Modern military planes can refuel while flying, which allows them to travel around the world several times during a single flight. This is somewhat similar to metabolic switching.
Metabolic switching is the body’s natural process of changing fuel sources during prolonged exercise. In simple terms, as one source of energy such as glycogen becomes depleted, the body transitions to using another source, like fatty acids.
How much training you have done will influence the amount of each stored energy source available and how smoothly your body adapts to this shift. However, no matter how well-prepared you are, if you push yourself to your absolute limit on race day, this process will not feel pleasant.
As your body switches from one main energy source to another, usually about 90 to 120 minutes into a marathon, you may feel a sudden drop in energy. Everything starts to feel harder, and self-doubt begins to creep in with thoughts like “I’m not sure I can finish this.” If you let these feelings take over, you might slow down significantly or even fail to finish the race.
But if you understand that your body is simply changing engines and stay calm and relaxed, even if it means running a bit slower for a few minutes, the energy often returns within three to five minutes. Soon enough, you find yourself back on pace, running strong again.
