The Three Energy Systems: By Coach Roman Siromakha

Ever wonder how energy is created for you to exercise/go about your normal day? Well, there are three different energy systems that your body uses to do this. They are called the Phosphagen, Glycolytic, and Oxidative systems. Our body does an amazing job of figuring out which one needs to be used for a specific task.

The first one is the Phosphagen system or short burst. It is used for any movement or exercise that lasts up to about 30 seconds. This energy system also doesn’t use oxygen for output. That doesn’t mean that you shouldn’t breathe, it simply means that your body doesn’t need oxygen for it to be activated. Think of a squat or a sprint for 1-3 reps.

The second energy system lasts up to about 2 minutes. It’s called the Glycolytic system. The main energy source for this system is carbohydrates. Imagine your muscles being filled with carbohydrates, well because they are. Then when your body requires them for fuel, you utilize those stores to complete the task. For example, think of a 400 meter dash or a 500 meter row.

The third is the Oxidative system. This is the cardiovascular, low intensity, long duration type of energy system. It uses oxygen for energy. Think of something that takes over an hour, like a jog or a half marathon. Even just sitting down, your body is using oxygen for energy, thus activating this system. This is the energy system that burns the most fat as well. Also, your heart rate doesn’t spike up as high, which means carbs won’t be burned for energy or phosphate stores aren’t utilized. It relies on fat stores and oxygen for energy. One can train this system to last hours. Ultra marathon runners are some of the best fat burners out there because their intensity is low, however their duration capabilities can be very long lasting. 

Now, let’s look at the specific benefits of each.  If you are trying to improve your strength and explosive power, it would best to train in that 10-30 second window. Short sprints, low reps and big weight. If you’re trying to improve your “Fran” time or a 500 meter row, that would be the carbohydrate dependent (glycolytic) system. More workouts of that type will train you to perform better. Last are the long duration types of workouts. If you dread long metcons, you probably need to work on this energy system. Your body just requires more adaptation in this specific window.

It is very important to train all of these systems if you want to improve your fitness. This is where beauty of Cross Training comes in. We vary the workouts, durations and the movements constantly. Your body is always being challenged. Being good in a single specific energy system isn’t as useful as one may think. For example, if you came into the gym on the days that the metcon is fairly short, you would only be good at that type of metcon. Same thing goes if you only attend classes that have long duration metcons, you’d be completely comfortable with those, however your power would be pretty low. Another thing to consider is your body’s ability to swap between different forms of energy requirements. Training all 3 types of energy systems will give you the most bang for your buck. No metcon will scare you.