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1.
J Appl Biomech ; : 1-7, 2024 Jun 26.
Article in English | MEDLINE | ID: mdl-38925535

ABSTRACT

Different forearm postures can modulate corticospinal excitability. However, there is no consensus on whether handedness plays a role in such a mechanism. This study investigated the effects of 3 forearm postures (pronation, neutral, and supination) on the corticospinal excitability of muscles from the dominant and nondominant upper limbs. Surface electromyography was recorded from the abductor digiti minimi, flexor pollicis brevis, and flexor carpi radialis from both sides of 12 right-handed volunteers. Transcranial magnetic stimulation pulses were applied to each muscle's hotspot in both cerebral hemispheres. Motor-evoked potential peak-to-peak amplitude and latency and resting motor threshold were measured. The data were evaluated by analysis of variance. The level of significance was set at 5%. The resting motor threshold was similar for the 3 muscles and both sides. Motor-evoked potential peak-to-peak amplitude from flexor pollicis brevis was lower during supination, and the dominant upper limb latency was longer. The flexor carpi radialis presented lower motor-evoked potential peak-to-peak amplitudes for neutral and shorter latencies during supination. Abductor digiti minimi seemed not to be affected by posture or side. Different muscles from dominant and nondominant sides may undergo corticospinal modulation, even distally localized from a particular joint and under rest.

2.
Scand J Med Sci Sports ; 33(12): 2524-2533, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37642219

ABSTRACT

The neurophysiological mechanisms underlying muscle force control for different wrist postures still need to be better understood. To further elucidate these mechanisms, the present study aimed to investigate the effects of wrist posture on the corticospinal excitability by transcranial magnetic stimulation (TMS) of extrinsic (flexor [FCR] and extensor carpi radialis [ECR]) and intrinsic (flexor pollicis brevis (FPB)) muscles at rest and during a submaximal handgrip strength task. Fourteen subjects (24.06 ± 2.28 years) without neurological or motor disorders were included. We assessed how the wrist posture (neutral: 0°; flexed: +45°; extended: -45°) affects maximal handgrip strength (HGSmax ) and the motor evoked potentials (MEP) amplitudes during rest and active muscle contractions. HGSmax was higher at 0° (133%) than at -45° (93.6%; p < 0.001) and +45° (73.9%; p < 0.001). MEP amplitudes were higher for the FCR at +45° (83.6%) than at -45° (45.2%; p = 0.019) and at +45° (156%; p < 0.001) and 0° (146%; p = 0.014) than at -45° (106%) at rest and active condition, respectively. Regarding the ECR, the MEP amplitudes were higher at -45° (113%) than at +45° (60.8%; p < 0.001) and 0° (72.6%; p = 0.008), and at -45° (138%) than +45° (96.7%; p = 0.007) also at rest and active conditions, respectively. In contrast, the FPB did not reveal any difference among wrist postures and conditions. Although extrinsic and intrinsic hand muscles exhibit overlapping cortical representations and partially share the same innervation, they can be modulated differently depending on the biomechanical constraints.


Subject(s)
Hand Strength , Muscle, Skeletal , Humans , Electromyography , Hand Strength/physiology , Muscle, Skeletal/physiology , Wrist/physiology , Upper Extremity , Muscle Contraction/physiology , Evoked Potentials, Motor/physiology , Transcranial Magnetic Stimulation
3.
Res Q Exerc Sport ; 94(1): 186-193, 2023 03.
Article in English | MEDLINE | ID: mdl-35040750

ABSTRACT

Purpose: Physical exercises on unstable surfaces have been largely applied for clinical practice as well as in sports training. Although the unsteadiness can lead to physiological and psychological adaptations, little is known about the autonomic and emotional acute responses during the practice of balance exercises. This study aimed to evaluate both cardiorespiratory and emotional responses while standing on different unstable surfaces. Methods: Eighty-eight healthy participants performed postural balance tasks in three experimental conditions: (1) a rigid surface (control); (2) balance pad; and (3) the Both Sides Up (BOSU) ball. Respiratory activity was recorded through the thoracic movement and the heart rate variability by the electrocardiographic signal during the balance tasks. After the participants evaluated the level of perceived stability and emotional aspects related to each experimental condition. Results: The main results showed that BOSU condition was perceived as more unstable, unpleasant, with higher arousal and lower dominance levels (p < .05). Accordingly, participants had also an increase in the mean respiratory frequency and heart rate (p < .05). Conclusion: These results showed that the postural task with greater instability prompted congruent physiological adjustments to ensure the homeostasis in the more challenging condition. Therefore, the cardiorespiratory and emotional responses should be considered to ensure the safety and benefits in rehabilitation programs in which the exercise progression is based on unstable surfaces.


