Exercise and Heavy Breathing. Part I.

Ever wonder why you get so out of breath at the beginning of exercise??  Well, don’t worry, it’s not because you’re THAT out of shape.  Now you may really be that out of shape, but that’s not the main reason.  It happens to every single person, and it is a physiological process within the human body that causes this to happen.  Here is my attempt to explain this process in very layman’s terms…

Whenever we exercise we use oxygen to convert fat into useful energy.  We use oxygen to burn fat at rest, we just simply use it at a quicker rate during activity.  The much faster speed of activity requires that we bring oxygen into our bodies at a much higher rate than during rest periods.  The difference between what our body requires and what we can supply at the beginning of activity is called “oxygen deficit.”  In other words, there is a period of time in which it takes our bodies’ energy systems to figure out how to bring in and utilize more oxygen than during rest.  What is amazing to me is the efficiency in which our bodies can do this.  When we begin exercise, our bodies’ realize that not only will we need more oxygen, but we’re going to need it quicker.  So what happens??  Well, simply put, there is both chemical and neural feedback sent to the lungs.  The lungs???  Yes.  I’ll explain….

  • What in the hell is chemical feedback???  So, when we exercise, our muscles produce all sorts of chemicals.  Some of these can be useful throughout the body, but many of them are harmful and need to be eliminated from the body.  These chemicals, through a series of VERY small blood capillaries connected to skeletal muscles, manage to get into the bloodstream and travel to the lungs.  When the lungs receive these chemicals, they realize not only that our muscles are working harder, but that we need to get rid of some of these products.  So, what do they do???  They increase our ventilation rate!!!  Not only will that clear out our bi-products of exercise, but it brings in MORE OXYGEN.
  • Okay, so we’ve briefly described chemical feedback..  Now what the hell is this neural feedback??  This has to do with the nervous system.  The nerves going to our muscles aren’t the only ones affected by increases in activity.  One of the fastest ways we can change our ventilation rate is through activation of the neurons traveling to our lungs.  We activate neurons traveling to our muscles during exercise, so it only makes sense that we match that in the lungs in order to meet our oxygen levels.

There are obviously many things that affect the rate of oxygen consumption by individuals, and, in turn, how long we stay “out of breath” at the beginning of exercise.  First and foremost, training will affect this the most.  The more you exercise, the better equipped your body will be at handling this shift from rest to exercise.  The intensity of exercise is also a major factor.  Think about it, how much more out of breath do you get after a long sprint as opposed to walking on a treadmill??  The more demanding the task, the more oxygen needed.   Similarly, the amount of muscle involved in the activity dictates the oxygen deficit.  This plays hand in hand with intensity, as most intense exercise involved larger amounts of muscle when compared to lower intensity activities.

Oxygen Uptake During Exercise


Ignore the green portion for right now (We’ll get to that later).  What I want you to notice is the difference between the bottom line (RESTING OXYGEN) and the top line (EXERCISE OXYGEN UPTAKE).  The red line is the breathing rate once exercise begins.  You’ll notice a rapid increase, which I’m sure you’ve all felt before.  After a few minutes, it begins to level off.  The blue portion of the graph is the difference between the two (resting and exercise) while our body figures out how to utilize the oxygen coming in.  This is your Oxygen Debt.

So, now we’re all experts on Oxygen Deficit, right???  While I highly doubt that’s the case, I hope this has shed some light on to something that plenty of people have asked me about throughout the years.  Next time you’re working out, just for fun, see if you can notice the difference during the beginning and middle segments of your workout.

Make sure and come back next week, as I’ll explain why we stay out of breath AFTER we get done exercising.


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