High pulse when exercising

Is a very high pulse during running dangerous?

"Wow, if I am exercising to long with a high pulse, isn’t that dangerous?" A fair question, which can not be answered easily or completely. There is no right or wrong in this sense. What exactly does actually dangerous mean at this point?
I would distinguish two cases here:

    "Dangerous" with the meaning of dangerous for your health or damaging to your health
    "Dangerous" in the sense of not productive for your further training progress

Let's start with the first point. A high pulse while running is dangerous to your health, if it is a warning signal of your body. If your body very clearly indicates "Attention, please think about what you're doing." That may be the case in the following situations.

You didn’t run for many years. The ravages of time take their toll. You gained a bit more weight. In order to get everything under control, you immediately start with a brisk run around your favorite lake. After a few meters, your pulse is so high that you can feel it in the neck . You're top-motivated and continue anyway.

In this case, the high pulse is one of many indicators, that you want to do it the sporty way. Your body is not used to that kind of load and shouts "Stop, please quit”. If you are taking in too much to be on the top, your body might press the emergency stop button.

You are in great shape. You are well trained. You know your pulse zone. The competition date is getting closer and closer. It is hot. The sun is burning. The thermometer shows nearly 40 ° C. You start to run. Your pulse is too high. You are not able to get it down. You are getting nervous, because the pace is unknown for your circumstances. Your head wants, the body won’t. You feel a little dizzy.

This is a clear case that "something is wrong". It is important and right, to go to the limits. Especially in endurance sports. However, a high pulse in line with other physical troubles is a clear sign of "sometimes it's just better to recognize the signs, to protect yourself and to look after your health as a top priority."

Let’s talk about the second point. Is a high pulse dangerous for the training progress? Meaning a too high pulse might say "Attention, today you're not quite fit"? Yes, it can be. There is always a reason for a too high pulse during training. You should be able to recognize this and to question it.

   Are you exercising according to a plan and with a heart rate monitor? Then you should know your training zones. Which pulse corresponds to a loose training for you? Which pulse is for you the pulse at a tempo run and what’s your pulse like, when you increase your speed as it would be during a competition?
If you know your pulse zones, then you can recognize a high pulse immediately. It is important to deal with it in a neutral way, which means that on the one hand you should not panic, but also on the other hand side, you should’t ignore it.
    Imagine the following question: Did I sleep bad last night, am I just under stress, maybe I still do have a bit of a cold or I simply have eaten too much? Perhaps you are back in training, although your last big competition was a few days ago?

It is important, that in the course of time you get a sense of when you do or do not have a high pulse. If a high pulse is caused by the fact that you had to much stress at work or the dinner in the evening was too much, you can be relaxed. The training is in this case not that easy, but you can be sure that you won’t put your health in danger.

The situation is different, if the cause for the high pulse lies in a not yet faded disease. A typical cold is one of the classics. It is also dangerous, if you get back too fast into your training routine right after a big event, like a marathon, half marathon or triathlon. Your body, your muscles are still too busy to regenerate. The individual muscle fibers are at a microscopic level damaged after an intense competition. You have to start the repair work after the race. If you give your body not enough time and space to recover, it reacts with incomprehension. It won’t give you the performance level that you're used to. The result? You can guess it: a too high pulse.

Cardiac shift

Another phenomenon could be the cause of a too high pulse. In science, it is known as the "Cardiac Shift". Underlying this is the observation that your heart rate increases by 10-15 beats per minute, although you are keeping a constant physical load in your training.

What exactly is the Cardiac Drift?

Cardiac drift is an indication, that your body core temperature, the current fluid balance and electrolyte supply are off balance.

Your body tries to transport to the skin as much blood as possible, to cool down during a workout. The result: there is less blood available to carry oxygen to the muscles. The consequence is, that your heart starts beating faster to compensate for the loss of oxygen transport. Your pulse rises.

The simultaneous loss of liquid (through sweating) ensures that your blood is significantly thicker, which means it gets more difficult for the heart to effectively transport the blood through the body. The consequence: the per time unit transported volume gets smaller. To pump about the same amount of blood per time unit to the muscles, the heart has to beat faster. When the heart beats faster, your pulse increases.

What exactly can you do against the Cardiac Drift?

There is no golden rule for that. There are rather a series of tips that you could consider as an athlete. It starts with the clothing. A rule of thumb is, that you should dress in such a way, that you feel like 20 degrees warmer than the outdoor temperature. Another option would be to drink regularly and deliberately. Even if you are not necessarily thirsty, it helps your body to ensure a "liquid" blood transport.