The following reasons are common: First, the process of practicing legs will produce a large number of acidic metabolites, lactic acid in the leg muscles will go through the blood circulation and enter the cranial cavity to stimulate the central nervous system, and also stimulate the digestive system, the patient may have the clinical symptom of wanting to vomit. Secondly, during the process of practicing legs, patients will experience severe pain in the leg muscles, and even cannot bear weight and walk, and there will be obvious pain in the legs, and the pain stimulation is a kind of negative stimulation, which affects the function of the central nervous system, and the patients may also experience the clinical symptoms of wanting to vomit. If you want to vomit, you must be timely treatment, you can drink a lot of water or intravenous fluids, to reduce the adverse stimuli, so that the acidic metabolites as soon as possible out of the body, you can alleviate the clinical symptoms of vomiting, the patient should control the intensity of exercise in the process of practicing legs, to avoid the intensity of the corresponding adverse reactions.