Jogging, hiking, playing tennis – many people have time for this, especially on vacation. But in high temperatures this can be a challenge for the body. Athletes should pay attention to this.
By Anna Küch and Constanze Alvarez, SWR
During their summer vacation, many people finally have more time for sports. But not everyone should jog or play football in the midday heat, says Karsten Köhler, Professor for Exercise, Nutrition and Health at the Technical University of Munich.
At 25 degrees it becomes problematic because the body has to work actively to dissipate the heat that is already generated during exercise. “At 30 degrees and above, and especially when the humidity is very high, the body is simply no longer able to get rid of this heat as well,” explains Köhler.
People with pre-existing medical conditions should avoid exercise in hot weather
This means that the hotter it gets, the harder it is for the body to cool down again. The pulse increases, the heart beats faster, and the body temperature approaches fever.
If you then feel weak and tired, these are clear warning signs: Circulatory collapse or heat stroke can occur. People with pre-existing conditions should be particularly careful, warns Köhler.
Drinking protects against overheating
If you don’t want to give up training despite the heat, you should take certain precautions: for example, wear airy clothing so that sweat can evaporate quickly. And drink plenty of fluids before jogging. If you’re training for half an hour or more in the heat, you should take a drink with you.
Jogging in the midday heat can, in the worst case, lead to heat stroke or collapse.
Water is enough for now. Sports drinks that provide the body with additional electrolytes only make sense for longer sessions, says sports scientist Köhler. Anyone who needs to cool down quickly while exercising can pour water over their head. Like the cyclists in the Tour de France or the athletes at the Olympics.
“This is particularly effective because the liquid cools the body down directly and doesn’t have to take a detour first.” Once training is over, everyone should cool down again, advises Köhler.
In professional sports, training in hot weather can be useful
But under special circumstances, exercise in hot weather can also be good. Researchers from Norway have found that in a study with professional cyclists. The athletes trained five times a week for 50 minutes in a heat chamber or in heat suits. After five weeks, the number of red blood cells had increased and with it the athletes’ performance.
“When we train in hot weather, it means that the body has to make its blood volume available in a different way,” explains sports scientist Köhler. Less blood goes to the muscles and more blood goes to the skin tissue, the skin turns red, we sweat more. You force the body into a different metabolic state, the same strain on the muscles becomes significantly more intense in hot weather – and you set a different training stimulus. This means you can get two or three percent more out of your performance, says Köhler.
This can certainly make sense for professional athletes. But only if they are well monitored medically and the critical body temperature is not exceeded. “If this is done, then the body temperature, for example, is measured very precisely,” explains Köhler. “Then you know: OK, we’re still in the green zone – and now we’re moving into the red zone, at which point you stop training accordingly.”
Switch to less hot hours
Amateur athletes should take it easy in the high temperatures. This is especially true for those with cardiovascular problems. In general, it is advisable to set off as early as possible when hiking and to go jogging or play tennis in the cooler morning or evening hours.
