Joint movements associated with minimum toe clearance variability in older adults during level overground walking.

Background: Approximately one-third of falls are caused by the swing foot contacting an object or the ground, resulting in a trip. The increased incidence of trip-related falls among older adults may be explained by greater within-person minimum toe clearance (MTC) variability.

Research Question: Will kinematic variability at any of the 6 major joints in the lower limbs, individually or in combination, be associated with MTC variability?

Methods: This cross-sectional study investigated whether single or multiple joint movements best explained MTC variability in older adults.

Naphthazarin-Polycyclic Conjugated Hydrocarbons and Iptycenes.

The synthesis of a set of naphthazarin-containing polycyclic conjugated hydrocarbons is described herein. Sequential Diels-Alder reactions on a tautomerized naphthazarin core were employed to access the final conjugated systems. Complete conjugation across the backbone can be achieved through complexation with BF, as observed by H NMR analysis and UV/vis spectroscopy.

Red Phosphorescence from Benzo[2,1,3]thiadiazoles at Room Temperature.

We describe the red phosphorescence exhibited by a class of structurally simple benzo[2,1,3]thiadiazoles at room temperature. The photophysical properties of these molecules in deoxygenated cyclohexane, including their absorption spectra, steady-state photoluminescence and excitation spectra, and phosphorescence lifetimes, are presented. Time-dependent density functional theory calculations were carried out to better understand the electronic excited states of these benzo[2,1,3]thiadiazoles and why they are capable of phosphorescence.

A Low Reabsorbing Luminescent Solar Concentrator Employing π-Conjugated Polymers.

A highly efficient thin-film luminescent solar concentrator (LSC) utilizing two π-conjugated polymers as antennae for small amounts of the valued perylene bisimide Lumogen F Red 305 is presented. The LSC exhibits high photoluminescence quantum yield, low reabsorption, and relatively low refractive indices for waveguide matching. A Monte Carlo simulation predicts the LSC to possess exceptionally high optical efficiencies on large scales.

NEUROMUSCULAR CONTROL DURING PERFORMANCE OF A DYNAMIC BALANCE TASK IN SUBJECTS WITH AND WITHOUT ANKLE INSTABILITY.

Design: Cross-sectional, controlled laboratory study.

Background: Lateral ankle sprains are common injuries and often lead to chronic ankle instability (CAI). Individuals who previously sustained a lateral ankle sprain, but did not develop CAI, termed copers, may have altered postural control strategies compared to individuals who have developed CAI.

The concurrent validity of three computerized methods of muscle activity onset detection.

Although the visual (VIS) method for muscle activation onset detection has been the gold standard, this method has been criticized because of its moderate reproducibility and for being laborious. The simple threshold (STH), approximated generalized likelihood-step (AGL-step), and k-means (KM) algorithms are more repeatable and less laborious but require validation for gait speeds encountered in clinical research. We, therefore, assessed the intra-rater reliability of the VIS method and the concurrent validity of the algorithms against the VIS for 3 gait speeds.

Alteration of ankle kinematics and muscle activity during heel contact when walking with external loading.

Purpose: The risk of recurrent ankle sprains could be reduced if the ankle joint is positioned in a more closed pack position (eversion and dorsiflexion) with enhanced co-activation of Tibialis Anterior (TA) and Peroneus Longus (PL) around heel contact in walking. We examined whether such alteration can be induced by augmenting ankle position error in the inversion and plantarflexion directions.

Methods: Fifteen young, healthy subjects participated in this study.

Neuromuscular control during stepping down in continuous gait in individuals with and without ankle instability.

Ankle sprains are a common injury and those affected are at a risk of developing chronic ankle instability (CAI). Complications of an acute sprain include increased risk of re-injury and persistent disability; however, the exact link between ankle sprains and chronic instability has yet to be elucidated. The purpose of this study was to investigate neuromuscular control (including kinematics, kinetics and EMG) during stepping down from a curb, a common yet challenging daily activity, in persons with ankle instability (n = 11), those with a history of ankle sprain without persistent instability, called ankle sprain "copers" (CPRs) (n = 9) and uninjured controls (CTLs) (n = 13).

The relationship between impact force, neck strength, and neurocognitive performance in soccer heading in adolescent females.

Head impacts are common in contact sports, but only recently has there been a rising awareness of the effects of subconcussive impacts in adolescent athletes. A better understanding of how to attenuate head impacts is needed and therefore, this study investigated the relationship between neck strength, impact, and neurocognitive function in an acute bout of soccer heading in a sample of female high school varsity soccer players. Seventeen participants completed the ImPACT neurocognitive test and had their isometric neck strength tested (flexion, extension, and bilateral flexion) before heading drills.

EMG and tibial shock upon the first attempt at barefoot running.

As a potential means to decrease their risk of injury, many runners are transitioning into barefoot running. Habitually shod runners tend to heel-strike (SHS), landing on their heel first, while barefoot runners tend to mid-foot or toe-strike (BTS), landing flat-footed or on the ball of their foot before bringing down the rest of the foot including the heel. This study compared muscle activity, tibial shock, and knee flexion angle in subjects between shod and barefoot conditions.

Coordination variability during load carriage walking: can it contribute to low back pain?

