Every doctor recommends some type of physical activity to be added to your daily routine to protect yourself from colds and flu or any other health issues as it is an ultimate form of an immunity booster. Studies have proven that moderate aerobic exercise done regularly for around 30 to 45 minutes like walking, biking or running can shield you from more than half of your risk related to respiratory infections and other common winter illnesses.

Exercise can help improve our immune system as it helps to increase the circulation of immune cells along with our blood. But it becomes a completely different story once you have contracted a respiratory illness and are feeling physically unwell. It is to be noted that exercise is a great method of prevention, but not a very effective treatment.

Research from Ball State University shows that moderate exercise does not have an impact on the course or severity of the cold. Moreover, if you are experiencing symptoms above your neck like sinus and nasal congestion, sore throat, etc, mild exercise does not make any difference so, it would not be of any harm in continuing to work out. But if the flu symptoms are experienced around the chest or below, like congestion or muscle aches, if it is communicable, like COVID-19 19 or if it is other forms of fever-causing systemic infections, exercise will only have negative effects. 

Should you exercise with the flu?

Mild to moderate physical activity is usually not harmful during a common cold with no fever. Exercise might aid in opening your nasal passages and providing temporary relief from nasal congestion. To help you decide, consider this general guide for exercise and illness:

"Above the neck” rule: 

Exercising after catching a cold is usually alright if the signs and symptoms experienced are all “above the neck”, such as runny nose, nasal congestion, sneezing and minor sore throat. It is a good idea to reduce the intensity and duration of your workout for example, instead of going for a run, take a walk. But when the signs and symptoms are “below the neck,” such as chest congestion, a chronic cough or an upset stomach or a systemic infection, do not exercise as it will do more harm than good. As exercising demands more energy, the body cannot focus much on building your immunity, thus retarding the healing process.

Fever

In case of a high temperature or fever, you should avoid exercising. This is because working out elevates your body temperature, which can be troublesome as your ability to maintain a stable temperature is already impaired. Studies done on animals indicate that high-intensity exercises done with a fever can deteriorate the illness and in extreme cases, it could be life-threatening. It is well known that your precision and coordination decrease during fever which can lead to injury.

Flu

It is strictly recommended to stop exercising when you contract the flu (or lung infection) with symptoms such as fever, body aches, fatigue, a headache around and behind the eyes, and loss of smell. There have been cases in which exercising with the flu caused myocarditis (inflammation of the heart). If you experience symptoms such as chest pain, rapid heart rate, shortness of breath, and fatigue while working out when sick, you should call your doctor immediately as it might be myocarditis.

Flu can also be communicable, such as COVID-19 or other contagious illnesses, so it is not recommended to work out in public places and avoid it completely if any symptoms of fever, fatigue or widespread muscle aches are experienced.

After your recovery, check once with your doctor if it's safe to restart your exercise.

Stomach Flu

People with gastroenteritis or “stomach flu” should not be carrying out any strenuous exercise as it will only make your symptoms worse and will lead to dehydration. You should not exercise as your body is not able to take up enough food or water, which will anyway make you low on energy for a workout. Therefore until you begin to recover, do not exert your body. 

Conclusion:

In conclusion, listen to your body, let it be your guide. So, on days you don’t feel too well, take some rest. Taking off while you are sick will not affect your performance but rather help you get back to it sooner. Exercising with a mild cold might prove to help clear your sinuses. However, it is advisable to drop the intensity and duration of your workout while you feel physically unwell. For example, choose walking instead of running, lift lighter weights, etc. Once the body shows signs of recovery you can gradually resume your normal workout routine. Talk to your physician when in doubt. They might even advise on specific exercises you can do to recover faster.