Effects of leg muscle fatigue on gait in patients with Parkinson's disease and controls with high and low levels of daily physical activity

Publication date: Available online 11 April 2016
Source:Gait & Posture
Author(s): Paulo Cezar Rocha Santos, Lilian Teresa Bucken Gobbi, Diego Orcioli-Silva, Lucas Simieli, Jaap H. van Dieën, Fabio Augusto Barbieri
Patients with Parkinson's disease (PD) are more susceptible to muscle fatigue, which can damage their gait. Physical activity can improve muscle condition, which is an important aspect during walking. The aim of this study was to analyze the effects of lower limb muscle fatigue on gait in patients with PD and healthy individuals, grouped according to physical activity level. Twenty Patients with PD (PD group) and 20 matched individuals (control group) were distributed according to physical activity level into four subgroups of ten individuals (active and inactive). Participants performed three walking trials before and after lower limb muscle fatigue, induced by a repeated sit-to-stand task on a chair. Kinematic (stride length, width, duration, velocity and percentage of time in double support) and kinetic (propulsive and breaking anterior-posterior and medio-lateral impulse) gait parameters were analyzed. In both groups, participants increased stride length and velocity and decreased stride duration and braking vertical impulse after lower limb muscle fatigue. The PD groups presented higher step width and percentage of double time support than the control groups before muscle fatigue. The control groups increased step width and decreased percentage of time in double support, while the PD groups did not change these parameters. For physical activity level, active individuals presented longer stride length, greater stride velocity, higher braking and propulsive anterior-posterior impulse and shorter step width than inactive individuals. Groups sought more balance and safety after lower limb muscle fatigue. Physical activity level does not appear to modify the effects of lower limb muscle fatigue during unobstructed walking in individuals with PD or controls.



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Effects of leg muscle fatigue on gait in patients with Parkinson's disease and controls with high and low levels of daily physical activity

Publication date: Available online 11 April 2016
Source:Gait & Posture
Author(s): Paulo Cezar Rocha Santos, Lilian Teresa Bucken Gobbi, Diego Orcioli-Silva, Lucas Simieli, Jaap H. van Dieën, Fabio Augusto Barbieri
Patients with Parkinson's disease (PD) are more susceptible to muscle fatigue, which can damage their gait. Physical activity can improve muscle condition, which is an important aspect during walking. The aim of this study was to analyze the effects of lower limb muscle fatigue on gait in patients with PD and healthy individuals, grouped according to physical activity level. Twenty Patients with PD (PD group) and 20 matched individuals (control group) were distributed according to physical activity level into four subgroups of ten individuals (active and inactive). Participants performed three walking trials before and after lower limb muscle fatigue, induced by a repeated sit-to-stand task on a chair. Kinematic (stride length, width, duration, velocity and percentage of time in double support) and kinetic (propulsive and breaking anterior-posterior and medio-lateral impulse) gait parameters were analyzed. In both groups, participants increased stride length and velocity and decreased stride duration and braking vertical impulse after lower limb muscle fatigue. The PD groups presented higher step width and percentage of double time support than the control groups before muscle fatigue. The control groups increased step width and decreased percentage of time in double support, while the PD groups did not change these parameters. For physical activity level, active individuals presented longer stride length, greater stride velocity, higher braking and propulsive anterior-posterior impulse and shorter step width than inactive individuals. Groups sought more balance and safety after lower limb muscle fatigue. Physical activity level does not appear to modify the effects of lower limb muscle fatigue during unobstructed walking in individuals with PD or controls.



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Effects of leg muscle fatigue on gait in patients with Parkinson's disease and controls with high and low levels of daily physical activity

Publication date: Available online 11 April 2016
Source:Gait & Posture
Author(s): Paulo Cezar Rocha Santos, Lilian Teresa Bucken Gobbi, Diego Orcioli-Silva, Lucas Simieli, Jaap H. van Dieën, Fabio Augusto Barbieri
Patients with Parkinson's disease (PD) are more susceptible to muscle fatigue, which can damage their gait. Physical activity can improve muscle condition, which is an important aspect during walking. The aim of this study was to analyze the effects of lower limb muscle fatigue on gait in patients with PD and healthy individuals, grouped according to physical activity level. Twenty Patients with PD (PD group) and 20 matched individuals (control group) were distributed according to physical activity level into four subgroups of ten individuals (active and inactive). Participants performed three walking trials before and after lower limb muscle fatigue, induced by a repeated sit-to-stand task on a chair. Kinematic (stride length, width, duration, velocity and percentage of time in double support) and kinetic (propulsive and breaking anterior-posterior and medio-lateral impulse) gait parameters were analyzed. In both groups, participants increased stride length and velocity and decreased stride duration and braking vertical impulse after lower limb muscle fatigue. The PD groups presented higher step width and percentage of double time support than the control groups before muscle fatigue. The control groups increased step width and decreased percentage of time in double support, while the PD groups did not change these parameters. For physical activity level, active individuals presented longer stride length, greater stride velocity, higher braking and propulsive anterior-posterior impulse and shorter step width than inactive individuals. Groups sought more balance and safety after lower limb muscle fatigue. Physical activity level does not appear to modify the effects of lower limb muscle fatigue during unobstructed walking in individuals with PD or controls.



