A labyrinth for stable walking:The role of head orientation and vestibular information in stabilizing gait

A labyrinth for stable walking: The role of head orientation and vestibular information in stabilizing gait Summary The central nervous system integrates a range of sensory inputs with motor outputs to ensure an essential function: the control of gait stability. The visual, somatosensory, and vestibular systems provide information to the central nervous system to keep the center of mass within the base of support while walking. The vestibular system plays a primary role in spatial orientation and head stabilization and has been related to mediolateral gait stability. This thesis aimed to study the role of vestibular information in the control of gait stability. Chapter 1 provides a brief overview of how the sensory systems contribute to the control of gait stability, and especially the findings of the vestibular system's role, it also covers the mechanisms of gait stability. Chapter 2 entails an experiment using daily tasks that constrain head motion and the visual field by using a cell phone to observe the effects on gait stability in healthy young adults. The conditions in which head movement (head roll) and visual field were constrained such as talking and texting on a cell phone, impaired gait stability compared to the control condition. In chapter 3, the aim was to compare the effects of imposed head orientation only (forward, upward, downward, and yaw movement) on gait stability, and for that we studied different populations, which we assumed to have different levels of stability (dancers, young adults, older adults). Head orientation changes influenced the gait pattern and yaw motion reduced gait stability the most. Also, the findings showed that older adults had a less stable gait, but dancers were not more stable than young adults. Chapter 4 addressed how the motor output evoked by the vestibular system varies according to the demands on the control of stability of walking. The results showed that vestibulomuscular coherence differed according to the gait stabilization demands. In comparison to the control condition, stabilized and wide-base walking conditions showed reduced coherence and narrow-base walking showed increased coherence overall. The results indicated that vestibulomuscular coupling varies systematically over the gait cycle and according to the need to control gait stability. Given that vestibular information is used more in conditions with stronger stabilization demands, the destabilizing effects of a vestibular error signal, given by electrical vestibular stimulation, were expected to be larger in the conditions with higher vestibulomuscular coherence in chapter 4 (e.g. narrow-base walking). In chapter 5, we studied the effects of electrical vestibular stimulation as a vestibular error signal on gait stability. The vestibular error signal decreased gait stability, increased center of mass variability, and decreased coupling between the center of mass state and foot placement, the main mechanism to stabilize walking. The expected interactions of electrical vestibular stimulation and stabilization demands were not found. This indicates that although the use of vestibular information is dependent on stabilization demands, this is not directly reflected in gait stability. Chapter 6 present a reflection on the findings to shed a light on the role of the vestibular system in the control of gait stability. It also discusses the limitations of the studies presented and the practical implications of the findings. Taken together, this thesis revealed that the use of vestibular information is phase-dependent and varies with the stabilizing demands of gait. Head orientation changes, presumably through effects on vestibular output combined with effects on visual information, influence gait stability. Older adults were less stable than young adults, but dance training in young adults did not reduce the effects of head orientation changes

Head orientation and gait stability in young adults, dancers and older adults

Background: Control of body orientation requires head motion detection by the vestibular system and small changes with respect to the gravitational acceleration vector could cause destabilization. Research question: We aimed to compare the effects of different head orientations on gait stability in young adults, dancers and older adults. Methods: Three groups of 10 subjects were evaluated, the first composed of young adults (aged 18–30 years), the second composed of young healthy dancers under high performance dance training (aged 18–30 years), and the third group composed of community-dwelling older adults (aged 65–80 years). Participants walked on a treadmill at their preferred speed in four distinct head orientation conditions for four minutes each: control (neutral orientation); dynamic yaw (following a target over 45° bilaterally); up (15° neck extension), and down (40° neck flexion). Foot and trunk kinematic data were acquired using a 3D motion capture system and the gait pattern was assessed by basic gait parameters (step length, stride width and corresponding variability) and gait stability (local divergence exponents and margins of stability). Main effects of conditions and groups, as well as their interaction effects, were evaluated by repeated-measures analysis of variance. Results: Interactions of group and head orientation were found for both step length and stride width variability; main effects of head orientation were found for all evaluated parameters and main effects of group were found for step length and its variability and local divergence exponents in all directions. Significance: As expected, the older adults group showed less stable gait (higher local divergence exponent), the shortest step length and greater step length variability. However, contrary to expectation, the dancers were not more stable. The yaw condition was the most challenging for all groups and the down condition seemed to be least challenging

