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What is oxygen deficit?

Train Smarter Not Longer.

Ever wondered what the difference between a long lets say 60 minute walk and a 30 minute HIIT (High Intensity Interval Training) would do for your calorie burn? In this chapter we’ll answer this question specifically, try to give you a better understanding of how the body reacts to both sessions and let you know both the pros and cons that go along with it because, we’re here to educate you on both exercise and nutrition right?

As you may have read a previous chapter, we have 3 different Energy Systems:

The ATP-PCr system The Glycolytic pathway The Oxiadative Phosphorylative pathway

You may of heard about some of these when talking about Anaerobic and Aerobic systems….the names above are just fancier and harder to pronounce but they’re rarely used to describe the energy systems so no need to memorise these either, although, if you have, you’re one step ahead of us already!

As we begin to exercise our oxygen doesn’t immediately match the new level of muscle demands and because our muscles will need more oxygen than we’re taking in we’ll go into what’s known as Oxygen Deficit. Even if we’re going for a slow walk with our partner, the ATP-PCr system will get us started before the Glycolytic pathway is required. Once you start to begin working out an intense level, you breathe heavier, your heart is racing and your body struggles to keep up. If you’ve ever felt like this, put your hand up, we know we have. The heavy feeling that comes after a hard workout can sometimes be followed by a small headache. This comes from a lack of oxygen but quite often disappears once the body returns to a relaxed state. Oxygen deficit is the reason why even once we’ve stopped working, our breathing is still through the roof. This is how we slow our heart rate down and begin the task of repairing our muscles.

That’s all well and good you might say, interesting? yes but what does that mean for us when discussing the 2 workouts at the beginning of the chapter?


Whilst our long romantic walk may take up an hour of our time, an hour and a half if we’re in a good mood, the lack of Oxygen Deficit means that whilst we’re walking we’re burning calories but once our walk comes to an end, so does our heightened calorie burn.


We just smashed some heavy weights or completed 10 x 400m Sprints and we’re on all fours trying to recover. The Oxygen deficit will be quite significant so therefore the body needs time to recover. Whilst your body recovers, it’s burning calories at an increased rate, so whilst you only worked out for 30 minutes, your body could be benefitting for the next couple of hours!

HIIT isn’t possible for everyone but if given the option and you’re short on time, HIIT will be the more effective way to burn calories in a shorter space of time and is therefor the preferred option. This is only our opinion and we’d suggest you speak to a medical specialist to get the all clear before trying this.

We hope that this answers any questions you may have on this topic but if it doesn’t, by all means feel free to ask us to clarify for you.

Justin Beard Pn1


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