Subject(s)
Exercise Therapy , Sports , Humans , Exercise Therapy/methods , Postural Balance/physiology , Exercise , Emotions
4.
J Bodyw Mov Ther ; 24(3): 227-234, 2020 Jul.
Article in English | MEDLINE | ID: mdl-32825993

ABSTRACT

BACKGROUND: Different terms are used to refer to postural balance training, but the ontological debate involving the concepts to pursue nomenclature consensus is unusual. OBJECTIVE: The goal of this study was to analyze how often the terms balance, neuromuscular, proprioceptive, functional and sensorimotor training/exercise are used in the literature, and to propose a conceptual critical appraisal to determine the most appropriate terminology to address postural balance exercises. METHODS: A literature search was conducted in the Scopus electronic database. Eligibility criteria: papers with the selected expressions on the title or keywords, published in English, were included. RESULTS: The most used term was balance training (471 of 1105 included papers). Europe, followed by Asia and North America, had the highest number of publications. In the 21st century, the number of publications increased considerably. However, the terms have conceptual differences and controversies regarding its use. CONCLUSION: Despite a large variety of exercise types and divergences, balance training seems to be the most suitable term, given it refers to postural equilibrium exercises.


Subject(s)
Exercise Therapy , Postural Balance , Europe , Exercise , Humans , Proprioception
5.
Movimento (Porto Alegre) ; 25(1): e25072, jan.- dez. 2019. Figura
Article in Portuguese | LILACS | ID: biblio-1049104

ABSTRACT

Colocar em perspectiva as representações sociais não é tarefa fácil. Neste trabalho, as percepções de dez estudantes de Educação Física antes e após a Caminhada do Privilégio ­ dinâmica que representa a trajetória de vida dos participantes através de passos ­ foram analisadas visando compreender os efeitos da atividade sobre o grupo a partir das percepções de suas posições sociais, dos fatores atribuídos a tais posições e das mudanças de perspectiva desencadeadas pela Caminhada do Privilégio. Os estudantes estimaram corretamente suas posições finais na Caminhada, porém esperavam encontrar pouca diferença entre eles, decorrente do esforço individual e do acesso a direitos e privilégios. Contudo, após a Caminhada do Privilégio, observaram uma grande distância entre eles e questões como gênero, orientação sexual, apoio familiar e condição econômica foram percebidas como centrais. O racismo foi citado, mas de forma reservada, em questionário, indicando a dificuldade de debate aberto de temas sociais


Putting social representations at school in perspective is not an easy task. This study analyzed perceptions of ten Physical Education students before and after the Privilege Walk ­ activity that represents individual histories through steps ­ in order to understand its effects on the group, considering the previous perceptions of their own social positions, factors related to those positions, and changes of perspective triggered by the Privilege Walk. Students correctly estimated their final positions in the Walk, but they expected smaller differences among them as a result of individual effort and access to rights and privileges. However, after the Privilege Walk, they observed major distances among them, and issues of gender, sexual orientation, family support and economic condition were perceived as crucial. Racism was mentioned in the questionnaire but not in the group, indicating the difficulty of holding an open debate about social issues


Discutir las representaciones sociales no es una tarea fácil. En este trabajo, las percepciones de diez estudiantes de EF antes y después de la Caminata del Privilegio ­dinámica que representa la trayectoria de vida de los participantes a través de pasos­ fueron analizadas con el objetivo de comprender los efectos de la actividad sobre el grupo, a partir de las percepciones de sus posiciones sociales, de los factores atribuidos a tales posiciones y de los cambios de perspectiva desencadenados por la Caminata del Privilegio. Los estudiantes estimaron correctamente sus posiciones finales en la Caminata, aunque esperaban encontrar poca diferencia entre ellos producto del esfuerzo individual y del acceso a derechos y privilegios. Sin embargo, después de la Caminata del Privilegio, observaron una gran distancia entre ellos y cuestiones como género, orientación sexual, apoyo familiar y condición económica fueron percibidas como centrales. El racismo fue citado, pero de forma reservada, en cuestionario, indicando la dificultad en el debate abierto de cuestiones sociales


