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In this study, we analyzed the effect of mental and muscular fatigue on the accuracy and kinematics of dart throwing. For this purpose, 28 young adults (19 females and 9 males) aged 25–35 years, without any regular experience in dart throwing, participated in this study. We evaluated their dart throwing skills in mental fatigue, muscular fatigue, and non-fatigue conditions. To induce mental fatigue, we used the Stroop task for 70 minutes and a simulated dart throwing exercise with an elastic band. In all three conditions, we collected accuracy data, based on the score of the dart on the board and the kinematic properties with a motion capture device. For analyzing the data and testing the research hypotheses, we employed ANOVA analyses with repeated measures after examining the normality of data distributions using skewness and kurtosis. We observed a significant decrease in the accuracy of dart throwing following mental fatigue (p = 0.027) and muscular fatigue (p = 0.001) compared to non-fatigue and following muscular fatigue compared to mental fatigue (p = 0.001). In the kinematic results, we observed a significant difference in the mean velocity of the elbow between different experimental conditions (p = 0.001). This variable decreased due to muscular fatigue, compared to the other two conditions. On the other hand, there was no significant difference among the three experimental conditions for the variables of elbow range of motion, shoulder range of motion, and mean velocity of the shoulder joint. These findings affirm mental and muscular fatigue effects on dart throwing and provide further detail regarding the specific aspects of these effects on dart throwing skills or other fine motor activities. [ABSTRACT FROM AUTHOR]

Context: Kinesio tape (KT) is a widely used intervention in the fields of sports and rehabilitation. However, its effects on lower-extremity behavior during functional activities are not entirely known. Objective: To test the hypothesis that application of KT can change performance and vertical stiffness (VS) during the countermovement jump (CMJ) before and after a fatigue protocol. Design: A predesign and postdesign to study the effect of KT in 2 situations, prefatigue and postfatigue. In each fatiguing condition, there were 2 conditions with and without KT application on the gastrocnemius muscle. Setting: Biomechanics laboratory. Participants: Fifty healthy, nonathlete participants (26 females and 24 males). Interventions: KT application on the gastrocnemius muscle and a fatigue protocol to induce fatigue in plantar flexor muscles. Main Outcome Measures: Various jumping parameters, including jump height, maximum force, maximum power, rate of force development, eccentric lower-limb stiffness, and VS, were calculated using the vertical ground reaction force data. Eccentric lower-limb stiffness and VS were calculated using a mass-spring model. The studied variables can present lower-extremity elastic behavior and performance during CMJ. Results: The results of a 2-way repeated-measures analysis of variance showed no significant effect for KT application. Fatigue resulted in lower values of jump height, maximum power, and VS. Moreover, male subjects showed greater values of jump height, maximum force, and maximum power than did females. Conclusions: The main finding of this study was that gastrocnemius KT has no effect on performance or elastic behavior of the lower-extremity during CMJ. Moreover, KT cannot reduce the adverse effect of fatigue in a functional activity such as CMJ. It seems that gastrocnemius KT is not effective for demanding activities. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the fatigue effect on the viscoelastic behavior of the musculoskeletal system between the two sexes in a landing task. Stiffness and shock absorption capacity were studied from ground reaction force data using a mass-spring-damper model. A parametric simulation was also performed to demonstrate the effect of different values of model parameters on the vertical ground reaction force. Following fatigue, the shock absorption capacity reduced in men. According to the parametric simulation, this reduction can result in lower rate of force development which may make men less susceptible to impact injuries than women. [ABSTRACT FROM AUTHOR]

Postural control is influenced by cognition. In most studies, variability of motor output has been considered regardless of variability in patterns of joint coordination. Uncontrolled manifold framework has been applied to decompose the joint's variance in two components. The first component leaves position of the center of mass in anterior-posterior direction (CoMAP) unchanged (VUCM) while the second component is in charge of variations of CoM (VORT). In this study, 30 healthy young volunteers were recruited. The experimental protocol consisted of three random conditions: quiet standing on a narrow wooden block without a cognitive task (NB), quiet standing on a narrow wooden block with an easy cognitive task (NBE), and quiet standing on a narrow wooden block with a difficult cognitive task (NBD). Results showed that CoMAP sway in NB condition was higher than both NBE and NBD conditions (p =.001). VORT in NB condition was higher than NBE and NBD conditions (p =.003). VORT in NB condition was higher than NBE and NBD conditions (p =.003). VUCM was unchanged in all conditions (p = 1.00) and synergy index in NB condition was smaller than NBE and NBD conditions (p =.006). These results showed that postural synergies increased under dual-task conditions. [ABSTRACT FROM AUTHOR]

This study aimed to determine the effect of added noise, filtering and time series length on the largest Lyapunov exponent (LyE) value calculated for time series obtained from a passive dynamic walker. The simplest passive dynamic walker model comprising of two massless legs connected by a frictionless hinge joint at the hip was adopted to generate walking time series. The generated time series was used to construct a state space with the embedding dimension of 3 and time delay of 100 samples. The LyE was calculated as the exponential rate of divergence of neighboring trajectories of the state space using Rosenstein’s algorithm. To determine the effect of noise on LyE values, seven levels of Gaussian white noise (SNR = 55–25 dB with 5 dB steps) were added to the time series. In addition, the filtering was performed using a range of cutoff frequencies from 3 Hz to 19 Hz with 2 Hz steps. The LyE was calculated for both noise-free and noisy time series with different lengths of 6, 50, 100 and 150 strides. Results demonstrated a high percent error in the presence of noise for LyE. Therefore, these observations suggest that Rosenstein’s algorithm might not perform well in the presence of added experimental noise. Furthermore, findings indicated that at least 50 walking strides are required to calculate LyE to account for the effect of noise. Finally, observations support that a conservative filtering of the time series with a high cutoff frequency might be more appropriate prior to calculating LyE. [ABSTRACT FROM AUTHOR]

