The Effect of Water Walking on the Lower Limb Motion of Older Adults

The authors investigated the lower limb movements for older adults walking at their preferred speed in shallow water to obtain information to help professionals prescribe exercises in a pool. The 8 participants presented a) similar hip and thigh motions in water and on land, although a reduced thigh velocity was observed in the water; b) increased knee flexion at the beginning of the walking cycle and reduced knee extension throughout the walking cycle in water; c) reduced ankle motion throughout the walking cycle and plantar flexion during the swing phase in water; d) reduced shank motion and velocity in water; and e) different intralimb coordination resulting from a different relative phase between the shank and thigh segments. These results support the use of the water as an alternative environment for gait training in older adults. Water resistance and buoyancy factors seem to be the major forces to overcome when older adults walk in shallow water, so the authors suggest paying special attention to the immersion level and movement velocity when prescribing aquatic exercises

Postural control: the influence of vision to multi-muscle synergies

TITLE: Postural control: the influence of vision to multi-muscle synergies PRESENTATION TYPE: Research Report – Oral AUTHORS/INSTITUTIONS: A. Degani1, A. Danna-dos-Santos1, C. Leonard1. 1School of Physical Therapy and Rehabilitation Science, University of Montana, Missoula, MT. Significance: Falls are the leading cause of injury, deaths, and hospital admissions for traumatic injuries among people aged 65 years and older (Centers for Disease Control and Prevention, 2013). The costs related to the morbidity resulting from these falls are increasing dramatically. In order to reduce costs, increase quality of life, and prolong the longevity of the US work force, several studies are currently focusing on how to assess the risk of falls and prevent their occurrence. However, very little efforts is concentrated to the understanding of the neurophysiological mechanisms associated with upright postural control. Posture and postural reactions to mechanical perturbations require a precise harmonic modulation of the activity of multiple muscles. It is our premise that a comprehensive understanding of such neurophysiological mechanisms may improve current methods and/or result in the development of new approaches of assessing the risk and managing comorbidities generated by fall-related injuries. This study was designed to investigate the role of common neural inputs to the organization of multi-muscle synergies and the possible effects of disruption of visual input to this mechanism of control. Hypotheses: We hypothesize that (1) the central nervous system uses correlated neural inputs to coordinate the formation of postural muscle synergies, and (2) this mechanism is affected by the interruption of visual input. Methods: Our hypotheses were investigated by analyzing the strength and distribution of correlated neural inputs to postural muscles, as measured by electromyography (EMG) coherence, during the execution of a quiet stance tasks. Nine healthy participants, five females and four males with mean age of 26 years (± 6.1 SD) performed the task of maintaining a quiet stance on a force platform for 30 seconds under two experimental conditions: availability or absence of visual information (open eyes and closed eyes respectively). Center of pressure displacement were recorded by the force platform, and the activity of six postural muscles (soleus, biceps femoris, lumbar erector spinae, tibialis anterior, rectus femoris, and rectus abdominis) were recorded by surface electrodes. Intermuscular EMG-EMG coherence estimates were computed for all possible muscle pairs formed by these muscles. Pooled coherence estimations were also computed for anterior and posterior muscles. Results: Intermuscular coherence was found only to be significant within a distinct frequency band bounded between 1-10 Hz; and when visual information was available (“open eyes” trials). This significant coherence occurred only for muscle pairs formed solely by either posterior or anterior muscles. No synchronization patterns were observed for pairs of muscles formed by one anterior and one posterior muscle. In addition, the absence of visual information caused a significant decrease in intermuscular coherence estimates profiles within this same frequency band of 1-10Hz. Conclusion: These findings are consistent with the hypothesis that synchronization patterns of postural muscular activation are organized by correlated neural inputs. Moreover, the intermuscular coherence decreases significantly when the same task was performed under short-term absence of visual information. Clinical Relevance: Increased risk of falls is possibly linked to impairments in the ability of the neuromuscular system to generate optimal multi-muscle synergies. This impairment can result from several factors, such as poor vision caused by maculopathies. This study has provided a step forward towards the understanding of the mechanisms involved in coordination of multiple postural muscles, and the role of the vision on balance control. In addition, this study prepares the foundation for future clinical studies focusing on balance interventions for individuals with postural control disorders and/or visual impairments

