Gastric cancer and esophageal cancer are common malignant tumors that threaten people's life and health. Esophagogastroduodenoscopy (EGD) is an important tool for screening upper gastrointestinal tumors, especially early tumors, and an effective method for detecting other upper gastrointestinal lesions, including ulcers and polyps. However, during EGD examination, mucus and foam can reduce the cleanliness of the mucosa and limit the operator's visual field, resulting in missed lesions and misdiagnosis. Previous studies have shown that preoperative medication with pronase and dimeticone is correlated with the improvement of upper gastrointestinal mucosal cleanliness. However, the number of samples in such studies is limited, and the artificial judgment is not objective enough to evaluate the cleanliness of upper digestive tract mucosa. And, whether a postural exercise is necessary for premedication with pronase or dimeticone remains unclear. Our team design this experiment to examine the efficacy of using premedication of dimeticone/pronase with a postural exercise on visualization of the mucosa before painless EGD. The investigators aim to provide new evidence to optimize the use of premedication with EGD.