Why do I have high heart rates as soon as I start running?

  • At the beginning of each sport session, muscles require more blood flow.
  • If you start too hard you put your body to stress, requiring blood flow before the vessels dilate.
  • Peak heart rate thus indicates insufficient aerobic activation and inadequate warm-up before activity.


Ifyou pay attention to your heart rate when you run, you may have noticed that in some cases you have a spike at the beginning of your runs, which goes down and then stabilizes after a few minutes of keeping your physical effort constant. Our muscles burn incredible amounts of fuel (no, we won’t go into too much detail, don’t worry), and to do so they are supplied by an even more incredible number of vessels and capillaries that allow blood-which howoxygen, the fuel for our muscles, is transported-to reach every single muscle fiber. While we are at rest-it goes without saying-this rush of blood is minimized, because to conserve fuel most of our body’s internal organs are inactive, and our muscles are no different. Blood comes and goes from the heart to the lungs, coming relatively calmly to the fingertips, and coming back to start again. All this serves to lighten the cardiac load during rest, since keeping the vessels closed benefits the whole system in terms of the effort to be made. Imagine having to walk a fifty-meter round trip to carry a bucket of water from one point to another, or being able to do the same of only ten meters. Of course, it would be preferable to do the ten meters one, and our hearts think the same.

Setting off at full throttle

When we begin to run, muscles require a huge volume of blood flow, and vessels and capillaries try to meet the demand by dilating so that as much blood as possible gets to the fibers. Our bodies, however, have a serious flaw in this respect: they are not designed in such a way as to allow preventive expansion of vessels and capillaries. For this to happen, one has to start doing something, like running. Starting too quickly puts our body under great stress: it has to move blood abruptly from where it was and has to push it into muscles whose capillaries, however, have not yet had time to dilate, and this can be a risk. If the capillary networks have not yet reached adequate perfusion capacity (I swear, that’s the only difficult word this time), very little blood gets to the muscles in the first few minutes. No blood, no oxygen, that is, no fuel. But even without oxygen we are trying to get it to move, our body, and it does what we tell it to, or at least tries to. In this situation, the only way to be able to do this is to increase the number of beats and thus blood movement from the heart to the muscles, working in an anaerobic state.

Let’s not get hurt

The heart rate begins to drop to an acceptable level only once our body begins to take full advantage of the vessels and capillaries again, when-that is, the entire aerobic system has entered its full capacity. This highlights the real point to think about: the spike in heart rate is not only an indicator that our aerobic system had not yet fully activated, it also tells us-most importantly-that our warm-up was not adequate for the intensity of the effort we are asking our body to do. The spike in beats in our watch report reads only one way: blood and oxygen were largely absent from the muscles and we asked our body for excessive exertion.

Yet another reason, if it needed reminding, why an adequate warm-up, with a very low-intensity start to the activity, is important for all sports, but it is really critical for running: every time we take a step our legs have to cushion the controlled fall we are engaged in and give us the strength to make the leap that will propel us forward later. For ten, one thousand or forty-two thousand one hundred and ninety-five steps. Let’s pay attention to it!


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