All rights reserved. Objective: To compare the performance of the isometric single leg squat exercise on a rigid surface versus a spongy surface in relation to the center of pressure and activation patterns of the muscles of the dominant lower limb and spine in healthy young women. Method: 12 healthy women performed the isometric single leg squat on a rigid surface (control) and a spongy surface. A posturograph recorded the area and velocity of displacement of the pressure center. A surface electromyograph evaluated the muscular activity of multifidus, gluteus maximus, gluteus medius, vastus medialis and biceps femoris of the supporting leg. Results: The area and the speed of displacement of the center of pressure increased (p <0.05 and p <0.01 respectively) in spongy surface. Femoral biceps increase its muscular activity on the spongy surface (p<0.05). There is a correlation between the greater muscular activity of the biceps femoris and the area and the velocity of the pressure center (p <0.01). Conclusion: Isometric single leg squat performed on a spongy surface, produces a greater disturbance of postural control and greater activity of the biceps femoris in healthy young women. The increased activity of this muscle is directly related to the displacement of the pressure center.
- Isometric contraction.
- Postural balance