Neuromuscular and motor patterns in breaststroke technique / Padrões motores e musculares na técnica de bruços

Abstract The aim of this study was to analyze the inter-temporal neuromuscular and motor patterns in breaststroke technique. Five national level male swimmers performed 200 m breaststroke at maximal effort. Electromyography data onbiceps brachii, deltoid anterior, pectoralis major and triceps brachiiwere analysed. The relative duration of active and non-active phase and the average rectified value for the neuromuscular patterns were recorded. The swim bouts were videotaped in sagittal plane with a pair of cameras and the Theme software 5.0 was used toanalyse the detected patterns in each swimmer. The neuromuscular pattern revealed that by the average rectified value the biceps brachiiand triceps brachiiwere increased at the end of the test for swimmers 1 and 5, while biceps brachii. deltoid anteriorand pectoralis majorwere increased for swimmers 2 and 4. Different motor patterns between cycles, and between swimmers were observed.We found similarities between the swimmers, adjusting their style to the technical model. The absence of a neuromuscular pattern for all swimmers could be related to different technical models used by each swimmer, as presented in the motor patterns. These findings suggested that each swimmers adapted their own motor and neuromuscular pattern in a unique and distinct way.

Resumo O objetivo deste estudo consistiu em analisar a relação entre os padrões neuromusculares e motores na técnica do nado de peito. Cinco nadadores masculinos de nível nacional realizaram 200 mnado peito na máxima intensidade.Foram registrados dados de Electromiografia do bicepsbrachii, deltoid anterior, pectoralis major etricepsbrachii. A duração relativa da fase ativa e não ativa e o valor médio retificado dos padrões neuromusculares foram analisados. Os percursos de nado foram gravados no plano sagital e analisados para detectar os padrões motores de cadanadador através do software THÉME software 5.0. Os padrões neuromusculares indicaram, por meio do valor médio retificado que a atividade dos músculos bíceps brachii e tríceps brachii aumentam no final do teste para o nadador 1 e 5, enquanto que o bíceps brachii. deltoid anterior. pectoralis major aumentam para o nadador 2 e 4. Diferentes padrões motores entre ciclos e entre nadadores foram observados, indicando que existem semelhanças entre eles, levando a um ajuste do estilo e modelo técnico de nado. A ausência de um padrão neuromuscular para todos os nadadores poderá estar relacionada com os diferentes modelos técnicos utilizados por cada nadador, como demonstrado nos padrões motores. Esses resultados sugerem que cada nadador adapta o seu padrão motor e muscular de uma forma única e distinta.

Effect of Kettle Bell Swing Exercise on the Body Composition and Lower Limb Muscular Activity

PURPOSE: This study examined the effect of Kettle bell swing exercise on the body composition and lower limb muscular activity. METHODS: As subjects, 26 normal adults in their twenties were divided randomly into the experiment group (n=13), in which Kettle bell exercise was applied, and the control group (n=13), in which bar exercise was applied. Both groups participated in the interventions for eight weeks with three sessions per week. Each group was assessed before training and four and eight weeks into the training to determine the effects of training intervention within and between the groups. The body composition was measured with a body composition analyzer. The changes in muscle activity were measured with a surface electromyography. An independent t-test was conducted to test the significance between the groups according to the measurement points and Repeated measured ANOVA was performed to compare the groups according to the periods with the statistical significance level set to α=0.05. RESULTS: No significant changes to the main effects of time and the interactions of time according to the measurement points were observed in the Kettle bell and control groups in the body composition (p>0.05). The muscular activity of both muscles were significantly different between the Kettle bell and control groups according to the measurement points with the exception of the right lateral gastrocnemius muscle (p<0.05). CONCLUSION: These findings suggest that Kettle bell swing exercise can have positive effects on the development of lower limb muscles.

