Digital Commons Network^™

Locomotor Sensory Organization Test: A Novel Paradigm For The Assessment Of Sensory Contributions In Gait, Jung Hung Chien, Diderik-Jan Eikema, Mukul Mukherjee, Nicholas Stergiou

Journal Articles

Feedback based balance control requires the integration of visual, proprioceptive and vestibular input to detect the body’s movement within the environment. When the accuracy of sensory signals is compromised, the system reorganizes the relative contributions through a process of sensory recalibration, for upright postural stability to be maintained. Whereas this process has been studied extensively in standing using the Sensory Organization Test (SOT), less is known about these processes in more dynamic tasks such as locomotion. In the present study, ten healthy young adults performed the six conditions of the traditional SOT to quantify standing postural control when exposed to …

Locomotor Sensory Organization Test: A Novel Paradigm For The Assessment Of Sensory Contributions In Gait, Jung Hung Chien, Diderik Jan Anthony Eikema, Mukul Mukherjee, Nikolaos Stergiou

Journal Articles

Feedback based balance control requires the integration of visual, proprioceptive and vestibular input to detect the body’s movement within the environment. When the accuracy of sensory signals is compromised, the system reorganizes the relative contributions through a process of sensory recalibration, for upright postural stability to be maintained. Whereas this process has been studied extensively in standing using the Sensory Organization Test (SOT), less is known about these processes in more dynamic tasks such as locomotion. In the present study, ten healthy young adults performed the six conditions of the traditional SOT to quantify standing postural control when exposed to …

Gaze And Posture Coordinate Differently With The Complexity Of Visual Stimulus Motion, Joshua L. Haworth, Srikant Vallabhajosula, Nikolaos Stergiou

Journal Articles

In this study, we explored whether gaze and posture would exhibit coordination with the motion of a presented visual stimulus, specifically with regard to the complexity of the motion structure. Fourteen healthy adults viewed a set of four visual stimulus motion conditions, in both self-selected and semi-tandem stance, during which the stimulus moved horizontally across a screen, with position updated to follow a sine, chaos, surrogate, or random noise trajectory. Posture was measured using a standard force platform in self-selected and semi-tandem stance conditions while gaze was recorded using image-based eye-tracking equipment. Cross-correlation confirmed the continuous coordination of gaze with …

Lower Extremity Injury In Female Basketball Players Is Related To A Large Difference In Peak Eversion Torque Between Barefoot And Shod Conditions, Jenna M. Yentes, Max J. Kurz, Nikolaos Stergiou

Journal Articles

Background
The majority of injuries reported in female basketball players are ankle sprains and mechanisms leading to injury have been debated. Investigations into muscular imbalances in barefoot versus shod conditions and their relationship with injury severity have not been performed. The purpose of this study was to investigate the effects of wearing athletic shoes on muscular strength and its relationship to lower extremity injuries, specifically female basketball players due to the high incidence of ankle injuries in this population.

Methods
During pre-season, 11 female collegiate basketball players underwent inversion and eversion muscle strength testing using an isokinetic dynamometer in both …

The Influence Of Auditory-Motor Coupling On Fractal Dynamics In Human Gait, Nathaniel Hunt, Denise Mcgrath, Nikolaos Stergiou

Journal Articles

Humans exhibit an innate ability to synchronize their movements to music. The field of gait rehabilitation has sought to capitalize on this phenomenon by invoking patients to walk in time to rhythmic auditory cues with a view to improving pathological gait. However, the temporal structure of the auditory cue, and hence the temporal structure of the target behavior has not been sufficiently explored. This study reveals the plasticity of auditory-motor coupling in human walking in relation to ‘complex’ auditory cues. The authors demonstrate that auditory-motor coupling can be driven by different coloured auditory noise signals (e.g. white, brown), shifting the …

Adaptation And Prosthesis Effects On Stride-To-Stride Fluctuations In Amputee Gait, Shane R. Wurdeman, Sara A. Myers, Adam L. Jacobsen, Nikolaos Stergiou