CORRELAÇÃO DO CONTROLE POSTURAL E AUMENTO DA IDADE EM IDOSAS ATIVAS

O controle postural depende dos sistemas vestibular, visual e somatosensorial para a manutenção do equilíbrio dinâmico e estabilização do centro de massa corporal dentro da base de suporte dos pés. O processo do envelhecimento tem demonstrado efeitos sobre a integração sensorial e nas respostas motoras eferentes devido as alterações do sistema neuromuscular.  Objetivo: Avaliar o controle postural de idosas ativas em relação ao avanço da idade. Métodos: A amostra composta de 51 idosas, divididas em dois grupos de acordo com a faixa etária para a análise de comparação, sendo G1= 60 à 70 anos e o G2= 71 à 86 anos. A oscilação do centro de massa corporal foi avaliada através da estabilometria e o equilíbrio dinâmico através do instrumento clínico escala de equilíbrio de Berg, então os dados foram correlacionados com a idade e comparados entre os grupos. Resultados: A idade média dos grupos foi de 65,7±3,03 para G1 e 74,7±3,85 para G2. O G1 apresentou valores médios de oscilação do centro de massa de 1,64±0,84 cm², enquanto que G2 apresentou valores médios de 2,41±1,24 cm², a diferença foi estatisticamente significante (p<0,001).  Já na escala de equilíbrio de Berg, G1 apresentou escore médio de 52,5±2,80, enquanto que G2 mostrou escore médio de 51,4±3,06, e não foi encontrada diferença estatisticamente significante. Conclusão: Foi identificado uma maior oscilação corporal conforme notou-se o avanço de idade dessas idosas

EFFECTS OF TRICEPS SURAE FATIGUE ON GAIT LOCAL DYNAMIC STABILITY IN WOMEN AS PRACTITIONERS AND NON-PRACTITIONERS OF STRENGTH TRAINING

This study evaluated the effects of plantar flexors fatigue on gait local dynamic stability in young women. Strength-training practitioners (n = 20), and non-practitioner women (n = 21) performed a 4-min treadmill walking before and after a unilateral fatigue protocol of the triceps surae. The major findings of the study demonstrated that localized fatigue did not affect the local dynamic stability, independent of the participant’s training condition. Participants appear to be able to cope with muscle fatigue, adapting to maintain gait performance. Even so, the need for a recovery interval should be considered in order to minimize the risk of injuries and falls in individuals susceptible to muscle fatigue in sports

DESEMPENHO DE ATLETAS PROFISSIONAIS DE FUTEBOL FEMININO NA EXECUÇÃO DOS TESTES STEP DOWN E SINGLE LEG HOP TEST

ABSTRACT: Introduction: Female soccer athletes are target of musculoskeletal injuries in a proportional way to the intensity and level of competitiveness. They have a higher prevalence of lower limb injuries, which are related to knee valgus. The evaluations made through functional tests such as the Step-Down and the Single Leg Hop Test are an important method for identifying the movement that may interfere with the athletes’ performance during the games. Objective: To evaluate the performance of female soccer athletes during the execution of the Step-Down and Single Leg Hop Tests. Methods: The study has a cross-sectional design. It was carried out with a sample composed of 26 female soccer athletes and it was characterized by a sample characterization form. The functional evaluation was performed by the symmetry index in the Single Hop Test and the Step-Down Test. Results: The average age of the athletes was 21.38 years old (±3.82), they have been practicing the sport for 10 (±5.02) years and trained for 2 (±1) hours a day on 6(±2) days a week; 57.7% had a history of sports-related injuries. There was no statistically significant difference between the dominant and non-dominant limb for the mean distance (p=0.773) and normalized distance (p=0.678) in the Single Leg Hop Test. There were no statistically significant differences between the dominant and non-dominant limb for the degree of changes for pelvis drop (p=0.442) and hip adduction (p=0.390) in the Step-Down Test. Conclusion: The athletes obtained good performance with LSI in the Single Leg Hop Test and low performance in the Step-Down Test due to balance alterations in pelvic drop and knee adduction. There was no significant difference in the improvement of performance in relation to lower limb dominance in both tests. Keywords: Football. Women. Physiotherapy. Trauma in Athletes.Introdução: As atletas profissionais de futebol são alvo de lesões musculoesqueléticas de forma proporcional a intensidade e ao nível de competitividade. Apresentam maior prevalência de lesões em membros inferiores, que estão relacionadas ao valgo de joelho. As avaliações através dos testes funcionais como o Step Down e o Single Leg Hop Test são um método importante para identificação do movimento que poderá interferir no desempenho das atletas durante os jogos. Objetivo: Avaliar o desempenho das atletas de futebol feminino durante a execução dos testes funcionais Step Down e Single Leg Hop Test. Métodos: O delineamento do estudo foi do tipo transversal. A amostra foi composta por 26 atletas de futebol feminino e foi caracterizada por uma ficha de caracterização da amostra. A avaliação funcional realizada pelo índice de simetria nos testes Single Hop Test e Step Down. Resultados: As atletas tinham idade média 21,38 (±3,82), praticavam o esporte a 10 (±5,02) anos e treinavam 2 (±1) horas por dia ao longo de 6 (±2) dias da semana, (57,7%) apresentam histórico de lesão relacionada ao esporte. Não houve diferença estatisticamente significante entre o membro dominante e não dominante para a distância média (p=0,773) e normalizada (p=0,678) no Single Leg Hop Test. Não foram encontradas diferenças estatisticamente significantes entre o membro dominante e não dominante quanto ao grau das alterações para a queda da pelve (p=0,442) e adução do quadril (p=0,390) no Step Down Test. Conclusão: As atletas obtiveram bom desempenho com ISM no Single Leg Hop Test e baixo desempenho  no Step Down pelas alterações de equilíbrio em queda pélvica e adução de joelho. Não houve diferença significativa na melhora do desempenho em relação dominância de membros inferiores em ambos os testes. Palavras-chave: Futebol. Mulheres. Fisioterapia. Traumatismos em Atletas

