Abstract

MULLER, Evelyn S. M. et al. Electromyografic comparison of abdominal exercises in and out of water. Rev. Port. Cien. Desp. [online]. 2005, vol.5, n.3, pp.255-265. ISSN 1645-0523.

The electric activity of the obliqus externus abdominis, rectus femoris and the upper and lower portions of the rectus abdominis muscles were monitored during the "sit up" exercise in two different conditions land and water. Twenty women aged 21-29 year were studied. The electric activity was measured with surface electrodes. The value root mean square (RMS) of the ascending phase of this exercise was used for the normalization of the signal amplitude that was collected during the other variations of speed and conditions. The exercise was performed in a standard rhythm and at maximum speed. For each muscle, ANOVA was used for the factors phase, speed, and condition. The Shapiro-Wilk test of normality was applied. When the exercise was performed at maximum speed, the observed EMG activity was stronger than at standard speed, both in water and on land. The EMG activity of the rectus femoris at maximum speed in water was lower than on land. When analyzing the ascending phase in water at maximum speed, the abdominal muscles showed as much as EMG on land. These results demonstrate that the instability of the horizontal position and the resistance against the movement compensate the reduction of the weight by the effect hydrostatic pressure when the exercise is executed at maximum speed. The same pattern did not occur at standard speed.

Keywords : abdominal muscles; electromyography; water; land; velocity.

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