Journal Articles

Twenty-four individuals with transtibial amputation were recruited to a randomized, crossover design study to examine stride-to-stride fluctuations of lower limb joint flexion/extension time series using the largest Lyapunov exponent (λ). Each individual wore a “more appropriate” and a “less appropriate” prosthesis design based on the subject's previous functional classification for a three week adaptation period. Results showed decreased λ for the sound ankle compared to the prosthetic ankle (F_1,23 = 13.897, p = 0.001) and a decreased λ for the “more appropriate” prosthesis (F_1,23 = 4.849, p = 0.038). There was also a significant effect for the time …

Sitting And Looking: The Development Of Stability And Visual Exploration, Regina T. Harbourne, Bridget O. Ryalls, Nikolaos Stergiou

Journal Articles

This longitudinal study focused on the interaction of developing sitting postural control with look time, which served as a measure for cognitive processing. Twenty-eight typically developing infants and 16 infants with motor delays were evaluated using center-of-pressure measures to assess stability of sitting postural control and videography to assess look time at objects, at three progressive stages of sitting development. Results indicated that look time decreased significantly in conjunction with a significant increase in postural stability in both groups as sitting progressed to independence. Infants with motor delays showed significantly longer looks when compared to typical infants at the middle …

Amputation Effects On The Underlying Complexity Within Transtibial Amputee Ankle Motion, Shane R. Wurdeman, Sara A. Myers, Nikolaos Stergiou

Journal Articles

The presence of chaos in walking is considered to provide a stable, yet adaptable means for locomotion. This study examined whether lower limb amputation and subsequent prosthetic rehabilitation resulted in a loss of complexity in amputee gait. Twenty-eight individuals with transtibial amputation participated in a 6 week, randomized cross-over design study in which they underwent a 3 week adaptation period to two separate prostheses. One prosthesis was deemed “more appropriate” and the other “less appropriate” based on matching/mismatching activity levels of the person and the prosthesis. Subjects performed a treadmill walking trial at self-selected walking speed at multiple points of …

Persistent Fluctuations In Stride Intervals Under Fractal Auditory Stimulation, Vivien Marmelat, Kjerstin Torre, Peter J. Beek, Andreas Daffertshofer

Journal Articles

Stride sequences of healthy gait are characterized by persistent long-range correlations, which become anti-persistent in the presence of an isochronous metronome. The latter phenomenon is of particular interest because auditory cueing is generally considered to reduce stride variability and may hence be beneficial for stabilizing gait. Complex systems tend to match their correlation structure when synchronizing. In gait training, can one capitalize on this tendency by using a fractal metronome rather than an isochronous one? We examined whether auditory cues with fractal variations in inter-beat intervals yield similar fractal inter-stride interval variability as isochronous auditory cueing in two complementary experiments. …

Changes In Predicted Muscle Coordination With Subject-Specific Muscle Parameters For Individuals After Stroke, Brian A. Knarr, Darcy S. Reiman, Stuart A. Binder-Macleod, Jill S. Higginson

Journal Articles

Muscle weakness is commonly seen in individuals after stroke, characterized by lower forces during a maximal volitional contraction. Accurate quantification of muscle weakness is paramount when evaluating individual performance and response to after stroke rehabilitation. The objective of this study was to examine the effect of subject-specific muscle force and activation deficits on predicted muscle coordination when using musculoskeletal models for individuals after stroke. Maximum force generating ability and central activation ratio of the paretic plantar flexors, dorsiflexors, and quadriceps muscle groups were obtained using burst superimposition for four individuals after stroke with a range of walking speeds. Two models …

Mechanomyographic Parameter Extraction Methods: An Appraisal For Clinical Applications, Morufu Olusola Ibitoye, Nur Azah Hamzaid, Jorge M. Zuniga, Nazirah Hasnan, Ahmad Khairi Abdul Wahab

Journal Articles

The research conducted in the last three decades has collectively demonstrated that the skeletal muscle performance can be alternatively assessed by mechanomyographic signal (MMG) parameters. Indices of muscle performance, not limited to force, power, work, endurance and the related physiological processes underlying muscle activities during contraction have been evaluated in the light of the signal features. As a non-stationary signal that reflects several distinctive patterns of muscle actions, the illustrations obtained from the literature support the reliability of MMG in the analysis of muscles under voluntary and stimulus evoked contractions. An appraisal of the standard practice including the measurement theories …