Study Design: Clinical pilot study. Purpose: To objectively evaluate the compliance rate of lumbar-support use in patients with chronic nonspecific low back pain, as well as to assess low back pain intensity, disability, and fear-avoidance beliefs. Overview of Literature: Wearing time is an important factor in the assessment of the efficacy of lumbar-support use in patients with chronic nonspecific low back pain. Previous studies have measured lumbar-support wearing time based on subjective assessment, and these evaluations are not easily verifiable and are usually overestimated by subjects. Methods: Twelve subjects with chronic nonspecific low back pain who had been wearing semirigid lumbar supports for 6 weeks were evaluated. Compliance was objectively monitored using temperature sensors integrated into the semirigid lumbar supports. Subjects wore their lumbar supports for 8 hour/day on workdays and 3 hour/day on holidays during the first 3 weeks. During the next 3 weeks, subjects were gradually weaned off the lumbar supports. Pain intensity was measured using a numerical rating scale. The Oswestry disability index was used to assess the subjects’ disability. Fear-avoidance behavior was evaluated using a fear-avoidance beliefs questionnaire. Results: The mean compliance rate of the subjects was 78.16%±13.9%. Pain intensity was significantly lower in patients with a higher compliance rate (p=0.001). Disability index and fear-avoidance beliefs (functional outcomes) significantly improved during the second 3-weeks period of the treatment (p<0.001, p=0.02, respectively). Conclusions: The compliance rate of patients wearing lumbar supports is a determining factor in chronic low back pain management. Wearing semirigid lumbar supports, as advised, was associated with decreased pain intensity, improved disability index scores, and improved fear-avoidance beliefs in patients with chronic nonspecific low back pain. [ABSTRACT FROM AUTHOR]

The nonlinear Lyapunov exponent (LyE) has been proven effective for evaluating the local stability of human movement and exploring the effects of load, speed and direction of individuals with and without nonspecific chronic low back pain (CLBP). The purpose of this study was to examine spinal and lower joint stability and response to fatigue of individuals with and without CLBP while performing lifting-lowering movements. Fourteen healthy individuals and 14 patients with nonspecific CLBP were recruited to perform lifting movement repeatedly while holding two equally-sized dumbbells in their hands. The participants continued lifting until they reported their highest level of fatigue. Kinematic data for the spine and its coordinated lower joints were recorded during the task (more than 40 lifting cycles on average). The first and last 20 cycles of each cyclic time series were defined as early- and late-fatigue conditions, respectively. The maximum LyE was estimated to quantify the local dynamic stability of the angular displacement time series of the spine, hip, knee and ankle on different anatomical planes in both the early- and late-fatigue conditions. The results revealed that local stability of the spine and hip was affected by fatigue. Spinal stability decreased as fatigue increased on the sagittal plane (p<0.05). The hip exhibited a similar affectation (destabilization under fatigue) on all anatomical planes. Patients with CLBP showed more stable hip movement on the frontal and transverse planes (p<0.05). These results suggested that lifting/progressive fatigue could increase the risk of injury to the spine and hip. These findings indicate that patients with CLBP applied different control strategies for the hip; thus, spinal control stability should be evaluated together with the stability of the lower joints. [ABSTRACT FROM AUTHOR]

Motor abundance allows reliability of motor performance despite its variability. The nature of this variability provides important information on the flexibility of control strategies. This feature of control may be affected by low back pain (LPB) and trunk flexion/extension conditions. Goal equivalent manifold (GEM) analysis was used to quantify the ability to exploit motor abundance during repeated trunk flexion/extension in healthy individuals and people with chronic non-specific LBP (CNSLBP). Kinematic data were collected from 22 healthy volunteers and 22 CNSLBP patients during metronomically timed, repeated trunk flexion/extension in three conditions of symmetry, velocity, and loading; each at two levels. A goal function for the task was defined as maintaining a constant movement time at each cycle. Given the GEM, flexibility index and performance index were calculated respectively as amounts of goal-equivalent variability and the ratio of goal-equivalent to non-goal-equivalent variability. CNSLBP group was as similar as healthy individuals in both flexibility index (p = 0.41) and performance index (p = 0.24). Performance index was higher in asymmetric (p < 0.001), high velocity (p < 0.001), and loaded (p = 0.006) conditions. Performance and flexibility in using motor abundance were influenced by repeated trunk flexion/extension conditions. However, these measures were not significantly affected by CNSLBP. [ABSTRACT FROM AUTHOR]

Motor abundance allows reliability of motor performance despite its variability. The nature of this variability provides important information on the flexibility of control strategies. This feature of control may be affected by low back pain (LPB) and trunk flexion/extension conditions. Goal equivalent manifold (GEM) analysis was used to quantify the ability to exploit motor abundance during repeated trunk flexion/extension in healthy individuals and people with chronic non-specific LBP (CNSLBP). Kinematic data were collected from 22 healthy volunteers and 22 CNSLBP patients during metronomically timed, repeated trunk flexion/extension in three conditions of symmetry, velocity, and loading; each at two levels. A goal function for the task was defined as maintaining a constant movement time at each cycle. Given the GEM, flexibility index and performance index were calculated respectively as amounts of goal-equivalent variability and the ratio of goal-equivalent to non-goal-equivalent variability. CNSLBP group was as similar as healthy individuals in both flexibility index (p=0.41) and performance index (p=0.24). Performance index was higher in asymmetric (p<0.001), high velocity (p<0.001), and loaded (p=0.006) conditions. Performance and flexibility in using motor abundance were influenced by repeated trunk flexion/extension conditions. However, these measures were not significantly affected by CNSLBP. [ABSTRACT FROM AUTHOR]

