Sport in the heat: the most important questions and answers

Sport bei Hitze: Die wichtigsten Fragen und Antworten

On hot days in the summer months, temperatures can reach dangerously high levels. This danger is especially present if you intend to do sports. From ordinary jogging to burn calories to training in top-class sports - when it's hot, you have to pay special attention to your own body.

In this article, we address the question of whether sport on hot days makes sense or is dangerous and how our body reacts to such extreme stress. In addition, we summarize all the factors that play an important role in heat sports.

the essentials in brief

  • Sport in the heat is possible, depending on your physical and health condition, but should be postponed to a cooler period if the opportunity arises.
  • In addition to hydration, cooling and sun protection factors play an important role in exercising in the heat.
  • Physical exertion when ozone levels are high can result in damage to your health. In a longer period of fine weather, special caution and adaptation of the training is required.

Exercising in the heat: What you should know

In summer, people's desire for outdoor activities increases. In addition, due to the bikini and swimming trunks season, more sports are being practiced. In addition to the well-known sporting events such as the Tour de France in cycling or the major global tournaments in soccer, "health and fitness" is the biggest sporting motive among Germans (1).

In order to be able to pursue your hobby as carefree as possible even on hot days, some important questions must be clarified and essential factors collected.

Should you exercise when it's hot?

Outdoor sports are much more pleasant in summer than in winter. Apart from classic winter sports activities such as skiing, snowboarding or ice skating, we are happy not to have to wear a hood or gloves.

In recent years, however, the temperature has risen significantly higher in the summer months. Sport is still possible. If you don't let yourself be dissuaded from doing sports even at extremely high temperatures, you can definitely do so. Especially in club and top-class sports, the training times are clocked and do not allow any changes due to preparations for competitive games and tournaments.

Sport in hot weather

You can also do sports at higher temperatures. However, you should pay attention to a few things. (Image source: unsplash / Maarten van den Heuvel)

If you are not a top athlete or are registered in a club with fixed training times, you are more flexible in deciding when you want to practice your sport. If you enjoy a healthy physical condition, there is nothing wrong with exercising in the heat.

The most important rule, however, is: Sport should be good for your health and not harmful to your health. If you suffer from asthma, cardiovascular disease, chronic bronchitis or other respiratory problems, you are particularly at risk on hot days (2).

Why is exercise more strenuous in the heat?

During physical exertion, enormous heat leads to environmental conditions that are unfamiliar to the human body and thus to thermal stress, which impairs aerobic performance.

By reaching maximum aerobic capacity, cardiovascular workload increases and thus decreases voluntary surge. In addition, the enormous physical exertion leads to an increased development of hyperthermia, which increases the risk of developing heat illness (7).

Which factors play an important role in sports on hot days?

In order to be able to exercise even when it is extremely hot, you need to be aware of a number of important factors. We have summarized the most important ones for you:

factor function
hydrogenation Drinking and nutrition should protect the body from dehydration during physical exertion.
cooling Ensures acclimatization during physical exertion and thus prevents overheating.
sun protection Applying sunscreen while exercising is essential to protect the skin and entire body from heat illness.

Hydration: The type of liquid intake during physical exertion differs from sport to sport. While you have enough breaks in tennis and therefore enough opportunities to hydrate your body, long-distance runners or soccer players have fewer opportunities to avoid dehydration.

For this reason, preparation in the form of sufficient fluid intake before the upcoming physical exertion is an essential factor if you want to do sports in the heat (3). After sport, drinking enough liquid is important for optimal regeneration. In order to make up for the fluid deficit, an intake of 150% of the losses within one hour is recommended (5).

Cooling: In order to be able to guarantee optimal performance of the body in hot temperatures, cooling plays an important role. Wearing breathable clothing ensures proper acclimatization during exercise in hot weather. In addition, cooling the skin reduces cardiovascular stress and lowers the temperature of organs and skeletal muscles (3,4).

Sun protection: The body regulates its temperature by sweating. The ejection of the liquid cools the skin and counteracts overheating. However, this self-cooling also leads to underestimating the heat load. During physical exertion, the body is usually exposed to pure sunlight, since there is hardly any protection in the shade in outdoor sports.

