Association of Premorbid Anxiety and Depression Symptoms in Concussion Recovery in Collegiate Student-Athletes.

Background: Mental health disorders are linked to prolonged concussion symptoms. However, the association of premorbid anxiety/depression symptoms with postconcussion return-to-play timelines and total symptom burden is unclear.

Objective: To examine the association of self-reported premorbid anxiety/depression symptoms in collegiate student-athletes with (1) recovery times until asymptomatic, (2) return-to-play, and (3) postconcussion symptom burden.

The effect of forward postural lean on running economy, kinematics, and muscle activation.

Background: Running economy, commonly defined as the metabolic energy demand for a given submaximal running speed, is strongly associated with distance running performance. It is commonly believed among running coaches and runners that running with increased forward postural lean either from the ankle or waist improves running economy. However, recent biomechanical research suggests using a large forward postural lean during running may impair running economy due to increased demand on the leg muscles.

King-Devick testing and concussion recovery time in collegiate athletes.

Objectives: To assess whether the King-Devick (KD) test is useful as a prognostic test for prolonged concussion symptoms by examining the relationship between a) change in performance on KD test from baseline to within two days post-injury and b) the absolute KD time at post-concussion testing, with an outcome of time to return to play (RTP).

Design: Prospective Cohort Study.

Methods: Collegiate varsity athletes in the Concussion Assessment, Research, and Education (CARE) Consortium completed baseline and post-injury King-Devick tests from 2014 to 2018.

Estimated age of first exposure to American football and outcome from concussion.

Objective: To examine the association between estimated age at first exposure (eAFE) to American football and clinical measures throughout recovery following concussion.

Methods: Participants were recruited across 30 colleges and universities as part of the National Collegiate Athletic Association (NCAA)-Department of Defense Concussion Assessment, Research and Education Consortium. There were 294 NCAA American football players (age 19 ± 1 years) evaluated 24-48 hours following concussion with valid baseline data and 327 (age 19 ± 1 years) evaluated at the time they were asymptomatic with valid baseline data.

Bicycling Exercise Helps Maintain a Youthful Metabolic Cost of Walking in Older Adults.

The decline of walking performance is a key determinant of morbidity among older adults. Healthy older adults have been shown to have a 15-20% lower walking economy compared with young adults. However, older adults who run for exercise have a higher walking economy compared with older adults who walk for exercise.

King-Devick Test Reliability in National Collegiate Athletic Association Athletes: A National Collegiate Athletic Association-Department of Defense Concussion Assessment, Research and Education Report.

Context: The King-Devick (KD) test has received considerable attention in the literature as an emerging concussion assessment. However, important test psychometric properties remain to be addressed in large-scale independent studies.

Objective: To assess (1) test-retest reliability between trials, (2) test-retest reliability between years 1 and 2, and (3) reliability of the 2 administration modes.

Relationship Between the King-Devick Test and Commonly Used Concussion Tests at Baseline.

Context: Comprehensive assessments are recommended to evaluate sport-related concussion (SRC). The degree to which the King-Devick (KD) test adds novel information to an SRC evaluation is unknown.

Objective: To describe relationships at baseline among the KD and other SRC assessments and explore whether the KD provides unique information to a multimodal baseline concussion assessment.

Neither total muscle activation nor co-activation explains the youthful walking economy of older runners.

Background: Older adults (≥65 years) exhibit greater metabolic rates during walking (worse walking economy) compared to young adults. Yet, previous research suggests that habitual running, but not habitual walking, exercise mitigates the age-related deterioration of walking economy.

Research Question: Does total leg muscle activation and/or agonist-antagonist co-activation explain the superior walking economy of older runners versus older walkers?

Methods: We quantified metabolic power, leg muscle activation, and co-activation in older walkers and older runners during walking at 0.

King-Devick Test Time Varies by Testing Modality.

Objective: To explore differences in baseline King-Devick Test (KD) completion time between 2 testing modalities: (1) spiral-bound paper cards (cards) and (2) iPad application (iPad).

Design: Cross-sectional cohort analysis.

Setting: National Collegiate Athlete Association (NCAA) institutions.

Influences of Mental Illness, Current Psychological State, and Concussion History on Baseline Concussion Assessment Performance.

Background: A student-athlete's mental state, including history of trait anxiety and depression, or current psychological state may affect baseline concussion assessment performance.