ANÁLISE SOBRE A UTILIZAÇÃO DE PROPAGANDA NO FACEBOOK

Com a popularização da internet, mais pessoas incluíram o mundo digital em suas vidas. Hoje, qualquer pessoa pode criar e compartilhar conteúdo na internet, expondo suas opiniões para milhares de internautas. A informação deixou de ser de poucos para agora ser de muitos. Consequentemente, essa mudança modificou o panorama conhecido da comunicação de massa. As empresas começaram a prestar mais atenção na internet, principalmente em razão das redes sociais. Além de disseminar conteúdo, as redes sociais tornaram-se uma ferramenta eficaz para o marketing de relacionamento e também para a realização de ações de propaganda. O consumidor, criador de conteúdo, está mais exigente, e cada vez mais buscando informações sobre produtos e serviços no meio digital. Por isso da necessidade da presença cada vez mais forte das empresas nas redes sociais, especialmente no Facebook, pois é lá que o consumidor está.Palavras-chave: Marketing digital. Facebook. Propaganda. Internet.

ANÁLISE SOBRE A EFICÁCIA DA UTILIZAÇÃO DE PROPAGANDA NO FACEBOOK: CASE TIROL

Este trabalho de conclusão de curso trata-se de uma pesquisa sobre a eficácia da utilização de propaganda no Facebook, analisando a fanpage da Tirol. Com a popularização da Internet, mais pessoas incluíram o mundo digital em suas vidas. Hoje, qualquer pessoa pode criar e compartilhar conteúdo na Internet, expondo suas opiniões para milhares de internautas. A informação deixou de ser de poucos para agora ser de muitos. Consequentemente, essa mudança modificou o panorama conhecido da comunicação de massa. As empresas começaram a prestar mais atenção na Internet, principalmente em decorrência das redes sociais. Além de disseminar conteúdo, as redes sociais tornaram-se uma ferramenta eficaz para o marketing de relacionamento e também para a realização de ações de propaganda. O consumidor, criador de conteúdo, está mais exigente e cada vez mais está buscando informações sobre produtos e serviços no meio digital. Por isso a necessidade da presença cada vez mais forte das empresas nas redes sociais, especialmente no Facebook, pois é lá que o consumidor está. O objetivo da pesquisa é descobrir o perfil dos fãs da Tirol no Facebook, se as ações de propaganda são percebidas pelo público-alvo e se elas induzem à compra. Aplicou-se uma pesquisa quantitativa nos usuários do Facebook que curtiam a fanpage da Tirol. Como resultado, pôde-se perceber que o Facebook é uma ferramenta essencial na manutenção da marca e no relacionamento com o consumidor, em razão da facilidade de acesso pelo público-alvo. Observou-se também que ações de branding podem induzir à compra de produtos, transformando curtidas em compras.  Palavras-chave: Marketing digital. Facebook. Propaganda. Internet. Tirol

The influence of visual information on multi-muscle control during quiet stance: a spectral analysis approach

Standing upright requires the coordination of neural drives to a large set of muscles involved in controlling human bipedal stance (i.e., postural muscles). The coordination may deteriorate in situations where standing is performed under more challenging circumstances, such as standing on a smaller base of support or not having adequate visual information. The present study investigates the role of common neural inputs in the organization of multi-muscle synergies and the effects of visual input disruption to this mechanism of control. We analyzed the strength and distribution of correlated neural inputs (measured by intermuscular coherence) to six postural muscles previously recognized as components of synergistic groups involved in the maintenance of the body's vertical positioning. Two experimental conditions were studied: quiet bipedal stance performed with opened eyes (OEs) and closed eyes (CEs). Nine participants stood quietly for 30 s while the activity of the soleus, biceps femoris, lumbar erector spinae, tibialis anterior, rectus femoris, and rectus abdominis muscles were recorded using surface electrodes. Intermuscular (EMG-EMG) coherence was estimated for 12 muscle pairs formed by these muscles, including pairs formed solely by either posterior, anterior, or mixed (one posterior and one anterior) muscles. Intermuscular coherence was only found to be significant for muscle pairs formed solely by either posterior or anterior muscles, and no significant coherence was found for mixed muscle pairs. Significant intermuscular coherence was only found within a distinct frequency interval bounded between 1 and 10 Hz when visual input was available (OEs trials). The strength of correlated neural inputs was similar across muscle pairs located in different joints but executing a similar function (pushing body either backward or forward) suggesting that synergistic postural groups are likely formed based on their functional role instead of their anatomical location. Absence of visual information caused a significant decrease in intermuscular coherence. These findings are consistent with the hypothesis that correlated neural inputs are a mechanism used by the CNS to assemble synergistic muscle groups. Further, this mechanism is affected by interruption of visual input