The application of a sunscreen is therefore strongly recommended. It's important to note that most sunscreens take about 20 minutes to take effect (6). You should therefore calculate this time before you practice your sport in the heat.

What do athletes drink when it's hot?

Due to the increased sweating and the associated higher loss of liquid, the body also needs more liquid. The color of the urine serves as a general check on the water balance in the body. In the case of clear or light yellow urine, you have consumed enough liquid. However, if the urine is dark or even smells, this is a signal of a lack of liquid.

After intense sports with high fluid loss, electrolyte drinks are useful.

When exercising, the body can survive without liquid for about an hour. So if you want to train longer, you should make sure that your body is supplied with liquid during breaks. In addition to tap water, you can also choose sports isotonic drinks as your choice of drink. These are characterized by the rapid provision of minerals such as zinc and iron and hardly or not at all burden the digestive tract (8).

When should you exercise when it's hot?

In the summer months, longer periods of fine weather can be expected. These days of intense sunshine result in higher ozone levels from 11am to 7pm. During this period, a higher air temperature and possibly also higher humidity can also be expected.

Such environmental conditions are not conducive to practicing sports. If the ozone concentration exceeds 180 µg/m3, more demanding endurance activities should be postponed because the risk of heat illness is too great (2).

In the event of a longer period of fine weather or if the ozone concentration is too high, you should postpone training to the early morning hours or the later afternoon to evening hours.

At which heat temperatures is sport unhealthy?

As previously mentioned, exercise is discouraged when the ozone concentration is too high. This is often the case during or after long periods of good weather in the summer months. The following table should give you an overview (2).

ozone concentration Advice
up to 180 µg/m3 Nothing stands in the way of physical exertion.
more than 180 µg/m3 There is a risk of heat illnesses, which is why training should be postponed.
up to 240 µg/m3 Activities such as swimming or boating are possible, but vigorous endurance activities are critical.

If you put your body under strain through strenuous training at maximum temperatures, this can lead to a deterioration in lung function values ​​and thus to a significant drop in endurance performance (2).

heat waves

A heat wave and high ozone concentration can, under certain conditions, have drastic consequences. (Image source: Greg Rosenke / unsplash)

Does exercise burn more calories when it's hot?

Difficult environmental conditions such as a higher outside temperature also increase your body temperature at the same time. Your body has to work harder to reach normal operating temperature, which puts more strain on your lungs and heart. At the same time, this leads to higher energy consumption and thus to higher fat burning (9).

What alternatives are there to exercising in the heat?

As you have often read, it is possible to do sports in the heat and there are hardly any risks if the physical conditions are healthy and the training is adapted. Nevertheless, these circumstances do not always exist. For this reason, we have collected alternatives that still lead to a calorie deficit or replace exercise in the heat.

  • Nutrition: You are what you eat. This is not just a saying.
  • Hydration: Better skin, fewer headaches, healthier joints, and more energy - these are just a fraction of the benefits of drinking plenty of water each day.
  • Sleep: Sufficient sleep reduces the feeling of hunger and thus has a positive effect on weight loss.
  • Sport in air-conditioned studios: If sport not only helps you to lose weight but also to reduce stress, air-conditioned studios offer a lucrative alternative.
  • Stress Reduction: When exercise isn't an option due to the heat, there are other ways to reduce stress that have a positive impact on both mental and physical well-being.
  • Time: Postponing the sport to the early morning or late evening hours is also an alternative.

As you have now read, there are definitely alternatives to exercising in the heat. We will now explain these again in detail.


If it is not possible to exercise due to the extreme heat, the focus is on the right diet. Many experts often appeal that a balanced diet is more important than exercise itself. As long as you are in a calorie deficit, weight loss is assured.

If weight loss isn't what motivates you to exercise, diet can still be a good alternative to exercise. By eating the right food, the body gets the energy it needs to cope with upcoming tasks. With an unbalanced diet and too little physical activity, there could also be a lack of important vitamins. In extreme situations, this can be compensated for with help.


