Alterations in Active and Passive Behavior of Lower Back Tissues Following Six Sessions of High Velocity Low Amplitude Spinal Manipulative Therapy for Healthy Participants

Non-specific low back pain (LBP) is a major health problem affecting a substantial portion of the population. The current treatments offered for non-specific LBP are oftentimes unsuccessful because the acting mechanism(s) of most treatment options are unknown. Obtaining a better understanding about the acting mechanism behind existing treatment options is, therefore, essential for the improvement of non-specific LBP treatment and management. The objective of this study was to gain a more comprehensive understanding about the acting mechanism of high velocity low amplitude spinal manipulative therapy, specifically the impact that high velocity low amplitude spinal manipulative therapy may have on the active and passive spinal musculoskeletal stabilizing subsystems along with the resultant spinal stability for healthy participants. A pre-post intervention study design completed by six healthy participants was used to quantify changes in the above noted aspects of spinal stability using a series of tests performed both before and after six sessions of high velocity low amplitude spinal manipulative therapy. The tests included seated balancing tests, lower back range of motion tests, and stress relaxation test. The six sessions of high velocity low amplitude spinal manipulative therapy did not significantly affect any of the test measurements among our healthy participant group

The Impact of Coordination Quality on Coordination Dynamics and Team Performance: When Humans Team with Autonomy

abstract: This increasing role of highly automated and intelligent systems as team members has started a paradigm shift from human-human teaming to Human-Autonomy Teaming (HAT). However, moving from human-human teaming to HAT is challenging. Teamwork requires skills that are often missing in robots and synthetic agents. It is possible that adding a synthetic agent as a team member may lead teams to demonstrate different coordination patterns resulting in differences in team cognition and ultimately team effectiveness. The theory of Interactive Team Cognition (ITC) emphasizes the importance of team interaction behaviors over the collection of individual knowledge. In this dissertation, Nonlinear Dynamical Methods (NDMs) were applied to capture characteristics of overall team coordination and communication behaviors. The findings supported the hypothesis that coordination stability is related to team performance in a nonlinear manner with optimal performance associated with moderate stability coupled with flexibility. Thus, we need to build mechanisms in HATs to demonstrate moderately stable and flexible coordination behavior to achieve team-level goals under routine and novel task conditions.Dissertation/ThesisDoctoral Dissertation Engineering 201

Nonlinear dynamics of postural control system under visual-vestibular habituation balance practice: evidence from EEG, EMG and center of pressure signals

Human postural control system is inherently complex with nonlinear interaction among multiple subsystems. Accordingly, such postural control system has the flexibility in adaptation to complex environments. Previous studies applied complexity-based methods to analyze center of pressure (COP) to explore nonlinear dynamics of postural sway under changing environments, but direct evidence from central nervous system or muscular system is limited in the existing literature. Therefore, we assessed the fractal dimension of COP, surface electromyographic (sEMG) and electroencephalogram (EEG) signals under visual-vestibular habituation balance practice. We combined a rotating platform and a virtual reality headset to present visual-vestibular congruent or incongruent conditions. We asked participants to undergo repeated exposure to either congruent (n = 14) or incongruent condition (n = 13) five times while maintaining balance. We found repeated practice under both congruent and incongruent conditions increased the complexity of high-frequency (0.5–20 Hz) component of COP data and the complexity of sEMG data from tibialis anterior muscle. In contrast, repeated practice under conflicts decreased the complexity of low-frequency (<0.5 Hz) component of COP data and the complexity of EEG data of parietal and occipital lobes, while repeated practice under congruent environment decreased the complexity of EEG data of parietal and temporal lobes. These results suggested nonlinear dynamics of cortical activity differed after balance practice under congruent and incongruent environments. Also, we found a positive correlation (1) between the complexity of high-frequency component of COP and the complexity of sEMG signals from calf muscles, and (2) between the complexity of low-frequency component of COP and the complexity of EEG signals. These results suggested the low- or high-component of COP might be related to central or muscular adjustment of postural control, respectively

Individuality in balance control: Using conventional analytical & machine learning approaches to reveal person-specific differences in standing balance control.

