Postural Orientation and Equilibrium

Horak, Fay B.; Macpherson, Jane M.

doi:10.1002/cphy.cp120107

Cited by 506 publications

(456 citation statements)

References 201 publications

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“…Considering that the CNS controls muscles not only at an individual muscle level, but possibly also at a higher more functionally relevant level, such as at the joint level or at the muscle groups level [16][17][18], muscle synergies, expressed through reciprocal activation and co-activation indexes, were evaluated at these levels. The selection of these indexes was based on ideas expressed within the framework of the equilibrium-point hypothesis [19], particularly on the idea of two control variables, reciprocal and co-activation commands, describing the control of a single degree-of-freedom joint [20,21].…”

Section: Introductionmentioning

confidence: 99%

Influence of long-term wearing of unstable shoes on compensatory control of posture: An electromyography-based analysis

et al. 2014

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Purpose: This study investigated the influence of long-term wearing of unstable shoes (WUS) on compensatory postural adjustments (CPA) to an external perturbation.Methods: Participants were divided into two groups: one wore unstable shoes while the other wore conventional shoes for 8 weeks. The ground reaction force signal was used to calculate the anterior-posterior (AP) displacement of the centre of pressure (CoP) and the electromyographic signal of gastrocnemius medialis (GM), tibialis anterior (TA), rectus femoris (RF) and biceps femoris (BF) muscles was used to assess individual muscle activity, antagonist co-activation and reciprocal activation at the joint (TA/GM and RF/(BF+GM) pairs) and muscle group levels (ventral (TA+RF)/dorsal (GM+BF) pair) within time intervals typical for CPA. The electromyographic signal was also used to assess muscle latency. The variables described were evaluated before and after the 8-week period while wearing the unstable shoes and barefoot. Results: Long-term WUS led to: an increase of BF activity in both conditions (barefoot and wearing the unstable shoes); a decrease of GM activity; an increase of antagonist co-activation and a decrease of reciprocal activation level at the TA/GM and ventral/dorsal pairs in the unstable shoe condition. Additionally, WUS led to a decrease in CoP displacement. However, no differences were observed in muscle onset and offset. Conclusion: Results suggest that the prolonged use of unstable shoes leads to increased ankle and muscle groups' antagonist co-activation levels and higher performance by the postural control system.

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Section: Introductionmentioning

confidence: 99%

Influence of long-term wearing of unstable shoes on compensatory control of posture: An electromyography-based analysis

et al. 2014

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“…Human erect posture is known to depend on the coordination of numerous biomechanical degrees of freedom (Creath et al 2005;Hsu et al 2007;Pinter et al 2008), based on the integration of vestibular, visual and somatosensory information (Peterka 2002), to stabilize equilibrium and orientation (Horak and MacPherson 1996;Massion 1994). Here, equilibrium refers to the biomechanical requirements of upright stance (stabilizing the center of mass, CoM, within the base of support), while orientation refers to the relative or absolute positions of different body parts such as trunk and head.…”

Section: Introductionmentioning

confidence: 99%

“…Due to motor equivalence, the extent to which joint angle variability results in variability in taskrelated variables depends on the coordination among the joint angles. In the case of upright postural control, CoM and head position, as well as trunk and head orientation, have been proposed as relevant (Horak and MacPherson 1996;Hsu et al 2007). Here, we follow the approach of Müller and Sternad (2003), in which joint angles time series are randomly permuted to produce ''decorrelated'' surrogate data.…”

Section: Introductionmentioning

confidence: 99%

Local and global effects of neck muscle vibration during stabilization of upright standing

et al. 2011

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Neck muscle vibration (NMV) during upright standing is known to induce forward leaning, which has been explained as a global response to the (illusory) perception of a lengthening of the dorsal neck muscles. However, the effects of NMV both at the level of individual joints and on whole-body postural coordination, and its potential modulation by vision, have not yet been analyzed in detail. Eight healthy young adult participants completed a total of ten trials each, with a 10-s period of unperturbed standing followed by a 10-s period of NMV. Participants were instructed to stand ''as still as possible''. This postural task was executed under two visual conditions: eyes open (EO) and eyes closed (EC). Postural responses were measured in terms of center of pressure (CoP) and center of mass (CoM) profiles, and whole-body kinematics. Responses to NMV at the level of individual body segments and joints were assessed by decomposing the time series into linear trends and residual fluctuations. Inter-segmental coordination was analyzed using a decorrelation technique, assessing motor-equivalent stabilization of four task-related variables: CoM position, trunk orientation, as well as head position and orientation. NMV induced a general forward leaning response under both visual conditions, visible in CoP, CoM, segment positions and orientations. Locally, NMV induced a pronounced extension of the atlanto-occipital joint. Residual fluctuations were higher with EC and unaffected by NMV. Coordination analysis showed that stabilization of different body parts was differentially affected by NMV. Head orientation was consistently stabilized across all conditions, with weaker coordination in the EC condition. In contrast, motor-equivalent stabilization of CoM and head position, and trunk orientation was only observed during no-vibration periods. Taken together, our results demonstrate specific effects of vision and proprioception on different aspects of local and global postural control. While perturbed neck proprioception seemed to affect the postural ''set point'' (inducing forward leaning), vision appeared to mainly serve in noise reduction (residual fluctuations) and control of head orientation.

