Avaliação eletromiográfica do exercício swan na Wunda Chair: Co-ativação dos músculos do core / Electromyographic evaluation of the swan exercise in the Wunda Chair: Co-activation of the core muscles

A principal finalidade do método Pilates é desenvolver uma automação dos músculos do core. Sendo assim, o objetivo deste estudo foi analisar a razão eletromiográfica dos músculos Oblíquo Interno (OI) e Reto do Abdômen (RA) localizados na parte anterior do tronco, a razão eletromiográfica dos músculos Multífido (MU) e Longuíssimo do Tórax (LO) localizados na parte posterior do tronco, e também a razão ântero-posterior (A/P=RA+IO/LO+MU) desses músculos durante o exercício swan do método Pilates, realizado sobre a Wunda Chair. Na comparação entre as três razões, foram encontradas diferenças estatísticas (p = 0,0103), apenas entre as razões ântero-posterior (A/P), e entre a razão dos músculos localizados na parte posterior do tronco (MU/LO). Os resultados demonstraram que houve um predomínio na atividade eletromiográfica dos músculos da região posterior em relação aos músculos da região anterior do tronco e que os músculos estabilizadores apresentaram maior atividade eletromiográfica em comparação com os músculos globais ou mobilizadores. O exercício swan pode ser utilizado como forma de treinamento para a musculatura do tronco, e como consequência gerar maior estabilidade a coluna vertebral, pois o exercício prioriza a diminuição da carga sobre a coluna vertebral. (AU)

The main purpose of the Pilates method is to develop an automation of core muscles. Thus, the aim of this study was to analyze the electromyographic ratio of the Internal Oblique (IO) and Rectus Abdominis (RA) muscles located in the anterior part of the trunk, the electromyographic ratio of the Multifidus (MU) and Longissimus Thoracis (LO) muscles, located in the posterior part of the trunk, and also the ratio antero- posterior (A/P=RA+IO/LO+MU) of these muscles during the swan exercise of the Pilates, performed on the Wunda Chair. In the comparison between the three ratios, statistical differences (p = 0.0013) were found only between the antero-posterior (A/P) ratios and the ratio of the muscles located in the posterior part of the trunk (MU/LO). The results showed a predominance of the electromyographic activity in the muscles of the posterior region in relation to the muscles of the anterior region of the trunk. The stabilizing muscles presented greater electromyographic activity in comparison to the global or mobilizing muscles. The swan can be used as training for the trunk muscles, and therefore generates greater stability of the spine, since exercise prioritizes the decrease of the load on the spine. (AU)

Study on Neural Co-activation during Human Upper Limb Muscle Fatigue Based on Surface Electromyography / 中国运动医学杂志

Objectives To observe the co-activation phenomenon during exercise fatigue induced by the proximal muscles on the upper limbs.Methods Sixteen undergraduates not majoring in sports participated in this study,and their left arms were chosen as the observed arms and right arms were selected as the weighted arms.The weighted arm was alternatively in the state of relaxation without any load and fatigue after bending and extending elbow joints to uphold a 5 kg dumbbell.However,the observed arm kept weighing a 4 kg dumbbell with 90 degrees elbow flexion until the muscles were exhausted.The surface electromyography of biceps brachii and triceps brachii of the observed arms was measured using the ME6000.And the integrated surface electromyography (IEMG),root of mean square (RMS),mean power frequency (MPF)and median frequency (MF)were further analyzed.Results The IEMG and RMS of biceps brachii and triceps brachii of the observed arms increased gradually after the exercise began (P＜0.05)regardless of in the relaxed state or in the in the state of weighing a 5 kg dumbbell for the weighted arm,but in the state of weighting a 5 kg dumbbell the IEMG and RMS increased more significantly (P＜0.01),Meanwhile the electrical activities of the triceps brachii as an antagonistic muscle were intensively inhibited.The changes of MPF and MF of biceps brachii in the observed arms were more significant in the state of exercise fatigue than in the relaxed state (P＜0.01),but without such an impact on the triceps brachii.Conclusions The fatigue in one arm can trigger contingent changes in sEMG time domain and frequency domain indexes of its contralateral parallel muscles,suggesting that sEMG changes of upper limb proximal muscles have the co-activation effect.

Effect of Flexion Angle of Knee Joint on Co-contractions of Agonist and Antagonist Muscles / 中国康复理论与实践

@# Objective To test the effect of different flexion angles of knee joint on the myoelectric activity and torque of quadriceps femoris and hamstring muscle when these muscles contracting.MethodsElectromyographic activities and isometric torque measurements were performed on 10 healthy subjects at 30°, 60° and 90° of knee joint flexion.ResultsThe results indicated that the greatest maximal voluntary isometric contracture-torque of quadriceps femoris occurred during knee extension at 60° of knee flexion ( P<0.01). However, no significant relationship of maximal voluntary isometric contracture-electromyography and maximal voluntary isometric contracture-torque of quadriceps femoris were found in 10 subjects. But when knee joint was at 90° flexion, hamstring muscle had a greatest neuro-myoelectric activity.ConclusionThe exercise of maximal voluntary isometric contraction of quadriceps femoris and hamstrings muscles at certain knee joint angle can help to maintain the stability of knee joint.