Magnitude of Neck-Surface Vibration as an Estimate of Subglottal Pressure During Modulations of Vocal Effort and Intensity in Healthy Speakers

Purpose

This study examined the relationship between the magnitude of neck-surface vibration (NSV_Mag; transduced with an accelerometer) and intraoral estimates of subglottal pressure (P′_sg) during variations in vocal effort at 3 intensity levels.

Method

Twelve vocally healthy adults produced strings of /pɑ/ syllables in 3 vocal intensity conditions, while increasing vocal effort during each condition. Measures were made of P′_sg (estimated during stop-consonant closure), NSV_Mag (measured during the following vowel), sound pressure level, and respiratory kinematics. Mixed linear regression was used to analyze the relationship between NSV_Mag and P′_sg with respect to total lung volume excursion, levels of lung volume initiation and termination, airflow, laryngeal resistance, and vocal efficiency across intensity conditions.

Results

NSV_Mag was significantly related to P′_sg (p < .001), and there was a significant, although small, interaction between NSV_Mag and intensity condition. Total lung excursion was the only additional variable contributing to predicting the NSV_Mag–P′_sg relationship.

Conclusions

NSV_Mag closely reflects P′_sg during variations of vocal effort; however, the relationship changes across different intensities in some individuals. Future research should explore additional NSV-based measures (e.g., glottal airflow features) to improve estimation accuracy during voice production.

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Longitudinal Associations Across Prematurity, Attention, and Language in School-Age Children

Purpose

This research note explores the potential role of attention in mediating previously reported associations between language outcomes and prematurity.

Method

As a follow-up investigation to Mahurin Smith, DeThorne, Logan, Channell, and Petrill (2014), we employed multilevel modeling to analyze longitudinal data on language and attention collected when children were, on average, ages of 7, 8, and 10 years. The sample of 114 children taken from the Western Reserve Reading and Math Project was selected to oversample children with a history of prematurity while also controlling for differences in confounding influences such as age, gender, parental education, and race.

Results

As predicted, attention differentially predicted language outcomes based on form of measurement. Specifically, parent and examiner ratings of attention were significantly associated with standardized test performance at all 3 time points (R ² = 15.2%–20%). Associations between attention and language sample measures were less consistent across home visits and tended to be smaller in effect size.

Conclusion

Attention abilities are associated with children's language performance even in the absence of an attention-deficit/hyperactivity disorder diagnosis. Clinical implications, particularly as related to assessment, are discussed.

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Receptive Vocabulary, Cognitive Flexibility, and Inhibitory Control Differentially Predict Older and Younger Adults' Success Perceiving Speech by Talkers With Dysarthria

Purpose

Previous research has demonstrated equivocal findings related to the effect of listener age on intelligibility ratings of dysarthric speech. The aim of the present study was to investigate the mechanisms that support younger and older adults' perception of speech by talkers with dysarthria.

Method

Younger and older adults identified words in phrases produced by talkers with dysarthria. Listeners also completed assessments on peripheral hearing, receptive vocabulary, and executive control functions.

Results

Older and younger adults did not differ in their ability to perceive speech by talkers with dysarthria. Younger adults' success in identifying words produced by talkers with dysarthria was associated only with their hearing acuity. In contrast, older adults showed effects of working memory and cognitive flexibility and interactions between hearing acuity and receptive vocabulary and between hearing acuity and inhibitory control.

Conclusions

Although older and younger adults had equivalent performance identifying words produced by talkers with dysarthria, older adults appear to utilize more cognitive support to identify those words.

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Modeling Speech Level as a Function of Background Noise Level and Talker-to-Listener Distance for Talkers Wearing Hearing Protection Devices

Purpose

Studying the variations in speech levels with changing background noise level and talker-to-listener distance for talkers wearing hearing protection devices (HPDs) can aid in understanding communication in background noise.

Method

Speech was recorded using an intra-aural HPD from 12 different talkers at 5 different distances in 3 different noise conditions and 2 quiet conditions.

Results

This article proposes models that can predict the difference in speech level as a function of background noise level and talker-to-listener distance for occluded talkers. The proposed model complements the existing model presented by Pelegrín-García, Smits, Brunskog, and Jeong (2011) and expands on it by taking into account the effects of occlusion and background noise level on changes in speech sound level.

Conclusions

Three models of the relationship between vocal effort, background noise level, and talker-to-listener distance for talkers wearing HPDs are presented. The model with the best prediction intervals is a talker-dependent model that requires the users' unoccluded speech level at 10 m as a reference. A model describing the relationship between speech level, talker-to-listener distance, and background noise level for occluded talkers could eventually be incorporated with radio protocols to transmit verbal communication only to an intended set of listeners within a given spatial range—this range being dependent on the changes in speech level and background noise level.

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The Influence of Target and Masker Characteristics on Infants' and Adults' Detection of Speech

Purpose

Several investigators have compared infants' detection of speech in speech and nonspeech maskers to evaluate developmental differences in masking. Such comparisons have produced contradictory results, possibly because each investigation used different stimuli. The current study examined target and masker effects on infants' and adults' detection of speech.

Method

An observer-based procedure was used to compare infants' and adults' detection of the vowel /ʌ/ and the word “baby” in a 2-talker speech masker and matched speech-spectrum noise. The measure of performance was d′. A total of 43 7-month-old infants and 41 young adults were randomly assigned to 1 target–masker combination condition, and mean performance was compared across conditions at each age.

Results

Adults' detection was influenced by an interaction between the target and the masker: Adults detected the vowel better in the 2-talker masker than in speech-spectrum noise but detected the word equally well in the 2 maskers. In contrast, infants detected both targets better in speech-spectrum noise than in the 2-talker masker.

Conclusions

The relative effects of the masker on target detection by infants and adults depend on the target to be detected. Thus, conclusions drawn about differences between infants and adults in the mechanisms responsible for masking will depend on the stimuli. Standardization of speech stimuli in developmental research would help clarify the nature of infants' segregation difficulties.

Supplemental Material

http://ift.tt/2jDMsKA

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Receptive Vocabulary, Cognitive Flexibility, and Inhibitory Control Differentially Predict Older and Younger Adults' Success Perceiving Speech by Talkers With Dysarthria

Purpose

Previous research has demonstrated equivocal findings related to the effect of listener age on intelligibility ratings of dysarthric speech. The aim of the present study was to investigate the mechanisms that support younger and older adults' perception of speech by talkers with dysarthria.

Method

Younger and older adults identified words in phrases produced by talkers with dysarthria. Listeners also completed assessments on peripheral hearing, receptive vocabulary, and executive control functions.

Results

Older and younger adults did not differ in their ability to perceive speech by talkers with dysarthria. Younger adults' success in identifying words produced by talkers with dysarthria was associated only with their hearing acuity. In contrast, older adults showed effects of working memory and cognitive flexibility and interactions between hearing acuity and receptive vocabulary and between hearing acuity and inhibitory control.

Conclusions

Although older and younger adults had equivalent performance identifying words produced by talkers with dysarthria, older adults appear to utilize more cognitive support to identify those words.

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Modeling Speech Level as a Function of Background Noise Level and Talker-to-Listener Distance for Talkers Wearing Hearing Protection Devices

Purpose

Studying the variations in speech levels with changing background noise level and talker-to-listener distance for talkers wearing hearing protection devices (HPDs) can aid in understanding communication in background noise.

Method

Speech was recorded using an intra-aural HPD from 12 different talkers at 5 different distances in 3 different noise conditions and 2 quiet conditions.

Results

This article proposes models that can predict the difference in speech level as a function of background noise level and talker-to-listener distance for occluded talkers. The proposed model complements the existing model presented by Pelegrín-García, Smits, Brunskog, and Jeong (2011) and expands on it by taking into account the effects of occlusion and background noise level on changes in speech sound level.

Conclusions

Three models of the relationship between vocal effort, background noise level, and talker-to-listener distance for talkers wearing HPDs are presented. The model with the best prediction intervals is a talker-dependent model that requires the users' unoccluded speech level at 10 m as a reference. A model describing the relationship between speech level, talker-to-listener distance, and background noise level for occluded talkers could eventually be incorporated with radio protocols to transmit verbal communication only to an intended set of listeners within a given spatial range—this range being dependent on the changes in speech level and background noise level.

from #Audiology via xlomafota13 on Inoreader http://article/doi/10.1044/2017_JSLHR-S-17-0052/2665791/Modeling-Speech-Level-as-a-Function-of-Background
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The Influence of Target and Masker Characteristics on Infants' and Adults' Detection of Speech

Purpose

Several investigators have compared infants' detection of speech in speech and nonspeech maskers to evaluate developmental differences in masking. Such comparisons have produced contradictory results, possibly because each investigation used different stimuli. The current study examined target and masker effects on infants' and adults' detection of speech.

Method

An observer-based procedure was used to compare infants' and adults' detection of the vowel /ʌ/ and the word “baby” in a 2-talker speech masker and matched speech-spectrum noise. The measure of performance was d′. A total of 43 7-month-old infants and 41 young adults were randomly assigned to 1 target–masker combination condition, and mean performance was compared across conditions at each age.

Results

Adults' detection was influenced by an interaction between the target and the masker: Adults detected the vowel better in the 2-talker masker than in speech-spectrum noise but detected the word equally well in the 2 maskers. In contrast, infants detected both targets better in speech-spectrum noise than in the 2-talker masker.

Conclusions

The relative effects of the masker on target detection by infants and adults depend on the target to be detected. Thus, conclusions drawn about differences between infants and adults in the mechanisms responsible for masking will depend on the stimuli. Standardization of speech stimuli in developmental research would help clarify the nature of infants' segregation difficulties.