Group statistical analysis may mask individual differences in response to interaction with rehabilitative devices such as prostheses. This study sets out to evaluate the effect of asymmetric prosthesis using a single subject methodology on individuals with unilateral transfemoral amputation. Acceleration data of 17 participants with unilateral transfemoral amputation were collected using a triaxial accelerometer attached at the L3 level of the spine during level ground walking under four prosthesis conditions: 1) no added mass; 2) the knee joint relocated downwards by 18% of the total shank length, shank mass decreased by 68%, thigh mass increased by 7%; 3) the knee joint relocated downwards by 37% of the total shank length, shank mass decreased by 68%, thigh mass increased by 7%, and 4) thigh mass increased 17%, shank mass decreased by 38%. Step length, step time, step length variability, step time variability and Floquet multiplier were statistically assessed. The single subject analysis highlighted that under prosthetic modifications, intact limb step length was increased and prosthetic step length was deceased in most participants (n > 9). No significant changes were observed in Floquet multiplier (n > 14), step length (n > 6) and step time variability (n > 9) across all conditions. Single subject analysis showed that in response to the immediate effect of asymmetric prosthesis, increase in the intact limb step length and decrease in the prosthetic limb step length emerged as a dominant strategy for most participants. Regarding Floquet multiplier, step length, and step time variability, our prosthetic modifications did not produce the anticipated effects. • Group analysis masks individual variation of amputees in response to modifications. • Based on single subject analysis, asymmetric prosthesis improved step length. • Asymmetric prosthesis did not improve stability and variability. [ABSTRACT FROM AUTHOR]

Background While several studies have investigated the traditional linear measures in patients with knee osteoarthritis, no study has yet reported the non-linear structure of postural sway in these patients. Methods We used two non-linear methods, recurrence quantification analysis (percent of determinism-%DET) and central tendency measure, to respectively investigate differences in the complexity and variability of sway dynamics between two groups of knee osteoarthritis patients (n = 27) and healthy controls (n = 27) under different conditions of postural and cognitive tasks. The experimental conditions included standing on (1) rigid surface with open eyes; (2) rigid surface with closed eyes; (3) foam surface with open eyes; and (4) foam surface with closed eyes. All these conditions were performed isolated (single-task) and while performing concurrent cognitive task (dual-task). Findings The results showed greater %DET and lesser central tendency measure (both in mediolateral direction) in patients compared with healthy subjects. Moreover, in both groups, the %DET increased and central tendency measure decreased with increasing postural difficulty while %DET decreased and central tendency measure increased when moving from single- to dual-task conditions. Interpretations The complexity loss was observed in patients compared with healthy controls. The observed increase in the variability coupled with a decrease in the complexity could be explained by the exploratory behavior of postural control system to gather information during difficult postural conditions relative to the easy ones. Moreover, the observed increase in the complexity coupled with the decrease in the amount of variability may enhance the flow of information to facilitate the perceptual control of standing balance during dual-task conditions. [ABSTRACT FROM AUTHOR]

Multiple joint interactions are critical to produce stable coordinated movements and can be influenced by low back pain and task conditions. Inter-segmental coordination pattern and variability were assessed in subjects with and without chronic nonspecific low back pain (CNSLBP). Kinematic data were collected from 22 CNSLBP and 22 healthy volunteers during repeated trunk flexion-extension in various conditions of symmetry, velocity, and loading; each at two levels. Sagittal plane angular data were time normalized and used to calculate continuous relative phase for each data point. Mean absolute relative phase (MARP) and deviation phase (DP) were derived to quantify lumbar-pelvis and pelvis-thigh coordination patterns and variability. Statistical analysis revealed more in-phase coordination pattern in CNSLBP (p=0.005). There was less adaptation in the DP for the CNSLBP group, as shown by interactions of Group by Load (p=.008) and Group by Symmetry by Velocity (p=.03) for the DP of pelvis-thigh and lumbar-pelvis couplings, respectively. Asymmetric (p<0.001) and loaded (p=0.04) conditions caused less in-phase coordination. Coordination variability was higher during asymmetric and low velocity conditions (p<0.001). In conclusion, coordination pattern and variability could be influenced by trunk flexion-extension conditions. CNSLBP subjects demonstrated less adaptability of movement pattern to the demands of the flexion-extension task. [ABSTRACT FROM AUTHOR]

Background Comparison of the kinematic variability and dynamic stability of the trunk between healthy and low back pain patient groups can contribute to gaining valuable information about the movement patterns and neuromotor strategies involved in various movement tasks. Methods Fourteen chronic low back pain patients with mild symptoms and twelve healthy male volunteers performed repeated trunk flexion–extension movements in the sagittal plane at three different speeds: 20 cycles/min, self-selected, and 40 cycles/min. Mean standard deviations, coefficient of variation and variance ratio as variability measures; maximum finite-time Lyapunov exponents and maximum Floquet multipliers as stability measures were computed from trunk kinematics. Findings Higher speed significantly reduced the kinematic variability, while it increased short-term Lyapunov exponents. Long-term Lyapunov exponents were higher at self-selected speed and lower in low back pain patients as compared to control volunteers. Floquet multipliers were larger at self-selected speed and during higher pace trunk movements. Interpretation Our findings suggest that slower pace flexion–extension trunk movements are associated with more motor variation as well as local and orbital stability, implying less potential risk of injury for the trunk. Individuals with and without low back pain consistently recruited a closed-loop control strategy towards achieving trunk stability. Chronic low back pain patients exhibited more stable trunk movements over long-term periods, indicating probable temporary pain relief functional adaption strategies. These results may be used towards the development of more effective personalized rehabilitation strategies and quantitative spinal analysis tools for low back pain detection, diagnosis and treatment, as well as improvement of workspace and occupational settings. [ABSTRACT FROM AUTHOR]

