Effect of Task Constraints on Neurobiological Systems Involved in Postural Control in Individuals with and without Chronic Ankle Instability.

The purpose of this study is to investigate the effect of task constraints on the neurobiological systems while maintaining postural control under various sensory feedback manipulations in individuals with and without Chronic Ankle Instability (CAI). Forty-two physically active individuals, with and without CAI, were enrolled in a case-control study conducted at a biomechanics research laboratory. All participants underwent the Sensory Organization Test (SOT), which assesses individuals' ability to integrate somatosensory, visual, and vestibular feedback to maintain postural control in double-, uninjured-, and injured-limb stances under six different conditions in which variations in the sway-referenced support surface (platform) and visual surroundings, with and without vision, are manipulated to affect somatosensory and visual feedback.

Differences in pre-season balance among student athletes based on level of contact, age, and sex.

Background: Assessing postural control is important for the assessment of motor function after concussion. Data used for postural control assessment typically do not take the sport played, age, or sex of the athlete into consideration. It is plausible these variables may be significant when making return-to-play decisions.

Understanding the effects of a sudden directional shift in somatosensory feedback and increasing task complexity on postural adaptation in individuals with and without chronic ankle instability.

Background: Individuals with chronic ankle instability (CAI) present somatosensory dysfunction following an initial ankle sprain. However, little is known about how individuals with CAI adapt to a sudden sensory perturbation of instability with increasing task and environmental constraints to maintain postural stability.

Methods: Forty-four individuals with and without unilateral CAI performed the Adaptation Test to a sudden somatosensory inversion and plantarflexion perturbations (environment) in double-, injured-, and uninjured- limbs.

Sensory Reweighting System Differences on Vestibular Feedback With Increased Task Constraints in Individuals With and Without Chronic Ankle Instability.

Context: Chronic ankle instability (CAI) is associated with a less flexible and adaptable sensorimotor system. Thus, individuals with CAI may present an inadequate sensory reweighting system, inhibiting their ability to place more emphasis (upweight) on reliable sensory feedback to control posture. However, how individuals with CAI reweight sensory feedback to maintain postural control in bilateral and unilateral stances has not been established.

The Impact of Differential Knee Laxity on Brain Activation During Passive Knee Joint Loading.

Although higher anterior knee laxity is an established risk factor of ACL injury, underlying mechanisms are uncertain. While decreased proprioception and altered movement patterns in individuals with anterior knee laxity have been identified, the potential impact of higher laxity on brain activity is not well understood. Thus, the purpose of this study is to identify the impact of different magnitudes of knee laxity on brain function during anterior knee joint loading.

Modified proximal thigh kinematics captured with a novel smartphone app in individuals with a history of recurrent ankle sprains and altered dorsiflexion with walking.

Background: We examined sagittal-plane thigh angular kinematics in individuals with and without recurrent ankle sprains using a clinical smartphone app called AccWalker. Sagittal-plane ankle kinematics were also compared to ascertain that altered ankle dorsiflexion, which is typically displayed with chronic ankle instability, is also present in individuals with recurrent ankle sprains.

Methods: Participants with (n = 22) and without (n = 22) recurrent ankle sprains were evaluated on average sagittal-plane ankle kinematics during walking and average sagittal-plane thigh angular kinematics during stepping-in-place with AccWalker.

Neuromotor changes in participants with a concussion history can be detected with a custom smartphone app.

Neuromotor dysfunction after a concussion is common, but balance tests used to assess neuromotor dysfunction are typically subjective. Current objective balance tests are either cost- or space-prohibitive, or utilize a static balance protocol, which may mask neuromotor dysfunction due to the simplicity of the task. To address this gap, our team developed an Android-based smartphone app (portable and cost-effective) that uses the sensors in the device (objective) to record movement profiles during a stepping-in-place task (dynamic movement).

Direction-Specific Signatures of Sport Participation in Center of Pressure Profiles of Division I Athletes.

Background: Descriptive and comparative studies of human postural control generally report effects for component or resultant dimensions of a measured signal, which may obscure potentially important information related to off-cardinal directionality. Recent work has demonstrated highly specific balance behavior that is often not easily reconciled with conventional theories of postural control.

Purpose: The purpose of this study was to quantify the effects of sport-specific training history on directional profiles of center of pressure (COP) displacement and velocity among collegiate athletes.

Relationship of Anterior Cruciate Ligament Volume and T2* Relaxation Time to Anterior Knee Laxity.

Background: High anterior knee laxity (AKL) has been prospectively identified as a risk factor for anterior cruciate ligament (ACL) injuries. Given that ACL morphometry and structural composition have the potential to influence ligamentous strength, understanding how these factors are associated with greater AKL is warranted.

Hypothesis: Smaller ACL volumes combined with longer T2* relaxation times would collectively predict greater AKL.

The Effects of Gluteal Strength and Activation on the Relationship Between Femoral Alignment and Functional Valgus Collapse During a Single-Leg Landing.

Context: A bias toward femoral internal rotation is a potential precursor to functional valgus collapse. The gluteal muscles may play a critical role in mitigating these effects.

Objective: Determine the extent to which gluteal strength and activation mediate associations between femoral alignment measures and functional valgus collapse.

Temporal kinematic differences throughout single and double-leg forward landings.

Screening methods for anterior cruciate ligament (ACL) injuries often involve double-leg landings, though the majority of ACL injuries occur during single-leg landings. Differences in kinematic temporal characteristics between single-leg and double-leg landings are poorly understood. The purpose of this study was to examine discrete and temporal kinematics associated with functional valgus collapse during single-leg and double-leg landings (LAND and LAND).

ACL Size and Notch Width Between ACLR and Healthy Individuals: A Pilot Study.