Supplemental Material

http://ift.tt/2jDMsKA

from #Audiology via xlomafota13 on Inoreader http://article/doi/10.1044/2017_JSLHR-H-16-0464/2665222/The-Influence-of-Target-and-Masker-Characteristics
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Magnitude of Neck-Surface Vibration as an Estimate of Subglottal Pressure During Modulations of Vocal Effort and Intensity in Healthy Speakers

Purpose

This study examined the relationship between the magnitude of neck-surface vibration (NSV_Mag; transduced with an accelerometer) and intraoral estimates of subglottal pressure (P′_sg) during variations in vocal effort at 3 intensity levels.

Method

Twelve vocally healthy adults produced strings of /pɑ/ syllables in 3 vocal intensity conditions, while increasing vocal effort during each condition. Measures were made of P′_sg (estimated during stop-consonant closure), NSV_Mag (measured during the following vowel), sound pressure level, and respiratory kinematics. Mixed linear regression was used to analyze the relationship between NSV_Mag and P′_sg with respect to total lung volume excursion, levels of lung volume initiation and termination, airflow, laryngeal resistance, and vocal efficiency across intensity conditions.

Results

NSV_Mag was significantly related to P′_sg (p < .001), and there was a significant, although small, interaction between NSV_Mag and intensity condition. Total lung excursion was the only additional variable contributing to predicting the NSV_Mag–P′_sg relationship.

Conclusions

NSV_Mag closely reflects P′_sg during variations of vocal effort; however, the relationship changes across different intensities in some individuals. Future research should explore additional NSV-based measures (e.g., glottal airflow features) to improve estimation accuracy during voice production.

from #Audiology via ola Kala on Inoreader http://article/doi/10.1044/2017_JSLHR-S-17-0180/2665792/Magnitude-of-NeckSurface-Vibration-as-an-Estimate
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Longitudinal Associations Across Prematurity, Attention, and Language in School-Age Children

Purpose

This research note explores the potential role of attention in mediating previously reported associations between language outcomes and prematurity.

Method

As a follow-up investigation to Mahurin Smith, DeThorne, Logan, Channell, and Petrill (2014), we employed multilevel modeling to analyze longitudinal data on language and attention collected when children were, on average, ages of 7, 8, and 10 years. The sample of 114 children taken from the Western Reserve Reading and Math Project was selected to oversample children with a history of prematurity while also controlling for differences in confounding influences such as age, gender, parental education, and race.

Results

As predicted, attention differentially predicted language outcomes based on form of measurement. Specifically, parent and examiner ratings of attention were significantly associated with standardized test performance at all 3 time points (R ² = 15.2%–20%). Associations between attention and language sample measures were less consistent across home visits and tended to be smaller in effect size.

Conclusion

Attention abilities are associated with children's language performance even in the absence of an attention-deficit/hyperactivity disorder diagnosis. Clinical implications, particularly as related to assessment, are discussed.

from #Audiology via ola Kala on Inoreader http://article/doi/10.1044/2017_JSLHR-L-17-0015/2665790/Longitudinal-Associations-Across-Prematurity
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Receptive Vocabulary, Cognitive Flexibility, and Inhibitory Control Differentially Predict Older and Younger Adults' Success Perceiving Speech by Talkers With Dysarthria

Purpose

Previous research has demonstrated equivocal findings related to the effect of listener age on intelligibility ratings of dysarthric speech. The aim of the present study was to investigate the mechanisms that support younger and older adults' perception of speech by talkers with dysarthria.

Method

Younger and older adults identified words in phrases produced by talkers with dysarthria. Listeners also completed assessments on peripheral hearing, receptive vocabulary, and executive control functions.

Results

Older and younger adults did not differ in their ability to perceive speech by talkers with dysarthria. Younger adults' success in identifying words produced by talkers with dysarthria was associated only with their hearing acuity. In contrast, older adults showed effects of working memory and cognitive flexibility and interactions between hearing acuity and receptive vocabulary and between hearing acuity and inhibitory control.

Conclusions

Although older and younger adults had equivalent performance identifying words produced by talkers with dysarthria, older adults appear to utilize more cognitive support to identify those words.

from #Audiology via ola Kala on Inoreader http://article/doi/10.1044/2017_JSLHR-H-17-0119/2665789/Receptive-Vocabulary-Cognitive-Flexibility-and
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Modeling Speech Level as a Function of Background Noise Level and Talker-to-Listener Distance for Talkers Wearing Hearing Protection Devices

Purpose

Studying the variations in speech levels with changing background noise level and talker-to-listener distance for talkers wearing hearing protection devices (HPDs) can aid in understanding communication in background noise.

Method

Speech was recorded using an intra-aural HPD from 12 different talkers at 5 different distances in 3 different noise conditions and 2 quiet conditions.

Results

This article proposes models that can predict the difference in speech level as a function of background noise level and talker-to-listener distance for occluded talkers. The proposed model complements the existing model presented by Pelegrín-García, Smits, Brunskog, and Jeong (2011) and expands on it by taking into account the effects of occlusion and background noise level on changes in speech sound level.

Conclusions

Three models of the relationship between vocal effort, background noise level, and talker-to-listener distance for talkers wearing HPDs are presented. The model with the best prediction intervals is a talker-dependent model that requires the users' unoccluded speech level at 10 m as a reference. A model describing the relationship between speech level, talker-to-listener distance, and background noise level for occluded talkers could eventually be incorporated with radio protocols to transmit verbal communication only to an intended set of listeners within a given spatial range—this range being dependent on the changes in speech level and background noise level.

from #Audiology via ola Kala on Inoreader http://article/doi/10.1044/2017_JSLHR-S-17-0052/2665791/Modeling-Speech-Level-as-a-Function-of-Background
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The Influence of Target and Masker Characteristics on Infants' and Adults' Detection of Speech

Purpose

Several investigators have compared infants' detection of speech in speech and nonspeech maskers to evaluate developmental differences in masking. Such comparisons have produced contradictory results, possibly because each investigation used different stimuli. The current study examined target and masker effects on infants' and adults' detection of speech.

Method

An observer-based procedure was used to compare infants' and adults' detection of the vowel /ʌ/ and the word “baby” in a 2-talker speech masker and matched speech-spectrum noise. The measure of performance was d′. A total of 43 7-month-old infants and 41 young adults were randomly assigned to 1 target–masker combination condition, and mean performance was compared across conditions at each age.

Results

Adults' detection was influenced by an interaction between the target and the masker: Adults detected the vowel better in the 2-talker masker than in speech-spectrum noise but detected the word equally well in the 2 maskers. In contrast, infants detected both targets better in speech-spectrum noise than in the 2-talker masker.

Conclusions

The relative effects of the masker on target detection by infants and adults depend on the target to be detected. Thus, conclusions drawn about differences between infants and adults in the mechanisms responsible for masking will depend on the stimuli. Standardization of speech stimuli in developmental research would help clarify the nature of infants' segregation difficulties.

Supplemental Material

http://ift.tt/2jDMsKA

from #Audiology via ola Kala on Inoreader http://article/doi/10.1044/2017_JSLHR-H-16-0464/2665222/The-Influence-of-Target-and-Masker-Characteristics
via IFTTT

Magnitude of Neck-Surface Vibration as an Estimate of Subglottal Pressure During Modulations of Vocal Effort and Intensity in Healthy Speakers

Purpose

This study examined the relationship between the magnitude of neck-surface vibration (NSV_Mag; transduced with an accelerometer) and intraoral estimates of subglottal pressure (P′_sg) during variations in vocal effort at 3 intensity levels.

Method

Twelve vocally healthy adults produced strings of /pɑ/ syllables in 3 vocal intensity conditions, while increasing vocal effort during each condition. Measures were made of P′_sg (estimated during stop-consonant closure), NSV_Mag (measured during the following vowel), sound pressure level, and respiratory kinematics. Mixed linear regression was used to analyze the relationship between NSV_Mag and P′_sg with respect to total lung volume excursion, levels of lung volume initiation and termination, airflow, laryngeal resistance, and vocal efficiency across intensity conditions.

Results

NSV_Mag was significantly related to P′_sg (p < .001), and there was a significant, although small, interaction between NSV_Mag and intensity condition. Total lung excursion was the only additional variable contributing to predicting the NSV_Mag–P′_sg relationship.

Conclusions

NSV_Mag closely reflects P′_sg during variations of vocal effort; however, the relationship changes across different intensities in some individuals. Future research should explore additional NSV-based measures (e.g., glottal airflow features) to improve estimation accuracy during voice production.

from #Audiology via xlomafota13 on Inoreader http://article/doi/10.1044/2017_JSLHR-S-17-0180/2665792/Magnitude-of-NeckSurface-Vibration-as-an-Estimate
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Spatial orientation and postural control in patients with Parkinson’s disease

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): E. Pawlitzki, C. Schlenstedt, N. Schmidt, I. Rotkirch, F. Gövert, G. Hartwigsen, K. Witt
Postural instability is one of the most disabling and risky symptoms of advanced Parkinson's disease (PD). The purpose of this study was to investigate whether and how this is mediated by a centrally impaired spatial orientation. Therefore, we performed a spatial orientation study in 21 PD patients (mean age 68years, SD 8.5 years, 9 women) in a medically on condition and 21 healthy controls (mean age 68.9years, SD 5.5years, 14 women). We compared their spatial responses to the horizontal axis (Sakashita's visual target cancellation task), the vertical axis (bucket-test), the sagittal axis (tilt table test) and postural stability using the Fullerton Advanced Balance Scale (FAB). We found larger deviations on the vertical axis in PD patients, although the direct comparisons of performance in PD patients and healthy controls did not reveal significant differences. While the total scores of the FAB Scale were significantly worse in PD (25.9 points, SD 7.2 points) compared to controls (35.1 points, SD 2.3 points, p<0.01), the results from the spatialorientation task did not correlate with the FAB Scale. In summary, our results argue against a relation between perceptional deficits of spatial information and postural control in PD. These results are in favor of a deficit in higher order integration of spatial stimuli in PD that might influence balance control.