Highlights: [•] Similar dynamical structure of sway path was seen between patients and healthy. [•] Decreased regularity and complexity were seen by increased postural difficulty. [•] Decreased regularity and complexity were seen by increased cognitive difficulty. [ABSTRACT FROM AUTHOR]

The effect of muscular fatigue on temporal and spectral features of muscle activities and motor performance, i.e., kinematics and kinetics, has been studied. It is of value to quantify fatigue related kinematic changes in biomechanics and sport sciences using simple measurements of joint angles. In this work, a new approach was introduced to extract kinematic changes from 2D phase portraits to study the fatigue adaptation patterns of subjects performing elbow repetitive movement. This new methodology was used to test the effect of load and repetition rate on the temporal changes of an elbow phase portrait during a dynamic iso-inertial fatiguing task. The local flow variation concept, which quantifies the trajectory shifts in the state space, was used to track the kinematic changes of an elbow repetitive fatiguing task in four conditions (two loads and two repetition rates). Temporal kinematic changes due to muscular fatigue were measured as regional curves for various regions of the phase portrait and were also expressed as a single curve to describe the total drift behavior of trajectories due to fatigue. Finally, the effect of load and repetition rate on the complexity of kinematic changes, measured by permutation entropy, was tested using analysis of variance with repeated measure design. Statistical analysis showed that kinematic changes fluctuated more (showed more complexity) under higher loads (p = 0.014), but did not differ under high and low repetition rates (p = 0.583). Using the proposed method, new features for complexity of kinematic changes could be obtained from phase portraits. The local changes of trajectories in epochs of time reflected the temporal kinematic changes in various regions of the phase portrait, which can be used for qualitative and quantitative assessment of fatigue adaptation of subjects and evaluation of the influence of task conditions (e.g., load and repetition rate) on kinematic changes. [ABSTRACT FROM AUTHOR]

Investigating the complexity of movement systems can be insightful in clinical decision making. The study conducted to evaluate whether complexity of ground reaction force is affected by hallux valgus grades and footwear or foot side conditions. A sample of 120 females including 30 participants in each group of healthy and mild, moderate, and severe hallux valgus were recruited in this case-control study. Hallux valgus grades were assessed using Manchester scale. Ground reaction force were measured in bare foot and shod conditions for both feet and weighted permutation entropy was used to calculate the complexity. Nonparametric tests were employed for statistical inference. The first important result was that hallux valgus caused loss of complexity of ground reaction force with a medium to large effect size. However, we did not find any difference between three grades of hallux valgus entropy. The second finding was that entropy of healthy group decreased from barefoot to shod condition with a large effect size and the third finding was that ground reaction force entropy were similar in both feet. The findings are aligned with the theory that loss of complexity appears when the biological systems become functionally impaired. As soon as hallux valgus initiates, all potential risks related to the reduction of complexity appear. So, we suggest to administer conservative treatments in the early stages of hallux valgus. The study outcomes can be used for evaluation of foot function, classification of the foot types, or footwear selection. Unlabelled Image [ABSTRACT FROM AUTHOR]

People with knee osteoarthritis are at higher risk of postural deficits and locomotor adaptations which could be manifested in transient tasks like gait initiation. To better understand the effect of early knee osteoarthritis on gait initiation, we measured the gait initiation in two groups of early knee osteoarthritis and healthy age-matched controls and assessed the effect of lateral wedge insole in knee osteoarthritis group. Twenty-one individuals with early knee osteoarthritis, mean (SD) age = 53.1 (7.4, years), and 19 age- and sex-matched asymptomatic healthy individuals, mean (SD) age = 47.5 (11.2, years), participated. Centre of pressure trajectories were used to quantify the two phases of gait initiation in barefoot condition: anticipatory postural adjustment, and locomotor phase. The immediate and four-week effect of lateral wedge insole and shod condition were also compared for individuals in knee osteoarthritis group. Longer duration of anticipatory postural adjustment phase (P = 0.046), locomotor phase (P = 0.049), and total duration of gait initiation (P = 0.035) with lower length and velocity of the center of pressure trajectories in anticipatory postural adjustment phase (P = 0.002, and 0.008, respectively) were observed in knee osteoarthritis group compared to controls. Lateral wedge insole could increase the length and velocity of the centre of pressure in locomotor phase compared to barefoot condition (P = 0.001, and 0.002, respectively). Our study outlined that people with early knee osteoarthritis adopt different gait initiation strategies mainly in postural preparation phase. The potential effect of lateral wedge insole was shown with better performance of the locomotor phase. IRCT2016060628310N1. Unlabelled Image • Early knee osteoarthritis is associated with longer gait initiation cycle. • Anticipatory postural adjustment phase is longer in early knee osteoarthritis. • Bipedal standing phase is longer in early knee osteoarthritis. • Lateral wedge insole can improve locomotor phase in knee osteoarthritis. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to employ nonlinear dynamic approaches to assess trunk dynamic stability with speed, symmetry, and load during repetitive flexion-extension (FE) movements for individuals with and without nonspecific low back pain (NSLBP). Background: Repetitive trunk FE movement is a typical work-related LBP risk factor contingent on speed, symmetry, and load. Improper settings/adjustments of these control parameters could undermine the dynamic stability of the trunk, hence leading to low back injuries. The underlying stability mechanisms and associated control impairments during such dynamic movements remain elusive. Method: Thirty-eight male volunteers (19 healthy, 19 NSLBP) enrolled in the current study. All participants performed repetitive trunk FE movements at high/low speeds, in symmetric/asymmetric directions, with/without a wearable loaded vest. Trunk instantaneous rotation angle was computed for each trial to be assessed in terms of local and orbital stability, using maximum finite-time Lyapunov exponents (LyEs) and Floquet multipliers (FMs), respectively. Results: Both groups demonstrated equivalent competency in terms of trunk control and stability, suggesting functional adaptation strategies may be used by the NSLBP group. Wearing the loaded vest magnified the effects of trunk control impairment for the NSLBP group. The combined presence of high-speed and symmetrical FE movements was associated with least trunk local stability. Conclusion: Nonlinear dynamic techniques, particularly LyE, are potentially effective for assessing trunk dynamic stability dysfunction for individuals with NSLBP during various activities. Application: This work can be applied toward the development of quantitative personalized spinal evaluation tools with a wide range of potential occupational and clinical applications. [ABSTRACT FROM AUTHOR]