Análise da ativação neuromuscular do vasto medial oblíquo e vasto lateral com o uso da bandagem funcional

Muscular and anatomical changes are mostly responsible for patella femoral syndrome (PFPS). Knowing that the quadriceps muscles are very important to stabilize the patella, studies have questioned the influence of the Vastus Medialis Oblique (VMO) in the patellar stabilization avoiding the PFPS. Many researchers have investigated the use of taping as a means of muscle activation. Objective: The present study aimed to analyze the use of functional taping to activate the VMO during the squat exercise. Method: The activity of the VMO and Vastus Lateralis (VL) was assessed by electromyography during squats and squats with adduction using functional taping. The sample composed for 39 individuals was divided into four groups: sedentary males and athletes, and females also divided into sedentary and athletes. Results: Although it has been found greater activation of VMO in comparison with the VL, with the applied methodology and variables, we could not demonstrate a statistical difference between groups in squats with and without the use of functional taping. However, it is important to emphasize that the lack of difference in the activation of VMO during squats with adduction and tapping suggest a positive effect of the tapping in muscle activation. This result is very important in the treatment of acute injuries where active movement is limited. Conclusion: Future studies should be done with other electromyography parameters and reflex activation in order to investigate the actual role of functional taping on muscle activation.Alterações musculares e anatômicas são em sua maioria responsáveis pela síndrome patelofemoral (SDPF). Sabendo que a musculatura do quadríceps é de grande importância na estabilização da patela, questiona-se como o músculo Vasto Medial Oblíquo (VMO) influencia na estabilização patelar evitando a SDPF. Muitos pesquisadores tem investigado o uso da bandagem funcional como meio de ativação muscular. Objetivo: O presente estudo teve como objetivo analisar o uso da bandagem como meio de ativação do VMO no exercício de agachamento. Método: A atividade dos músculos VMO e Vasto lateral (VL) foi avaliada através de eletromiografia durante o agachamento com adução e o agachamento com o uso de bandagem. A amostra composta por 39 indivíduos foi dividida em quatro grupos: indivíduos do sexo masculino sedentários e atletas, e indivíduos do sexo feminino sedentárias e atletas. Resultados: Embora tenha sido encontrada uma maior ativação do VMO em relação ao VL, com a presente metodologia e variáveis estudadas, não foi possível demonstrar diferença estatística entre os grupos nos agachamentos com e sem o uso da bandagem. No entanto, é importante ressaltar que a ausência de diferença na ativação do VMO durante o agachamento com adução e com bandagem sugerem um efeito positivo e facilitador da bandagem na ativação muscular. Este resultado é muito importante no tratamento de lesões agudas onde o movimento ativo está limitado. Conclusão: Sugere-se a execução de novos estudos aonde outros parâmetros da eletromiografia e estimulação reflexa sejam abordados, a fim de investigar o real papel da bandagem funcional na ativação muscular

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AVALIAÇÃO DO EQUILÍBRIO, MEDO DE QUEDAS E INDEPENDÊNCIA FUNCIONAL DE IDOSAS ATIVAS