Evaluation of Interhandle Distance During Pushing and Pulling of a Four-Caster Cart for Upper Limb Exertion

BACKGROUND: This study examined the relationship between interhandle distances and upper limb exertion during simply pushing and pulling of a cart with four swivel wheels, defined by a roll box pallet (RBP) in a Japanese industrial standard. METHODS: Six healthy young male participants were asked to push and pull an RBP at a distance of 5.2 m under six conditions corresponding to different interhandle distances (40 cm, 60 cm, and 80 cm) and weights (130 kg and 250 kg). The upper limb exertion was studied by shoulder abduction and flexion, and elbow flexion, as well as surface electromyogram (EMG) in shoulder extensor, and elbow flexor and extensor. Participants were required to provide subjective evaluations on operability after each trial. RESULTS: Subjective operability indicated that a narrower interhandle distance had a better operability for pushing. Interhandle distance was also related to upper limb exertion especially for pushing. A narrow interhandle distance caused smaller shoulder adduction but larger elbow flexion. The normalized EMG data revealed that muscular activity became smaller with a narrow interhandle distance in shoulder extensor. During the pulling task, elbow flexion was smaller at a narrow interhandle distance, although subjective operability and normalized EMG were not significantly varied. CONCLUSION: A wider interhandle distance, such as 80 cm, was not suitable in the forwardbackward movement of the RBP. Therefore, this study concluded that an interhandle distance of 40 cm would be suitable for pushing and pulling an RBP to protect the workers' hands against the risk of injury by installing inner handles.

Ativação muscular durante a pedalada em diferentes posições do selim / Muscle activation during pedaling in different saddle position

O objetivo do presente estudo foi analisar os efeitos de diferentes posicionamentos do selim no padrão de ativaçãoelétrica durante a pedalada. Três ciclistas de elite foram submetidos a um protocolo que constou da avaliação de quatrodiferentes posições de selim (para frente, para trás, para cima e para baixo), assumindo como posição de referência aposição usada durante os treino e competição. O deslocamento do selim foi de 1 cm para todas as posições. As bicicletasdos ciclistas foram acopladas a um ciclossimulador magnético. A carga do teste foi normalizada utilizando um critériofi siológico, garantindo assim o mesmo nível de esforço para todos os sujeitos. A atividade elétrica de seis músculos domembro inferior foi mensurada: gluteus maximus, rectus femoris, biceps femoris, vastus lateralis, gastrocnemius medialis,e tibialis anterior. Os resultados demonstram que pequenos ajustes na posição do selim podem afetar os padrões deativação elétrica e provavelmente a técnica de pedalada...

The purpose of this study was to analyze the effects on muscle activation pattern of different saddle positionsduring cycling. Three elite cyclists followed a protocol that consisted of four different saddles positions, displaced forward,backward, upward and downward with relation to the reference position used in training and competition. In all tests thesaddle was displaced by 1cm. The cyclists? bicycles were mounted on a magnetic cycle simulator. The load was normalizedat the second ventilatory threshold. Muscle activation of six lower limb muscles was registered: gluteus maximus, rectusfemoris, biceps femoris, vastus lateralis, gastrocnemius medialis, and tibialis anterior. The results demonstrated that relativelysmall saddle adjustments can affect the pattern of muscle activation and probably cycling technique...

Atividade eletromiográfica no agachamento nas posições de 40º, 60º e 90º de flexão do joelho / Electromyograhic activity in squatting at 40°, 60° and 90° knee flexion positions

