knee extensor moment ( p = 0.032) during landing when compared to the multi-sport group. These biomechanical changes are indicative of potentially compromised neuromuscular control that may increase injury risk pre- to post-puberty in sport-specialized female athletes. Consideration of maturation status may be an important factor in assessing the injury risk profiles of adolescent athletes who specialize in sport.

BackgroundHistorical 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, resulting in cerebral venous engorgement to reduce head impact energy absorption during collision. Specifically, we investigated the effect of collar wearing during head impact exposure on brain microstructure integrity following a competitive high school American football season.MethodsA prospective longitudinal controlled trial was employed to evaluate the effects of collar wearing (n=32) relative to controls (CTRL; n=30) during one competitive football season (age: 17.04±0.67 years). Impact exposure was collected using helmet sensors and white matter (WM) integrity was quantified based on diffusion tensor imaging (DTI) serving as the primary outcome.ResultsWith similar overall g-forces and total head impact exposure experienced in the two study groups during the season (p>0.05), significant preseason to postseason changes in mean diffusivity, axial diffusivity and radial diffusivity in the WM integrity were noted in the CTRL group (corrected p<0.05) but not in the collar group (p>0.05). The CTRL group demonstrated significantly larger preseason to postseason DTI change in multiple WM regions compared with the collar group (corrected p<0.05).DiscussionReduced WM diffusivity alteration was noted in participants wearing a neck collar after a season of competitive football. Collar wearing may have provided a protective effect against brain microstructural changes after repetitive head impacts.Trial registration numberNCT02696200.

Assessment of deficits in oculomotor function may be useful to detect visuomotor impairments due to a closed head injury. Systematic analysis schemes are needed to reliably quantify oculomotor deficits associated with oculomotor impairment via brain trauma. We propose a systematic, automated analysis scheme using various eye-tracking tasks to assess oculomotor function in a cohort of adolescents with acute concussion symptoms and aged-matched healthy controls. From these data we have evidence that these methods reliably detect oculomotor deficits in the concussed group, including reduced spatial accuracy and diminished tracking performance during visually guided prosaccade and self-paced saccade tasks. The accuracy and tracking deficits are consistent with prior studies on oculomotor function, while introducing novel discriminatory measures relative to fixation assessments -methodologically, a less complicated measure of performance -and thus represent a reliable and simple scheme of detection and analysis of oculomotor deficits associated with brain injury.

ObjectivesUtilize 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.MethodsThis project utilized a prospective randomized controlled trial to evaluate effects of mild jugular vein (neck) compression (collar) relative to controls (no collar) during a competitive hockey season (males; 16.3 ± 1.2 years). The collar was designed to mildly compress the jugular vein bilaterally with the goal to increase intracranial blood volume to reduce risk of brain slosh injury during head impact exposure. Helmet sensors were used to collect daily impact data in excess of 20 g (games and practices) and the primary outcome measures, which included changes in white matter (WM) microstructure, were assessed by diffusion tensor imaging (DTI). Specifically, four DTI measures: fractional anisotropy, mean diffusivity (MD), axial diffusivity, and radial diffusivity (RD) were used in the study. These metrics were analyzed using the tract-based Spatial Statistics (TBSS) approach – a voxel-based analysis. In addition, electroencephalography-derived event-related potentials were used to assess changes in brain network activation (BNA) between study groups.ResultsFor athletes not wearing the collar, DTI measures corresponding to a disruption of WM microstructure, including MD and RD, increased significantly from pre-season to mid-season (p < 0.05). Athletes wearing the collar did not show a significant change in either MD or RD despite similar accumulated linear accelerations from head impacts (p > 0.05). In addition to these anatomical findings, electrophysiological network analysis of the degree of congruence in the network electrophysiological activation pattern demonstrated concomitant changes in brain network dynamics in the non-collar group only (p < 0.05). Similar to the DTI findings, the increased change in BNA score in the non-collar relative to the collar group was statistically significant (p < 0.01). Changes in DTI outcomes were also directly correlated with altered brain network dynamics (r = 0.76; p < 0.05) as measured by BNA.ConclusionGroup differences in the longitudinal changes in both neuroanatomical and electrophysiological measures, as well as the correlation between the measures, provide initial evidence indicating that mild jugular vein compression may have reduced alterations in the WM response to head impacts during a competitive hockey season. The data indicate sport-related alterations in WM microstructure were ameliorated by application of jugular compression during head impact exposure. These results may lead to a novel line of research inquiry to evaluate the effects of protecting the brain from sports-related head impacts via optimized intracranial fluid dynamics.

Context: A limiting factor for reducing anterior cruciate ligament 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 transfer. Objective: To determine the neural mechanisms for injury risk–reducing biomechanics transfer to sport after anterior cruciate ligament injury prevention training. Design: Cohort study. Setting: Research laboratory. Participants: Four healthy high school soccer athletes. Interventions: Participants completed augmented neuromuscular training utilizing real-time visual feedback. An unloaded knee extension task and a loaded leg press task were completed with neuroimaging before and after training. A virtual reality soccer-specific landing task was also competed following training to assess transfer of movement mechanics. Main Outcome Measures: Landing mechanics during the virtual reality soccer task and blood oxygen level–dependent signal change during neuroimaging. Results: Increased motor planning, sensory and visual region activity during unloaded knee extension and decreased motor cortex activity during loaded leg press were highly correlated with improvements in landing mechanics (decreased hip adduction and knee rotation). Conclusion: Changes in brain activity may underlie adaptation and transfer of injury risk–reducing movement mechanics to sport activity. Clinicians may be able to target these specific brain processes with adjunctive therapy to facilitate intervention improvements transferring to sport.