Summer is the best time for many to be active outdoors. Jogging in the park, cycling, or an outdoor yoga session - exercise in the sunshine is often twice as much fun. At the same time, trends like Hot Yoga or Hot Pilates are booming, where people deliberately train in heated rooms. But is exercise at temperatures over 30 degrees (86°F) actually healthy, or are you exposing your body to unnecessary risks?
The short answer: Exercise is generally possible even in the heat - but only with the right adjustments. Because the hotter it gets, the harder the body has to work to keep its temperature constant.
Why Heat Stresses the Body
During exercise, the body produces heat, which is primarily released through sweating. According to the Centers for Disease Control and Prevention (CDC), this cooling mechanism works less efficiently in extreme heat - especially when there is also high humidity. At the same time, the heart has to work harder to supply both the skin and the muscles with sufficient blood.
There is no fixed temperature limit above which exercise automatically becomes dangerous. Rather, several factors are decisive: How intense is the training? How high is the humidity? Does the training take place in direct sunlight or in the shade? And is the body already accustomed to high temperatures?
Nevertheless, this applies: As temperatures rise, so does the risk of heat-related complaints. Particularly intense workouts like HIIT, long runs, or challenging bike tours can quickly push the body to its limits in extreme heat.
Which Types of Exercise Are Suitable?
Anyone who wants to stay active even on hot days should adjust their training. The CDC recommends scheduling intense exercise for the early morning or late evening hours whenever possible. Instead of HIIT or long runs, light jogging, walks, leisurely cycling, or swimming are much more suitable.
Caution is also advised with Hot Yoga or Hot Pilates. While these popular classes are often attributed benefits such as higher fat burning or better flexibility, there is only limited scientific evidence for this. The increased sweating primarily means a higher fluid loss - not automatically a greater training effect.
When Exercise Can Become Dangerous
Exercise becomes particularly critical when high temperatures, direct sun exposure, and intense exertion come together. According to the CDC, elderly people, children, pregnant women, as well as people with cardiovascular diseases or diabetes also have an increased risk of heat-related complaints.
Warning signs such as dizziness, severe headaches, nausea, muscle cramps, unusual weakness, or confusion should definitely be taken seriously. They can indicate heat exhaustion or even heat stroke - a medical emergency in which body temperature can rise above 40 degrees (104°F).
What to Watch Out For
Anyone who doesn't want to give up exercise even on hot days should adjust their training to the conditions. The early morning or late evening hours are best, when temperatures are lower. It's also worth reducing pace and training duration and paying attention to adequate hydration.
Light, breathable athletic clothing and shaded routes provide additional relief for the body. If dizziness, nausea, severe headaches, muscle cramps, or unusual weakness occur during training, exertion should be stopped immediately and a cool place should be sought. On particularly hot days, this also applies: Better to do a light session or take a rest day than to unnecessarily overtax the body.