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“…Qualquer postura adotada pelo corpo exige uma ação efetiva do sistema de controle postural com o objetivo de manter a orientação e o equilíbrio do corpo. A orientação postural refere-se à posição do corpo em relação aos segmentos corporais entre si e o ambiente (HORAK & MACPHERSON, 1996). Mecanicamente, as condições de equilíbrio do corpo dependem das forças e momentos que são aplicados sobre ele.…”

Section: Controle Posturalunclassified

“…Nessa estratégia, denominada de "estratégia do quadril", a ordem de recrutamento dos músculos é invertida para uma seqüência de ativação proximal-distal na tentativa de reduzir os deslocamentos do CM (BARDY, MARIN, STOFFREGEN & BOOTSMA, 1999;HORAK & MACPHERSON, 1996;NASHNER & MCCOLLUM, 1985;RUNGE et al, 1999). (BUCHANAN & HORAK, 1999;MARIN et al, 1999;RUNGE et al, 1999 …”

Section: Sinergias Posturaisunclassified

Coordenação postural em adultos e idosos durante movimentos voluntários na postura ereta

Freitas¹

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É impossível expressar toda a minha felicidade por ter chegado até aqui. Mais impossível ainda é citar o nome de todas as pessoas que contribuíram, direta ou indiretamente, para a conclusão deste trabalho. Então, agradeço antecipadamente a VOCÊ que, por algum motivo, está lendo esta tese. Meus sinceros agradecimentos ...Ao meu orientador, Prof. Dr. MARCOS DUARTE, pela imensurável atenção durante todo o meu doutorado. Obrigada pela orientação, pela paciência, pela amizade, pelo respeito e por todas as oportunidades que me concedeu durante todo o processo.Ao Prof. Dr. MARK LATASH, meu supervisor de estágio na Universidade da Pensilvânia-E.U.A., pelos ensinamentos e pela amizade.À minha grande família, LUIZ, DIVARLEY, KÁTIA e NELSON, SIMONE, LUIZ e ÉRIKA, MARCELO e LUCIENE, pelo apoio e incentivo.Ao meu esposo, PAULO B. FREITAS JR, pelo carinho, auxílio e dedicação.Ao Prof. Dr. LUIS MOCHIZUKI e Prof. Dr. UMBERTO CORREA, pelo incentivo.Aos membros e ex-membros do LABORATÓRIO DE BIOFÍSICA, pela troca de experiências, em especial, PAULO, ROGÉRIO e SANDRO, pela amizade. Aos membros do LABORATÓRIO DE CONTROLE MOTOR da Universidade daPensilvânia-E.U.A., em especial, ao JAE e à NUI, pela amizade e auxílio.Às amigas ANA, BRENDA, ELI, e SILVANA, pela amizade.Ao meu avô, DIRCEU SIMÕES, pela inspiração no tema.À FAPESP, pelo apoio financeiro da bolsa de doutorado.À CAPES, pelo apoio financeiro do estágio sanduíche.A DEUS, pela vida.

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Postural Orientation and Equilibrium

Abstract: The sections in this article are: Neural Control of Postural Orientation and Equilibrium Behavioral Goals Biomechanical Principles Postural Strategies Postural Orientation Stiffness and Tonic Muscle Activation Controlling Postural Orientation … Show more

Cited by 506 publications

References 201 publications

Influence of long-term wearing of unstable shoes on compensatory control of posture: An electromyography-based analysis

Influence of long-term wearing of unstable shoes on compensatory control of posture: An electromyography-based analysis

Local and global effects of neck muscle vibration during stabilization of upright standing

Coordenação postural em adultos e idosos durante movimentos voluntários na postura ereta

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