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What Is Oxygen Debt?

Oxygen debt, or excess post-exercise oxygen consumption (EPOC), is the body’s oxygen deficiency from strenuous exercise. As we exercise, oxygen needs increase, causing us to take in more of this essential gas. While we take in more oxygen, our body can’t keep up and goes into anaerobic exercise. We are at an oxygen deficit.

Once we reach an oxygen debt, lactic acid begins to build in our bodies since we aren’t getting the right amount of oxygen required to oxidize it. We’ve heard of lactic acid. It builds in our muscles and makes them sore. Once the oxygen deficit occurs, lactic acid has a party in our bodies.

Because of this, oxygen debt, or EPOC, is vital to return our bodies to their original state. By receiving extra oxygen after a strenuous exercise, our bodies can break down lactic acid into carbon dioxide and water that are flushed from the body.

Oxygen Debt Deep Dive

Try saying that heading five times fast. Now that you understand more about oxygen debt or EPOC, let’s discuss why and how it happens.

Let’s say you start running and immediately notice you are breathing heavier to provide more oxygen for your energy expenditure. If you live in a high-altitude climate, breathing is more complicated, and the body produces more red blood cells to counteract the lack of oxygen. For ways to increase your lung capacity, see our Airofit review.

Anyway, you are running, and breathing is more complicated. Because your body isn’t getting enough oxygen, it becomes anaerobic training. Lactic acid, flushed out by oxygen, starts to build in your muscles. ATP (adenosine triphosphate), the energy carried to cells, slows due to the lack of oxygen.

Before you worry, this is your body’s normal response to exercise. When you stop exercising, your breathing slows gradually and eventually returns to normal. This process can take seconds to minutes, depending on the intensity of exercise and the individual’s fitness level. That’s not the end of oxygen debt. The body must catch up to its previous oxygen levels and perform functions that paused during those exercises. This process takes a bit longer.

EPOC or oxygen debt occurs in the long process. The body temperature returns to a normal range, breathing slows, and the heart rate normalizes. Now the body has more oxygen available to it, the ATP process begins to restore energy, and lactic acid begins to break down. Oxygen changes lactic acid into carbon dioxide, which we exhale, and water, which we urinate. Muscle cells feel relief as the lactic acid leaves.

Oxygen debt changes based on exercises’ duration and intensity as well as an individual’s fitness level. It can take a few hours or days for your body to return to homeostasis, the body’s metabolic resting level. During this time, the body is working hard to restore itself to homeostasis, which is why calories are burned long after vigorous exercise is complete. As our oxygen intake increases, we remove lactic acid, increase the ATP process, and continue to burn calories.

Measuring Oxygen Debt

Measuring oxygen debt occurs by calculating the extra oxygen consumption used above our resting oxygen levels for 30 minutes to an hour after exercise ends. Studies research oxygen consumption and the number of calories burned after intense exercise to measure oxygen debt. By understanding what is called oxygen debt, researchers know how the body recovers, how long it takes, and how much energy expenditure happens after exercise is complete.

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Concluding Words of Wisdom

Oxygen deficit, known as oxygen debt or EPOC, is your body’s natural way of restoring your body to metabolic resting levels called homeostasis. There are ways to increase lung capacity the Airofit or Airphysio. For even more options, read here. All of those can change your levels of oxygen debt, like exercise intensity and fitness levels. Getting that additional oxygen into your lungs and increasing aerobic respiration to turn food into energy allows your body to return to its normal levels. It’s a bonus that calories continue to burn long after the exercise is complete.

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Kristen holds a bachelors in English from Louisianna university. With a longstanding passion for fitness, she owns and operate her own gym and is a certified jazzercise instructor.

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