Subject(s)
Humans , Male , Female , Physical Education and Training , Social Perception , Students , Emotions , Socioeconomic Factors
6.
Physiol Behav ; 177: 189-195, 2017 Aug 01.
Article in English | MEDLINE | ID: mdl-28476285

ABSTRACT

Although some studies have reported significant changes in autonomic responses according to the perspective-taking during motor imagery [first person perspective (1P) and third person perspective (3P)], investigations on how the strategies adopted to mentally simulate a given movement affect the heart rate variability (HRV) seem so far unexplored. Twenty healthy subjects mentally simulated the movement of middle-finger extension in 1P and 3P, while electrocardiogram was recorded. After each task, the level of easiness was self-reported. Motor imagery ability was also assessed through the revised version of Movement Imagery Questionnaire (MIQ-R) and a mental chronometry index. The traditional measures of HRV in the time- and frequency-domain were compared between 1P and 3P tasks by using Student's t-test for dependent samples. The MIQ-R results showed that subjects had the same facility to imagine movements in 1P or 3P. The mental chronometry index revealed a similar temporal course only between 1P and execution, while the 3P strategy had a shorter duration. Additionally, the subjective report was similar between the experimental tasks. Regarding the HRV measures, the low frequency component, in log-transformed unit, was significantly higher (p=0.017) in 1P than 3P, suggesting a higher activity of the sympathetic system during 1P. This log-transformed HRV parameter seems to be more sensitive than normalized values for the assessment of the motor imagery ability, together with questionnaires, scales and mental chronometry.


Subject(s)
Heart Rate , Imagination/physiology , Psychomotor Performance/physiology , Self Concept , Social Perception , Electrocardiography , Electromyography , Fingers/physiology , Heart Rate/physiology , Humans , Male , Muscle, Skeletal/physiology , Self Report , Young Adult
7.
Eur J Appl Physiol ; 116(9): 1771-9, 2016 Sep.
Article in English | MEDLINE | ID: mdl-27431210

ABSTRACT

PURPOSE: The aim of this study was to evaluate whether different types of visual feedback influence the control of standing balance. METHODS: Twenty-six subjects performed three tasks on a force platform: (1) standing with eyes open; (2) maintaining the own center of pressure (COP) displacement (internal feedback) on a target; and (3) pointing with a handheld laser pointer (external feedback) on a target. The COP and ankle displacements were measured through a force platform and a biaxial electrogoniometer, respectively, during 60 s in each task. Global posturographic parameters were computed in the anterior-posterior and medial-lateral directions. In addition, the standard deviation and mean frequency of the ankle movements were also calculated in the sagittal plane. RESULTS: The sway area and standard deviation of COP differed between conditions, wherein smaller and higher values were typically observed during the internal and external feedback, respectively. Conversely, both the mean frequency and the mean velocity of COP were greater during internal feedback compared with other tasks, while external feedback usually leads to smaller values. Additionally, smaller and higher values for the ankle standard deviation and the ankle mean frequency, respectively, were observed during internal feedback, with the external feedback condition showing an opposite behavior. CONCLUSIONS: These results showed that the global postural sway and the postural adjustments at ankle during standing balance change depending on the type of visual feedback information.


Subject(s)
Feedback, Sensory/physiology , Postural Balance/physiology , Posture/physiology , Psychomotor Performance/physiology , Adaptation, Physiological/physiology , Ankle Joint/physiology , Foot/physiology , Humans , Male , Pressure , Range of Motion, Articular/physiology , Young Adult
8.
J Neurophysiol ; 109(2): 405-14, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23136345

ABSTRACT

It is well established that the mental simulation of actions involves visual and/or somatomotor representations of those imagined actions. To investigate whether the total absence of vision affects the brain activity associated with the retrieval of motor representations, we recorded the readiness potential (RP), a marker of motor preparation preceding the execution, as well as the motor imagery of the right middle-finger extension in the first-person (1P; imagining oneself performing the movement) and in the third-person (3P; imagining the experimenter performing the movement) modes in 19 sighted and 10 congenitally blind subjects. Our main result was found for the single RP slope values at the Cz channel (likely corresponding to the supplementary motor area). No difference in RP slope was found between 1P and 3P in the sighted group, suggesting that similar motor preparation networks are recruited to simulate our own and other people's actions in spite of explicit instructions to perform the task in 1P or 3P. Conversely, reduced RP slopes in 3P compared with 1P found in the blind group indicated that they might have used an alternative, nonmotor strategy to perform the task in 3P. Moreover, movement imagery ability, assessed both by means of mental chronometry and a modified version of the Movement Imagery Questionnaire-Revised, indicated that blind and sighted individuals had similar motor imagery performance. Taken together, these results suggest that complete visual loss early in life modifies the brain networks that associate with others' action representations.


