Christopher A. DiCesare

Augmented Feedback Supports Skill Transfer and Reduces High-Risk Injury Landing Mechanics A Double-Blind, Randomized Controlled Laboratory Study

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.

Rates of Concussion Are Lower in National Football League Games Played at Higher Altitudes

STUDY DESIGN Retrospective epidemiologic investigation. OBJECTIVE To investigate the relationship between altitude and concussion rate in the National Football League (NFL). Because of the physiologic responses that occur during acclimatization to altitude, it was hypothesized that games played on fields at a higher altitude would have reduced concussion rates compared to games played on fields at a lower altitude. BACKGROUND Recent research indicates that the elevation above sea level at which football games are played may be associated with the likelihood of a concussion in high school football athletes. METHODS Data on incident concussions and athlete exposures for the first 16 weeks of the NFL 2012 and 2013 regular seasons were obtained from publicly available web-based sources and used to calculate competition concussion rates for each NFL stadium. Concussion rates were analyzed in relation to game elevation. RESULTS During the first 16 weeks of the 2012 and 2013 NFL regular seasons, 300 concussions, involving 284 players, were reported (64.3 primary cases per 10,000 game exposures). The odds of a concussion were 30% lower when playing at a higher elevation (equal to or greater than 644 ft [196.3 m] above sea level) compared to a lower elevation (odds ratio = 0.70; 95% confidence interval: 0.53, 0.94). A multivariable generalized linear model controlling for season, week, and clustering of team at home and away confirmed these results, showing that the odds of at least 1 concussion were reduced by 32% in games played at higher elevation. CONCLUSION The results of this epidemiological investigation indicate that increased altitude was associated with a reduction in the odds of a sport-related concussion in NFL athletes. The reported relationship of concussion incidence and field elevation should be further investigated, and, if verified, further work will be needed to understand why that relationship exists. LEVEL OF EVIDENCE Prognosis, level 2c.

Preliminary Evidence of Altered Biomechanics in Adolescents With Juvenile Fibromyalgia

Juvenile fibromyalgia (FM) is characterized by chronic musculoskeletal pain and marked reduction in physical activity. Despite recommendations for exercise to manage juvenile FM pain, exercise adherence is poor. Because of pain and activity avoidance, adolescents with juvenile FM are at risk for altered joint mechanics that may make them susceptible to increased pain and reduced tolerance for exercise. The primary aim of this study was to assess functional deficits in patients with juvenile FM compared to healthy controls using objective biomechanical assessment.

Real-time biofeedback to target risk of anterior cruciate ligament injury: a technical report for injury prevention and rehabilitation.

CONTEXT Biofeedback training enables an athlete to alter biomechanical and physiological function by receiving biomechanical and physiological data concurrent with or immediately after a task. OBJECTIVE To compare the effects of 2 different modes of real-time biofeedback focused on reducing risk factors related to anterior cruciate ligament injury. DESIGN Randomized crossover study design. SETTING Biomechanics laboratory and sports medicine center. PARTICIPANTS Female high school soccer players (age 14.8 ± 1.0 y, height 162.6 ± 6.8 cm, mass 55.9 ± 7.0 kg; n = 4). INTERVENTION A battery of kinetic- or kinematic-based real-time biofeedback during repetitive double-leg squats. MAIN OUTCOME MEASURES Baseline and posttraining drop vertical jumps were collected to determine if either feedback method improved high injury risk landing mechanics. RESULTS Maximum knee abduction moment and angle during the landing was significantly decreased after kinetic-focused biofeedback (P = .04). The reduced knee abduction moment during the drop vertical jumps after kinematic-focused biofeedback was not different (P = .2). Maximum knee abduction angle was significantly decreased after kinetic biofeedback (P < .01) but only showed a trend toward reduction after kinematic biofeedback (P = .08). CONCLUSIONS The innovative biofeedback employed in the current study reduced knee abduction load and posture from baseline to posttraining during a drop vertical jump.

Quantification and analysis of saccadic and smooth pursuit eye movements and fixations to detect oculomotor deficits

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.