Deciphering the functional role of spatial and temporal muscle synergies in whole-body movements

International audienceVoluntary movement is hypothesized to rely on a limited number of muscle synergies, the recruitment of which translates task goals into effective muscle activity. In this study, we investigated how to analytically characterize the functional role of different types of muscle synergies in task performance. To this end, we recorded a comprehensive dataset of muscle activity during a variety of whole-body pointing movements. We decomposed the electromyographic (EMG) signals using a space-by-time modularity model which encompasses the main types of synergies. We then used a task decoding and information theoretic analysis to probe the role of each synergy by mapping it to specific task features. We found that the temporal and spatial aspects of the movements were encoded by different temporal and spatial muscle synergies, respectively, consistent with the intuition that there should a correspondence between major attributes of movement and major features of synergies. This approach led to the development of a novel computational method for comparing muscle synergies from different participants according to their functional role. This functional similarity analysis yielded a small set of temporal and spatial synergies that describes the main features of whole-body reaching movements

Variations in task constraints shape emergent performance outcomes and complexity levels in balancing

This study investigated the extent to which specific interacting constraints of performance might increase or decrease the emergent complexity in a movement system, and whether this could affect the relationship between observed movement variability and the central nervous system's capacity to adapt to perturbations during balancing. Fifty-two healthy volunteers performed eight trials where different performance constraints were manipulated: task difficulty (three levels) and visual biofeedback conditions (with and without the center of pressure (COP) displacement and a target displayed). Balance performance was assessed using COP-based measures: mean velocity magnitude (MVM) and bivariate variable error (BVE). To assess the complexity of COP, fuzzy entropy (FE) and detrended fluctuation analysis (DFA) were computed. ANOVAs showed that MVM and BVE increased when task difficulty increased. During biofeedback conditions, individuals showed higher MVM but lower BVE at the easiest level of task difficulty. Overall, higher FE and lower DFA values were observed when biofeedback was available. On the other hand, FE reduced and DFA increased as difficulty level increased, in the presence of biofeedback. However, when biofeedback was not available, the opposite trend in FE and DFA values was observed. Regardless of changes to task constraints and the variable investigated, balance performance was positively related to complexity in every condition. Data revealed how specificity of task constraints can result in an increase or decrease in complexity emerging in a neurobiological system during balance performance

Neuromechanical response of the upper body to unexpected perturbations during gait initiation in young and older adults

Background: Control of upper body motion deteriorates with ageing leading to impaired ability to preserve balance during gait, but little is known on the contribution of the upper body to preserve balance in response to unexpected perturbations during locomotor transitions, such as gait initiation. Aim: To investigate differences between young and older adults in the ability to modify the trunk kinematics and muscle activity following unexpected waist lateral perturbations during gait initiation. Methods: Ten young (25 ± 2 years) and ten older adults (73 ± 5 years) initiated locomotion from stance while a lateral pull was randomly applied to the pelvis. Two force plates were used to define the feet centre-of-pressure displacement. Angular displacement of the trunk in the frontal plane was obtained through motion analysis. Surface electromyography of cervical and thoracic erector spinae muscles was recorded bilaterally. Results: A lower trunk lateral bending towards the stance leg side in the preparatory phase of gait initiation was observed in older participants following perturbation. Right thoracic muscle activity was increased in response to the perturbation during the initial phase of gait initiation in young (+ 68%) but not in older participants (+ 7%). Conclusions: The age-related reduction in trunk movement could indicate a more rigid behaviour of the upper body employed by older compared to young individuals in response to unexpected perturbations preceding the initiation of stepping. Older adults’ delayed activation of thoracic muscles could suggest impaired reactive mechanisms that may potentially lead to a fall in the early stages of the gait initiation