Subject(s)
Blindness/physiopathology , Contingent Negative Variation , Psychomotor Performance , Adult , Brain/physiopathology , Fingers , Humans , Imagination , Male , Movement
9.
PLoS One ; 7(9): e45235, 2012.
Article in English | MEDLINE | ID: mdl-23024811

ABSTRACT

BACKGROUND: Contemporary theories of motor control propose that motor planning involves the prediction of the consequences of actions. These predictions include the associated costs as well as the rewarding nature of movements' outcomes. Within the estimation of these costs and rewards would lie the valence, that is, the pleasantness or unpleasantness of a given stimulus with which one is about to interact. The aim of this study was to test if motor preparation encompasses valence. METHODOLOGY/PRINCIPAL FINDINGS: The readiness potential, an electrophysiological marker of motor preparation, was recorded before the grasping of pleasant, neutral and unpleasant stimuli. Items used were balanced in weight and placed inside transparent cylinders to prompt a similar grip among trials. Compared with neutral stimuli, the grasping of pleasant stimuli was preceded by a readiness potential of lower amplitude, whereas that of unpleasant stimuli was associated with a readiness potential of higher amplitude. CONCLUSIONS/SIGNIFICANCE: We show for the first time that the sensorimotor cortex activity preceding the grasping of a stimulus is affected by its valence. Smaller readiness potential amplitudes found for pleasant stimuli could imply in the recruitment of pre-set motor repertoires, whereas higher amplitudes found for unpleasant stimuli would emerge from a discrepancy between the required action and their aversiveness. Our results indicate that the prediction of action outcomes encompasses an estimate of the valence of a stimulus with which one is about to interact.


Subject(s)
Emotions/physiology , Hand Strength/physiology , Adolescent , Adult , Cerebral Cortex/physiology , Electroencephalography , Humans , Male , Young Adult
10.
J Mot Behav ; 40(2): 83-9, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18400675

ABSTRACT

The authors collected and compared mechanomyo-graphic (MMG) signal behavior from the biceps brachii of left and right arms of right-handed men (n = 19) and women (n = 20) who performed isometric contractions at 5 contraction levels. Mean frequency (MF) and RMS values were calculated from the MMG signals that arose from lateral oscillations of muscle fibers. Across genders and arms, RMS values increased with contraction level and MF values decreased with increase in muscle contraction. The authors found no significant difference in those parameters between dominant and nondominant arms. Therefore, summation of muscle twitches obtained from the MMG signal collected in biceps brachii muscle does not reveal any difference between dominant and nondominant arms.


Subject(s)
Arm/physiology , Functional Laterality/physiology , Isometric Contraction/physiology , Movement/physiology , Muscle, Skeletal/physiology , Adolescent , Adult , Analysis of Variance , Electromyography/methods , Female , Humans , Male , Reference Values , Stress, Mechanical
11.
Neurosci Lett ; 410(1): 52-6, 2006 Dec 13.
Article in English | MEDLINE | ID: mdl-17056179

ABSTRACT

The ability to identify safety and danger is critical to survival. However, not much is known about human somatic body reactions in these contexts. We performed a posturographic study comparing body reactions to the sight of pictures of smiling babies and families (affiliative) versus matched neutral people, and to pictures depicting body envelope violations (mutilation) versus matched neutral people. The participants stood on a force platform and heart rate and displacement of the center of pressure were recorded while the pictures were presented. Pictures of mutilation induced a freezing-like reaction consisting of a medial-lateral (M-L) decrease in the amplitude of sway (immobility) and increase of the mean power frequency (rigidity), associated with bradycardia. Affiliative stimuli also induced an immobility and rigidity behavior but in the anterior-posterior (A-P) axis. This resembles the "immobility-without-fear reaction" proposed to occur when, upon detection of safety cues, mammals including humans are involved in pro-social activities. We conclude that the sight of visual cues of affiliation and danger produce distinct body somatic reactions.