White matter alterations over the course of two consecutive high-school football seasons and the effect of a jugular compression collar: A preliminary longitudinal diffusion tensor imaging study

The cumulative effects of repetitive subclinical head impacts during sports may result in chronic white matter (WM) changes and possibly, neurodegenerative sequelae. In this pilot study, we investigated the longitudinal WM changes over the course of two consecutive high‐school football seasons and explored the long‐term effects of a jugular vein compression collar on these WM alterations. Diffusion tensor imaging data were prospectively collected both pre‐ and postseason in the two consecutive seasons. Participants were assigned into either collar or noncollar groups. Tract‐based spatial statistics (TBSS) approach and region of interest‐based approach were used to quantify changes in WM diffusion properties. Despite comparable exposure to repetitive head impacts, significant reductions in mean, axial, and/or radial diffusivity were identified in Season 1 in multiple WM regions in the noncollar group but not in the collar group. After an 8‐ to 9‐month long off‐season, these changes observed in the noncollar group partially and significantly reversed but also remained significantly different from the baseline. In Season 2, trend level WM alterations in the noncollar group were found but located in spatially different regions than Season 1. Last, the WM integrity in the collar group remained unchanged throughout the four time points. In conclusion, we quantitatively assessed the WM structural changes and partial reversal over the course of two consecutive high‐school football seasons. In addition, the mitigated WM alterations in athletes in the collar group might indicate potential effect of the collar in ameliorating the changes against repetitive head impacts. Hum Brain Mapp 39:491–508, 2018.

A pilot study of biomechanical assessment before and after an integrative training program for adolescents with juvenile fibromyalgia.

BackgroundAdolescents with juvenile fibromyalgia (JFM) tend to be very sedentary and avoid participation in physical activity. A prior study suggested that JFM patients show altered biomechanics compared to healthy adolescents which may make them more prone to pain/injury during exercise. A new intervention combining well established cognitive behavioral therapy (CBT) techniques with specialized neuromuscular exercise —Fibromyalgia Integrative Training for Teens (FIT Teens) was developed and shown to be promising in improving functioning in adolescents with JFM. In contrast to traditional exercise programs such as aerobic or resistance training, neuromuscular training is a tailored approach which targets gait, posture, balance and movement mechanics which form the foundation for safe exercise participation with reduced risk for injury or pain (and hence more tolerable by JFM patients). The aim of this pilot feasibility study was to establish whether objective biomechanical assessment including sophisticated 3-D motion analysis would be useful in measuring improvements in strength, balance, gait, and functional performance after participation in the 8-week FIT Teens program.MethodsEleven female participants with JFM (ages 12–18 years) completed pre- and post-treatment assessments of biomechanics, including walking gait analysis, lower extremity strength assessment, functional performance, and dynamic postural stability.ResultsDescriptive data indicated that mechanics of walking gait and functional performance appeared to improve after treatment. Hip abduction strength and dynamic postural control also demonstrated improvements bilaterally.ConclusionsOverall, the results of this pilot study offer initial evidence for the utility of biomechanical assessment to objectively demonstrate observable changes in biomechanical performance after an integrated training intervention for youth with JFM. If replicated in larger controlled studies, findings would suggest that through the FIT Teens intervention, adolescents with JFM can progress towards normalized strength and biomechanics, which may enhance their ability to engage in physical exercise.

Red Blood Cell Response to Blast Levels of Force Impartations Into Freely Moveable Fluid Surfaces Inside a Closed Container

Background: Blast waves have plagued mankind for centuries, yet their interaction with blood has been largely overlooked. Recent studies of ways to mitigate traumatic brain injury (TBI) in sport have utilized slosh reducing techniques with varying success. However, hydrodynamic principles have not been used to assess the interaction of intense blast waves and the red blood cells themselves. Objective: To establish the benefits of slosh reduction by analyzing the degree of damaging effects from a blast wave imparted on human red blood cells both fully and partially contained by rigid surfaces. Methods: Approximately 40 mL of blood was collected from 13 males and 25 females ages 18 – 55 and aliquoted into three separate steel containers (5 cc- control, 15 cc- full and 10 cc -partially filled) in preparation for blast testing. An improvised explosive device (IED) blast level model (Vandenberg) was developed by using a nail gun plunger to impart approximately 150 kPa of pressure over a 4 to 6 microsecond timespan into a target container. Blood in steel containers, with and without IED blast exposure, was assayed for cell hemolysis products including serum free hemoglobin (HgB), lactate dehydrogenase (LDH), and potassium (K-ABL) when the containers were fully-filled or partially filled (no-slosh versus slosh). Hemolysis products were measured 1 hour, 4 hrs, 24 hrs, 48 hrs, and 72 hrs after blast exposure. Results: In both the slosh and no-slosh groups, hemolysis increased significantly at each time point after IED blast energy impartation. However, the no-slosh blood samples had less hemolysis. Compared to the slosh group, blood from the no slosh group contained less extracellular HgB (p<.0001), lactate dehydrogenase (LDH) (p<.0001), and potassium (K+) (p<.0001) at all time points. Conclusions: Damage to human blood resulting from the impartation of a force similar to an IED blast was mitigated by fully containing blood within a volume and thereby reducing fluid slosh.

