Burping has long enjoyed something of a bad reputation. But, in fact, it fulfils an important biological function, allowing the body to expel a build-up of trapped gases in the upper part of the digestive tract. Being unable to burp can cause enormous pain and distress — and the problem is so misunderstood that it was identified as a medical condition only two years ago. Given the name retrograde cricopharyngeus dysfunction, or abelchia, the inability to burp occurs when the cricopharyngeus muscle, which sits at the top of the gullet, cannot relax to release the trapped air. Normally, the muscle serves as a valve; it relaxes for a second when we swallow, but otherwise remains closed. It also relaxes briefly when we burp.