Competing effects of pain and fear of pain on postural control in low back pain?

Study Design: A cross-sectional, observational study.

Objective: To determine whether pain and fear of pain have competing effects on postural sway in patients with low back pain (LBP).

Summary Of Background Data: Competing effects of pain and pain-related fear on postural control can be proposed as the likely explanation for inconsistent results regarding postural sway in the LBP literature.

Time to stabilization in single leg drop jump landings: an examination of calculation methods and assessment of differences in sample rate, filter settings and trial length on outcome values.

Time to stabilization (TTS) is the time it takes for an individual to return to a baseline or stable state following a jump or hop landing. A large variety exists in methods to calculate the TTS. These methods can be described based on four aspects: (1) the input signal used (vertical, anteroposterior, or mediolateral ground reaction force) (2) signal processing (smoothed by sequential averaging, a moving root-mean-square window, or fitting an unbounded third order polynomial), (3) the stable state (threshold), and (4) the definition of when the (processed) signal is considered stable.

Associations between measures of gait stability, leg strength and fear of falling.

Fear of falling (FoF) in elderly frequently leads to decreased quality of life. FoF is suggested to be associated with changes in gait quality and muscle strength with aging. The aim of this study was to determine whether gait quality and maximal voluntary torque (MVT) of knee extensor muscles are associated with FoF.

Prediction of trapezius muscle activity and shoulder, head, neck, and torso postures during computer use: results of a field study.

Background: Due to difficulties in performing direct measurements as an exposure assessment technique, evidence supporting an association between physical exposures such as neck and shoulder muscle activities and postures and musculoskeletal disorders during computer use is limited. Alternative exposure assessment techniques are needed.

Methods: We predicted the median and range of amplitude (90th-10th percentiles) of trapezius muscle activity and the median and range of motion (90th-10th percentiles) of shoulder, head, neck, and torso postures based on two sets of parameters: the distribution of keyboard/mouse/idle activities only ("task-based" predictions), and a comprehensive set of task, questionnaire, workstation, and anthropometric parameters ("expanded model" predictions).

The effect of lifting during work on low back pain: a health impact assessment based on a meta-analysis.

Lifting at work is considered an important risk factor for low back pain (LBP). However, contradictory findings have been reported, partly because frequency, duration and intensity (ie, the weight of the load) of lifting have not been systematically considered. This has hampered developments of threshold values for lifting.

Fast online corrections of tripping responses.

Tripping over obstacles is one of the main causes of falls. One potential hazard to actually fall when tripped is inadequate foot landing. Adequate landing is required to control the body's angular momentum, while avoiding dangerous surfaces (slippery patch, uneven ground).

Effect of bed height and use of hands on trunk angular velocity during the sit-to-stand transfer.

Unlabelled: The ability to rise from a chair or bed is critical to an individual's quality of life because it determines functional independence. This study was to investigate the effect of bed height and use of hands on trunk angular velocity and trunk angles during the sit-to-stand (STS) performance. Twenty-four older persons (median age 74 years) were equipped with a body-fixed gyroscopic sensor and stood up from a bed adjusted to different heights, with and without the use of hands at each height.

Single level lumbar laminectomy alters segmental biomechanical behavior without affecting adjacent segments.

Background: Degenerative lumbar spinal stenosis causes neurological symptoms due to neural compression. Lumbar laminectomy is a commonly used treatment for symptomatic degenerative spinal stenosis. However, it is unknown if and to what extent single level laminectomy affects the range of motion and stiffness of treated and adjacent segments.

How does postural stability following a single leg drop jump landing task relate to postural stability during a single leg stance balance task?

We aimed to verify whether the static phase after a single leg drop jump (DJ) landing on a force plate may serve as a proxy for a single leg stance (SLS) balance task, as this would increase the application possibilities of landing tasks in the evaluation of sensorimotor function in relation to injury rehabilitation or performance assessment. Twenty-five healthy participants performed two sessions of five valid trials for both tasks in a reproducibility-agreement design. Three postural stability outcome measures ('COP speed', 'COP sway' and 'Horizontal GRF') were calculated for DJ (5-20s after landing) and for SLS (15s), and were averaged per session.

Office workers' computer use patterns are associated with workplace stressors.

This field study examined associations between workplace stressors and office workers' computer use patterns. We collected keyboard and mouse activities of 93 office workers (68F, 25M) for approximately two work weeks. Linear regression analyses examined the associations between self-reported effort, reward, overcommitment, and perceived stress and software-recorded computer use duration, number of short and long computer breaks, and pace of input device usage.

Reproducibility of a knee and hip proprioception test in healthy older adults.

Background: Proprioception can be assessed by measuring joint position sense (JPS). Most studies have focused on JPS of the knee joint while literature for other joints especially for hip JPS is scarce. Although some studies have evaluated proprioception of the knee joint, the reproducibility of methods has rarely been investigated.

Elevated C-reactive protein is associated with lower increase in knee muscle strength in patients with knee osteoarthritis: a 2-year follow-up study in the Amsterdam Osteoarthritis (AMS-OA) cohort.

Introduction: The aim of this study was to examine the associations of elevated serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) with change in muscle strength in patients with established knee osteoarthritis (OA), at 2 years.

Methods: Data from 186 patients with knee OA were gathered at baseline and at 2-year follow-up. CRP (in milligrams per liter) and ESR (in millimeters per hour) were measured in serum from patients' blood.

