[Standing-up/sitting-down movement. Electromyographic analysis of 4 muscles of lower limb and the erector spinae muscle: study of anticipatory postural adjustments].

This study was conducted to evaluate the activity of the Erector Spinae and four other muscles of the lower limb during the 1500 first milliseconds of the sitting movement. Electromyographic activities of the Soleus, Tibialis Anterior, Biceps Femoris, Vastus Lateralis, and Erector Spinae muscles were recorded together with cinematic and kinematic data. An inhibition of the Erector Spinae activity was found at the beginning of the movement. It preceded the displacement of the first mobile kinematic marker in 8 of 15 trials. This muscular inhibition created a postural forward movement before the voluntary backward movement. This inhibition of the Erector Spinae could be considered as an anticipatory adjustment movement because of its postural function and its precocity. These results, obtained in healthy young people, should be compared with results in old people, especially with people who suffer from psychomotor dysadaptation syndrome, in whom this inhibition of the Erector Spinae seems to be absent.