Electromyography of the abdominal muscles and rectus femoris in abdominal exercises with and without the unstable surfaces

The abdominal exercises are performed to the preventing and/or rehabilitation of lower back pain, improved athletic performance, increased strength and resistance of the trunk during the performance of activities of daily living and aesthetics. The objective was to analyze and compare the electromyographic activity of the upper (URA) and lower rectus abdominis (LRA), external oblique (EO), internal oblique (IO) and rectus femoris (RF) during traditional abdominal exercise with and without using the bosu and gymnastics ball. The sample was composed of 10 male volunteers, active physically and without neuromuscular disorder. Data collection was performed using a single differential surface electrodes, with a gain of 20 times, and recorded by a computerized electromyography. The electromyographic signal was quantified by the Root Mean Square (RMS) and normalized (RMSn) by maximal voluntary isometric contraction. The data were subjected to parametric statistical analysis, using the analysis of variance (ANOVA) for repeated measures. The results showed that the URA muscle activity in the exercise with bosu was significantly higher compared to the traditional (p < 0.05), however, for the LRA, EO, IO and RF muscles, there were no significant differences (p > 0.05) among all abdominal exercises (traditional, bosu and gymnastics ball). We conclude that the use of the bosu in the abdominal exercises can be a necessary and desirable factor in specific stages of rehabilitation programs and / or physical training, mainly to increase the recruitment of the upper (URA) rectus abdominis muscle.Os exercícios abdominais são realizados visando a prevenção e/ou reabilitação de dores na região lombar, a melhoria do rendimento atlético, aumento da resistência e força do tronco durante o desempenho das atividades da vida diária e pela estética. Objetivou-se analisar e comparar a atividade eletromiográfica dos músculos rectus abdominis parte superior (RAS) e parte inferior (RAI), obliquus externus abdominis (OE), obliquus internus abdominis (OI) e rectus femoris (RF) durante o exercício abdominal tradicional com e sem a utilização do bosu e bola de ginástica. A amostra foi composta por dez voluntários do gênero masculino, fisicamente ativos e sem distúrbio neuromuscular. A coleta de dados foi realizada utilizando-se eletrodos de superfície diferenciais simples, com ganho de 20 vezes, e registrada por meio de um eletromiógrafo computadorizado. O sinal eletromiográfico foi quantificado pela Raiz Quadrada da Média (Root Mean Square [RMS]) e normalizado (RMSn) pela Contração Isométrica Voluntária Máxima. Os dados foram submetidos à análise estatística paramétrica, empregando-se teste de análise de variância de medidas repetidas (Anova). Os resultados demonstraram que atividade do músculo RAS no exercício com bosu foi significativamente maior em relação ao tradicional (p < 0.05), todavia, não foram encontradas diferenças significativas (p > 0.05) para músculos RAI, OE, OI e RF, entre todos exercícios abdominais (tradicional, bosu e bola de ginástica). Conclui-se que a utilização do bosu no exercício abdominal pode ser um fator desejável e necessário em estágios específicos de programas de reabilitação e/ou treinamento físico, principalmente quando objetiva-se aumentar o recrutamento da parte superior do músculo rectus abdominis (RAS)

Lactacidemia in two different weight training models

The knowledge of the physiological aspects in the execution of the training in the bodybuilding is important to improve the training; being the lactate concentration an important marker applied in several types of exercises. Some studies have evaluated lactacidemia and training models but did not use squatting in their protocols. The aim of the study was to analyze blood lactate concentration in free squat exercise training in two training models: strength and resistance. Experimental study with a sample of five men of 24 ± 4.6 years, physically active and practicing for at least one year, with no history of orthopedic and cardiovascular problems. The tests were performed in two days, in the strength session the volunteers performed 12 sets, 6 to 12 maximal repetitions and in the resistance session 12 series, 13 to 20 maximum repetitions. In both tests the interval was 1 minute and 30 seconds between sets and 2 minutes every 4 sets. Blood lactate was collected at rest, during and after the test. No significant differences were found in the lactate concentration during and after the tests in the strength training and the resistance training. However, the lactacidemia variation between the first and last collection presented a significantly higher result in strength training. We conclude that the models of strength and resistance training, in the free squat exercise, do not present significant differences in lactate concentration during and after the tests. The total lactacidemia variation was greater in strength training