ABSTRACT
The muscle co-contraction is a phenomenon characterized by the simultaneous contraction of two or more muscles around a joint. The objective of this study was to compare the antagonist co-contraction of the local and global trunk muscles during side bridge exercise, in four situations: (a) stable; (b) instability in the upper limbs with bosu; (c) instability in the upper limbs with disc and (d) double instability. The sample consisted of 20 male volunteers and data collection was performed with simple differential surface electrodes. The electromyographic activity was collected from the Rectus Abdominis (RA), Internal Oblique Abdominis (IO), Multifidus (MF) and Erector Spinae (ES). Were utilized specific routines developed in the Matlab program (Mathworks Natick, USA) to calculate the percentage of antagonist co-contraction between local (IO/MF) and global muscles (RA/ES). The collected data were submitted to parametric statistical analysis (repeated measures ANOVA) or non-parametric (Friedman). The results demonstrated that no significant differences were observed in the pattern of global and local co-contraction in the different side bridge exercises with and without unstable surface. It is concluded that the use of unstable surface in the side bridge stabilization exercise does not increase the level of co-contraction of the trunk flexor and extensor muscles compared to normal stability. However, future studies should use a longer time ofisometric contraction in trunk stabilization exercises to optimize the understanding of the effects of different unstable equipment on global and local levels of co-contraction of the trunk muscles
A cocontração muscular é um fenômeno caracterizado pela contração simultânea de dois ou mais músculos em torno de uma articulação. Objetivou-se comparar a cocontração antagonista da musculatura local e global do tronco durante o exercício prancha lateral, em quatro situações: (a) estável; (b) instabilidade no membro superior com bosu; (c) instabilidade no membro superior com disco e (d) instabilidade dupla. A amostra foi composta por 20 voluntários do gênero masculino e a coleta de dados foi realizada com eletrodos de superfície diferenciais simples. A atividade eletromiográfica foi coletada dos músculos Reto do Abdome (RA), Oblíquo Interno do Abdome (OI), Multifido (MU) e Eretor da Espinha (EE). Foram utilizadasrotinas específicas desenvolvidas no programa Matlab (Mathworks Natick, EUA) para calcular a porcentagem de cocontração antagonista entre os músculos locais (OI / MU) e globais (RA / ES). Os dados obtidos foram submetidos à análise estatística paramétrica (ANOVA medidas repetidas) ou não paramétrica (Friedman). Os resultados demonstraram que não foram observadas diferenças significativas no padrão de cocontração global e local nos distintos exercícios de prancha lateral com e sem superfície instável. Conclui-se que a utilização de superfície instável no exercício de estabilização de prancha lateral não aumenta o nível de cocontração dos músculos flexores e extensores do tronco em comparação a estabilidade normal. Todavia, futuros estudosdevem utilizar um tempo maior de contração isométrica nos exercícios de estabilização do tronco para otimizar a compreensão dos efeitos dos diferentes equipamentos instáveis sobre os níveis de cocontração global e local dos músculos do tronco.
Subject(s)
Exercise , Electromyography , Muscle ContractionABSTRACT
AbstractIntroduction: Sleep Bruxism (SB) is a non-functional rhythmic movement of the mandible with multifactorial aetiology and complex diagnose. It has been the subject of various studies over the past decades and it is considered a result of actions of the Central Nervous System modulated by Autonomous Nervous System. In this work, we test the hypothesis that SB subjects present a typical and defined neurobehavioral pattern that can be distinct from that of non-bruxers subjects and can be measured during wakefulness. Methods Fifteen sleep bruxers (experimental-group EG) and fifteen non-bruxers (control-group CG) took part in the experiments. To verify the presence and severity of SB, clinical examinations, anamneses and questionnaires, including Visual Analogic Scale - faces (VAS-f) and State-Trait Anxiety Inventory (STAI) were applied. To legitimate the diagnoses of SB, a disposable instrument (Bitestrip®) to assess the masseter activity during sleep was employed. All subjects were submitted to a set of experiments for measuring various visual evoked responses during the presentation of visual stimuli (pleasant, unpleasant and neutral images). Events in Visual Evoked Potential (VEP) were used to compare the neural responses of both CG and EG. Results VAS-f showed EG with higher perception of stress than CG (trait: p=0.05), and lower quality of life for (state: p=0.007). STAI I and II showed significant differences of anxiety between CG and EG (p=0.013 and p=0.004, respectively), being EG the highest. The EG Bitestrip scores confirmed that 100% of subjects were sleep bruxers. Significant differences were found between EG and CG for events associated with emotional (pleasant and unpleasant) images in the first 250 ms after stimulation. In general, EG subjects showed higher amplitude and shorter latency of VEP events. Conclusion It is possible to distinguish between SB and non-bruxers subjects during wakefulness, based on differences in amplitude and latency of cortical event related potentials elicited by visual stimulation. SB subjects show greater amplitudes in specific events in frontal areas when non-pleasant images are shown. Latencies tend to be anticipated in SB compared to CG subjects.