Background. Abdominal distention is produced by an abnormal somatic postural tone. We developed an original biofeedback technique based on electromyography-guided control of abdominothoracic muscular activity. In a randomized, placebo-controlled trial we demonstrated the superiority of biofeedback over placebo for the treatment of abdominal distention. However, the technique is technically complex and unpractical.

Aim. To prove the efficacy of a simplified biofeedback technique for the treatment of abdominal distension.

Selection criteria. Visible abdominal distension after meal ingestion; patients are able to identify the offending meal.

Intervention. Patients will be randomized into biofeedback in placebo groups.Three sessions of either biofeedback or placebo intervention will be performed 30 min after ingestion of the offending meal during the first 3 weeks of the intervention period.

Biofeedback: patients will be taught to control abdominal and thoracic muscular activity by providing a visual display of the abdominal and thoracic perimeter; specifically, they will be instructed to reduce the abdominal perimeter (girth); patients will be instructed to perform the same exercises before and after breakfast, lunch and dinner during the 4-week intervention period.

Placebo: abdominal and thoracic perimeter will be recorded but not shown to the patient and a pill of placebo containing 0.5 g glucose will be administered; patients will be instructed to take a pill of placebo before breakfast, lunch and dinner during the 4-week intervention period.

Primary Outcome Measure:

Effect of the probe meal on the activity of thoraco-abdominal muscles (intercostals, external oblique, internal oblique, upper rectus, lower rectus) measured by electromyography before and after the probe meal. The response to the probe meal will be measured before and after treatment.

Secondary Outcome Measures:

• Effect of the probe meal on sensation of abdominal distension measured by 0-6 scales after the probe meal.
• Changes in girth produced by the probe meal measured using a non-stretch belt placed over the umbilicus before and after the probe meal.
• Sensation of abdominal distension measured by 0-6 scales after each meal (breakfast, lunch, dinner) over a 7-day clinical evaluation period before and during the 4th week of the intervention.

Inclusion Criteria:

• episodes of visible abdominal distension triggered by meal ingestion
• patients are able to identify the offending foodstuff

Exclusion Criteria:

• organic cause detected by clinical work-up
• constipation
• abdominal distension not confirmed by the 7-day clinical questionnaires of after the probe meal in the pre-intervention evaluation