Adequate hydration is essential for a healthy and functioning body. The best drinks for this are still water, mineral water, cool tea, or diluted fruit juices. The daily drinking amount should be around 2 liters.

Depending on the physical exertion, which can also occur through work in addition to sport, you should also drink more (2). The feeling of satiety is a positive side effect. With a lot of water in the stomach, the cravings are satisfied and the body always stays hydrated.


In addition to a balanced diet and sufficient fluid intake, sleep is another important pillar for health. Regardless of your individual sleeping habits, you should sleep between 6 and 8 hours to be optimally rested.

During this time, the brain processes the information gained from the past day. In addition, sleep influences many physiological and psychological processes such as learning, metabolism and mood (10).

Sport in air-conditioned studios

Air-conditioned studios are ideal if you don’t want to do any sport at all and it’s too hot even in the apartment. In most cases, a membership fee has to be paid for these, but afterwards they offer enough opportunities for physical exertion in a cooled environment.

In addition to strength training options, treadmills and ergometers also enable cardio units. In rare cases, even group activities such as badminton are offered in cooled gyms.

stress reduction

Hardly anything robs the body of as much energy as stress. Energy that the body would rather spend on other aspects of everyday life. But how can stress be reduced if sport is not an option in the heat?

It is acutely helpful to reduce the amount of activities and tasks that stress you and to take time for more pleasant things in life. Furthermore, the scale can be a cause of stress. The urgent feeling of having to lose weight is a burden and a blockage.


In addition to improving mobility and strengthening the supporting muscles, yoga also has a positive effect on general well-being. (Image source: Carl Barcelo / unsplash)

A third variant is to start and end the day calmly. Far too often you start the day hectic and don't give your body time to prepare for the upcoming activities and challenges. The day ended just as hectic. To avoid this, yoga, meditation and diaphragmatic breathing before and after sleeping are recommended.


If you are only interested in exercising outside, but the outside temperature makes it difficult, you should move your workout to the early morning hours, late afternoon or evening. As previously mentioned, temperatures and ozone levels peak between 11am and 7pm. On hot days, no intensive workout should be done during this period.


The practice of physical activities is just as possible in summer as in winter. Due to the difficult environmental conditions, the training is more strenuous, but not necessarily harmful to health. This depends on the outside temperatures and ozone levels.

You should also ensure that you drink enough fluids before, during and after your workout. One hour after exercise, water loss must be compensated for by adequate rehydration.


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  2. Sport with ozone pollution and heat Source
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  4. Booth J, Marino F, Ward JJ. Improved running performance in hot humid conditions following whole body precooling. Med Sci Sports Exerc. 1997 Jul;29(7):943-9. doi: 10.1097/00005768-199707000-00014. PMID: 9243494. Source
  5. Burke LM. Nutritional needs for exercise in the heat. Comp Biochem Physiol A Mol Integr Physiol. 2001 Apr;128(4):735-48. doi: 10.1016/s1095-6433(01)00279-3. PMID: 11282317. Source
  6. Health center Parsberg, health report: How should you exercise when it's hot? Source
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  8. Urdampilleta A, Gómez-Zorita S. From dehydration to hyperhydration isotonic and diuretic drinks and hyperhydratant aids in sport. Nutr Hosp. 2014 Jan 1;29(1):21-5. doi: 10.3305/nh.2014.29.1.6775. PMID: 24483958. Source
  9. Matthew A Tucker, Aaron R Caldwell, Cory L Butts, Forrest B Robinson, Haley C Reynebeau, Stavros A Kavouras, Brendon P McDermott, Tyrone A Washington, Ronna C Turner, and Matthew S Ganio (2017): Effect of hypohydration on thermoregulatory responses in men with low and high body fat exercising in the heat Source
  10. Acosta Mt. Sueño, memoria y aprendizaje [Sleep, memory and learning]. Medicina (B Aires). 2019;79 Suppl 3:29-32. Spanish. PMID: 31603840. Source
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