gastroesophageal reflux disease, is a chronic digestive disorder that occurs when acid backs up from your stomach to the esophagus. Bile backs up and causes heartburn and acid reflux. While many people experience heartburn occasionally, when it happens to you more than twice a week, you probably have GERD. While some foods and activities can exacerbate the condition, the pressure that lifting weights puts on your abdominal muscles is an important factor when evaluating your symptoms.