• Stability and symmetry usually decrease in transfemoral amputees compared to healthy peers. • Traditional symmetric designs of prosthetics are not still satisfactory. • Theoretically, models suggest an asymmetric prosthesis with stable and symmetric gait. • Experimentally, asymmetric prosthesis did not improve stability and symmetry. • Modeling predictions may not be directly applicable to real human gait. The aim of the current study was to examine the effect of asymmetric prosthesis derived from the passive dynamic walking (PDW) concept on dynamic stability and symmetry in unilateral transfemoral amputees. Seventeen transfemoral amputees were asked to walk on 77.8 m in preferred speed under four conditions: 1) no added mass, 2) the knee joint relocated downwards by 18% of the total shank length, shank mass decreased by 68%, thigh mass increased by 7%, 3) the knee joint relocated downwards by 37% of the total shank length, shank mass decreased by 68%, thigh mass increased by 7% and 4) thigh mass increased 17%, shank mass decreased by 38%. Trunk accelerations were recorded by a triaxle accelerometer, attached at the L3 level of spine. For each condition, stability (orbital and local), intra-limb step length and step time variability, step length and step time symmetry, were estimated from the vertical acceleration. Our findings showed no significant change in the orbital stability (P = 0.627) and the local stability (P = 0.748). In addition, no significant difference was found in the step length symmetry (P = 0.891), intra-limb step length variability (P > 0.234), the step time symmetry (P = 0.960) and intra-limb step time variability (P > 0.847) with the new prosthetic configurations. Our empirical findings indicate that contrary to the modeling predictions, manipulating physical parameters does not improve gait pattern in terms of stability, variability and symmetry in transfemoral amputees. It suggests that proposed modifications based on PDW cannot be directly applied to real human conditions without further elaborations. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Bracing is the most effective nonoperative treatment for adolescents with Scheuermann's kyphosis; however, its outcome is not equal for all patients. The effects of potential predictive parameters for the outcome of bracing have not been well evaluated in the literature. The aim of the study was to investigate the potential prognostic factors that affect in-brace curve correction in adolescents with Scheuermann's kyphosis. MATERIALS AND METHODS: In this prospective cohort study, patients with thoracic Scheuermann's kyphosis treated with the Milwaukee brace with a curve of 55° to 86° were included. The primary prognostic factors for in-brace curve correction, including brace compliance and daily exercise by log book, pad pressure by a modified sphygmomanometer, joint hypermobility by Beighton's scale, patients' sex, and initial Cobb angle were measured. Analyses considered multiple linear regression and independent sample t -test. RESULTS: Nineteen boys (13.74 ± 1.55 years) and 33 girls (13.67 ± 1.61 years) were included in the study. The results of the multiple linear regression analysis showed that the degrees of in-brace curve correction were significantly associated with brace compliance and initial Cobb angle (R 2 = 0.48). The results of the independent t -test showed a significant difference in average curve correction, brace compliance, and in-brace pressure between girls and boys. CONCLUSIONS: Results of the current study indicated that the amount of in-brace curve correction is primarily affected by brace compliance and initial Cobb angle. Brace compliance, curve correction, and pad pressure in boys were significantly higher than in girls. [ABSTRACT FROM AUTHOR]