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From strategy to delivery: taking the ENT, Hearing and Balance research agenda into the future.

From strategy to delivery: taking the ENT, Hearing and Balance research agenda into the future.

Clin Otolaryngol. 2016 Apr 5;

Authors: Bohm N, Lund V, Blackshaw H, Narula T, Schilder A

PMID: 27059767 [PubMed - as supplied by publisher]

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From strategy to delivery: taking the ENT, Hearing and Balance research agenda into the future.

From strategy to delivery: taking the ENT, Hearing and Balance research agenda into the future.

Clin Otolaryngol. 2016 Apr 5;

Authors: Bohm N, Lund V, Blackshaw H, Narula T, Schilder A

PMID: 27059767 [PubMed - as supplied by publisher]

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Assessing the validity of subjective reports in the auditory streaming paradigm

While subjective reports provide a direct measure of perception, their validity is not self-evident. Here, the authors tested three possible biasing effects on perceptual reports in the auditory streaming paradigm: errors due to imperfect understanding of the instructions, voluntary perceptual biasing, and susceptibility to implicit expectations. (1) Analysis of the responses to catch trials separately promoting each of the possible percepts allowed the authors to exclude participants who likely have not fully understood the instructions. (2) Explicit biasing instructions led to markedly different behavior than the conventional neutral-instruction condition, suggesting that listeners did not voluntarily bias their perception in a systematic way under the neutral instructions. Comparison with a random response condition further supported this conclusion. (3) No significant relationship was found between social desirability, a scale-based measure of susceptibility to implicit social expectations, and any of the perceptual measures extracted from the subjective reports. This suggests that listeners did not significantly bias their perceptual reports due to possible implicit expectations present in the experimental context. In sum, these results suggest that valid perceptual data can be obtained from subjective reports in the auditory streaming paradigm.

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Computationally efficient method for estimation of angle of arrival with non-uniform reconfigurable receiver arrays

The main focus of this paper is the design and formulation of a computationally efficient approach to the estimation of the angle of arrival with non-uniform reconfigurable receiver arrays. Subsequent to demodulation and matched filtering, the main signal processing task is a double-integration operation. The simplicity of this algorithm enables the implementation of the estimation procedure with simple operational amplifier (op-amp) circuits for real-time realization. This technique does not require uniform and structured array configurations, and is most effective for the estimation of angle of arrival with dynamically reconfigurable receiver arrays.

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The role of continuous low-frequency harmonicity cues for interrupted speech perception in bimodal hearing

Low-frequency acoustic cues have been shown to enhance speech perception by cochlear-implant users, particularly when target speech occurs in a competing background. The present study examined the extent to which a continuous representation of low-frequency harmonicity cues contributes to bimodal benefit in simulated bimodal listeners. Experiment 1 examined the benefit of restoring a continuous temporal envelope to the low-frequency ear while the vocoder ear received a temporally interrupted stimulus. Experiment 2 examined the effect of providing continuous harmonicity cues in the low-frequency ear as compared to restoring a continuous temporal envelope in the vocoder ear. Findings indicate that bimodal benefit for temporally interrupted speech increases when continuity is restored to either or both ears. The primary benefit appears to stem from the continuous temporal envelope in the low-frequency region providing additional phonetic cues related to manner and F1 frequency; a secondary contribution is provided by low-frequency harmonicity cues when a continuous representation of the temporal envelope is present in the low-frequency, or both ears. The continuous temporal envelope and harmonicity cues of low-frequency speech are thought to support bimodal benefit by facilitating identification of word and syllable boundaries, and by restoring partial phonetic cues that occur during gaps in the temporally interrupted stimulus.

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Predictions of middle-ear and passive cochlear mechanics using a finite element model of the pediatric ear

A finite element (FE)model was developed based on histological sections of a temporal bone of a 4-year-old child to simulate middle-ear and cochlear function in ears with normal hearing and otitis media. This pediatric model of the normal ear, consisting of an ear canal, middle ear, and spiral cochlea, was first validated with published energy absorbance (EA) measurements in young children with normal ears. The model was used to simulate EA in an ear with middle-ear effusion, whose results were compared to clinical EA measurements. The spiral cochlea component of the model was constructed under the assumption that the mechanics were passive. The FEmodel predicted middle-ear transfer functions between the ear canal and cochlea. Effects of ear structure and mechanical properties of soft tissues were compared in model predictions for the pediatric and adult ears. EA responses are predicted to differ between adult and pediatric ears due to differences in the stiffness and damping of soft tissues within the ear, and any residual geometrical differences between the adult ear and pediatric ear at age 4 years. The results have significance for predicting effects of otitis media in children.