The balance control system ensures that humans can perform tasks in a variety of postures despite bipedal stance being inherently unstable. It manages this instability by producing motor outputs that are appropriate to sensory input given the objective of maintaining balance. An inability to maintain this balance may result in a fall which can have both short and long-term physical, psychological, and social effects. The ability to maintain balance is a strong predictor of fall-risk and mobility limitations. Falling has been associated with specific populations such as older adults and those with neurological and neuromuscular pathologies. However, it is possible that some younger individuals may have poor balance control which places them at a greater fall-risk in the face of age and pathology-related influences. The potential importance of revealing person-specific differences in balance control in healthy, young adults has led to the focus of this thesis. This thesis was designed to determine whether a healthy, young adult’s balance control system, as measured by their balance performance, is specific to the individual and could be distinguished from any other individual. The thesis explores the use of different methods of measuring of body movement (kinetic or kinematic), and the analytical techniques which, when collectively applied, may more sensitively reveal these individual differences. General methodology consisted of sixty-one healthy, young adults (ages 18-35), free of any neurological or neuromuscular disorders, performing a series of static standing balance trials. Four task conditions, Base of Support (standard and narrow) and Vision (open and closed), were performed five times, each for thirty seconds. Balance performance was measured kinetically using two floor-mounted force plates, and kinematically using three inertial measurement units placed on the head, sternum, and lumbar region of the back. The resulting data became the substrate for the analyses used in the three studies. Study 1 quantified the consistency of an individual’s balance performance across task conditions relative to the other individuals. Centre-of-pressure data collected from force plates was analyzed using established linear and non-linear analytical methods within the time- and frequency-domains and then input into a linear mixed-effects model. Subject-specific factors, such as anthropometrics and vision quality, were controlled to reduce the number of confounding variables. Correlational analysis of the random-effect, participant, revealed moderate to strong correlations of individual balance performances across task conditions with the strength of these correlations dependent on the analytical technique used. Study 1 confirmed that (1) task-related differences in balance performance could be detected by a variety of analytical techniques, and that (2) the correlations found in relative balance performance across task conditions suggest that an individuals’ balance control system may be specific to the individual. Study 2 expanded on Study 1 by representing body movement kinematically using body-worn inertial measurement units. Similar analytical approaches were used and moderate to excellent correlations in relative balance performance across task conditions were observed. The use of kinematic data in this study also revealed kinematic strategies that could only be obtained by modelling a person as a multi-link, rigid body and not as a single-link, inverted pendulum; an assumption commonly made when using kinetic data. Like Study 1, this work demonstrated that relative balance performance within persons were comparable across tasks of varying difficulty and, as such, indirectly supports the idea that balance control that may be specific to the individual. Study 3 focused on analytical approaches that could more directly reveal the unique features of balance control within individuals. This study employed a machine-learning, classification algorithm in an attempt to identify individuals by their balance performance using kinetic or kinematic measures. Once provided with the prototypical balance performances of a discrete number of individuals, the algorithm was able to correctly attribute the balance performance of a mystery person to one of those individuals with an accuracy greater that what could be achieved by random chance. Representing body movement with kinetic, time-series data yielded the highest accuracies (Accuracy (nway = 5) = 92.08%; Accuracy (nway = 20) = 74.69%). However, it is believed that if kinematic data was recorded with more fidelity, then even greater accuracies could be possible. Study 3 demonstrated that (1) balance performance data contains features specific to the individual which may quantitatively indicate individuality in the balance control system, and (2) that the ability to reveal this individuality is dependent on how the balance performance is represented. This thesis provided two main contributions, (1) support for the idea that balance control during quiet standing, as revealed through balance performance, contains features that are specific to the individual, and (2) an, outline, albeit preliminary, of the task conditions, methods of measurement, and analytical techniques best suited to reveal this individuality

What are the differences between subjects with and without flatfoot condition, with the aid of ultrasonography, kinematics, and kinetics in posture and gait?