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Effect of robotic-assisted gait rehabilitation on dynamic equilibrium control in the gait of children with cerebral palsy

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): L. Wallard, G. Dietrich, Y. Kerlirzin, J. Bredin
Due to the intensity and repetition of movement, roboticassisted gait training therapy could have a beneficial effect on the recovery and improvement of postural and locomotor functions of the patient. This study sought to highlight the effects of robotic-assisted gait rehabilitation in gait of children with Cerebral Palsy (CP). We analyzed the different strategies before and after this rehabilitation which was used in order to generate forward motion while maintaining balance. Data were collected by a motion analysis system (Vicon® - Oxford Metrics, Oxford, UK). The children were divided into two groups in such a way as to obtain a randomized controlled population: i) a group of fourteen children (Treated Group) underwent 20 sessions of roboticassisted gait training therapy using the driven gait orthosis Lokomat®Pediatric (Hocoma AG, Volketswil, Switzerland) compared to ii) a group of sixteen children without sessions of Lokomat®Pediatric (Control Group). Significant differences are observed for the TG between the preand post-test values of the locomotor parameters and of the kinetic data of the propulsive forces of the Center of Mass (COM) and of the Center of Pressure (COP) dynamic trajectory. This first study, although performed on a limited number of patients, shows the usefulness of this robotic gait rehabilitation mainly in the balance control in gait. Indeed after this rehabilitation, these children improve their gait that is especially characterized by a more appropriate time lag between the time instant of COM-COP trajectory divergence and the time instant when the forward propulsive forces became apparent.



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Evaluating the immediate effects of wearing foot orthotics in children with Joint Hypermobility Syndrome (JHS) by analysis of temperospatial parameters of gait and dynamic balance: A preliminary study

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): P. McDermott, E. Wolfe, C. Lowry, K. Robinson, H.P. French
Joint Hypermobility Syndrome (JHS) in children, presents with increased joint range of motion and can lead to altered gait strategies and reduced dynamic balance. Despite limited evidence foot orthoses are sometimes prescribed to patients with JHS with the aim to improve the stability of their gait pattern and theoretically reduce associated symptoms of fatigue and joint pain. The purpose of this study was therefore to analyse the immediate effects of ‘off the shelf’ orthoses on temporospatial parameters of gait and dynamic balance in this cohort.MethodsA total of 21 patients were recruited for the study (13 female) with a median age of 10 years (IRQ=4.12). Each patient had their gait analysed using the GAITRite walkway in their own footwear and immediately after being prescribed the orthoses. Gait was tested at both the patients’ preferred speed and when asked to walk slower to challenge their dynamic balance.ResultsGait appeared more synchronised, with a reduction in step length and width variability, when participants were provided with orthotics. The variation was greatest when participants were asked to walk slower. Double stance was significantly less at slower speeds when orthotics were added (1.61%, 95% CI=0.34, 2.89, p=0.015)ConclusionResults of this study indicate that orthotics have a definite immediate influence on gait patterns in patients with JHS. Future studies should investigate the long-term effects of orthotics in this population and include outcome measures for symptoms such as pain.



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Are there associations with age and sex in walking stability in healthy older adults?

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Daan van Kooten, Florentina Hettinga, Kim Duffy, Jo Jackson, Matthew J.D. Taylor
The variability of the centre of pressure (COP) during walking can provide information in relation to stability when walking. The aim of this study was to investigate if age and sex were associated with COP variability, COP excursions, and COP velocities during walking. One-hundred and fourteen older adults (age 65.1±5.5 yrs.) participated in the study. A Kistler force platform (1000Hz) recorded the ground reaction forces and COPs during walking at a self-selected walking speed. The stance phase was divided, using the vertical GRF, into four sub-phases: loading response (LR), mid-stance (MSt), terminal stance (TSt), and pre-swing (PSw). The standard deviations of the COP displacement (variability), the COP velocity, and COP excursion in the medial–lateral and anterior–posterior directions, as well as the resultant magnitude were assessed. When controlling for walking speed, a greater age was associated with a higher variability and excursion of the COP during LR only suggesting that stability is maintained during the majority of the stance phase. During LR lower COP velocity was significantly associated for females for anterior-posterior and total COP, which may be a strategy to facilitate stability before, and moving into, MSt and TSt.



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Prediction of walk-to-run transition using stride frequency: A test-retest reliability study

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Ernst Albin Hansen, Andreas Møller Nielsen, Lasse Andreas Risgaard Kristensen, Pascal Madeleine, Michael Voigt
The transition from walking to running has previously been predicted to occur at a point where the stride frequency starts getting closer to the running attractor than to the walking attractor. The two behavioural attractors were considered to be represented by the freely chosen stride frequencies during unrestricted treadmill walking and running. The aim of the present study was to determine the relative and absolute test-retest reliability of the predicted walk-to-run transition stride frequency. Healthy individuals (n=25) performed walking and running on a treadmill in a day-to-day test-retest design. The two behavioral attractors were determined during walking and running at freely chosen velocities and stride frequencies. Subsequently, the walk-to-run transition stride frequency was predicted using camera recordings and a previously reported equation for prediction. The walk-to-run transition occurred at a velocity of 7.7±0.5kmh⁻¹ at day 1 as well as at day 2. Besides, the predicted walk-to-run transition stride frequencies were 69.7±3.3 strides min⁻¹ and 70.5±3.4 strides min⁻¹ on day 1 and day 2, respectively (p=0.08). A further comparison between the predicted walk-to-run transition stride frequencies at day 1 and day 2 showed an ICC3,1 of 0.89, which indicated almost perfect relative reliability. The absolute reliability was reflected by a%-value of the standard error of the measurement (SEM%) of 1.6% and a%-value of the smallest real difference (SRD%) of 4.4%. In conclusion, the predicted walk-to-run transition stride frequency can be considered reliable across days.



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Neuromuscular compensatory strategies at the trunk and lower limb are not resolved following an ACL reconstruction

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Grant Boggess, Kristin Morgan, Darren Johnson, Mary Lloyd Ireland, Jeffrey A. Reinbolt, Brian Noehren
BackgroundFollowing anterior cruciate ligament reconstruction (ACLR), patients present with greater trunk ipsilateral lean, which may affect knee kinetics and increase re-injury risk. However, there has been little research into neuromuscular factors controlling the trunk and their relation to the knee between healthy and ACLR subjects. This is critical to establish in order to develop more directed and effective interventions.HypothesisAs compared to healthy control subjects, ACLR subjects will demonstrate increased erector spinae and rectus abdominis co-contraction, greater rectus abdominis force and greater hamstring force that is correlated to increased forward trunk lean.Study designCross-sectional study, Level of Evidence: 3.MethodsEleven healthy and eleven ACLR subjects were matched for age, mass and height. Subjects were asked to run at a self-selected speed while instrumented gait analysis was performed. An anthropometrically scaled OpenSim model was created for each subject. Trunk and hamstring muscle forces from Static Optimization were analyzed at impact peak. Additionally, directed co-contraction ratios were calculated for the erector spinae and erector spinae/rectus abdominis combinations.ResultsACLR subjects showed more balanced erector spinae co-contraction [p<0.01], and greater hamstring force [biceps femoris long head (p=0.02), semimembranosus (0.01), semitendinosus (0.01)]. There was no statistical difference for any other muscle group.ConclusionDespite release to return to sport, ACLR subjects are continuing to increase the stiffness of their trunk as well increase their hamstring force to potentially reduce anterior tibial translation.Clinical relevanceClinicians may anticipate ACLR subjects using their erector spinae and hamstrings to maintain a sense of stability in their trunk and at their knee.



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Altered postural control variability in older-aged individuals with a history of lateral ankle sprain

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Masafumi Terada, Kyle Kosik, Nathan Johnson, Phillip Gribble
The current study aimed to examine postural control performance during a single-leg balance task in elderly individuals with and without a previous history of lateral ankle sprain (LAS). Eighteen adults with a previous hisoty of LAS (mean age=66years old) and 12 healthy controls (mean age=65years old) were included in the study. Participants performed three trials of a single-leg balance task during an eyes-opened condition for 20-s. Center of pressure (COP) trajectories in the anteroposterior (AP) and mediolateral (ML) directions were collected with a force plate. The following postural control measures were calculated in the AP and ML directions: 1) Sample Entropy (SampEn); 2) Approximate Entropy (ApEn); 3) mean of Time-to-Boundary minima (mean TTB); and 4) COP velocity (COPV). Older-age participants with a history LAS exhibited lower ApEn-AP, SampEn-AP, and SampEn-ML values compared to healthy controls (p<0.05). The information gained from this investigation indicates more rigid postural control patterns, less adaptability, and more difficulty maintaining COP during a single-leg balance task in adults with a previous history of LAS. Our data suggest that there is a need to consider history of musculoskeletal injury when evaluating factors for postural control and fall risk in the elderly. Future investigations are needed to assess the effect of LAS on age-related declines in postural control and discern associations between potential risk factors of fall-related injuries and LAS in an elderly population.



