Before running in the morning is generally not recommended to eat, eat something after the gastrointestinal tract is bound to digest, absorb, and digestion, absorption requires sufficient blood supply for metabolism, and after eating and then running, the blood must be from the new distribution, so that the blood flow to the exercise system more, relative flow to the digestive system is less. If long-term, will inevitably lead to stomach disorders, such as chronic gastritis, peptic ulcer, gastroptosis, etc.; then after breakfast exercise, relatively speaking, the blood supply of the exercise system is also the stomach, intestines, so it is easy to fatigue.