O complexo do pé tem um papel importante na postura, equilíbrio, estabilidade e movimento, durante as posições estáticas e nos padrões gerais de movimento. Alterações estruturais ou funcionais no complexo do pé e no seu posicionamento podem afetar a postura e o movimento das estruturas distais e proximais. Comumente, indivíduos com pé plano desenvolvem restrições neurológicas ou musculares, frouxidão ligamentar ou articular, movimento excessivo e atividade muscular. Essa condição leva a maiores riscos de desenvolver lesões por sobrecarga mecânica nas articulações dos membros inferiores adjacentes. O objetivo é determinar se existem diferenças entre indivíduos com pé plano em comparação com indivíduos com pé neutro, em relação à postura e à análise do padrão de marcha. A amostra foi constituída por sujeitos com pé plano e neutro, alocados em dois grupos. Todos os sujeitos foram submetidos a procedimentos de avaliação para serem alocados em um dos grupos. Cada participante foi submetido à avaliação do padrão de marcha e postura, com auxílio de sistema MOCAP, e à avaliação da rigidez muscular com Ultrassonografia e, por fim, à avaliação da pressão plantar com uma plataforma de pressões. Os sujeitos com pé plano mostraram várias alterações e diferenças quando comparados aos participantes com pé neutro, de acordo com os principais resultados da análise da postura e do padrão de marcha. Considerando todos os estudos realizados e incluídos nesta tese, várias diferenças foram encontradas em indivíduos de pé plano. Porém, a maioria desses resultados são contraditórios com os resultados presentes na literatura, dando um crescimento da evidência científica sobre a condição de pé plano e a sua influência na postura, e no padrão de marcha. No entanto, em relação à falta de consenso sobre os resultados e condições de avaliação, vários estudos necessitam ser realizados para criar uma maior robustez da evidência científica. Porém, no que se refere ao rigor metodológico em relação a diferentes parâmetros, novos estudos precisam de abranger variáveis que foquem a avaliação geral da condição e não apenas do complexo do pé. Palavras-chave: POSTURA DE PÉ, PADRÕES DE MOVIMENTO, PÈ PLANO, BIOMECÂNICA.The foot complex has an important role in posture, balance, stability, and movement, during the static positions and in overall movements' patterns. Structural or functional alteration in the foot complex and foot posture may have an impact on posture and movement on distal and proximal structures. Commonly, subjects with flatfoot develop neurological or muscular restrictions, ligament or joint laxity, excessive motion, and muscle activity. This condition leads to higher risks of developing mechanical overloading injuries on adjacent lower-limb joints. The aim of this study is to determine if there are differences between flatfoot subjects compared to neutral foot subjects, regarding posture and gait pattern analysis. The sample was constituted by subjects with a flat and neutral foot, allocated in two groups. All subjects were submitted to assessment procedures to be allocated in one of the groups. Therefore, each participant was submitted to gait pattern and posture assessment, with the aid of a MOCAP system, and to muscle stiffness assessment with an ultrasound-based Shear- Wave Elastography and, finally to plantar pressure assessment with a baropodometric platform. Flatfoot subjects showed several alterations and differences when compared to neutral foot participants considering all principal outcomes along with posture and gait pattern. Considering all studies realized and included in this thesis, several differences were found in flatfoot subjects. Thus, most of those results are contradictory to those found in the literature, giving a growth of evidence relatively to foot posture condition and influence in posture and gait pattern. However, regarding the lack of consensus about the outcomes and assessment conditions, further studies need to be performed to create a more robust body of evidence. Although, regarding methodological deficiency regarding influencing aspects, further studies need to encompass methodological variables handling to focus on an overall evaluation of the condition and not only on the foot complex