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An exploratory study examining factors underpinning postural instability in older adults with idiopathic neck pain

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): June Quek, Julia Treleaven, Ross A Clark, Sandra G Brauer
There is limited understanding of potential mechanisms underpinning postural control deficits in people with neck pain. This study examined several characteristics that might explain impaired postural stability in a group of older adults with neck pain, and compared the results in this cohort with that of asymptomatic controls. In this cross-sectional study we compared physical activity, lower limb motor and sensory function, vestibular and visual function, falls efficacy and dizziness handicap in 84 older adults with (n=35, age 69.6±6.3) and without (n=49, age 69.4±4.7) idiopathic neck-pain. Additionally, dynamic balance was assessed using the dynamic gait index (DGI) and standard and wavelet analysis of static balance was computed after data capture. Physical activity levels, lower limb motor and sensory function, vestibular function and visual contrast sensitivity were not different between groups (p>0.05). The neck-pain group demonstrated higher falls efficacy (p=0.01), greater levels of dizziness handicap (p<0.01), and higher CoP velocity measures in the moderate (1.56–6.25Hz) and low (0.39–1.56Hz) frequency bandwidths. Our results suggest that neck-pain induced postural control deficits in older adults may not be associated with the physical activity levels, lower limb motor and sensory function, or vestibular and visual function. Inferring from wavelet analysis results, we speculated that sensory re-weighting may have occurred to compensate for the deficits in neck proprioception. Further research is warranted to determine neck specific mechanisms underpinning postural control dysfunction in neck pain.



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Effect of tibia marker placement on knee joint kinematic analysis

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Yuhui Wen, Hongshi Huang, Yuanyuan Yu, Si Zhang, Jie Yang, Yingfang Ao, Shihong Xia
Variability of kinematic measures determined by different marker sets among sites participating in a collaborative study is necessary for determining the reliability of a multi-site gait analysis research. We compared knee kinematics based on different marker sets on the tibia, calculating by segmental optimization (SO) and multi-body optimization (MBO) methods respectively, in order to assess the effect of marker locations on the methods. 11 healthy subjects participated in the study with 33 markers attached to the lower extremity segments, and 4 groups were identified according to markers on the tibia. Knee joint kinematics during level walking were measured and then compared among the 4 groups using statistical parametric mapping. For SO method, the results showed that there were no significant differences in the knee joint angles when used different marker sets on the tibia. However, significant differences were found in the transverse plane kinematics for MBO method. It was concluded that MBO method was more likely to be influenced by different marker sets. More attention should be paid to marker sets, specifically for MBO method, when three-dimensional gait analysis data are shared and interpreted among sites for clinical decision-making.



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Joint mechanical asymmetries during low- and high-demand mobility tasks: Comparison between total knee arthroplasty and healthy-matched peers

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Jesse C. Christensen, Paul C. LaStayo, Ryan L. Mizner, Robin L. Marcus, Christopher E. Pelt, Gregory J. Stoddard, K. Bo Foreman
Chronic inter-limb joint mechanical asymmetry has been reported following total knee arthroplasty (TKA) during low-demand mobility tasks such as level walking. However, no study has compared the inter-limb asymmetry during a high-demand mobility task such as decline walking. The objective of this cross-sectional study was to compare inter-limb asymmetry differences during both level and decline walking tasks at six months following TKA compared to asymmetry present in an age, gender, body mass index and activity level matched healthy cohort. Kinetic and kinematic gait analysis was conducted on 42 patients with TKA and 15 healthy-matched peers. Our inter-limb asymmetry results demonstrated significantly (p<0.05) greater combined limb support moment (MS) (mean differences [MD]=0.17; 95% CI=0.07, 0.22), knee extensor moment (MK) (MD=0.05; 95% CI=0.02, 0.09) and vertical ground reaction force (vGRF) (MD=0.03; 95% CI=0.01, 0.08) differences during decline walking compared to level walking in patients with TKA. Greater MS (MD=0.24; 95% CI=0.13, 0.35), MK (MD=0.08; 95% CI=0.03, 0.18), vGRF (MD=0.04; 95% CI=0.01, 0.08) and knee joint angle (MD=2.4; 95% CI=0.37, 3.80) differences were present in patients with TKA compared to healthy-matched peers during decline walking. Greater MS (MD=0.13; 95% CI=0.05, 0.20) and plantarflexor moment (MD=0.06; 95% CI=0.04, 0.16) differences were present in patients with TKA compared to healthy-matched peers during level walking. Post-TKA inter-limb asymmetry during level walking worsens as the physical demands of the task are increased. Thus, even patients with good self-reported outcomes after TKA exhibit substantial deficits in their mobility reserves that could limit their independence and community mobility as they age.



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Differences in pattern of variability for lower extremity kinematics between walking and running

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Amanda Estep, Steven Morrison, Shane Caswell, Jatin Ambegaonkar, Nelson Cortes
This study characterizes walking and running patterns in healthy individuals using linear and nonlinear methods Seventeen individuals (12 males, 5 females) volunteered for the study. 3D kinematic data during walking (WA) and running (RU) on a motorized treadmill were captured using reflective markers placed on lower body (200Hz). A single 25s trial (5000 data points) was collected for each gait task. WA speed was 1.39±0.12m/s, whereas RU speed was 2.56±0.27m/s. Variables of interest included ankle plantar/dorsi flexion, knee flexion/extension, knee abduction/adduction, hip flexion/extension, and hip abduction/adduction angles. For linear analysis, standard deviation (SD) and coefficient of variation (CV) were calculated for the entire time series for both conditions. Nonlinear analysis included assessing pattern of regularity of respective kinematic time series using approximate entropy (ApEn). Inferential analyses were conducted using MANOVA to compare selected dependent measures (p<0.05). SD for knee flexion/extension angle (WA=23.34±4.17, RU=27.51±5.25) and ankle plantar/dorsi flexion angle (WA=9.24±2.37, RU=12.88±2.00) were both greater during running. For all other variables, there were no significant differences in degree of variability between walking and running (p’s>0.05). Running ApEn values were greater than walking ApEn values for knee flexion/extension (WA=0.14±0.02, RU=0.23±0.04), knee abduction/adduction (WA=0.18±0.07, RU=0.24±0.07), hip flexion/extension (WA=0.09±0.02, RU=0.17±0.04), and hip abduction/adduction (WA=0.12±0.03, RU=0.21±0.05). Greater variability was demonstrated during running across all joints compared to walking. This suggests that ApEn is more sensitive to detecting changes between different gait conditions than standard discrete measures of variability (SD).



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Using phone sensors and an artificial neural network to detect gait changes during drinking episodes in the natural environment

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Brian Suffoletto, Pedram Gharani, Tammy Chung, Hassan Karimi
BackgroundPhone sensors could be useful in assessing changes in gait that occur with alcohol consumption. This study determined (1) feasibility of collecting gait-related data during drinking occasions in the natural environment, and (2) how gait-related features measured by phone sensors relate to estimated blood alcohol concentration (eBAC).MethodsTen young adult heavy drinkers were prompted to complete a 5-step gait task every hour from 8pm to 12am over four consecutive weekends. We collected 3-axis accelerometer, gyroscope, and magnetometer data from phone sensors, and computed 24 gait-related features using a sliding window technique. eBAC levels were calculated at each time point based on Ecological Momentary Assessment (EMA) of alcohol use. We used an artificial neural network model to analyze associations between sensor features and eBACs in training (70% of the data) and validation and test (30% of the data) datasets.ResultsWe analyzed 128 data points where both eBAC and gait-related sensor data were captured, either when not drinking (n=60), while eBAC was ascending (n=55) or eBAC was descending (n=13). 21 data points were captured at times when the eBAC was greater than the legal limit (0.08mg/dl). Using a Bayesian regularized neural network, gait-related phone sensor features showed a high correlation with eBAC (Pearson’s r>0.9), and >95% of estimated eBAC would fall between −0.012 and +0.012 of actual eBAC.ConclusionsIt is feasible to collect gait-related data from smartphone sensors during drinking occasions in the natural environment. Sensor-based features can be used to infer gait changes associated with elevated blood alcohol content.



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Reference values and equations reference of balance for children of 8 to 12 years

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Thiele de Cássia Libardoni, Carolina Buzzi da Silveira, Larissa Milani Brognoli Sinhorim, Anamaria Siriani de Oliveira, Márcio José dos Santos, Gilmar Moraes Santos
PurposeThere are still no normative data in balance sway for school-age children in Brazil. We aimed to establish the reference ranges for balance scores and to develop prediction equations for estimation of balance scores in children aged 8 to 12 years old.MethodsThe study included 165 healthy children (83 boys and 82 girls; age, 8–12 years) recruited from a public school in the city of Florianópolis, Santa Catarina, Brazil. We used the Sensory Organization Test to assess the balance scores and both a digital scale and a stadiometer to measure the anthropometric variables. We tested a stepwise multiple-regression model with sex, height, weight, and mid-thigh circumference of the dominant leg as predictors of the balance score.ResultsFor all experimental conditions, girls’ age accounted for over 85% of the variability in balance scores; while, boys’ age accounted only 55% of the variability in balance scores. Therefore, balance scores increase with age for boys and girls.ConclusionThis study described the ranges of age- and sex-specific normative values for balance scores in children during 6 different testing conditions established by the sensory organization test. We confirmed that age was the predictor that best explained the variability in balance scores in children between 8 and 12 years old. This study stimulates a new and more comprehensive study to estimate balance scores from prediction equations for overall Brazilian pediatric population.



