Ever wondered how some people can run so fast?In 2009 Olympics, Usain bolt broke the record for 100m dash by 0.3 seconds. Now, if you know anything about the 100m dash, 0.3 seconds, is a large gap.Running that fast not only requires muscles, it requires your body to be aerodynamic to reduce as much air resistant as you can, and genetics to compete at the highest level.But did you know?The most important thing when running that fast, is your 3 main energy system? This energy system allows you to complete daily activities ranging from lifting up a pencil to jogging to your class so you are not late.When we first start running, we don’t really pay attention to how our body works, we just put one foot in front of one another to make ourselves go as fast as we can. However, this changes as we grow up when we want to learn about how we can improve our speed. When we run, our aerobic endurance is the more important than your actual speed. These 3 major energy contributes/determines how fast we are able to run and how long we can run for.In running, you want to have an explosive start in order to get a head start and maintain that speed as long as possible to win the race. The energy system that helps with “explosive start” and gives you that fast and sudden, explosive energy output (lifting heavy weight, short distance run, etc..) is the Phosphagen system also commonly known as ATP/CP system. This energy system does not require any oxygen to work (anaerobic). Because it has to react fast, it can only output intense energy for a short amount of time (usually 5 seconds max). It uses creatine phosphate to work which, is limited and is depleted relatively quickly. When creatine phosphate is used up, it depends on other energy systems to transfer their energy in order to continue the activity.After a good explosive start, maintaining that speed is very crucial to winning the race. This other energy system that does not require oxygen to function is glycolysis system aka lactate system. Unlike the first system which can only produce energies in short period of time, this energy system produces enough ATP to continue doing the activity for 1~3 minutes. During the process of glycolysis, glucose is broken down into ATP and 2 molecules pyruvate. At the same time, hydrogen is also produced and is bonded with pyruvate molecules to produce more ATP only if oxygen is present in the body. Often, the body cannot keep up with the production of hydrogen, so it bonds with another molecule of pyruvate which produces lactic acid. The lactic acid then enters the bloodstream which decreases the pH level. The point where lactate production rate is higher than lactate clearance rate is called lactate threshold. As the acidity in the bloodstream increases, the body starts to rely on carbs and glycolysis. When the carbs start to run out, the muscles began to fatigue and are unable to continue the activity. Constant exercise is crucial when it comes to improving your lactate threshold.Third and final energy system is called the aerobic system. This system uses carbs, fats and protein to produce energy. Now, this energy system usually kicks in when you are running for more than 100m at a much slower pace. Even though this system doesn’t contribute much to 100m dash we have been talking about, this energy system is very important in cardio and endurance activities. This process is relatively slow when compared to phosphagen and glycolysis. However, it is way more efficient than the other 2 systems. When we are performing low-intensity activities, our body burns off fat which then gets converted to an energy source. Because our body has almost unlimited storage for fat and since it produces more energy per gram, it is a very efficient and reliable source for our body to depend on when we are doing activities for a long period of time.All 3 of these energy systems work together to fuel the body during short and long exercises. Always keep in mind that each of these energy systems can be “trained” to suit your need by constantly exercising and using these 3 systems.Because that is what humans are best at.The ability to keep on improving.