Automatic postural responses are generated according to feet orientation and perturbation magnitude

Azzi, Nametala Maia; Coelho, Daniel Boari; Teixeira, Luís Augusto

doi:10.1016/j.gaitpost.2017.06.003

Cited by 21 publications

(13 citation statements)

References 23 publications

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“…Automatic postural responses (APR) are the primary resource to recover upright balance stability following unanticipated stance perturbations, with scaled reactions being mandatory for balance recovery (cf. Azzi, Coelho, & Teixeira, ). Distinctive features of APR to sudden support base displacements are the capacity to prevent critical body disequilibrium in the first perturbation, and fast adaptation to repetitive events inducing balance loss.…”

Section: Introductionmentioning

confidence: 99%

Instantaneous interjoint rescaling and adaptation to balance perturbation under muscular fatigue

Rinaldin

Oliveira

Coelho

et al. 2019

Eur J of Neuroscience

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Adaptation of automatic postural responses (APR) to balance perturbations might be thought to be impaired by muscle fatigue, given the associated proprioceptive and effector deficits. In this investigation, we aimed to evaluate the effect of muscular fatigue on APR adaptation over repetitive balance perturbations through support base backward translations. APR adaptation was evaluated in three epochs: (a) pre‐fatigue; (b) post‐fatigue, immediately following fatigue of the plantiflexor muscles through isometric contractions and (c) post‐recovery, 30 min after the end of fatiguing activity. Results showed the following: (a) Decreasing amplitudes of joints' maximum excursion over repetitive perturbations in the three fatigue‐related epochs. (b) Modulation of joints' excursion was observed in the first trial in the post‐fatigue epoch. (c) In the post‐fatigue epoch, we found interjoint rescaling, with greater amplitude of hip rotation associated with reduced amplitude of ankles' rotation. (d) Amplitudes of ankles' rotation were similar between the post‐fatigue and post‐recovery epochs. These findings lead to the conclusions that adaptation of automatic postural responses over repetitive trials was effective under focal muscular fatigue; modulation of the postural response took place in the first perturbation under fatigue, and generalization of response characteristics from post‐fatigue to post‐recovery suggests that feedforward processes in APRs generation are affected by the recent history of postural responses to stance perturbations.

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Section: Introductionmentioning

confidence: 99%

Instantaneous interjoint rescaling and adaptation to balance perturbation under muscular fatigue

Rinaldin

Oliveira

Coelho

et al. 2019

Eur J of Neuroscience

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“…17 But, there are controversial results regarding the intensity of the perturbation in the CoP parameters. 13,16,18 Sarraf et al (2014) 18 found no differences in the peak of CoP displacement in high-intensity perturbations. However, our results corroborate partially with Babic et al (2014) 16 and Azzi et al (2017), 13 showing an increase in CoP parameters, such as displacement, range and mean velocity in these situations.…”

Section: Discussionmentioning

confidence: 97%

“…Postural adjustments are essential to avoid falls after external perturbations, and the cerebral cortex seems to be involved in controlling these adjustments. 2,12 The perturbations can be performed by external and unexpected 9,13 or internal. 9,14 mechanisms, causing postural adjustments such as muscle activity and CoP oscillation to modify their control patterns according to the perturbation.…”

Section: Discussionmentioning

confidence: 99%

“…9,14 mechanisms, causing postural adjustments such as muscle activity and CoP oscillation to modify their control patterns according to the perturbation. 10,13,15,16 In situations of high-intensity perturbation, the involvement of the hip muscles is necessary to maintain balance, while at low intensities control is mainly performed by the ankle muscles. 17 But, there are controversial results regarding the intensity of the perturbation in the CoP parameters.…”

Section: Discussionmentioning

confidence: 99%

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Postural Adjustments of Active Youths in Perturbation and Dual-Task Conditions

Beretta

Santos

Rojas

et al. 2019

Rev Bras Med Esporte

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Introduction Cognitive components are necessary to maintain posture during external perturbations. However, few studies have investigated postural control when external perturbations are associated with a concomitant cognitive task (DT). Objectives To analyze the behavior of reactive adjustments after perturbation with different intensities and displacements in active young adults; and to analyze the influence of DT on predictive and reactive adjustments in different perturbation conditions. Methods Twenty-eight physically active young adults stood on an item of equipment that produced displacements of the base. Four experimental conditions were introduced in a single task (ST) and DT (cognitive-report how many times a pre-established number appeared in the audio): 1 (5 cm and 10 cm/s); 2 (5 cm and 25 cm/s); 3 (12 cm and 10 cm/s) and 4 (12 cm and 25 cm/s). Three attempts were carried out for each condition (total=24). Center of pressure (CoP) parameters were analyzed considering the following windows: predictive (-250 to +50 ms), reactive 1 (+50 to +200 ms) and reactive 2 (+200 to +700 ms), in comparison to the start of the CoP activity. One-way ANOVAs were performed to analyze predictive adjustments, while two-way ANOVAs with factor for task (STxDT) and condition (1x2x3x4), with repeated measurements, were performed for the reactive adjustments. Results One-way ANOVA (predictive) indicated that the subjects had higher CoP parameters in ST vs DT. In reactive adjustments 1 and 2, ANOVA indicated greater CoP parameters in condition 2 and 4 when compared to 1 and 3, and in the ST vs DT. The subjects took longer to recover stable position in conditions 1 and 3 than in conditions 2 and 4. Conclusion Perturbation intensity has a greater influence on postural adjustments to maintain balance than on magnitude. Moreover, the association of cognitive tasks with external perturbation decreases CoP oscillation. Therefore, cognitive resources play an important role in postural control after perturbation. Level of evidence III; Study of nonconsecutive patients, with no “gold” standard applied uniformly.

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“…Assim, a capacidade de manter os pés no lugar equivale à resposta de pernas mais estável para se recuperar da perturbação. Nesta situação, o centro de massa é mantido dentro dos limites de estabilidade sobre a área da base de suporte inalterada, sendo escalonada de acordo com a magnitude de perturbação por ativação diferencial dos músculos agonistas (32). Quando não é possível recuperar o equilíbrio corporal mantendo os pés no lugar, um ou vários passos são necessários como estratégias compensatórias alternativas (33).…”

Section: Métodounclassified

Efeito de interferência contextual na aquisição de estabilidade de movimentos compensatórios a perturbações imprevisíveis do equilíbrio corporal

Takazono¹

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Automatic postural responses are generated according to feet orientation and perturbation magnitude

Cited by 21 publications

References 23 publications

Instantaneous interjoint rescaling and adaptation to balance perturbation under muscular fatigue

Instantaneous interjoint rescaling and adaptation to balance perturbation under muscular fatigue

Postural Adjustments of Active Youths in Perturbation and Dual-Task Conditions

Efeito de interferência contextual na aquisição de estabilidade de movimentos compensatórios a perturbações imprevisíveis do equilíbrio corporal

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