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Effect of parameter selection on entropy calculation for long walking trials

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Jennifer M. Yentes, William Denton, John McCamley, Peter C. Raffalt, Kendra K. Schmid
It is sometimes difficult to obtain uninterrupted data sets that are long enough to perform nonlinear analysis, especially in pathological populations. It is currently unclear as to how many data points are needed for reliable entropy analysis. The aims of this study were to determine the effect of changing parameter values of m, r, and N on entropy calculations for long gait data sets using two different modes of walking (i.e., overground versus treadmill). Fourteen young adults walked overground and on a treadmill at their preferred walking speed for one-hour while step time was collected via heel switches. Approximate (ApEn) and sample entropy (SampEn) were calculated using multiple parameter combinations of m, N, and r. Further, r was tested under two cases r*standard deviation and r constant. ApEn differed depending on the combination of r, m, and N. ApEn demonstrated relative consistency except when m=2 and the smallest r values used (rSD=0.015*SD, 0.20*SD; rConstant=0 and 0.003). For SampEn, as r increased, SampEn decreased. When r was constant, SampEn demonstrated excellent relative consistency for all combinations of r, m, and N. When r constant was used, overground walking was more regular than treadmill. However, treadmill walking was found to be more regular when using rSD for both ApEn and SampEn. For greatest relative consistency of step time data, it was best to use a constant r value and SampEn. When using entropy, several r values must be examined and reported to ensure that results are not an artifact of parameter choice.



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Spatial orientation and postural control in patients with Parkinson’s disease

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): E. Pawlitzki, C. Schlenstedt, N. Schmidt, I. Rotkirch, F. Gövert, G. Hartwigsen, K. Witt
Postural instability is one of the most disabling and risky symptoms of advanced Parkinson's disease (PD). The purpose of this study was to investigate whether and how this is mediated by a centrally impaired spatial orientation. Therefore, we performed a spatial orientation study in 21 PD patients (mean age 68years, SD 8.5 years, 9 women) in a medically on condition and 21 healthy controls (mean age 68.9years, SD 5.5years, 14 women). We compared their spatial responses to the horizontal axis (Sakashita's visual target cancellation task), the vertical axis (bucket-test), the sagittal axis (tilt table test) and postural stability using the Fullerton Advanced Balance Scale (FAB). We found larger deviations on the vertical axis in PD patients, although the direct comparisons of performance in PD patients and healthy controls did not reveal significant differences. While the total scores of the FAB Scale were significantly worse in PD (25.9 points, SD 7.2 points) compared to controls (35.1 points, SD 2.3 points, p<0.01), the results from the spatialorientation task did not correlate with the FAB Scale. In summary, our results argue against a relation between perceptional deficits of spatial information and postural control in PD. These results are in favor of a deficit in higher order integration of spatial stimuli in PD that might influence balance control.



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Effect of robotic-assisted gait rehabilitation on dynamic equilibrium control in the gait of children with cerebral palsy

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): L. Wallard, G. Dietrich, Y. Kerlirzin, J. Bredin
Due to the intensity and repetition of movement, roboticassisted gait training therapy could have a beneficial effect on the recovery and improvement of postural and locomotor functions of the patient. This study sought to highlight the effects of robotic-assisted gait rehabilitation in gait of children with Cerebral Palsy (CP). We analyzed the different strategies before and after this rehabilitation which was used in order to generate forward motion while maintaining balance. Data were collected by a motion analysis system (Vicon® - Oxford Metrics, Oxford, UK). The children were divided into two groups in such a way as to obtain a randomized controlled population: i) a group of fourteen children (Treated Group) underwent 20 sessions of roboticassisted gait training therapy using the driven gait orthosis Lokomat®Pediatric (Hocoma AG, Volketswil, Switzerland) compared to ii) a group of sixteen children without sessions of Lokomat®Pediatric (Control Group). Significant differences are observed for the TG between the preand post-test values of the locomotor parameters and of the kinetic data of the propulsive forces of the Center of Mass (COM) and of the Center of Pressure (COP) dynamic trajectory. This first study, although performed on a limited number of patients, shows the usefulness of this robotic gait rehabilitation mainly in the balance control in gait. Indeed after this rehabilitation, these children improve their gait that is especially characterized by a more appropriate time lag between the time instant of COM-COP trajectory divergence and the time instant when the forward propulsive forces became apparent.



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Evaluating the immediate effects of wearing foot orthotics in children with Joint Hypermobility Syndrome (JHS) by analysis of temperospatial parameters of gait and dynamic balance: A preliminary study

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): P. McDermott, E. Wolfe, C. Lowry, K. Robinson, H.P. French
Joint Hypermobility Syndrome (JHS) in children, presents with increased joint range of motion and can lead to altered gait strategies and reduced dynamic balance. Despite limited evidence foot orthoses are sometimes prescribed to patients with JHS with the aim to improve the stability of their gait pattern and theoretically reduce associated symptoms of fatigue and joint pain. The purpose of this study was therefore to analyse the immediate effects of ‘off the shelf’ orthoses on temporospatial parameters of gait and dynamic balance in this cohort.MethodsA total of 21 patients were recruited for the study (13 female) with a median age of 10 years (IRQ=4.12). Each patient had their gait analysed using the GAITRite walkway in their own footwear and immediately after being prescribed the orthoses. Gait was tested at both the patients’ preferred speed and when asked to walk slower to challenge their dynamic balance.ResultsGait appeared more synchronised, with a reduction in step length and width variability, when participants were provided with orthotics. The variation was greatest when participants were asked to walk slower. Double stance was significantly less at slower speeds when orthotics were added (1.61%, 95% CI=0.34, 2.89, p=0.015)ConclusionResults of this study indicate that orthotics have a definite immediate influence on gait patterns in patients with JHS. Future studies should investigate the long-term effects of orthotics in this population and include outcome measures for symptoms such as pain.



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Are there associations with age and sex in walking stability in healthy older adults?

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Daan van Kooten, Florentina Hettinga, Kim Duffy, Jo Jackson, Matthew J.D. Taylor
The variability of the centre of pressure (COP) during walking can provide information in relation to stability when walking. The aim of this study was to investigate if age and sex were associated with COP variability, COP excursions, and COP velocities during walking. One-hundred and fourteen older adults (age 65.1±5.5 yrs.) participated in the study. A Kistler force platform (1000Hz) recorded the ground reaction forces and COPs during walking at a self-selected walking speed. The stance phase was divided, using the vertical GRF, into four sub-phases: loading response (LR), mid-stance (MSt), terminal stance (TSt), and pre-swing (PSw). The standard deviations of the COP displacement (variability), the COP velocity, and COP excursion in the medial–lateral and anterior–posterior directions, as well as the resultant magnitude were assessed. When controlling for walking speed, a greater age was associated with a higher variability and excursion of the COP during LR only suggesting that stability is maintained during the majority of the stance phase. During LR lower COP velocity was significantly associated for females for anterior-posterior and total COP, which may be a strategy to facilitate stability before, and moving into, MSt and TSt.



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Prediction of walk-to-run transition using stride frequency: A test-retest reliability study

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Ernst Albin Hansen, Andreas Møller Nielsen, Lasse Andreas Risgaard Kristensen, Pascal Madeleine, Michael Voigt
The transition from walking to running has previously been predicted to occur at a point where the stride frequency starts getting closer to the running attractor than to the walking attractor. The two behavioural attractors were considered to be represented by the freely chosen stride frequencies during unrestricted treadmill walking and running. The aim of the present study was to determine the relative and absolute test-retest reliability of the predicted walk-to-run transition stride frequency. Healthy individuals (n=25) performed walking and running on a treadmill in a day-to-day test-retest design. The two behavioral attractors were determined during walking and running at freely chosen velocities and stride frequencies. Subsequently, the walk-to-run transition stride frequency was predicted using camera recordings and a previously reported equation for prediction. The walk-to-run transition occurred at a velocity of 7.7±0.5kmh⁻¹ at day 1 as well as at day 2. Besides, the predicted walk-to-run transition stride frequencies were 69.7±3.3 strides min⁻¹ and 70.5±3.4 strides min⁻¹ on day 1 and day 2, respectively (p=0.08). A further comparison between the predicted walk-to-run transition stride frequencies at day 1 and day 2 showed an ICC3,1 of 0.89, which indicated almost perfect relative reliability. The absolute reliability was reflected by a%-value of the standard error of the measurement (SEM%) of 1.6% and a%-value of the smallest real difference (SRD%) of 4.4%. In conclusion, the predicted walk-to-run transition stride frequency can be considered reliable across days.



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Neuromuscular compensatory strategies at the trunk and lower limb are not resolved following an ACL reconstruction

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Grant Boggess, Kristin Morgan, Darren Johnson, Mary Lloyd Ireland, Jeffrey A. Reinbolt, Brian Noehren
BackgroundFollowing anterior cruciate ligament reconstruction (ACLR), patients present with greater trunk ipsilateral lean, which may affect knee kinetics and increase re-injury risk. However, there has been little research into neuromuscular factors controlling the trunk and their relation to the knee between healthy and ACLR subjects. This is critical to establish in order to develop more directed and effective interventions.HypothesisAs compared to healthy control subjects, ACLR subjects will demonstrate increased erector spinae and rectus abdominis co-contraction, greater rectus abdominis force and greater hamstring force that is correlated to increased forward trunk lean.Study designCross-sectional study, Level of Evidence: 3.MethodsEleven healthy and eleven ACLR subjects were matched for age, mass and height. Subjects were asked to run at a self-selected speed while instrumented gait analysis was performed. An anthropometrically scaled OpenSim model was created for each subject. Trunk and hamstring muscle forces from Static Optimization were analyzed at impact peak. Additionally, directed co-contraction ratios were calculated for the erector spinae and erector spinae/rectus abdominis combinations.ResultsACLR subjects showed more balanced erector spinae co-contraction [p<0.01], and greater hamstring force [biceps femoris long head (p=0.02), semimembranosus (0.01), semitendinosus (0.01)]. There was no statistical difference for any other muscle group.ConclusionDespite release to return to sport, ACLR subjects are continuing to increase the stiffness of their trunk as well increase their hamstring force to potentially reduce anterior tibial translation.Clinical relevanceClinicians may anticipate ACLR subjects using their erector spinae and hamstrings to maintain a sense of stability in their trunk and at their knee.