O objetivo deste estudo foi comparar a atividade eletromiográfica (EMG) dos músculos reto femoral, bíceps femoral, tibial anterior e sóleo no agachamento, associando a posição de tronco ereto com 2 ângulos de flexão do joelho (40° e 60°) e a posição de tronco fletido a 45° com 3 ângulos de flexão do joelho (40°, 60° e 90°). Todas as combinações foram realizadas com e sem acréscimo de carga (10kg). A amostra foi composta por 12 indivíduos saudáveis com idade de 21,1 ± 2,5 anos e massa corporal de 62,8 ± 7,4kg. O EMG dos músculos citados foi registrado, isometricamente, em 10 posições de agachamento. Para a análise estatística foi aplicada ANOVA Two-Way de Friedman e o teste Post-Hoc de Newman-Keuls. Os resultados mostraram co-ativação entre os músculos reto femoral e bíceps femoral nas posições de tronco fletido e joelho em flexão de 40º e, entre os músculos reto femoral e sóleo, nas demais posições (p < 0,05). Houve co-ativação entre o tibial anterior e bíceps femoral com o joelho a 40º, com o tronco ereto e fletido e, entre o tibial anterior e sóleo, nas demais posições (p < 0,05). Quanto à ativação muscular isolada, a maior flexão do joelho no agachamento foi um fator determinante para maior ativação dos músculos, exceto para o sóleo. A posição do tronco e a carga adicional de 10kg influenciaram a ativação muscular do reto femoral, a 60° de flexão de joelho, na qual o tronco ereto proporcionou maior ativação. E para o bíceps femoral, a 40° de flexão de joelho, na qual o tronco flexionado proporcionou maior ativação. A co-ativação entre o reto femoral e o bíceps femoral na posição de tronco fletido, e entre o reto femoral e o sóleo nas demais posições, apontam para novas possibilidades de exercícios na reabilitação.

The aim of this study was to compare the electromyographic (EMG) activity of the femoris rectus, femoris biceps, tibialis anterior and soleus muscles in squatting, associating the trunk in erect position with two angles of knee flexion (40° and 60°) and the trunk at 45° flexion with three angles of knee flexion (40°, 60° and 90°). All associations were performed with and without additional load (10 kg). The sample was composed of 12 healthy individuals with mean age of 21.1 ± 2.5 years and weight of 62.8 ± 7.4 kg. The EMG of the cited muscles was isometrically registered in 10 squatting positions. For statistical analysis, Friedman Two-Way ANOVA and the Newman-Keuls Post-Hoc test were used. The results showed co-activation between the femoris rectus and femoris biceps muscles with the trunk in flexion and at 40° of knee flexion and between the femoris rectus and soleus muscles in the other positions considered (p < 0.05). It was also possible to observe co-activation between tibialis anterior and femoris biceps muscles with knee at 40° and 60° of flexion, with the trunk erect and in flexion and between the tibialis anterior and soleus muscles in the other positions (p < 0.05). Concerning isolated muscular activation, higher knee flexion in squatting was an important factor to greater muscles activation, except for the soleus. Trunk position and the additional load of 10 kg have influenced in the muscular activation of the femoris rectus at 60° of knee flexion, in which the erect trunk provided more activation. The femoris biceps presented greater activation when the knee was in 40° of flexion and the trunk flexioned. The co-activation between the femoris rectus and biceps with the trunk in flexion, and between the femoris rectus and soleus in the other positions, lead to new possibilities of exercises in rehabilitation.

EVALUATION OF MUSCULAR ACTIVITY LEVEL IN DAILY ACTIONS / 体力科学

The present study aimed to investigate the level of muscular activities such as postural mainte nance and change, and body weight transfer during daily physical activities, through electromyogram (EMG) recordings. In each of 27 prescribed movements, EMGs of a total of 8 muscles located in the upper arms, trunk and lower limbs were recorded in 12 young adult men and women using a port-able surface electromyograph apparatus. The percentage of integrated EMG per time (mEMG) to that during isometric maximum voluntary contraction (MVC) was calculated as an index by assessing the muscular activity level in each of the prescribed movements. In most of the prescribed movements, the muscular activity level of every muscle corresponded to about 20-30% of MVC, and tended to be higher in women than men. However, some actions induced an activity level of 40% and more of MVC in the soleus muscle. The activity levels of the lower limb muscles in going up and down stairs and a slope at a fast speed, and jogging were higher compared to other prescribed movements. Thus, the results indicate that body weight transfer actions in daily life raise the activities of the lower limb muscles to a level sufficient for maintaining and increasing their function.