Subject(s)
Emotions/physiology , Postural Balance/physiology , Posture/physiology , Visual Perception/physiology , Adolescent , Adult , Electroencephalography/methods , Female , Humans , Male , Photic Stimulation/methods
12.
Neurosci Lett ; 400(1-2): 181-5, 2006 May 29.
Article in English | MEDLINE | ID: mdl-16530330

ABSTRACT

Mental simulation of movements has been widely used to infer about representational aspects of action. On a daily basis, motor planning and execution depends crucially both upon vision and kinesthesia. What if the former is lost? In this study we investigate the physiological changes induced during a mental simulation task in subjects with early and late onset blindness, analyzing simultaneously stabilometric (body sway), electromyographic (EMG, lateral gastrocnemius) and eletrocardiographic (ECG) signals. Subjects were asked to stand up on a force platform and instructed either to: rest during 20s; count mentally from 1 to 15; imagine themselves executing a bilateral plantar flexion 15 times and execute the same movement 15 times. Discriminant analysis was employed to have access to the differences in the groups with respect to heart rate variability (HRV), EMG and body sway measurements for each condition. We found an overall correct classification of 100 and 90.9%, respectively, for the stabilometric parameters and HRV. This result was found only for the mental simulation task (p<0.05), being absent for resting, counting and executing. Previous studies have shown that motor simulation in a kinesthetic mode strongly associates with somatic and autonomic changes. In late blind subjects, however, movement simulation would tend to unfold with the use of both visual and kinesthetic representations. Thus, our results suggest that early and late blind subjects make use of distinct body representations during motor imagery.


Subject(s)
Blindness/physiopathology , Imagination/physiology , Movement/physiology , Perception/physiology , Adolescent , Adult , Discrimination, Psychological/physiology , Electrocardiography/methods , Electroencephalography/methods , Heart Rate/physiology , Humans , Male , Psychomotor Performance/physiology , Statistics, Nonparametric
13.
Rev. bras. med. esporte ; 11(5): 306-310, set.-out. 2005. ilus, graf
Article in Portuguese | LILACS | ID: lil-430340

ABSTRACT

O objetivo deste estudo foi caracterizar as componentes temporais e espectrais dos abalos musculares em diferentes níveis de contração muscular através da acelerometria. Participaram do estudo 15 indivíduos do sexo masculino e 12 do feminino, todos destros. O experimento constou de um teste de carga máxima (CM) que permitiu determinar cinco cargas percentuais administradas durante os testes de força (20 por cento, 40 por cento, 60 por cento, 80 por cento e 100 por cento da CM), em isometria e por oito segundos cada. Um acelerômetro biaxial foi colocado sobre o ventre muscular do bíceps braquial direito. A raiz média quadrática (valor RMS), um parâmetro temporal, e a freqüência média (FME), um parâmetro espectral, foram extraídas dos sinais de acelerometria (sinal de MMG). Estes parâmetros foram analisados nas direções X (perpendicular às fibras) e Y (paralela às fibras). Ambos os grupos apresentaram comportamento decrescente da FME (Y) com a carga, sendo mais pronunciado para o grupo feminino. A variável FME (X), no grupo feminino, apresentou comportamento semelhante à FME (Y), sendo apenas observada diferença estatística significativa entre 20 por cento da CM e todas as demais cargas (p = 0,0022 para 40 por cento e p < 0,0001 para as demais). O grupo masculino não apresentou diferença estatística significativa entre as cargas. O valor RMS (Y) apresentou comportamento crescente com a carga para ambos os grupos, havendo diferenças entre as cargas de 20 por cento e 40 por cento da CM (p = 0,000) e 80 por cento, e 100 por cento da CM (p = 0,01) para o grupo masculino. No entanto, não foi observada diferença estatística significativa entre as cargas para o grupo feminino. Discute-se que durante a contração muscular ocorrem variações não uniformes do diâmetro da fibra, além de oscilações laterais de baixa freqüência. Estas informações parecem ter forte correlação com a tipagem de fibras, o que poderia contribuir para melhor esclarecer os possíveis mecanismos envolvidos durante o processo de gradação da força muscular.