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Altered postural control variability in older-aged individuals with a history of lateral ankle sprain

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Masafumi Terada, Kyle Kosik, Nathan Johnson, Phillip Gribble
The current study aimed to examine postural control performance during a single-leg balance task in elderly individuals with and without a previous history of lateral ankle sprain (LAS). Eighteen adults with a previous hisoty of LAS (mean age=66years old) and 12 healthy controls (mean age=65years old) were included in the study. Participants performed three trials of a single-leg balance task during an eyes-opened condition for 20-s. Center of pressure (COP) trajectories in the anteroposterior (AP) and mediolateral (ML) directions were collected with a force plate. The following postural control measures were calculated in the AP and ML directions: 1) Sample Entropy (SampEn); 2) Approximate Entropy (ApEn); 3) mean of Time-to-Boundary minima (mean TTB); and 4) COP velocity (COPV). Older-age participants with a history LAS exhibited lower ApEn-AP, SampEn-AP, and SampEn-ML values compared to healthy controls (p<0.05). The information gained from this investigation indicates more rigid postural control patterns, less adaptability, and more difficulty maintaining COP during a single-leg balance task in adults with a previous history of LAS. Our data suggest that there is a need to consider history of musculoskeletal injury when evaluating factors for postural control and fall risk in the elderly. Future investigations are needed to assess the effect of LAS on age-related declines in postural control and discern associations between potential risk factors of fall-related injuries and LAS in an elderly population.



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An exploratory study examining factors underpinning postural instability in older adults with idiopathic neck pain

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): June Quek, Julia Treleaven, Ross A Clark, Sandra G Brauer
There is limited understanding of potential mechanisms underpinning postural control deficits in people with neck pain. This study examined several characteristics that might explain impaired postural stability in a group of older adults with neck pain, and compared the results in this cohort with that of asymptomatic controls. In this cross-sectional study we compared physical activity, lower limb motor and sensory function, vestibular and visual function, falls efficacy and dizziness handicap in 84 older adults with (n=35, age 69.6±6.3) and without (n=49, age 69.4±4.7) idiopathic neck-pain. Additionally, dynamic balance was assessed using the dynamic gait index (DGI) and standard and wavelet analysis of static balance was computed after data capture. Physical activity levels, lower limb motor and sensory function, vestibular function and visual contrast sensitivity were not different between groups (p>0.05). The neck-pain group demonstrated higher falls efficacy (p=0.01), greater levels of dizziness handicap (p<0.01), and higher CoP velocity measures in the moderate (1.56–6.25Hz) and low (0.39–1.56Hz) frequency bandwidths. Our results suggest that neck-pain induced postural control deficits in older adults may not be associated with the physical activity levels, lower limb motor and sensory function, or vestibular and visual function. Inferring from wavelet analysis results, we speculated that sensory re-weighting may have occurred to compensate for the deficits in neck proprioception. Further research is warranted to determine neck specific mechanisms underpinning postural control dysfunction in neck pain.



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Effect of tibia marker placement on knee joint kinematic analysis

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Yuhui Wen, Hongshi Huang, Yuanyuan Yu, Si Zhang, Jie Yang, Yingfang Ao, Shihong Xia
Variability of kinematic measures determined by different marker sets among sites participating in a collaborative study is necessary for determining the reliability of a multi-site gait analysis research. We compared knee kinematics based on different marker sets on the tibia, calculating by segmental optimization (SO) and multi-body optimization (MBO) methods respectively, in order to assess the effect of marker locations on the methods. 11 healthy subjects participated in the study with 33 markers attached to the lower extremity segments, and 4 groups were identified according to markers on the tibia. Knee joint kinematics during level walking were measured and then compared among the 4 groups using statistical parametric mapping. For SO method, the results showed that there were no significant differences in the knee joint angles when used different marker sets on the tibia. However, significant differences were found in the transverse plane kinematics for MBO method. It was concluded that MBO method was more likely to be influenced by different marker sets. More attention should be paid to marker sets, specifically for MBO method, when three-dimensional gait analysis data are shared and interpreted among sites for clinical decision-making.



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Joint mechanical asymmetries during low- and high-demand mobility tasks: Comparison between total knee arthroplasty and healthy-matched peers

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Jesse C. Christensen, Paul C. LaStayo, Ryan L. Mizner, Robin L. Marcus, Christopher E. Pelt, Gregory J. Stoddard, K. Bo Foreman
Chronic inter-limb joint mechanical asymmetry has been reported following total knee arthroplasty (TKA) during low-demand mobility tasks such as level walking. However, no study has compared the inter-limb asymmetry during a high-demand mobility task such as decline walking. The objective of this cross-sectional study was to compare inter-limb asymmetry differences during both level and decline walking tasks at six months following TKA compared to asymmetry present in an age, gender, body mass index and activity level matched healthy cohort. Kinetic and kinematic gait analysis was conducted on 42 patients with TKA and 15 healthy-matched peers. Our inter-limb asymmetry results demonstrated significantly (p<0.05) greater combined limb support moment (MS) (mean differences [MD]=0.17; 95% CI=0.07, 0.22), knee extensor moment (MK) (MD=0.05; 95% CI=0.02, 0.09) and vertical ground reaction force (vGRF) (MD=0.03; 95% CI=0.01, 0.08) differences during decline walking compared to level walking in patients with TKA. Greater MS (MD=0.24; 95% CI=0.13, 0.35), MK (MD=0.08; 95% CI=0.03, 0.18), vGRF (MD=0.04; 95% CI=0.01, 0.08) and knee joint angle (MD=2.4; 95% CI=0.37, 3.80) differences were present in patients with TKA compared to healthy-matched peers during decline walking. Greater MS (MD=0.13; 95% CI=0.05, 0.20) and plantarflexor moment (MD=0.06; 95% CI=0.04, 0.16) differences were present in patients with TKA compared to healthy-matched peers during level walking. Post-TKA inter-limb asymmetry during level walking worsens as the physical demands of the task are increased. Thus, even patients with good self-reported outcomes after TKA exhibit substantial deficits in their mobility reserves that could limit their independence and community mobility as they age.



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Differences in pattern of variability for lower extremity kinematics between walking and running

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Amanda Estep, Steven Morrison, Shane Caswell, Jatin Ambegaonkar, Nelson Cortes
This study characterizes walking and running patterns in healthy individuals using linear and nonlinear methods Seventeen individuals (12 males, 5 females) volunteered for the study. 3D kinematic data during walking (WA) and running (RU) on a motorized treadmill were captured using reflective markers placed on lower body (200Hz). A single 25s trial (5000 data points) was collected for each gait task. WA speed was 1.39±0.12m/s, whereas RU speed was 2.56±0.27m/s. Variables of interest included ankle plantar/dorsi flexion, knee flexion/extension, knee abduction/adduction, hip flexion/extension, and hip abduction/adduction angles. For linear analysis, standard deviation (SD) and coefficient of variation (CV) were calculated for the entire time series for both conditions. Nonlinear analysis included assessing pattern of regularity of respective kinematic time series using approximate entropy (ApEn). Inferential analyses were conducted using MANOVA to compare selected dependent measures (p<0.05). SD for knee flexion/extension angle (WA=23.34±4.17, RU=27.51±5.25) and ankle plantar/dorsi flexion angle (WA=9.24±2.37, RU=12.88±2.00) were both greater during running. For all other variables, there were no significant differences in degree of variability between walking and running (p’s>0.05). Running ApEn values were greater than walking ApEn values for knee flexion/extension (WA=0.14±0.02, RU=0.23±0.04), knee abduction/adduction (WA=0.18±0.07, RU=0.24±0.07), hip flexion/extension (WA=0.09±0.02, RU=0.17±0.04), and hip abduction/adduction (WA=0.12±0.03, RU=0.21±0.05). Greater variability was demonstrated during running across all joints compared to walking. This suggests that ApEn is more sensitive to detecting changes between different gait conditions than standard discrete measures of variability (SD).



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Using phone sensors and an artificial neural network to detect gait changes during drinking episodes in the natural environment

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Brian Suffoletto, Pedram Gharani, Tammy Chung, Hassan Karimi
BackgroundPhone sensors could be useful in assessing changes in gait that occur with alcohol consumption. This study determined (1) feasibility of collecting gait-related data during drinking occasions in the natural environment, and (2) how gait-related features measured by phone sensors relate to estimated blood alcohol concentration (eBAC).MethodsTen young adult heavy drinkers were prompted to complete a 5-step gait task every hour from 8pm to 12am over four consecutive weekends. We collected 3-axis accelerometer, gyroscope, and magnetometer data from phone sensors, and computed 24 gait-related features using a sliding window technique. eBAC levels were calculated at each time point based on Ecological Momentary Assessment (EMA) of alcohol use. We used an artificial neural network model to analyze associations between sensor features and eBACs in training (70% of the data) and validation and test (30% of the data) datasets.ResultsWe analyzed 128 data points where both eBAC and gait-related sensor data were captured, either when not drinking (n=60), while eBAC was ascending (n=55) or eBAC was descending (n=13). 21 data points were captured at times when the eBAC was greater than the legal limit (0.08mg/dl). Using a Bayesian regularized neural network, gait-related phone sensor features showed a high correlation with eBAC (Pearson’s r>0.9), and >95% of estimated eBAC would fall between −0.012 and +0.012 of actual eBAC.ConclusionsIt is feasible to collect gait-related data from smartphone sensors during drinking occasions in the natural environment. Sensor-based features can be used to infer gait changes associated with elevated blood alcohol content.



