Evaluation of the gluteus maximus and rectus abdominals muscles roll in the trunk and hip stabilizing function in different Pilates Method exercises in four-point kneeling position

Abstract

Background: Spine stabilization depends upon the coordinated work from several muscular groups. Trunk stabilization exercises like in four-point kneeling are used for dynamic force control and to minimize joint load. The Pilates method is a system of exercises aimed at an intense work of the abdominal muscles and this method has been widely spread among health professionals in the last decades. Although the scientific research and publications about the Pilates method are scarce and recent, this method has been applied into several rehabilitation fields, including low back dysfunctions. The "Knee Stretch" Pilates' exercises constitute an important aid in low back rehabilitation programs. These exercises are done in four-point kneeling position and they can optimize trunk stabilization and movement. Objectives: To evaluate and compare the electromyographic activity of the rectus abdominis and gluteus maximus muscles during four different "knee stretch" exercises type: anteverted pelvis and trunk extension; retroverted pelvis and trunk flexion; neutral pelvis and trunk tilted forward; and neutral pelvis and trunk parallel to the ground level.Methods: Twenty healthy subjects previously trained in the Pilates method will participate in this study. First a visual postural assessment will establish the subjects' neutral pelvis position. In sequence, electromyographic activity from the rectus abdominis and gluteus maximus muscles will be registered synchronously with an electrogoniometer hip joint angle measurement during the four "knee stretch" exercises. Hypothesis: 1) In the four "knee stretch" exercises there would be an anticipated activity from the rectus abdominis muscle in relation to the gluteus maximus muscle; 2) in the "knee stretch" exercise with the flexed trunk and pelvis in retroversion, the interval between the rectus abdominis and the gluteus maximus muscles activation will be smaller than in the others variations because of the shortened position of these muscles; 3) the relationship between the activation of the rectus abdominis and the gluteus maximus muscles in the trunk extended and anteverted pelvis position would be greater than in the others positions due to the increased isometric force to simultaneously control the isometric trunk extension and dynamic hip extension; and 4) the relationship between the rectus abdominis and the gluteus maximus muscle activity in the neutral pelvis and trunk parallel to the ground level position will be similar to the neutral pelvis and trunk tilted forward position, but the former position will have a greater force production by the gluteus maximus muscle than others exercise positions due to the greater hip range of motion and the lengthened gluteus maximus muscle starting position. Therefore the neutral pelvis and trunk parallel to the ground level position would be best indicated for initial phase of a low back rehabiliatation program.