Context: Clinical evaluation of the spine is commonplace in musculoskeletal therapies, such as physiotherapy, physical medicine/rehabilitation, osteopathic, and chiropractic clinics. Sit-to-stand (STS) is one of the most mechanically demanding daily activities and crucial to independence. Difficulty or inability to perform STS is common in individuals with a variety of motor disabilities, such as low back pain (LBP). Objective: The purpose of this systematic review was to evaluate available evidence in literature to determine 2-dimensional and 3-dimensional kinematics of the spine during STS in patients with LBP and healthy young adult participants using motion analysis systems (electromagnetic and marker based). Methods: Electronic databases (PubMed/MEDLINE [National Library of Medicine], Scopus, ScienceDirect, and Google Scholar) were searched between January 2002 and February 2017. Additionally, the reference lists of the articles that met the inclusion criteria were also searched. Prospective studies published in peer-reviewed journals, with full text available in English, investigating the kinematics of the spine during STS in healthy subjects (mean age between 18 and 50 y) or in patients with LBP using motion analysis systems, were included. Sixteen studies fulfilled the eligibility criteria. All information relating to methodology and kinematic modeling of the spine segments along with the outcome measures was extracted from the studies identified for synthesis. Results: The results indicated that the kinematics of the spine are greatly changed in patients with LBP. In order to develop a better understanding of spine kinematics, studies recommended that the trunk should be analyzed as a multisegment. It has been shown that there is no difference between the kinematics of patients with LBP and healthy population when the spine is analyzed as a single segment. Furthermore, between-gender differences are present during STS movement. Conclusion: This review provided a valuable summary of the research to date examining the kinematics of the spine during STS. [ABSTRACT FROM AUTHOR]

Background Context: Previous studies have proposed that there is a relationship between low back pain (LBP) and morphology and composition of paraspinal muscles. However, results have been conflicting, especially regarding fatty infiltration of muscles.Purpose: The primary goal of this study was to review and analyze results from imaging studies which investigated morphological and composition changes in the multifidus, erector spinae and psoas major muscles in people with LBP.Study Design/setting: Systematic review with meta-analysis.Patient Sample: A patient sample was not required OUTCOME MEASURES: This review did not have outcome measures.Methods: PubMed, Scopus, Web of Sciences, EMBASE and ProQuest were searched for eligible studies up to 31st July 2020 (all languages). A systematic search of electronic databases was conducted to identify studies investigating the association between the morphology and fat content of lumbar muscles in people with LBP compared with a (no LBP) control group. 13,795 articles were identified. Based on the screening for inclusion/ exclusion, 25 were included. The quality of the studies was evaluated using the Newcastle-Ottawa Scale. From the 25 articles, 20 were included in the meta-analysis.Results: Results showed that the total cross-sectional area of the multifidus was smaller in people with LBP (Standardized mean difference, SMD = -0.24, 95% CI = -0.5 to 0.03). Combined SMDs showed a medium effect of LBP on increasing multifidus muscle fat infiltration (SMD = 0.61, 95% CI = 0.30 to 0.91). There were no LBP related differences identified in the morphology or composition of the lumbar erector spine and psoas major muscles.Conclusions: People with LBP were found to have somewhat smaller multifidus muscles with a significant amount of intramuscular fat infiltration. Varying sample size, age and BMI of participants, quality of studies and the procedures used to measure fat infiltration are possible reasons for inconsistencies in results of previous studies. [ABSTRACT FROM AUTHOR]

BACKGROUND: There is a lack of evidence in reliability of the modified sphygmomanometer to measure the brace-interface pad pressure in adolescents with Scheuermann's kyphosis (SK). OBJECTIVES: To evaluate the intra- and inter-observer reliability of modified sphygmomanometer for measuring interface pad pressure in the Milwaukee brace. METHODS: Two observers measured the pressure of the shoulder and kyphosis pads in Milwaukee brace on 33 adolescents with SK with an average age of 14.67 ± 1.72 years and Cobb angle 64.48 ∘ ± 7.53 ∘. All measurements were obtained in one day. The measurements were done in the inhalation and exhalation of tidal breathing during standing and sitting positions. The intraclass correlation coefficient (ICC), 95% confidence interval (CI), and linear mixed model ANOVA effects were calculated. RESULTS: The intra-observer reliability varied from a good ICC of 0.81 (0.66–0.90) to an excellent of 0.97 (0.95–0.98). The inter-observer reliability also varied from a good ICC of 0.82 (0.67–0.91) to an excellent of 0.96 (0.93–0.98). The linear mixed model ANOVA analysis showed that the rater, position, and breathing had a significant effect on the pad pressure measurements. CONCLUSIONS: The modified sphygmomanometer is a reliable tool to measure the pad pressure of the Milwaukee brace for adolescents with SK. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The aim of this study was to examine the effect of Mulligan ankle taping on center of pressure (COP) parameters during performance of a functional upper limb task in patients with chronic ankle instability (CAI). METHODS: A clinical controlled trial study designed between 4 ankle conditions: untaped and taped, CAI and healthy subjects. Fifteen subjects with CAI and 15 healthy controls were asked to grasp an object at their waist level and release it above shoulder level in an oblique pattern during performance of single-leg stance balance test. All the subjects performed 3 trials of single-leg stance with eyes opened before and after Mulligan taping on a force plate during performance of functional upper limb task. The mean displacement (mdCOP), range of COP excursion (rangeCOP) and average speed of COP (velCOP) in anteroposterior (AP) and mediolateral (ML) directions were analysed for differences between groups. RESULTS: mdCOP and rangeCOP in AP direction were significantly increased (P = 0.04 and 0.03, respectively) in the CAI group. Mulligan taping significantly reduced velCOP in AP and ML directions (P = 0.02). CONCLUSION: In CAI patients Mulligan ankle taping can improve postural control by decreasing velCOP, therefore Mulligan taping can have immediate positive effects on postural parameters and maintenance of dynamic postural control. [ABSTRACT FROM AUTHOR]