Background: Given the relatively high risk of contralateral anterior cruciate ligament (ACL) injury in patients with ACL reconstruction (ACLR), there is a need to understand intrinsic risk factors that may contribute to contralateral injury.

Hypothesis: The ACLR group would have smaller ACL volume and a narrower femoral notch width than healthy individuals after accounting for relevant anthropometrics.

Study Design: Cross-sectional study.

Sex Comparisons of In Vivo Anterior Cruciate Ligament Morphometry.

Context: Females have consistently higher anterior cruciate ligament (ACL) injury rates than males. The reasons for this disparity are not fully understood. Whereas ACL morphometric characteristics are associated with injury risk and females have a smaller absolute ACL size, comprehensive sex comparisons that adequately account for sex differences in body mass index (BMI) have been limited.

Sex-Specific Dependence of Linear and Nonlinear Postural Control Metrics on Anthropometrics During Clinical Balance Tests in Healthy Young Adults.

Context: Previous work suggests that balance behavior is a sex-dependent, complex process that can be characterized by linear and nonlinear metrics. Although a certain degree of center of pressure variability may be expected based on sexual dimorphism, there is evidence to suggest that these effects are obscured by potential interactions between sex and anthropometric factors. To date, no study has accounted for such interactive effects using both linear and nonlinear measures.

Potential Mediators of Load-Related Changes in Movement Complexity in Young, Healthy Adults.

Context: Movement screening has become increasingly popular among tactical professionals. This popularity has motivated the design of interventions that cater to improving outcomes on the screens themselves, which are often scored in reference to an objective norm. In contrast to the assumptions underlying this approach, dynamical systems theory suggests that movements arise as a function of continuously evolving constraints and that optimal movement strategies may not exist.

Potential Mediators of Load-Related Decreases in Movement Quality in Young, Healthy Adults.

Context: Predicting and promoting physical performance are important goals within the tactical professional community. Movement screens are frequently used in this capacity but are poor predictors of performance outcomes. It has recently been shown that prediction improved when movement quality was evaluated under load, but the mechanisms underlying this improvement remain unclear.

Changes in Posture Following a Single Session of Long-Duration Water Immersion.

Transitioning between different sensory environments is known to affect sensorimotor function and postural control. Water immersion presents a novel environmental stimulus common to many professional and recreational pursuits, but is not well-studied with regard to its sensorimotor effects upon transitioning back to land. The authors investigated the effects of long-duration water immersion on terrestrial postural control outcomes in veteran divers.

Sport-specific biomechanical responses to an ACL injury prevention programme: A randomised controlled trial.

Anterior cruciate ligament (ACL) injury prevention programmes have not been as successful at reducing injury rates in women's basketball as in soccer. This randomised controlled trial (ClinicalTrials.gov #NCT02530333) compared biomechanical adaptations in basketball and soccer players during jump-landing activities after an ACL injury prevention programme.

A 6-week warm-up injury prevention programme results in minimal biomechanical changes during jump landings: a randomized controlled trial.

Purpose: To examine the extent to which an ACL injury prevention programme modifies lower extremity biomechanics during single- and double-leg landing tasks in both the sagittal and frontal plane. It was hypothesized that the training programme would elicit improvements in lower extremity biomechanics, but that these improvements would be greater during a double-leg sagittal plane landing task than tasks performed on a single leg or in the frontal plane.

Methods: Ninety-seven competitive multi-directional sport athletes that competed at the middle- or high-school level were cluster randomized into intervention (n = 48, age = 15.

Validity and reliability of smartphone orientation measurement to quantify dynamic balance function.

Objective: Postural control is frequently compromised after sub-concussive and concussive head trauma, and balance testing is an integral part of neuromotor assessment and management. The main objective of this paper is to develop a novel smartphone-based neuromotor assessment protocol for screening of dynamic balance decrements stemming from head trauma.

Approach: Experiments 1 and 2 compared Android smartphone orientation detection algorithms to a biomechanics laboratory motion capture system using a pendulum (i.

Biomechanical Differences of Multidirectional Jump Landings Among Female Basketball and Soccer Players.

Taylor, JB, Ford, KR, Schmitz, RJ, Ross, SE, Ackerman, TA, and Shultz, SJ. Biomechanical differences of multidirectional jump landings among female basketball and soccer players. J Strength Cond Res 31(11): 3034-3045, 2017-Anterior cruciate ligament (ACL) injury prevention programs are less successful in basketball than soccer and may be due to distinct movement strategies that these athletes develop from sport-specific training.

LOAD-ENHANCED MOVEMENT QUALITY SCREENING AND TACTICAL ATHLETICISM: AN EXTENSION OF EVIDENCE.

Background: Military organizations use movement quality screening for prediction of injury risk and performance potential. Currently, evidence of an association between movement quality and performance is limited. Recent work has demonstrated that external loading strengthens the relationship between movement screens and performance outcomes.

Development of a Portable Tool for Screening Neuromotor Sequelae From Repetitive Low-Level Blast Exposure.

Blast exposure is a prevalent cause of mild traumatic brain injury (mTBI) in military personnel in combat. However, it is more common for a service member to be exposed to a low-level blast (LLB) that does not result in a clinically diagnosable mTBI. Recent research suggests that repetitive LLB exposure can result in symptomology similar to symptoms observed after mTBI.

Altered Kinematics and Time to Stabilization During Drop-Jump Landings in Individuals With or Without Functional Ankle Instability.

Context: It has been proposed that altered dynamic-control strategies during functional activity such as jump landings may partially explain recurrent instability in individuals with functional ankle instability (FAI).

Objective: To capture jump-landing time to stabilization (TTS) and ankle motion using a multisegment foot model among FAI, coper, and healthy control individuals.

Design: Cross-sectional study.