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Blood taste and coughing after exercise: cause and solution

About one in six athletes experience it: the taste of blood in the mouth or coughing after extreme exertion. How does this actually occur and is it harmful? Little research has been done into this, but there are some causes that are now known and that are also increased by exercising in cold air. How is it possible that after a long run or skating you have the taste of blood in your mouth? And have you ever noticed that this is much worse and occurs more often when it is cold outside? The cause of this problem must be sought in the lungs.

The functioning of the lungs

The lungs are connected to your mouth and nasal cavity by the trachea. So you breathe in air through your nose or mouth and this air then ends up through the trachea into the two bronchi of the lungs. The bronchi are the first branch of the trachea and each bronchi has one lung attached to it. From the bronchi, the tubes through which the inhaled air passes become smaller and branch more often. Ultimately, the air ends up at the end of these tubes, where the alveoli are attached. The alveoli are surrounded by blood vessels and this is the place where oxygen is exchanged with the blood to provide the rest of the body with energy. The membrane that separates the alveoli and blood vessels is approximately 0.2 mm thin.

What happens differently during extreme exertion?

When you breathe calmly, you usually breathe through your nose. The hairs and mucous membrane in your nose warm the air, humidify the air and filter out the dirty particles. During extreme exertion you need a lot of oxygen, so you usually breathe through your mouth. As a result, the inhaled air is heated, humidified and filtered less effectively and the lungs therefore receive a greater ‘shock’ when breathing than with calm breathing.

What does cold have to do with this?

If the air outside is also extra cold, this ‘shock’ is even greater with each breath. The cold air that then enters the lungs can cause minor damage to the lung epithelium (the covering cells of the lungs) and can thus worsen the complaints.

The taste of blood in your mouth

If you examine the lung tissue of a skater or skier (i.e. someone who exercises intensively in cold air), you will see a similar picture to what is visible in asthma: many, small inflammations in the lungs. These inflammations and damage are caused by the cold air that damages the epithelium. This causes some blood to enter the lungs from the blood vessels, through the thin epithelium of the lungs.Another possible cause is that during extreme exertion the blood rushes through the blood vessels around the alveoli at high speed and with great force. If the force becomes too great, it damages the very thin membrane surrounding the alveoli and some blood also ends up in the lungs.Blood ends up in the lungs through both causes, which can cause the taste of blood in your mouth. Another theory is that when you exercise, the blood vessels everywhere expand a little more. This, for example, makes your head red, but this can also happen in your throat, for example. This could allow some particles of blood to leak through the wall of the blood vessel and into your throat, causing this taste. However, this theory has not been proven.

Coughing and burning sensation of the lungs

The coughing and burning sensation probably arise from the same cause: irritation of the lungs. It is also true that the complaints are worst when, for example, 1500 meters of skating. You can do 1000 meters with your sprint ability, but not quite 1500. If you skate a very long distance, for example 3000 meters, your breathing will remain more constant and it will be less difficult on the lungs, making the complaints less serious.

How can this phenomenon be solved or prevented?

The blood taste after exercise is most common in people who are not in good shape, for example if you are just starting out with endurance sports such as running. It also occurs in experienced or even professional athletes, but to a much lesser extent and less frequently than in novice athletes. A logical consequence of this fact is that it will naturally decrease when you are in better shape, and your body and blood vessels are stronger and can better withstand the increased ‘stress’ during exercise.It is good to take the blood taste and coughing into account during and after exercise. After all, it is a signal that your body sends because you have probably trained too hard and need to take it easy. A tool that many experienced endurance athletes use for this is a heart rate monitor. This device can help you determine the ideal training intensity for your body.

Heart rate monitor

A heart rate monitor consists of a strap that you wear around your chest and a watch on which the measured values of the strap are visible. Heart rate (how fast your heart beats per unit of time) is a good measure of the strain on your body and the intensity of the workout. Advantages of using a heart rate monitor during training are:

  • Preventing overtraining and injuries
  • Preventing substandard training and insufficient loading
  • Good motivation to get the most out of it


Determine training zones

The heart rate monitor can ensure that you exercise in the right heart rate zone, so that you exercise neither too hard nor too light. The heart rate zone, or training zone, is a percentage of your maximum heart rate. You can easily determine the training zone yourself using certain formulas. The most commonly used and easiest way of calculating is using the Karvonen formula: maximum heart rate = 220 – your age. This is a rough estimate and there may be a deviation of up to approximately 15 turns. A more accurate method is: 208 – (0.7 x your age). And for an exact calculation of the maximum heart rate, a sports medical examination can also be performed by a sports doctor.The most general guideline for the training zone you should exercise in is approximately 80% of your maximum heart rate. This varies a bit depending on the goal you are training for.Endurance training This is for people who want to improve their endurance. It is best to train at 60-70% of the maximum heart rate.Aerobic Threshold This is for people who want to improve their endurance and muscle strength and maintain a stable weight or even lose a little weight. It is best to train at 70-80% of your maximum heart rate.Anaerobic Threshold This training zone usually involves interval training. Training at a constant speed is also possible, but this is best done against resistance. These forms of training increase lung capacity and lactic acid tolerance. It is best to train for this at 80-90% of your maximum heart rate.VO2 Max This training zone ensures that your speed is optimized by putting maximum strain on your muscles a number of times in a row in a short training session. So you train almost maximally, at 90-100% of your maximum heart rate.