Multivariate multiscale complexity analysis

Established dynamical complexity analysis measures operate at a single scale and thus fail to quantify inherent long-range correlations in real world data, a key feature of complex systems. They are designed for scalar time series, however, multivariate observations are common in modern real world scenarios and their simultaneous analysis is a prerequisite for the understanding of the underlying signal generating model. To that end, this thesis first introduces a notion of multivariate sample entropy and thus extends the current univariate complexity analysis to the multivariate case. The proposed multivariate multiscale entropy (MMSE) algorithm is shown to be capable of addressing the dynamical complexity of such data directly in the domain where they reside, and at multiple temporal scales, thus making full use of all the available information, both within and across the multiple data channels. Next, the intrinsic multivariate scales of the input data are generated adaptively via the multivariate empirical mode decomposition (MEMD) algorithm. This allows for both generating comparable scales from multiple data channels, and for temporal scales of same length as the length of input signal, thus, removing the critical limitation on input data length in current complexity analysis methods. The resulting MEMD-enhanced MMSE method is also shown to be suitable for non-stationary multivariate data analysis owing to the data-driven nature of MEMD algorithm, as non-stationarity is the biggest obstacle for meaningful complexity analysis. This thesis presents a quantum step forward in this area, by introducing robust and physically meaningful complexity estimates of real-world systems, which are typically multivariate, finite in duration, and of noisy and heterogeneous natures. This also allows us to gain better understanding of the complexity of the underlying multivariate model and more degrees of freedom and rigor in the analysis. Simulations on both synthetic and real world multivariate data sets support the analysis

