Fitness Over 40

Lower Resting Metabolism? Look At Your EPOC First

I know personally I have recently become almost addicted to longer distance running.  Maybe I just enjoy punishing myself, but a month ago when I put back on the running shoes, I barely made it 2 miles and according to my Garmin watch, I was running at a plus 10 minute mile.  Several weeks later, a few runs per week, I am now at the 4-5 mile range and just yesterday was able to almost break a 9 minute mile average.  Laughable by a runner’s standards, but I am not doing this to compare myself to others, only to achieve a goal I have set for myself.  

So what is so bad about running? Well, technically nothing, it is amazing for the cardiorespiratory system, and musculoskeletal system; and for this period of still adapting and improving, my delayed onset muscle soreness shows that it still takes a couple days for my body to repair itself.  So what the hell does this have to do with metabolism and this “EPOC” thing?  If you haven’t heard of EPOC, it stands for EXERCISE POST OXYGEN CONSUMPTION which is basically in simple terms, how long does the body take to return to normal homeostasis?  Just in case, should I break this down even more?  If you understand this, you can skip the next paragraph, but a good refresher nonetheless.

As you can imagine, when we engage in physical activity, let’s say running as the example, we immediately begin contracting our muscles (in our lower half mainly) at a much more frequent and higher intensity pace.  In order for our muscles to be able to perform these shortening cycles (contractions), they require oxygen in the blood, which fortunately through our normal resting patterns of respiration, we supply that.  When this onslaught of muscular activity occurs, our muscles can quickly deplete these available stores of oxygen and must replenish before the muscles become fatigued and begin burning.

To accomplish the activity, our respiratory system begins increasing its output by breathing deeper and faster, attempting to replenish the lost supply of oxygen (oxygen debt).  As a result, our heart rate increases and our Cardio Output increases which is more blood is being pumped by the heart through our system, to travel to the working muscles.   As we continue this process, if the effort is normalized and our body is able to replenish oxygen supplies, we will be able to continue our activity and the muscles can continue to contract.  If our effort is too much for the cardiorespiratory system, we will fatigue and achieve shortness of breath.   So we fast forward and assume in this example we completed a 3 mile run/jog.  Let’s say it took us 30 minutes to accomplish this (par for my course).  Once exercise ends, our body will begin its process of returning to homeostasis (a level where all body functions are normal), ie, body temperature, heart rate, cellular repair, etc.    

To accomplish the activity, our respiratory system begins increasing its output by breathing deeper and faster, attempting to replenish the lost supply of oxygen (oxygen debt)

Darren Stroh MS CES CPT NASM Tweet

If we are new to running, such as myself, we have probably just pushed our cardiovascular system, as well as muscles beyond normal levels and in regards to muscle action, we more than likely created minor tissue damage (don’t worry this is normal) and our body will have to repair itself.  This needs oxygen.  Our muscles will need to replenish normal oxygen levels and our heart will continue to pump blood at an elevated level until our body returns back to normal resting levels.  This so-called “heightened level” of cardiorespiratory activity after exercise is referred to as the EXERCISE POST OXYGEN CONSUMPTION period, and the harder we pushed our system, the longer it will take to return to normal levels.  During this period, as you can imagine, it takes energy to return the body back to normal levels.  We derive energy from food, so this means we burn more calories after our bout of exercise.  Once returned, all levels return to normal.  

This so-called "heightened level" of cardiorespiratory activity after exercise is referred to as the EXERCISE POST OXYGEN CONSUMPTION period

Darren Stroh MS CES,CPT-NASM Tweet

Back to the point about running, even though its a wonderful form of exercise, as you can imagine, the more conditioned we become, the quicker we return to normal resting levels.   For a person who is at the early stages of exercise, it is important to keep in mind that if you do not feel your body is burning calories as effectively as you either wish or believed so, you may want to first look at your EPOC.   What I am referring to is that we all enjoy casual walks and a light jog, but if we are not increasing the intensity level, as soon as our activity is completed, our body returns to normal resting levels.  If we would like our metabolism to remain elevated throughout the day, the only method to create this is to engage in higher intensity effort.  If we are walking, attempt to incorporate some running.  If we are jogging, attempt to pick up the pace or incorporate some sprints.  

It goes without saying that anyone engaging in physical activity should always consult with a medical professional and I HIGHLY encourage to monitor ones heart rate when exercising.  If you have any up to date heart rate monitor, once you plug in your age, it will calculate your target heart rate zone.  

So next time you are out performing some physical activity and you feel you are carrying a few extra pounds, kick up the intensity.  Maybe try a new routine such as HIIT (High Intensity Interval Training), or mix in resistance training a few times per week to increase muscle tissue.  Monitor and record how you felt so the next time you can adapt and go farther.  


If you want to learn more about EPOC, here is a good blog by the American Council on Exercise.  Of course I am a NASM man, but no use in re-inventing the wheel and your education is my main target.  The purpose of my post was to provide a little more insight into the foundation of EPOC and why it’s important.  Cheers!

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