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Erratum: Factors limiting vocal-tract length discrimination in cochlear implant simulations [J. Acoust. Soc. Am. 137(3), 1298–1308 (2015)]

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Binaural hearing in children using Gaussian enveloped and transposed tones

Children who use bilateral cochlear implants (BiCIs) show significantly poorer sound localization skills than their normal hearing (NH) peers. This difference has been attributed, in part, to the fact that cochlear implants(CIs) do not faithfully transmit interaural time differences(ITDs) and interaural level differences (ILDs), which are known to be important cues for sound localization. Interestingly, little is known about binaural sensitivity in NH children, in particular, with stimuli that constrain acoustic cues in a manner representative of CI processing. In order to better understand and evaluate binaural hearing in children with BiCIs, the authors first undertook a study on binaural sensitivity in NH children ages 8–10, and in adults. Experiments evaluated sound discrimination and lateralization using ITD and ILD cues, for stimuli with robust envelope cues, but poor representation of temporal fine structure. Stimuli were spondaic words, Gaussian-enveloped tone pulse trains (100 pulse-per-second), and transposed tones. Results showed that discrimination thresholds in children were adult-like (15–389 μs for ITDs and 0.5–6.0 dB for ILDs). However, lateralization based on the same binaural cues showed higher variability than seen in adults. Results are discussed in the context of factors that may be responsible for poor representation of binaural cues in bilaterally implanted children.

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Audiovisual speech perception development at varying levels of perceptual processing

This study used the auditory evaluation framework [Erber (1982). Auditory Training (Alexander Graham Bell Association, Washington, DC)] to characterize the influence of visual speech on audiovisual (AV) speech perception in adults and children at multiple levels of perceptual processing. Six- to eight-year-old children and adults completed auditory and AV speech perception tasks at three levels of perceptual processing (detection, discrimination, and recognition). The tasks differed in the level of perceptual processing required to complete them. Adults and children demonstrated visual speech influence at all levels of perceptual processing. Whereas children demonstrated the same visual speech influence at each level of perceptual processing, adults demonstrated greater visual speech influence on tasks requiring higher levels of perceptual processing. These results support previous research demonstrating multiple mechanisms of AV speech processing (general perceptual and speech-specific mechanisms) with independent maturational time courses. The results suggest that adults rely on both general perceptual mechanisms that apply to all levels of perceptual processing and speech-specific mechanisms that apply when making phonetic decisions and/or accessing the lexicon. Six- to eight-year-old children seem to rely only on general perceptual mechanisms across levels. As expected, developmental differences in AV benefit on this and other recognition tasks likely reflect immature speech-specific mechanisms and phonetic processing in children.

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Nonlinear acoustic propagation in bubbly liquids: Multiple scattering, softening and hardening phenomena

The weakly nonlinear propagation of acoustic waves in monodisperse bubbly liquids is investigated numerically. A hydrodynamic model based on the averaged two-phase fluid equations is coupled with the Rayleigh-Plesset equation to model the dynamics of bubbles at the local scale. The present model is validated in the linear regime by comparing with the Foldy approximation. The analysis of the pressure signals in the linear regime highlights two resonance frequencies: the Minnaert frequency and a multiple scatteringresonance that strongly depends on the bubble concentration. For weakly nonlinear regimes, the generation of higher harmonics is observed only for the Minnaert frequency. Linear combinations between the Minnaert harmonics and the multiple scatteringresonance are also observed. However, the most significant effect observed is the appearance of softening-hardening effects that share some similarities with those observed for sandstones or cracked materials. These effects are related to the multiple scatteringresonance. Downward or upward resonance frequency shifts can be observed depending on the characteristic of the incident wave when increasing the excitation amplitude. It is shown that the frequency shift can be explained assuming that the acoustic wave velocity depends on a law different from those usually encountered for sandstones or cracked materials.

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20Q: Predicting the Future of Audiology

So can we forecast the future of audiology? We certainly can try. In this case, we take what we know or understand about the past and current state of the profession, and then consider what will happen given changes in the environment external to audiology. It is an attempt to identify the range of possible outcomes that might happen given any set of assumptions about the environment in the future.

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20Q: Predicting the Future of Audiology

So can we forecast the future of audiology? We certainly can try. In this case, we take what we know or understand about the past and current state of the profession, and then consider what will happen given changes in the environment external to audiology. It is an attempt to identify the range of possible outcomes that might happen given any set of assumptions about the environment in the future.

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20Q: Predicting the Future of Audiology

So can we forecast the future of audiology? We certainly can try. In this case, we take what we know or understand about the past and current state of the profession, and then consider what will happen given changes in the environment external to audiology. It is an attempt to identify the range of possible outcomes that might happen given any set of assumptions about the environment in the future.

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