Stepping asymmetry among individuals with unilateral transtibial limb loss might be functional in terms of gait stability.

Background: The asymmetry in step length in prosthetic gait is often seen as a detrimental effect of the impairment; however, this asymmetry also might be a functional compensation. An advantage of a smaller step length of the nonprosthetic leg, and specifically foot forward placement (FFP), might be that it will bring the center of mass closer to the base of support of the leading foot and thus increase the backward margin of stability (BW MoS).

Objective: The purpose of this study was to characterize differences in step length, FFP, and the concomitant difference in BW MoS between steps of the prosthetic and nonprosthetic legs (referred to as prosthetic and nonprosthetic steps, respectively) of people after transtibial amputation.

Arm swing in human walking: what is their drive?

Although previous research has studied arm swing during walking, to date, it remains unclear what the contribution of passive dynamics versus active muscle control to arm swing is. In this study, we measured arm swing kinematics with 3D-motion analysis. We used a musculoskeletal model in OpenSim and generated dynamic simulations of walking with and without upper limb muscle excitations.

Test-retest reliability of muscle vibration effects on postural sway.

The effect of alterations in the processing of proprioceptive signals, on postural control, has been studied using muscle vibration effects. However, reliability and agreement of muscle vibration have still to be addressed. This study aimed to assess intra- and interday reliability and agreement of vibration effects of lumbar paraspinal and triceps surae muscles in a non-selected sample of 20 subjects, standing on solid surface and on foam.

Consistency of gait characteristics as determined from acceleration data collected at different trunk locations.

Estimates of gait characteristics may suffer from errors due to discrepancies in accelerometer location. This is particularly problematic for gait measurements in daily life settings, where consistent sensor positioning is difficult to achieve. To address this problem, we equipped 21 healthy adults with tri-axial accelerometers (DynaPort MiniMod, McRoberts) at the mid and lower lumbar spine and anterior superior iliac spine (L2, L5 and ASIS) while continuously walking outdoors back and forth (20 times) over a distance of 20 m, including turns.

Effects of unilateral leg muscle fatigue on balance control in perturbed and unperturbed gait in healthy elderly.

This study assessed effects of unilateral leg muscle fatigue (ULMF) on balance control in gait during the stance and swing phases of the fatigued leg in healthy elderly, to test the assumption that leg muscle strength limits balance control during the stance-phase. Ten subjects (aged 63.4, SD 5.

Identification of fall risk predictors in daily life measurements: gait characteristics' reliability and association with self-reported fall history.

Background. Gait characteristics extracted from trunk accelerations during daily life locomotion are complementary to questionnaire- or laboratory-based gait and balance assessments and may help to improve fall risk prediction. Objective.

Cumulative mechanical low-back load at work is a determinant of low-back pain.

Objectives: Reported associations of physical exposures during work (eg, lifting, trunk flexion or rotation) and low-back pain (LBP) are rather inconsistent. Mechanical back loads (eg, moments on the low back) as a result of exposure to abovementioned risk factors have been suggested to be important as such loads provide a more direct relationship with tissue failure and thus LBP. Since information on the effect of such load metrics with LBP is lacking yet, we aimed to assess this effect in a prospective study.

Toward ambulatory balance assessment: estimating variability and stability from short bouts of gait.

Stride-to-stride variability and local dynamic stability of gait kinematics are promising measures to identify individuals at increased risk of falling. This study aimed to explore the feasibility of using these metrics in clinical practice and ambulatory assessment, where only a small number of consecutive strides are available. The concurrent validity and reliability were assessed compared to more continuous walking.

Clinimetric properties of a novel feedback device for assessing gait parameters in stroke survivors.

Introduction: Community-dwelling stroke survivors tend to become less physically active over time. There is no 'gold standard' to measure walking activity in this population. Assessment of walking activity generally involves subjective or observer-rated instruments.

Interactions of age and leg muscle fatigue on unobstructed walking and obstacle crossing.

Older adults commonly report muscle fatigue, which may be associated with reduced walking ability. Elderly may have insufficient awareness of the balance threat caused by muscle fatigue. The aim of this study was to analyze the interaction effects of aging and leg muscle fatigue on gait parameters in walking and obstacle crossing.

Steps to take to enhance gait stability: the effect of stride frequency, stride length, and walking speed on local dynamic stability and margins of stability.

The purpose of the current study was to investigate whether adaptations of stride length, stride frequency, and walking speed, independently influence local dynamic stability and the size of the medio-lateral and backward margins of stability during walking. Nine healthy subjects walked 25 trials on a treadmill at different combinations of stride frequency, stride length, and consequently at different walking speeds. Visual feedback about the required and the actual combination of stride frequency and stride length was given during the trials.

Increase in heterogeneity of biceps brachii activation during isometric submaximal fatiguing contractions: a multichannel surface EMG study.

The effects of fatigue emerge from the beginning of sustained submaximal contractions, as shown by an increase in the amplitude of the surface electromyogram (EMG). The increase in EMG amplitude is attributed to an augmentation of the excitatory drive to the motor neuron pool that, more importantly than increasing discharge rates, recruits additional motor units for the contraction. The aim of this study was to determine whether the spatiotemporal distribution of biceps brachii (BB) activity becomes more or less heterogeneous during a fatiguing isometric contraction sustained at a submaximal target force.