Neuromuscular Control Modeling: from Physics to Data-Driven Approaches

Il controllo neurale della postura umana è stato investigato a partire da un punto di vista fisico. Il paradigma di controllo intermittente è stato usato allo scopo di capire il peso di quest'ultimo nella generazione delle traiettorie del centro di pressione. Un primo contributo di questo lavoro rigurda quindi l'analisi del centro di pressione generato dal suddetto modello biomeccanico attraverso l'extended detrended fluctuation analysis, recentemente proposta in letteratura. Le proprietà di correlazione a lungo termine e disomogeneità sono risultate strettamente legate al guadagno derivativo del modello di controllo intermittente e anche al grado di intermittenza. Il paradigma di controllo è stato poi esteso verso un sistema biomeccanico più complesso, cioè un pendolo inverso doppio link con controllo intermittente alla caviglia. I contributi più significativi hanno riguardato la modellazione matematica del centro di pressione per una struttura multi-link e la verifica della sua plausibilità fisiologica. Si è poi preso in considerazione il caso della postura perturbata, integrando aspetti cinematici, dinamici e relativi all'attività muscolare. A tal fine, si è utilizzato sia un approccio fisico che basato su dati per l'identificazione dei modelli a struttura variabile Si sono prese in considerazione differenti condizioni di sperimentali, e in tutti i casi l'approccio utilizzato ha garantito un adeguato grado di interpretabilità riguardo il ruolo del sistema nervoso centrale nella regolazione del postura eretta in condizioni perturbate. La seconda parte della tesi ha riguardato la caratterizzazione del controllo motorio attraverso il segnale elettromiografico di superfice. Il primo contributo ha riguardato l'identifcazione dell'onset muscolare in condizioni di basso rapporto segnale rumore, sfruttando operatori energetico di tipo Teager-Kaiser al fine del precondizionamento del segnale mioelettrico. La versioe estesa di questo tipo di operatori è risultata particolarmente utile al miglioramento delle performance di numerosi algoritmi di detection. Si è poi proseguito con l'utilizzo di tali segnali al fine della classificazione dei gesti dell'arto superiore. In particoalre si è prerso in considerazione il problema della motion intention detection dei principali movimenti della spalla , utilizzando sia descrittori del segnale elettromiografico nel dominio del tempo e della frequenza. Quest'ultimo aspetto risulta essere un elemento di novità nel contesto scientifico in quanto si sono considerati il riconoscimento l'intezioni di movimento di otto gesti della spalla con particolare attenzione al ruolo dei descrittori del segnale per la classificazione. Infine, con approcci simili, si è preso in considerazione il problema del riconoscimento della scrittura manuale a partire dal dato elettromiografico. Tale aspetto risulta poco investigato sotto la prospettiva della pattern recognition mioelettrica, ma la sua valenza è data dalla crescente richiesta di interfacce uomo-macchina per compiti riabilitativi che coinvolgono una componente cognitiva significativa, Inoltre, vista la tendenza ad investigare il ruolo del polso per il prelievo del segnale elettromiografico al fine della realizzazione delle suddette interfacce, si è analizzato l'utilizzo dei segnali elettromiografici del polso rispetto a quelli dell'avambraccio al fine di predirre le cifre scritte dall'utente, noto che l'avambraccio risulta essere la zona di prelievo più comunemente utilizzata.The biomechanics and the neural control of the human stance was investigated starting from a physical point of view. In particular the intermittent motor control paradigm was investigated with the aim of understanding how such paradigm mirrors in the center of pressure (COP) trajectories. A first contribution given in this work of thesis regards the analysis of COP generated from intermittent controlled inverted pendulum through the extended detrended fluctuation analysis, which was recently introduced in the literature. It has been found that the long-term correlation and inohmogeniety properties of the COP time series strictly depend on the derivative gain term of the intermittent controller and on the degree of intermittency of the control action. Thus, , another contribution provided in this work of thesis regards the use of a more complex biomechanical model of the stance, e.g. a double-link inverted pendulum intermittently controlled at the ankle. In terms of novelty, it deserves to be pointed out the results regarding the mechanical modeling of the COP for a multi-link structure, and the assessment of its physiological plausibility. . On the other hand, when the perturbed posture motor task was taken into account, there was the need to enlarge the perspective, integrating kinematic, dynamic and muscle activity data. The idea of employing different sources of information to develop models of the CNS represents an important element that was investigated using tools related to hybrid system identification theory. Subjects underwent to impulsive support base translations in three different conditions: considering eyes open, closed, and performing mental counting. Although such data were essentially analyzed through a data-driven approach, the identified models guaranteed physical interpretations of the role played by the CNS in the three different conditions. The second main core of this thesis regards the characterization of the motor control using the surface electromyographic (sEMG) signals. A first contribution given in this work regarded the muscle onset detection considering low SNR scenarios. In this framework, energy operators such as the Teager-Kaiser energy operator (TKEO) and its extended version (ETKEO) were investigated as signal preconditioning steps before the application of state of the art onset detection algorithms. The latter have been significantly boosted when ETKEO was used with respect to TKEO. The use of extended energy operators for the sEMG signal preprocessing constitutes a novel element in this field that can be also further investigated in future studies. From the sEMG muscle, one can also predict which movement the subject is going to perform. This aspect can be enclosed in the motion intention detection (MID) field. In this thesis a MID problem was investigated by taking into account two important aspects: as first the study was centered on the shoulder joint movements. Secondly, the MID problem was faced under a pattern recognition perspective. This allowed to verify whether methodologies encountered in the myoelectric hand gesture recognition can be transferred in the affine field of MID In contrast to what reported in the literature, where MID problems generally consider only few movements, in this work of thesis up to eight shoulder movements have been investigated. Myoelectric pattern recognition architectures were also used in the assessment of the ten hand-written digits. Despite the handwriting can be considered a hand movement that involves fine muscular control actions, it has not been consistently investigated in the field of sEMG based hand gesture recognition. Further, since the literature supports the change from forearm to wrist in order to acquire EMG data for hand gesture recognition, it was investigated whether such exchange can be performed when a challenging classification task, as the handwriting recognition has to be performed

Models and analysis of vocal emissions for biomedical applications

This book of Proceedings collects the papers presented at the 3rd International Workshop on Models and Analysis of Vocal Emissions for Biomedical Applications, MAVEBA 2003, held 10-12 December 2003, Firenze, Italy. The workshop is organised every two years, and aims to stimulate contacts between specialists active in research and industrial developments, in the area of voice analysis for biomedical applications. The scope of the Workshop includes all aspects of voice modelling and analysis, ranging from fundamental research to all kinds of biomedical applications and related established and advanced technologies

Attention and time constraints in performing and learning a table tennis forehand shot

This is a section on p. S95 of article 'Verbal and Poster: Motor Development, Motor Learning and Control, and Sport and Exercise Psychology' in Journal of Sport and Exercise Psychology, 2010, v.32, p.S36-S237published_or_final_versio