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Reference values and equations reference of balance for children of 8 to 12 years

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Thiele de Cássia Libardoni, Carolina Buzzi da Silveira, Larissa Milani Brognoli Sinhorim, Anamaria Siriani de Oliveira, Márcio José dos Santos, Gilmar Moraes Santos
PurposeThere are still no normative data in balance sway for school-age children in Brazil. We aimed to establish the reference ranges for balance scores and to develop prediction equations for estimation of balance scores in children aged 8 to 12 years old.MethodsThe study included 165 healthy children (83 boys and 82 girls; age, 8–12 years) recruited from a public school in the city of Florianópolis, Santa Catarina, Brazil. We used the Sensory Organization Test to assess the balance scores and both a digital scale and a stadiometer to measure the anthropometric variables. We tested a stepwise multiple-regression model with sex, height, weight, and mid-thigh circumference of the dominant leg as predictors of the balance score.ResultsFor all experimental conditions, girls’ age accounted for over 85% of the variability in balance scores; while, boys’ age accounted only 55% of the variability in balance scores. Therefore, balance scores increase with age for boys and girls.ConclusionThis study described the ranges of age- and sex-specific normative values for balance scores in children during 6 different testing conditions established by the sensory organization test. We confirmed that age was the predictor that best explained the variability in balance scores in children between 8 and 12 years old. This study stimulates a new and more comprehensive study to estimate balance scores from prediction equations for overall Brazilian pediatric population.



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Effect of parameter selection on entropy calculation for long walking trials

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Jennifer M. Yentes, William Denton, John McCamley, Peter C. Raffalt, Kendra K. Schmid
It is sometimes difficult to obtain uninterrupted data sets that are long enough to perform nonlinear analysis, especially in pathological populations. It is currently unclear as to how many data points are needed for reliable entropy analysis. The aims of this study were to determine the effect of changing parameter values of m, r, and N on entropy calculations for long gait data sets using two different modes of walking (i.e., overground versus treadmill). Fourteen young adults walked overground and on a treadmill at their preferred walking speed for one-hour while step time was collected via heel switches. Approximate (ApEn) and sample entropy (SampEn) were calculated using multiple parameter combinations of m, N, and r. Further, r was tested under two cases r*standard deviation and r constant. ApEn differed depending on the combination of r, m, and N. ApEn demonstrated relative consistency except when m=2 and the smallest r values used (rSD=0.015*SD, 0.20*SD; rConstant=0 and 0.003). For SampEn, as r increased, SampEn decreased. When r was constant, SampEn demonstrated excellent relative consistency for all combinations of r, m, and N. When r constant was used, overground walking was more regular than treadmill. However, treadmill walking was found to be more regular when using rSD for both ApEn and SampEn. For greatest relative consistency of step time data, it was best to use a constant r value and SampEn. When using entropy, several r values must be examined and reported to ensure that results are not an artifact of parameter choice.



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Spatial orientation and postural control in patients with Parkinson’s disease

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): E. Pawlitzki, C. Schlenstedt, N. Schmidt, I. Rotkirch, F. Gövert, G. Hartwigsen, K. Witt
Postural instability is one of the most disabling and risky symptoms of advanced Parkinson's disease (PD). The purpose of this study was to investigate whether and how this is mediated by a centrally impaired spatial orientation. Therefore, we performed a spatial orientation study in 21 PD patients (mean age 68years, SD 8.5 years, 9 women) in a medically on condition and 21 healthy controls (mean age 68.9years, SD 5.5years, 14 women). We compared their spatial responses to the horizontal axis (Sakashita's visual target cancellation task), the vertical axis (bucket-test), the sagittal axis (tilt table test) and postural stability using the Fullerton Advanced Balance Scale (FAB). We found larger deviations on the vertical axis in PD patients, although the direct comparisons of performance in PD patients and healthy controls did not reveal significant differences. While the total scores of the FAB Scale were significantly worse in PD (25.9 points, SD 7.2 points) compared to controls (35.1 points, SD 2.3 points, p<0.01), the results from the spatialorientation task did not correlate with the FAB Scale. In summary, our results argue against a relation between perceptional deficits of spatial information and postural control in PD. These results are in favor of a deficit in higher order integration of spatial stimuli in PD that might influence balance control.



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Effect of robotic-assisted gait rehabilitation on dynamic equilibrium control in the gait of children with cerebral palsy

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): L. Wallard, G. Dietrich, Y. Kerlirzin, J. Bredin
Due to the intensity and repetition of movement, roboticassisted gait training therapy could have a beneficial effect on the recovery and improvement of postural and locomotor functions of the patient. This study sought to highlight the effects of robotic-assisted gait rehabilitation in gait of children with Cerebral Palsy (CP). We analyzed the different strategies before and after this rehabilitation which was used in order to generate forward motion while maintaining balance. Data were collected by a motion analysis system (Vicon® - Oxford Metrics, Oxford, UK). The children were divided into two groups in such a way as to obtain a randomized controlled population: i) a group of fourteen children (Treated Group) underwent 20 sessions of roboticassisted gait training therapy using the driven gait orthosis Lokomat®Pediatric (Hocoma AG, Volketswil, Switzerland) compared to ii) a group of sixteen children without sessions of Lokomat®Pediatric (Control Group). Significant differences are observed for the TG between the preand post-test values of the locomotor parameters and of the kinetic data of the propulsive forces of the Center of Mass (COM) and of the Center of Pressure (COP) dynamic trajectory. This first study, although performed on a limited number of patients, shows the usefulness of this robotic gait rehabilitation mainly in the balance control in gait. Indeed after this rehabilitation, these children improve their gait that is especially characterized by a more appropriate time lag between the time instant of COM-COP trajectory divergence and the time instant when the forward propulsive forces became apparent.



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Evaluating the immediate effects of wearing foot orthotics in children with Joint Hypermobility Syndrome (JHS) by analysis of temperospatial parameters of gait and dynamic balance: A preliminary study

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): P. McDermott, E. Wolfe, C. Lowry, K. Robinson, H.P. French
Joint Hypermobility Syndrome (JHS) in children, presents with increased joint range of motion and can lead to altered gait strategies and reduced dynamic balance. Despite limited evidence foot orthoses are sometimes prescribed to patients with JHS with the aim to improve the stability of their gait pattern and theoretically reduce associated symptoms of fatigue and joint pain. The purpose of this study was therefore to analyse the immediate effects of ‘off the shelf’ orthoses on temporospatial parameters of gait and dynamic balance in this cohort.MethodsA total of 21 patients were recruited for the study (13 female) with a median age of 10 years (IRQ=4.12). Each patient had their gait analysed using the GAITRite walkway in their own footwear and immediately after being prescribed the orthoses. Gait was tested at both the patients’ preferred speed and when asked to walk slower to challenge their dynamic balance.ResultsGait appeared more synchronised, with a reduction in step length and width variability, when participants were provided with orthotics. The variation was greatest when participants were asked to walk slower. Double stance was significantly less at slower speeds when orthotics were added (1.61%, 95% CI=0.34, 2.89, p=0.015)ConclusionResults of this study indicate that orthotics have a definite immediate influence on gait patterns in patients with JHS. Future studies should investigate the long-term effects of orthotics in this population and include outcome measures for symptoms such as pain.



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Are there associations with age and sex in walking stability in healthy older adults?

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Daan van Kooten, Florentina Hettinga, Kim Duffy, Jo Jackson, Matthew J.D. Taylor
The variability of the centre of pressure (COP) during walking can provide information in relation to stability when walking. The aim of this study was to investigate if age and sex were associated with COP variability, COP excursions, and COP velocities during walking. One-hundred and fourteen older adults (age 65.1±5.5 yrs.) participated in the study. A Kistler force platform (1000Hz) recorded the ground reaction forces and COPs during walking at a self-selected walking speed. The stance phase was divided, using the vertical GRF, into four sub-phases: loading response (LR), mid-stance (MSt), terminal stance (TSt), and pre-swing (PSw). The standard deviations of the COP displacement (variability), the COP velocity, and COP excursion in the medial–lateral and anterior–posterior directions, as well as the resultant magnitude were assessed. When controlling for walking speed, a greater age was associated with a higher variability and excursion of the COP during LR only suggesting that stability is maintained during the majority of the stance phase. During LR lower COP velocity was significantly associated for females for anterior-posterior and total COP, which may be a strategy to facilitate stability before, and moving into, MSt and TSt.



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Prediction of walk-to-run transition using stride frequency: A test-retest reliability study

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Ernst Albin Hansen, Andreas Møller Nielsen, Lasse Andreas Risgaard Kristensen, Pascal Madeleine, Michael Voigt
The transition from walking to running has previously been predicted to occur at a point where the stride frequency starts getting closer to the running attractor than to the walking attractor. The two behavioural attractors were considered to be represented by the freely chosen stride frequencies during unrestricted treadmill walking and running. The aim of the present study was to determine the relative and absolute test-retest reliability of the predicted walk-to-run transition stride frequency. Healthy individuals (n=25) performed walking and running on a treadmill in a day-to-day test-retest design. The two behavioral attractors were determined during walking and running at freely chosen velocities and stride frequencies. Subsequently, the walk-to-run transition stride frequency was predicted using camera recordings and a previously reported equation for prediction. The walk-to-run transition occurred at a velocity of 7.7±0.5kmh⁻¹ at day 1 as well as at day 2. Besides, the predicted walk-to-run transition stride frequencies were 69.7±3.3 strides min⁻¹ and 70.5±3.4 strides min⁻¹ on day 1 and day 2, respectively (p=0.08). A further comparison between the predicted walk-to-run transition stride frequencies at day 1 and day 2 showed an ICC3,1 of 0.89, which indicated almost perfect relative reliability. The absolute reliability was reflected by a%-value of the standard error of the measurement (SEM%) of 1.6% and a%-value of the smallest real difference (SRD%) of 4.4%. In conclusion, the predicted walk-to-run transition stride frequency can be considered reliable across days.