Age-Dependent Patellofemoral Pain: Hip and Knee Risk Landing Profiles in Prepubescent and Postpubescent Female Athletes:

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 PFP development. It was hypothesized that aberrant landing mechanics (reduced sagittal-plane and increased frontal- and transverse-plane kinematics and kinetics) would be associated with an increased risk for PFP. Study Design: Cohort study; Level of evidence, 2. Methods: There were 506 high school female athletes who completed a detailed medical history, the Anterior Knee Pain Scale, and a knee examination for the diagnosis of PFP and attended follow-up appointments. Athletes performed a drop vertical jump task instrumented with force plates, and biomechanical measures generated from standard 3-dimensional biomechanical analyses were used to classify participants into high- or low-risk knee and hip landing profiles for the development of PFP. The biomechanical measures used in the knee landing profile included sagittal-plane knee range of motion, peak knee abduction angle, peak knee abduction moment, and peak-to-peak transverse-plane knee moment. The biomechanical measures used in the hip landing profile included sagittal-plane hip range of motion, peak hip extensor moment, peak abductor moment, and peak hip rotator moment. Testing was conducted at sport-specific preseason appointments over the course of 2 years, and changes in pubertal status, landing profile, and PFP development were documented. Results: Female athletes with high-risk hip landing profiles experienced increased hip flexion and decreased abductor, rotator, and extensor moments. Participants with high-risk hip landing profiles who transitioned to postpubertal status at follow-up had higher odds (odds ratio, 2.1 [95% CI, 1.1-4.0]; P = .02) of moving to a low-risk hip landing profile compared with those who had not reached postpubertal status at follow-up. Participants with high-risk knee landing profiles experienced decreased knee flexion and increased knee abduction, external abductor, and external rotator moments. Pubertal maturation was not associated with a change in the high-risk knee landing profile at follow-up. Conclusion: The progression from prepubertal to postpubertal status may have a protective effect on high-risk hip mechanics but no similar adaptations in high-risk knee mechanics during maturation. These data indicate that before puberty, maladaptive hip mechanics may contribute to PFP, while aberrant knee mechanics associated with PFP are sustained throughout the maturational process in young female athletes.

Reliability of 3-Dimensional Measures of Single-Leg Cross Drop Landing Across 3 Different Institutions: Implications for Multicenter Biomechanical and Epidemiological Research on ACL Injury Prevention

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 the reliability of kinematic and kinetic measures of a single-leg cross drop task across 3 institutions. Study Design: Controlled laboratory study. Methods: Twenty-five female high school volleyball players participated in this study. Three-dimensional motion data of each participant performing the single-leg cross drop were collected at 3 institutions over a period of 4 weeks. Coefficients of multiple correlation were calculated to assess the reliability of kinematic and kinetic measures during the landing phase of the movement. Results: Between-centers reliability for kinematic waveforms in the frontal and sagittal planes was good, but moderate in the transverse plane. Between-centers reliability for kinetic waveforms was good in the sagittal, frontal, and transverse planes. Conclusion: Based on these findings, the single-leg cross drop task has moderate to good reliability of kinematic and kinetic measures across institutions after implementation of a standardized testing protocol. Clinical Relevance: Multicenter collaborations can increase study numbers and generalize results, which is beneficial for studies of relatively rare phenomena, such as ACL injury. An important step is to determine the reliability of risk assessments across institutions before a multicenter collaboration can be initiated.