Stomach acid after exercise may be caused by indigestion, gastritis, gastrinoma and other factors. 1. Indigestion: vagus nerve excitation can promote gastrointestinal peristalsis, while the sympathetic nerve is in a state of excitation during exercise, which will affect the peristalsis of the stomach, resulting in the occurrence of stomach acid after exercise. 2.. Gastritis: exercise will consume a lot of physical strength, so that the body is in a relatively weak state. If you suffer from gastritis, the gastric mucosa’s ability to resist the erosion of gastric acid decreases, and it is more likely to be stimulated by gastric acid, resulting in stomach acid after exercise. 3. Gastrinoma: Gastrinoma is a kind of neuroendocrine tumor, which can secrete gastrin, and the secretion of gastrin may increase after exercise, causing the acidity in stomach to increase, and the situation of stomach acid after exercise may also occur. When stomach acidity persists after exercise, you should seek medical attention in time to improve gastrointestinal dynamics measurement, gastroscopy, serum gastrin-stimulating measurement and other tests, to clarify the cause of the disease under the guidance of the doctor, and to carry out targeted treatment.