Glycogen is a good thing because it acts as a reserve tank of energy that your body can access when necessary.
糖原是一件好东西，因为它是你的能量储备，你的身体能需要能量的时候会去用它。
英语百科
Fuel reserve
（重定向自Reserve tank）
In motorcycles, small aircraft, and cars, fuel reserve is the extra fuel reserved by the manufacturer in the fuel tank of a car, small aircraft, or motorcycle before the main fuel capacity runs out.
In motorcycles, when the main fuel runs out, the rider has to manually turn the reserve knob, usually located in the left part of the engine, to the reserve position. This allows the rider to use the remaining fuel.