Sculling is relatively slow at the top depth. To move from the back tuck open to the back tuck closed position, the hip flexors contract to pull the thighs toward the chest. The knee flex only slightly, keeping the feet at the water surface. The thighs move under and around the knees until the hip joint is closed. The abdominals pull to create a rounding of the back from the lower rib cage to the end of the spine. The hips will surface as the thighs move around the knees. The head is flexed forward. Buoyancy uplift will aid the support of this position.