O envelhecimento provoca diversas alterações no organismo, dentre elas o equilíbrio postural, que depende da interação harmônica entre vários sistemas do corpo humano: vestibular, visual, somatossensorial e musculoesquelético. Objetivo: Avaliar o equilíbrio postural, independência funcional e medo de queda em idosas ativas em relação ao histórico de lesões osteomioarticulares e quedas. Metodologia: Trata-se de um ensaio clínico randomizado transversal realizado na UEG/ESEFFEGO. Os testes utilizados foram: QuickScreen Clinical Falls Risk Assessment (QS), Timed Up and Go (TUG), Escala de Equilíbrio de Berg (EEB), Falls Efficacy Scale-International (FES-I). Resultados: Participaram do estudo 59 idosas com idade média de 69,31 (±6,87) anos, das quais 83% já sofreram alguma queda nos últimos 12 meses. A FES-I apresentou uma média de 33,52 (±10,62); a EEB obteve pontuação de 51,84 (±3,22); o QS apresentou escore médio de 10,66 (±4,81); já o TUG apresentou tempo médio de 8,49 (±2,46) segundos, sendo que nas idosas com osteoartrose o tempo médio apresentado foi de 7,97 (±2, 13) segundos. Toda amostra praticava atividade física regular. Conclusão: Os testes funcionais apresentaram valores médios dentro dos pré-estabelecidos pela literatura, porém havendo uma diminuição dos escores do TUG para aquelas que possuíam histórico de artrose, observando portanto, o impacto da artrose na funcionalidade dos idosos

Effects of vestibular stimulation on gait stability when walking at different step widths

Vestibular information modulates muscle activity during gait, presumably to contribute to stability. If this is the case, stronger effects of perturbing vestibular information on local dynamic stability of gait, a measure of the locomotor system's response to small, naturally occurring perturbations, can be expected for narrow-base walking (which needs more control) than for normal walking and smaller effects for wide-base walking (which needs less control). An important mechanism to stabilize gait is to coordinate foot placement to center of mass (CoM) state. Vestibular information most likely contributes to sensing this CoM state. We, therefore, expected that stochastic electrical vestibular stimulation (EVS) would decrease the correlation between foot placement and CoM state during the preceding swing phase. In 14 healthy participants, we measured the kinematics of the trunk (as a proxy of the CoM), and feet, while they walked on a treadmill in six conditions: control (usual step width), narrow-base, and wide-base, each with and without stochastic EVS (peak amplitude of 5 mA; RMS of ~ 1.2 mA; frequency band from 0 to 25 Hz). Stochastic EVS decreased local dynamic stability irrespective of step width. Foot placement correlated stronger with trunk motion during walking with EVS than without in the control condition. However, residual variance in foot placement was increased when walking with EVS, indicating less precise foot placement. Thus, a vestibular error signal leads to a decrease in gait stability and precision of foot placement, but these effects are not consistently modulated by step width

ANÁLISE DOS EFEITOS DA PRÁTICA DE BOLÃO SOBRE CONTROLE POSTURAL E QUALIDADE DE VIDA EM IDOSAS

Objetivo: Verificar os efeitos da prática do Bolão no equilíbrio, na redução de quedas e qualidade de vida de idosos. Método: O estudo foi composto por 8 indivíduos, do sexo feminino, com idade média de 68 (±8,92) anos, divididos em dois grupos de quatro pessoas; o grupo controle (GC) e o grupo bolão (GB). A prática de bolão foi realizada para o GB por um período de 4 semanas, 2 vezes por semana, totalizando 8 sessões com duração de 60 minutos. A avaliação foi realizada antes e após a prática do Bolão. Para a avaliação destes indivíduos foram utilizadas a Escala Internacional de Eficácia de Quedas, Escala de Equilíbrio de Berg, questionário SF-36 e a Estabilometria. Resultado: O escore médio da escala de Quedas tanto para o grupo GC e GB sofreu um aumento, porém não apresentou significância estatística. O questionário de Berg, no entanto apresentou um aumento significativo no GB e um declínio no escore de GC; os escores do Sf-36 tiveram um aumento em 6 das 8 variáveis do grupo GB, e no grupo GC o aumento deu-se apenas em 2 variáveis. As variáveis estabilométricas do GC não apresentaram diferença estatística significante entre os momentos. Entretanto, no GB todas as variáveis estabilométricas dos dois momentos de coletas demonstraram diferenças estatísticas significantes (p<0,01). Conclusão: A prática de Bolão demonstrou ser eficiente na melhora do equilíbrio estático e, consequentemente, diminuindo a possibilidade de queda e otimizando a qualidade de vida