Subject(s)
Male , Female , Adult , Humans , Acceleration , Muscle Contraction/physiology , Physiology/instrumentation , Myography/methods , Muscles/physiology , Accelerograph
14.
Rev. bras. med. esporte ; 10(4): 299-307, jul.-ago. 2004. ilus, tab, graf
Article in Portuguese, English | LILACS | ID: lil-387125

ABSTRACT

A fadiga muscular, definida como a incapacidade na manutenção de um nível esperado de força, tem sido amplamente investigada nas áreas clínica e desportiva. Na investigação dos efeitos da fadiga sobre a regulação da contração, a eletromiografia de superfície (SEMG) tem sido uma importante ferramenta eletrodiagnóstica, pois diferentes parâmetros de análise podem ser extraídos a partir do sinal de EMG. Dentre estes parâmetros, a velocidade de condução dos potenciais de ação das unidades motoras (VCPAUMs) tem sido uma variável importante neste tipo de avaliação, apesar de comumente ser detectada através de técnicas invasivas, mediante eletrodos de arame ou agulha. Assim, o objetivo deste trabalho foi estimar a VCPAUM através da SEMG, avaliando o seu comportamento temporal, em contrações isométricas realizadas até a exaustão. Dezoito voluntários (nove homens e nove mulheres; idade de 25,6 ± 6,8 anos), alunos da EEFD/UFRJ, consentiram em participar do estudo. Os sinais de EMG foram colhidos a partir do músculo bíceps braquial direito em três diferentes níveis (25 por cento, 50 e 75 por cento da carga máxima (CM)), sendo, então, divididos em três trechos, correspondentes ao tempo total gasto na tarefa, assim denominados: início (T1), meio (T2) e fim (T3). A VCPAUM apresentou redução temporal durante a passagem pelos trechos (p < 0,0001), comparando todas as cargas. Entretanto, foi observada uma queda abrupta da VCPAUM em T3, principalmente em 50 e 75 por cento da CM (p < 0,05), quando comparadas com a carga de 25 por cento da CM. Os resultados apontam que a VCPAUM sofre modificações na medida em que há uma redução no pH intracelular, fundamental na permeabilidade da membrana celular e que pode ser decorrente de uma diminuição no aporte sanguíneo, pelo aumento no tempo e no nível de contração. Além disso, a adaptação no uso da SEMG para a estimativa da VCPAUM mostrou a viabilidade no uso do método como ferramenta diagnóstica.


Subject(s)
Adult , Male , Female , Humans , Action Potentials , Biomechanical Phenomena , Electromyography , Muscle Fatigue/physiology , Muscle, Skeletal/physiology
15.
Braz. J. Psychiatry (São Paulo, 1999, Impr.) ; 25(supl.2): 33-35, dez. 2003. ilus
Article in Portuguese | LILACS | ID: lil-355610

ABSTRACT

A construçäo e manipulaçäo espacial de imagens corporais têm origem basicamente visual e somato-motora. No entanto, a contribuiçäo relativa de cada modalidade sensorial nos processos de simulaçäo mental pode variar. Sirigu e Duhamel (2001) propuseram que a estratégia utilizada durante a simulaçäo mental de movimentos produziria a ativaçäo de circuitos neurais distintos. Neste estudo, investigamos o efeito da estratégia adotada na simulaçäo mental de uma tarefa motora que envolve ajustes posturais utilizando as técnicas de cronometria mental e de estabilometria. Os voluntários, posicionados sobre uma plataforma de força vertical com os pés unidos e os olhos fechados, foram solicitados a realizar as seguintes tarefas: a) manter a postura ereta normal durante 20 segundos; b) contar mentalmente de um a 15; c) imaginar-se realizando o movimento de flexäo plantar bilateral 15 vezes e d) executar o mesmo movimento por 15 vezes. Ao final do teste, relataram qual a estratégia utilizada para a realizaçäo da simulaçäo mental. Com base no relato verbal foram entäo distinguidos em dois grupos: visuais e somato-motores. A análise da cronometria mental mostrou que o tempo utilizado para simular mentalmente os movimentos de flexäo plantar näo foi diferente daquele gasto durante a sua execuçäo. Diferiu, porém, da condiçäo contar para ambos os grupos. Para a análise estabilométrica, calculou-se um índice de simulaçäo mental (ISM). Dos valores obtidos durante o imaginar, foram subtraídos os valores da condiçäo contar, dividindo-se entäo a resultante pela soma dos dois. O grupo somato-motor apresentou índices positivos e significativamente diferentes do grupo visual para a área elíptica de deslocamento e amplitude de deslocamento no eixo ântero-posterior (y). Esses dados indicam um menor bloqueio da saída motora durante o imaginar de um movimento que envolve ajustes posturais no primeiro grupo. Essa diferença sugere que circuitos corticais e sub-corticais distintos seräo ativados em funçäo da estratégia adotada para simular mentalmente o movimento


