Bananas were originally used as food in sports. Bananas are a good energy supplement in some sports that require a long tug of war. For example, when watching a tennis match, some players will eat a banana to supplement their energy in the middle of a few hours of competition. Because bananas have high sugar content and small amount, a small banana is enough, which will not cause digestive problems, and it doesn't matter after eating strenuous exercise. In the gym, some people eat to supplement sugar before fitness. Maybe he didn't eat to lose weight and was afraid of being hungry. Some people eat after training. This problem is more complicated. Blood sugar drop caused by strength training. After eating high-sugar foods such as bananas, blood sugar will surge, causing insulin secretion. Insulin is the strongest synthetic hormone in human body. This is the so-called principle of eating bananas to increase muscle. There are also professional players abroad who drink glucose directly after training. However, the people you see eating bananas are obviously amateurs if they only eat one banana. Those who know better will eat with protein and vegetables. On the contrary, real professionals will not see them eating in the gym except drinking water.