Purpose: (1) To determine if mental illness (anxiety, depression, anxiety with depression) influences baseline scores, (2) to determine if psychological state correlates with baseline performance, and (3) to determine if history of concussion affects Brief Symptom Inventory-18 (BSI-18) subscores of state anxiety, depression, and somatization.

Study Design: Cross-sectional study; Level of evidence, 3.

Older Runners Retain Youthful Running Economy despite Biomechanical Differences.

Purpose: Sixty-five years of age typically marks the onset of impaired walking economy. However, running economy has not been assessed beyond the age of 65 yr. Furthermore, a critical determinant of running economy is the spring-like storage and return of elastic energy from the leg during stance, which is related to leg stiffness.

Running for exercise mitigates age-related deterioration of walking economy.

Introduction: Impaired walking performance is a key predictor of morbidity among older adults. A distinctive characteristic of impaired walking performance among older adults is a greater metabolic cost (worse economy) compared to young adults. However, older adults who consistently run have been shown to retain a similar running economy as young runners.

Effects of aging on mechanical efficiency and muscle activation during level and uphill walking.

Purpose: The metabolic cost of walking is greater in old compared to young adults. This study examines the relation between metabolic cost, muscular efficiency, and leg muscle co-activation during level and uphill walking in young and older adults.

Procedures: Metabolic cost and leg muscle activation were measured in young (22.

High efficiency in human muscle: an anomaly and an opportunity?

Can human muscle be highly efficient in vivo? Animal muscles typically show contraction-coupling efficiencies <50% in vitro but a recent study reports that the human first dorsal interosseous (FDI) muscle of the hand has an efficiency value in vivo of 68%. We examine two key factors that could account for this apparently high efficiency value: (1) transfer of cross-bridge work into mechanical work and (2) the use of elastic energy to do external work. Our analysis supports a high contractile efficiency reflective of nearly complete transfer of muscular to mechanical work with no contribution by recycling of elastic energy to mechanical work.

Influence of zolpidem and sleep inertia on balance and cognition during nighttime awakening: a randomized placebo-controlled trial.

Objectives: To determine whether sleep inertia (grogginess upon awakening from sleep) with or without zolpidem impairs walking stability and cognition during awakenings from sleep.

Design: Three within-subject conditions hypnotic medication (zolpidem), placebo (sleep inertia), and wakefulness control randomized using balanced Latin square design.

Setting: Sleep laboratory.

Effects of aging and arm swing on the metabolic cost of stability in human walking.

To gain insight into the mechanical determinants of walking energetics, we investigated the effects of aging and arm swing on the metabolic cost of stabilization. We tested two hypotheses: (1) elderly adults consume more metabolic energy during walking than young adults because they consume more metabolic energy for lateral stabilization, and (2) arm swing reduces the metabolic cost of stabilization during walking in young and elderly adults. To test these hypotheses, we provided external lateral stabilization by applying bilateral forces (10% body weight) to a waist belt via elastic cords while young and elderly subjects walked at 1.

Individual limb work does not explain the greater metabolic cost of walking in elderly adults.

Elderly adults consume more metabolic energy during walking than young adults. Our study tested the hypothesis that elderly adults consume more metabolic energy during walking than young adults because they perform more individual limb work on the center of mass. Thus we compared how much individual limb work young and elderly adults performed on the center of mass during walking.

The amplitude of force variability is correlated in the knee extensor and elbow flexor muscles.

The purpose of this study was to determine motor output variability for different muscles in the same individuals. Ten young (21.7 +/- 3.

Minimizing center of mass vertical movement increases metabolic cost in walking.

A human walker vaults up and over each stance limb like an inverted pendulum. This similarity suggests that the vertical motion of a walker's center of mass reduces metabolic cost by providing a mechanism for pendulum-like mechanical energy exchange. Alternatively, some researchers have hypothesized that minimizing vertical movements of the center of mass during walking minimizes the metabolic cost, and this view remains prevalent in clinical gait analysis.

Task differences with the same load torque alter the endurance time of submaximal fatiguing contractions in humans.

Endurance time, muscle activation, and mean arterial pressure were measured during two types of submaximal fatiguing contractions that required each subject to exert the same net muscle torque in the two tasks. Sixteen men and women performed isometric contractions at 15% of the maximum voluntary contraction (MVC) force with the elbow flexor muscles, either by maintaining a constant force while pushing against a force transducer (force task) or by supporting an equivalent inertial load while maintaining a constant elbow angle (position task). The endurance time for the force task (1402 +/- 728 s) was twice as long as that for the position task (702 +/- 582 s, P < 0.