Subject(s)
Humans , Female , Adult , Motor Activity/physiology , Posture , Simulation Exercise/methods , Time and Motion Studies , Body Image
16.
Braz J Psychiatry ; 25 Suppl 2: 33-5, 2003 Dec.
Article in Portuguese | MEDLINE | ID: mdl-14978584

ABSTRACT

Recent studies have proposed that the mental rotation of body parts can be accomplished by calling upon visual and somatomotor resources which, at a functional level, would correspond to different routes toward a single solution [1]. In this study, we investigated the effect of somato-motor and visual strategies upon the mental simulation of a task that involved postural adjustments. Subjects were asked to stand up on a vertical force platform and instructed either to 1) rest during 20 s (ST), 2) count mentally from 1 to 15 (CO), 3) imagine themselves executing a bilateral plantar flexion 15 times (IM), and 4) execute the same movement 15 times (EX). They were further classified as visual or somato-motor dominant, according to the strategy reported as adopted to perform IM. Mental chronometry showed that mean time spent in IM matched that of EX, differing from CO for both groups. Index of stabilometric modulation during IM was computed by reference to CO. Higher index values for area and amplitude of displacement in the antero posterior (y) axis were found for the somato-motor as compared to the visual group. The stabilometric departure found for visual and somato-motor dominant subjects suggests that each imagery mode activates a distinct subset of cortical and subcortical brain networks.


Subject(s)
Imagination/physiology , Movement/physiology , Posture/physiology , Space Perception , Adult , Female , Humans , Male , Perception/physiology , Photic Stimulation
17.
Rev. paul. educ. fís ; 16(1): 43-52, jan.-jun. 2002. ilus, tab, graf
Article in Portuguese | LILACS | ID: lil-361631

ABSTRACT

A primeira posição em ponta do Balé Clássico consiste, principalmente, na manutenção do corpo ereto com apoio no solo sobre uma base de sustentação extremamente reduzida, correspondente ao bordo anterior dos pés. Neste estudo o objetivo foi comparar postura e equilíbrio corporal entre a primeira posição em ponta do balé clássico com os pés paralelos e a posição ereta normal. A amostra foi composta por quatro indivíduos do sexo feminino, bailarinas em atividade no balé clássico. Para a avaliação do equilíbrio foi utilizada uma plataforma de força e para a avaliação cinemática tridimensional da postura utilizou-se um sistema de três câmeras de infravermelho, a frequência de amostragem dos sinais foi de 60 Hz e cada teste teve a duração de 20s. Nos resultados observou-se diferença significativa (p<0,05) na velocidade de oscilação na direção ânteroposterior relacionada a alteração de suporte sofrida neste mesmo plano, comparando a posição em ponta e a postura normal...


Subject(s)
Humans , Female , Adult , Posture , Human Body , Postural Balance , Dancing
18.
Rev. bras. biomec ; 1(1): 33-38, nov. 2000. graf
Article in Portuguese | LILACS | ID: lil-358810

ABSTRACT

Some stabilometric parameters are known to be influenced by anthropometric characteristics. The purpose of this study was to determine an index of postural stability free from these influences. Stabilometry was used with unipodal and bipodal supports to a group of 24 men and 39 women, with right dominate leg. Three stabilometric tests of 60 seconds cach (sampling rate of 50 Hz) were applied in a randomic order: right and left foot support and feet together. The elliptical area (área), the mean power frequency (f) and mean velocity (v) of the centre of pressure were calculated for the lateral (x) and anterior posterior (y) displacements. For each parameter an index of stability was determinated by the rate of the unipodal and bipodal tests. There was no statistical difference between right and left foot for men and women. The results of area and mean velocity were higher for men. Stature was positive correlated with area and velocities and negative with frequency. All the indexes calculated bad no correlation with anthropometric values and resulted in no differences between sexes.


Subject(s)
Humans , Anthropometry , Postural Balance , Posture
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