Outcomes: Primary outcome: Change in sensation of abdominal sensation. Secondary outcomes: a) changes in thoraco-abdominal activity of the muscular walls; activity of thoraco-abdominal muscles (intercostals, diaphragm, external oblique, internal oblique, upper rectus, lower rectus) will be measured by electromyography; b) changes in girth; abdominal girth will be measured using a nonstretch belt (48mm wide) that is placed over the umbilicus. The overlapping ends of the belt will be adjusted carefully with two elastic bands to adapt constantly to the abdominal wall.