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Neuromuscular compensatory strategies at the trunk and lower limb are not resolved following an ACL reconstruction

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Grant Boggess, Kristin Morgan, Darren Johnson, Mary Lloyd Ireland, Jeffrey A. Reinbolt, Brian Noehren
BackgroundFollowing anterior cruciate ligament reconstruction (ACLR), patients present with greater trunk ipsilateral lean, which may affect knee kinetics and increase re-injury risk. However, there has been little research into neuromuscular factors controlling the trunk and their relation to the knee between healthy and ACLR subjects. This is critical to establish in order to develop more directed and effective interventions.HypothesisAs compared to healthy control subjects, ACLR subjects will demonstrate increased erector spinae and rectus abdominis co-contraction, greater rectus abdominis force and greater hamstring force that is correlated to increased forward trunk lean.Study designCross-sectional study, Level of Evidence: 3.MethodsEleven healthy and eleven ACLR subjects were matched for age, mass and height. Subjects were asked to run at a self-selected speed while instrumented gait analysis was performed. An anthropometrically scaled OpenSim model was created for each subject. Trunk and hamstring muscle forces from Static Optimization were analyzed at impact peak. Additionally, directed co-contraction ratios were calculated for the erector spinae and erector spinae/rectus abdominis combinations.ResultsACLR subjects showed more balanced erector spinae co-contraction [p<0.01], and greater hamstring force [biceps femoris long head (p=0.02), semimembranosus (0.01), semitendinosus (0.01)]. There was no statistical difference for any other muscle group.ConclusionDespite release to return to sport, ACLR subjects are continuing to increase the stiffness of their trunk as well increase their hamstring force to potentially reduce anterior tibial translation.Clinical relevanceClinicians may anticipate ACLR subjects using their erector spinae and hamstrings to maintain a sense of stability in their trunk and at their knee.



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Altered postural control variability in older-aged individuals with a history of lateral ankle sprain

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Masafumi Terada, Kyle Kosik, Nathan Johnson, Phillip Gribble
The current study aimed to examine postural control performance during a single-leg balance task in elderly individuals with and without a previous history of lateral ankle sprain (LAS). Eighteen adults with a previous hisoty of LAS (mean age=66years old) and 12 healthy controls (mean age=65years old) were included in the study. Participants performed three trials of a single-leg balance task during an eyes-opened condition for 20-s. Center of pressure (COP) trajectories in the anteroposterior (AP) and mediolateral (ML) directions were collected with a force plate. The following postural control measures were calculated in the AP and ML directions: 1) Sample Entropy (SampEn); 2) Approximate Entropy (ApEn); 3) mean of Time-to-Boundary minima (mean TTB); and 4) COP velocity (COPV). Older-age participants with a history LAS exhibited lower ApEn-AP, SampEn-AP, and SampEn-ML values compared to healthy controls (p<0.05). The information gained from this investigation indicates more rigid postural control patterns, less adaptability, and more difficulty maintaining COP during a single-leg balance task in adults with a previous history of LAS. Our data suggest that there is a need to consider history of musculoskeletal injury when evaluating factors for postural control and fall risk in the elderly. Future investigations are needed to assess the effect of LAS on age-related declines in postural control and discern associations between potential risk factors of fall-related injuries and LAS in an elderly population.



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An exploratory study examining factors underpinning postural instability in older adults with idiopathic neck pain

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): June Quek, Julia Treleaven, Ross A Clark, Sandra G Brauer
There is limited understanding of potential mechanisms underpinning postural control deficits in people with neck pain. This study examined several characteristics that might explain impaired postural stability in a group of older adults with neck pain, and compared the results in this cohort with that of asymptomatic controls. In this cross-sectional study we compared physical activity, lower limb motor and sensory function, vestibular and visual function, falls efficacy and dizziness handicap in 84 older adults with (n=35, age 69.6±6.3) and without (n=49, age 69.4±4.7) idiopathic neck-pain. Additionally, dynamic balance was assessed using the dynamic gait index (DGI) and standard and wavelet analysis of static balance was computed after data capture. Physical activity levels, lower limb motor and sensory function, vestibular function and visual contrast sensitivity were not different between groups (p>0.05). The neck-pain group demonstrated higher falls efficacy (p=0.01), greater levels of dizziness handicap (p<0.01), and higher CoP velocity measures in the moderate (1.56–6.25Hz) and low (0.39–1.56Hz) frequency bandwidths. Our results suggest that neck-pain induced postural control deficits in older adults may not be associated with the physical activity levels, lower limb motor and sensory function, or vestibular and visual function. Inferring from wavelet analysis results, we speculated that sensory re-weighting may have occurred to compensate for the deficits in neck proprioception. Further research is warranted to determine neck specific mechanisms underpinning postural control dysfunction in neck pain.



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Effect of tibia marker placement on knee joint kinematic analysis

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Yuhui Wen, Hongshi Huang, Yuanyuan Yu, Si Zhang, Jie Yang, Yingfang Ao, Shihong Xia
Variability of kinematic measures determined by different marker sets among sites participating in a collaborative study is necessary for determining the reliability of a multi-site gait analysis research. We compared knee kinematics based on different marker sets on the tibia, calculating by segmental optimization (SO) and multi-body optimization (MBO) methods respectively, in order to assess the effect of marker locations on the methods. 11 healthy subjects participated in the study with 33 markers attached to the lower extremity segments, and 4 groups were identified according to markers on the tibia. Knee joint kinematics during level walking were measured and then compared among the 4 groups using statistical parametric mapping. For SO method, the results showed that there were no significant differences in the knee joint angles when used different marker sets on the tibia. However, significant differences were found in the transverse plane kinematics for MBO method. It was concluded that MBO method was more likely to be influenced by different marker sets. More attention should be paid to marker sets, specifically for MBO method, when three-dimensional gait analysis data are shared and interpreted among sites for clinical decision-making.



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Joint mechanical asymmetries during low- and high-demand mobility tasks: Comparison between total knee arthroplasty and healthy-matched peers

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Jesse C. Christensen, Paul C. LaStayo, Ryan L. Mizner, Robin L. Marcus, Christopher E. Pelt, Gregory J. Stoddard, K. Bo Foreman
Chronic inter-limb joint mechanical asymmetry has been reported following total knee arthroplasty (TKA) during low-demand mobility tasks such as level walking. However, no study has compared the inter-limb asymmetry during a high-demand mobility task such as decline walking. The objective of this cross-sectional study was to compare inter-limb asymmetry differences during both level and decline walking tasks at six months following TKA compared to asymmetry present in an age, gender, body mass index and activity level matched healthy cohort. Kinetic and kinematic gait analysis was conducted on 42 patients with TKA and 15 healthy-matched peers. Our inter-limb asymmetry results demonstrated significantly (p<0.05) greater combined limb support moment (MS) (mean differences [MD]=0.17; 95% CI=0.07, 0.22), knee extensor moment (MK) (MD=0.05; 95% CI=0.02, 0.09) and vertical ground reaction force (vGRF) (MD=0.03; 95% CI=0.01, 0.08) differences during decline walking compared to level walking in patients with TKA. Greater MS (MD=0.24; 95% CI=0.13, 0.35), MK (MD=0.08; 95% CI=0.03, 0.18), vGRF (MD=0.04; 95% CI=0.01, 0.08) and knee joint angle (MD=2.4; 95% CI=0.37, 3.80) differences were present in patients with TKA compared to healthy-matched peers during decline walking. Greater MS (MD=0.13; 95% CI=0.05, 0.20) and plantarflexor moment (MD=0.06; 95% CI=0.04, 0.16) differences were present in patients with TKA compared to healthy-matched peers during level walking. Post-TKA inter-limb asymmetry during level walking worsens as the physical demands of the task are increased. Thus, even patients with good self-reported outcomes after TKA exhibit substantial deficits in their mobility reserves that could limit their independence and community mobility as they age.



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Differences in pattern of variability for lower extremity kinematics between walking and running

Publication date: February 2018
Source:Gait & Posture, Volume 60
Author(s): Amanda Estep, Steven Morrison, Shane Caswell, Jatin Ambegaonkar, Nelson Cortes
This study characterizes walking and running patterns in healthy individuals using linear and nonlinear methods Seventeen individuals (12 males, 5 females) volunteered for the study. 3D kinematic data during walking (WA) and running (RU) on a motorized treadmill were captured using reflective markers placed on lower body (200Hz). A single 25s trial (5000 data points) was collected for each gait task. WA speed was 1.39±0.12m/s, whereas RU speed was 2.56±0.27m/s. Variables of interest included ankle plantar/dorsi flexion, knee flexion/extension, knee abduction/adduction, hip flexion/extension, and hip abduction/adduction angles. For linear analysis, standard deviation (SD) and coefficient of variation (CV) were calculated for the entire time series for both conditions. Nonlinear analysis included assessing pattern of regularity of respective kinematic time series using approximate entropy (ApEn). Inferential analyses were conducted using MANOVA to compare selected dependent measures (p<0.05). SD for knee flexion/extension angle (WA=23.34±4.17, RU=27.51±5.25) and ankle plantar/dorsi flexion angle (WA=9.24±2.37, RU=12.88±2.00) were both greater during running. For all other variables, there were no significant differences in degree of variability between walking and running (p’s>0.05). Running ApEn values were greater than walking ApEn values for knee flexion/extension (WA=0.14±0.02, RU=0.23±0.04), knee abduction/adduction (WA=0.18±0.07, RU=0.24±0.07), hip flexion/extension (WA=0.09±0.02, RU=0.17±0.04), and hip abduction/adduction (WA=0.12±0.03, RU=0.21±0.05). Greater variability was demonstrated during running across all joints compared to walking. This suggests that ApEn is more sensitive to detecting changes between different gait conditions than standard discrete measures of variability (SD).



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