What Happens to Our Body when we Run

I saw a great post on active.com written by Laura Beil for Women’s Health describing our body’s reaction during a 30-minute run.  This pretty much sums up why it takes me about a mile before I feel good!

Within the first 90 seconds

  • Our bodies start using ATP (adenosine triphosphate) these are the energy molecules that our body makes from food
  • As only a limited amount of ATP can be stored in muscle cells, and so ATP is converted into ADP (adenosine diphosphate).
  • ADP will only provide 2-3 seconds worth of energy, so ADP needs to be converted back into ATP.  The body does this by breaking down glycogen (a form of glucose stored in our muscles), and through glucose in our blood.
  • This process causes our muscles to release lactic acid

After the initial surge, during the next few minutes

  • Our muscles require more oxygen to use the glucose that is releases
  • Our heart beats faster and directs blood to our muscles and away from bodily functions we aren’t currently using
  • We begin to breathe heavy
  • Our glutes, legs and core work to keep us erect, control our gait and extend the hip joint so our feet can push off the ground
  • We begin to burn calories at a rate of about 100 calories per mile.
  • As we burn glycogen and oxygen for energy, our body temperature rises.  In an effort to keep from overheating, our circulatory system diverts blood flow to our skin and our sweat glands release moisture.

Within the first 10 Minutes (or for me, at about the mile mark)

  • If we are in good shape our bodies efficiently uses oxygen, burns fat and glucose and we feel strong.
  • If we haven’t been keeping up with our training, or we are running faster than usual (as in a race) the ATP can’t keep up with demand, lactic acid floods our body, and we feel it!


  1. Good to know. If nothing else so that I can think about this when I run instead of thinking about how tired I am

  2. findingourwaynow.com says:

    Boy, now I get why I feel the way I do when I am power walking. I also need to be more consistent. Of late, I have stopped working out for no explicable reason … Sigh … other then laziness. Your post has given me a reason to start moving again. Thanks for that. 🙂

  3. Great information. You know how the body works when we are running. I am not a runner. I love to do long walks.

  4. These physiological effects occur with any moderate aerobic exercise so you would definitely feel the effects walking or even riding a bike. It helps to know that there isn’t anything wrong when I feel awful during that first few minutes!

  5. I’ve always said I’ve hated running long distances, that I’m a sprinter not a true runner. And my body really is better equipped for sprinting. But lately I’ve had the desire to run longer distances. I admire all of you runners! Maybe one day I’ll be one, too!

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