Study Design: In this prospective study, we measured the pad pressures of the Milwaukee brace in adolescent hyperkyphosis treatment. Purpose: We evaluated the skin-brace interface forces exerted by the main pads of the Milwaukee brace. Overview of Literature: A fundamental factor associated with brace effectiveness in spinal deformity is pad force adjustment. However, few studies have evaluated the in-brace force magnitude and its effect on curve correction. Methods: Interface forces at four pads of the Milwaukee brace were measured in 73 patients withround back deformity (mean age,14.04±1.97 years [range, 10-18]; mean initial Cobb angle,67.70°±9.23° [range, 50°-86°]). We used a modified aneroid sphygmomanometer to measure the shoulder and kyphosis pad pressures. Each patient underwent measurement in the standing and sitting positions during inhalation/exhalation. Results: The mean pad pressures were significantly higher in the standing than in thesitting position, and significantly higher pressures were observed during inhalation compared toexhalation (p =0.001).There were no statistically significant differences between right and left shoulder pad pressures (p >0.05); however, the pressure differences between the right and left kyphosis pads were statistically significant (p <0.05). In a comparison of corrective forces with bracing for less or more than 6 months, corrective force was larger with bracing for less than 6 months (p =0.02). In the standing position, there were no statistically significant correlations between pad pressures and kyphosis curve correction. Conclusions: In the sitting position, there was a trend toward lower forces at the skin-brace interface; therefore, brace adjustment in the standing position may be useful and more effective. There was no significant correlation between the magnitude of the pad pressures and the degree of in-brace curve correction. [ABSTRACT FROM AUTHOR]

An abstract of the article "Effect of functional fatigue on vertical ground reaction force among individuals with flat feet," by Sahar Boozari, Ali Ashraf Jamshidi, Mohammad Ali Sanjari, and Hassan Jafari is presented.

Objectives: Work-related musculoskeletal disorders in the neck and shoulder regions are common among carpet weavers. Working for prolonged hours in a static and awkward posture could result in an increased muscle activity and may lead to musculoskeletal disorders. Ergonomic workstation improvements can reduce muscle fatigue and the risk of musculoskeletal disorders.Material and Methods: The aim of this study is to assess and to compare upper trapezius and middle deltoid muscle activity in 2 traditional and improved design carpet weaving workstations. These 2 workstations were simulated in a laboratory and 12 women carpet weavers worked for 3 h. Electromyography (EMG) signals were recorded during work in bilateral upper trapezius and bilateral middle deltoid. The root mean square (RMS) and median frequency (MF) values were calculated and used to assess muscle load and fatigue. Repeated measure ANOVA was performed to assess the effect of independent variables on muscular activity and fatigue. The participants were asked to report shoulder region fatigue on the Borg's Category-Ratio scale (Borg CR-10).Results: Root mean square values in workstation A are significantly higher than in workstation B. Furthermore, EMG amplitude was higher in bilateral trapezius than in bilateral deltoid. However, muscle fatigue was not observed in any of the workstations.Conclusions: The results of the study revealed that muscle load in a traditional workstation was high, but fatigue was not observed. Further studies investigating other muscles involved in carpet weaving tasks are recommended. [ABSTRACT FROM AUTHOR]

Abstract: It was hypothesized that training in ‘static balance’ or ‘dynamic balance’ sports has differential effects on postural control and its attention demands during quiet standing. In order to test this hypothesis, two groups of female athletes practicing shooting, as a ‘static balance’ sport, and Taekwondo, as a ‘dynamic balance’ sport, and a control group of non-physically active females voluntarily participated in this study. Postural control was assessed during bipedal and unipedal stance with and without performing a Go/No-go reaction time task. Visual and/or support surface conditions were manipulated in bipedal and unipedal stances in order to modify postural difficulty. Mixed model analysis of variance was used to determine the effects of dual tasking on postural and cognitive performance. Similar pattern of results were found in bipedal and unipedal stances, with Taekwondo practitioners displaying larger sway, shooters displaying lower sway and non-athletes displaying sway characteristics intermediate to Taekwondo and shooting athletes. Larger effect was found in bipedal stance. Single to dual-task comparison of postural control showed no significant effect of mental task on sway velocity in shooters, indicating less cognitive effort invested in balance control during bipedal stance. We suggest that expertise in shooting has a more pronounced effect on decreased sway in static balance conditions. Furthermore, shooters invest less attention in postures that are more specific to their training, i.e. bipedal stance. [Copyright &y& Elsevier]

Abstract: Although the application of nonlinear tools including recurrence quantification analysis (RQA) has increasingly grown in the recent years especially in balance-disordered populations, there have been few studies which determine their measurement properties. Therefore, a methodological study was performed to estimate the intersession and intrasession reliability of some dynamic features provided by RQA for nonlinear analysis of center of pressure (COP) signals recorded during quiet standing in a sample of patients with musculoskeletal disorders (MSDs) including low back pain (LBP), anterior cruciate ligament (ACL) injury and functional ankle instability (FAI). The subjects completed postural measurements with three levels of difficulty (rigid surface-eyes open, rigid surface-eyes closed, and foam surface-eyes closed). Four RQA measures (% recurrence, % determinism, entropy, and trend) were extracted from the recurrence plot. Relative reliability of these measures was assessed using intraclass correlation coefficient and absolute reliability using standard error of measurement and coefficient of variation. % Determinism and entropy were the most reliable features of RQA for the both intersession and intrasession reliability measures. High level of reliability of % determinism and entropy in this preliminary investigation may show their clinical promise for discriminative and evaluative purposes of balance performance. [ABSTRACT FROM AUTHOR]