Load carriage walking is frequently associated with low back pain. Mechanical stress is a potential cause of such pain, and a lack of coordination variability may produce mechanical stress. We tested the hypothesis that coordination variability would decrease during load carriage walking.

A 2D covalent organic framework with 4.7-nm pores and insight into its interlayer stacking.

Two-dimensional layered covalent organic frameworks (2D COFs) organize π-electron systems into ordered structures ideal for exciton and charge transport and exhibit permanent porosity available for subsequent functionalization. A 2D COF with the largest pores reported to date was synthesized by condensing 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) and 4,4'-diphenylbutadiynebis(boronic acid) (DPB). The COF was prepared as both a high surface area microcrystalline powder as well as a vertically oriented thin film on a transparent single-layer graphene/fused silica substrate.

Reducing cardiovascular disease risk using patient navigators, Denver, Colorado, 2007-2009.

Introduction: Early identification of cardiovascular disease (CVD) risk is important to reach people in need of treatment. At-risk patients benefit from behavioral counseling in addition to medical therapy. The objective of this study was to determine whether enhanced counseling, using patient navigators trained to counsel patients on CVD risk-reduction strategies and facilitate patient access to community-based lifestyle-change services, reduced CVD risk among at-risk patients in a low-income population.

Examining neuromuscular control during landings on a supinating platform in persons with and without ankle instability.

Background: Ankle instability is a costly public health concern because of the associated recurrent sprains. It is evident there are neuromuscular control deficits predisposing these individuals to their ankle "giving way." Individuals with a history of lateral ankle sprain, who did not develop instability, may hold the key to understanding proper neuromuscular control after injury.

Temporal relationship between trunk and thigh contributes to balance control in load carriage walking.

Load carriage walking (LCW) challenges a person's balance as the load increases their forward trunk inclination, shifting the center of mass (COM) forward with respect to the base of support (BOS). We examined LCW to understand whether and how healthy people adjust the temporal relationship (TR) between the trunk and leg for balance control. Ten subjects were recruited to perform unloaded walking and LCW.

Effect of knee joint cooling on the electromyographic activity of lower extremity muscles during a plyometric exercise.

During sporting events, injured athletes often return to competition after icing because of the reduction in pain. Although some controversy exists, several studies suggest that cryotherapy causes a decrease in muscle activity, which may lead to a higher risk of injury upon return to play. The purpose of this study was to investigate the effect of a 20-min knee joint cryotherapy application on the electromyographic activity of leg muscles during a single-leg drop jump in twenty healthy subjects, randomly assigned to an experimental and a control group.

A novel dynamic ankle-supinating device.

Lateral ankle sprains (LAS) are among the most common joint injuries, and although most are resolved with conservative treatment, others develop chronic ankle instability (AI). Considerable attention has been directed toward understanding the underlying causes of this pathology; however, little is known concerning the neuromuscular mechanisms behind AI. A biomechanical analysis of the landing phase of a drop jump onto a device that simulates the mechanism of a LAS may give insight into the dynamic restraint mechanisms of the ankle by individuals with AI.

Neuromuscular control and ankle instability.

Lateral ankle sprains (LAS) are common injuries in athletics and daily activity. Although most are resolved with conservative treatment, others develop chronic ankle instability (AI)-a condition associated with persistent pain, weakness, and instability-both mechanical (such as ligamentous laxity) and functional (neuromuscular impairment with or without mechanical laxity). The predominant theory in AI is one of articular deafferentation from the injury, affecting closed-loop (feedback/reflexive) neuromuscular control, but recent research has called that theory into question.

A biomechanical comparison of back and front squats in healthy trained individuals.

The strength and stability of the knee plays an integral role in athletics and activities of daily living. A better understanding of knee joint biomechanics while performing variations of the squat would be useful in rehabilitation and exercise prescription. We quantified and compared tibiofemoral joint kinetics as well as muscle activity while executing front and back squats.

Effect of fatigue on neuromuscular function at the ankle.

Context: Lateral ankle sprains occur more frequently than any other orthopedic injury. Athletes often report sustaining more injuries late in competition when fatigue is present.

Objective: To evaluate neuromuscular function of the ankle musculature after fatigue.

Purposeful heading during a season does not influence cognitive function or balance in female soccer players.

Soccer participation, especially among females, is growing in popularity in the United States. Purposeful heading, an important soccer skill, has recently been scrutinized for safety reasons. The purpose of this study was to determine whether there was a relationship between purposeful heading and scores on cognitive function and balance in high school and collegiate female soccer players.

The effect of fatigue and habituation on the stretch reflex of the ankle musculature.

Many ankle injuries are said to occur when athletes are in a fatigued state; therefore, studies investigating the role that fatigue plays in ankle injuries are warranted. Furthermore, the contributions of the stretch reflex in countering the injury mechanism are still unclear. We hypothesized that (1) fatigue would impair the reflex response, (2) there would be no differences between genders, (3) habituation would be present, and (4) fatigue would exacerbate the effect of habituation.

Resistance training improves gait kinematics in persons with multiple sclerosis.

Objective: To evaluate the effects of an 8-week lower-body resistance-training program on walking mechanics in persons with multiple sclerosis (MS).

Design: Repeated-measures design, evaluating gait kinematics before and after an 8-week progressive resistance-training intervention.

Setting: Biomechanics laboratory and fitness center (with conventional, commercially available resistance-training equipment).