November 14, 2026, 5:10 pm | Read time: 4 minutes
Your nose is running and your throat is scratchy–but you have training scheduled today. Should you push through or take a break? And is the old rule “sweat it out” even true? FITBOOK explains with sports scientist and health expert Dr. Dr. Michael Despeghel when exercise might still be okay during an infection, which symptoms should stop you, and why misguided ambition can be dangerous in the worst case.
Expert does not advise against exercise in general
Despeghel does not impose a general ban on exercise as soon as your nose starts running; on the contrary, light activity could activate the body and the immune system, thereby helping to fight off potential pathogens. “In the face of an impending infection, this can strengthen the defense system,” the expert summarizes. Ideally, this could prevent a full-blown cold from developing. However, it is important to emphasize that moderate activity is what is meant by exercise.
Mild symptoms where training is still allowed
Among the mild symptoms where moderate exercise can even be beneficial are:
- Scratchy throat
- Runny nose
- Heavy legs
In these cases, Despeghel recommends light physical activities such as walking, cycling, or swimming. Extreme endurance and strength sports should be avoided, as the body and immune system are already weakened by cold symptoms.
“Slow down and reduce the usual physical exertion,” is the expert’s advice. How much to reduce it should always be based on your own well-being. In cases of extreme discomfort and fatigue, the rule is: bed rest, snuggle under the covers, and recover.
Symptoms where you should not exercise at all
For some illnesses, it is essential to completely refrain from exercise. These include:
- Fever
- Viral infections
- Bacterial infections
- Flu
- Sore throat
“Elevated temperature and fever from 100.4 degrees Fahrenheit are clear exclusion criteria for any physical exertion and activity,” warns Dr. Dr. Despeghel.
Getting fit for sports with medication? Absolutely not!
Some overly ambitious (amateur) athletes might consider using stimulants and painkillers to get fit despite symptoms. Especially when a workout seems impossible without medication. According to the health expert, this is not a good idea. In the worst case, it could lead to myocarditis, which can be life-threatening. Therefore, Dr. Dr. Despeghel advises “a sports break of up to three weeks after the illness,” especially if you have had the flu with fever.
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What health consequences there are
As mentioned, engaging in physical activity despite illness can lead to myocarditis. This can have fatal consequences, as myocarditis is often detected too late. Unfortunately, it is not the only condition that can develop from exercising while sick.
It can also lead to chronic fatigue syndrome (CFS).1 This condition lasts at least six months and can burden sufferers for several years.2 The syndrome weakens the immune system, and the body often develops strong negative reactions to stress or similar stimuli. This can even lead to patients declaring disability or requiring care assistance during the affected period.
Conclusion: Runny nose yes, fever no
With a mild runny nose and otherwise good general condition, exercise doesn’t have to be completely off the table–the key is to reduce intensity. Fever, severe fatigue, or a pronounced feeling of illness are clear stop signals. Then the body needs rest instead of training stimuli. A few days off won’t derail your fitness. But misguided ambition can seriously endanger your health.
Dr. Dr. Despeghel is a health coach, sports scientist, and author of numerous books. The health expert regularly lectures at universities in Germany and abroad and is a board member of the German Society for Preventive Men’s Medicine.