Abstract: Knowledge about the non-linear dynamical pattern of postural sway may provide important insights into the adaptability (flexibility) of human postural control in response to everyday stresses imposed on the body. A commonly used non-linear tool, i.e. recurrence quantification analysis, was chosen to investigate the effect of prior anterior cruciate ligament injury on the deterministic pattern of postural sway under different conditions of postural and cognitive difficulty. In double leg stance, as postural difficulty increased from open-eyes to closed-eyes and rigid-surface to foam-surface, the centre of pressure regularity (%determinism) increased as well. In comparison to healthy counterparts, subjects with prior anterior cruciate ligament injury produced more regularity when maintaining balance on their injured leg. Also, for both the double and single leg stance balance conditions, the performance of a secondary cognitive task (a backward digit span task) caused less center of pressure regularity than the single postural task, which suggests that both study populations required the same amount of cognitive involvement for maintaining balance. Center of pressure dynamic patterns exhibited by the anterior cruciate ligament deficient patients were more regular than those of the healthy controls indicating “complexity loss” and may be indicative of the reduced adaptability (flexibility) of a balance system to sudden perturbations. [Copyright &y& Elsevier]

Abstract: Recurrence quantification analysis (RQA), a nonlinear method of postural analysis, was used to explore the effects of dual-tasking on postural performance in people with nonspecific low back pain (LBP) compared with healthy participants. Postural performance was quantified by RQA % recurrence, % determinism, entropy and trend. People with nonspecific LBP (n =22) and unimpaired individuals (n =22) randomly performed quiet standing tasks with three levels of difficulty (rigid-surface eyes open, rigid-surface eyes closed and foam-surface eyes closed). These tasks were performed in isolation or concurrently with an easy or difficult cognitive task. Increasing postural difficulty was associated with higher % determinism, higher entropy and lower trend in anteroposterior (AP) and mediolateral (ML) directions in people with LBP and healthy participants. All RQA variables in the ML direction decreased as cognitive conditions became more difficult. Significant interactions between group and cognitive difficulty were shown for % recurrence, % determinism and trend in the AP direction. While healthy participants decreased % recurrence and trend by increasing the level of cognitive difficulty, the LBP patients did not. This preliminary study suggests that LBP may be one factor that modulates the posture–cognition interaction. [Copyright &y& Elsevier]

Reliability is a population-specific property, but to the authors' knowledge there has been no study to determine the test-retest reliability of the postural stability measures such as center of pressure (COP) measures in the population of patients with musculoskeletal disorders (MSDs), while their clinical applications have been presented in literature. So, 33 patients with low back pain (LBP), anterior cruciate ligament (ACL) injury and functional ankle instability (FAI) randomly completed postural measurements with three levels of difficulty (rigid surface-eyes open, rigid surface-eyes closed, and foam surface-eyes closed) in two sessions. COP data were used to calculate standard deviation of amplitude, standard deviation of velocity, phase plane portrait, mean total velocity and area (95% confidence ellipse). Relative reliability of these measures was assessed using intraclass correlation coefficient (ICC) and absolute reliability using standard error of measurement (SEM) and coefficient of variation (CV). Also, minimal metrically detectable change (MMDC) was calculated to quantify intervention effects. Among different COP parameters, mean total velocity in all conditions of postural difficulty showed high to very high reliability, with ICC range of 0.74-0.91, SEM range of 0.09-0.40cm/s, CV range of 5.31-8.29% and MMDC range of 0.19-0.79cm/s. Phase plane portrait in anteroposterior-mediolateral (AP-ML) and ML direction were other best parameters with respect to the level of reliability. Mean total velocity and phase plane portrait parameters are suggested as good candidates to use for quantification and assessment of balance performance and identifying those with MSDs. [ABSTRACT FROM AUTHOR]

Abstract: Reliability is a population-specific property, but to the authors’ knowledge there has been no study to determine the test–retest reliability of the postural stability measures such as center of pressure (COP) measures in the population of patients with musculoskeletal disorders (MSDs), while their clinical applications have been presented in literature. So, 33 patients with low back pain (LBP), anterior cruciate ligament (ACL) injury and functional ankle instability (FAI) randomly completed postural measurements with three levels of difficulty (rigid surface-eyes open, rigid surface-eyes closed, and foam surface-eyes closed) in two sessions. COP data were used to calculate standard deviation of amplitude, standard deviation of velocity, phase plane portrait, mean total velocity and area (95% confidence ellipse). Relative reliability of these measures was assessed using intraclass correlation coefficient (ICC) and absolute reliability using standard error of measurement (SEM) and coefficient of variation (CV). Also, minimal metrically detectable change (MMDC) was calculated to quantify intervention effects. Among different COP parameters, mean total velocity in all conditions of postural difficulty showed high to very high reliability, with ICC range of 0.74–0.91, SEM range of 0.09–0.40cm/s, CV range of 5.31–8.29% and MMDC range of 0.19–0.79cm/s. Phase plane portrait in anteroposterior–mediolateral (AP–ML) and ML direction were other best parameters with respect to the level of reliability. Mean total velocity and phase plane portrait parameters are suggested as good candidates to use for quantification and assessment of balance performance and identifying those with MSDs. [Copyright &y& Elsevier]

Background: Strength of knee extension and squat were compared between anterior cruciate ligament reconstructed (ACLR) patients and healthy subjects. Materials and Methods: Twenty ACLR and twenty control subjects were participated in this non-exprimental study. Isokinetic peak strength of knee extension and squat in involved and uninvolved side of the ACLR patient and control group were measured. Results: Concentric and eccentric knee extension strength of the involved leg was decreased but squat strength showed no difference. Conclusion: In spite of return to sport activity and normal squat strength weakness of knee extensor muscles in the involved side of the ACLR patient was existed. [ABSTRACT FROM AUTHOR]