When you’re unwell, deciding whether to exercise can be difficult. If you start your exercise routine too early, your illness will worsen. So, what are the risks of working out while sick? When can you exercise with a cold? What guidelines can you use to return to the gym and sport safely?      

What happens to your immune system when you exercise  

Generally, exercise has a beneficial effect on your immune system. We know that exercise can enhance your immune system function. It helps circulate immune cells more efficiently throughout your body, potentially aiding in faster recovery. Those who exercise generally get less sick than those who don’t. However, intense exercise without rest can have a reverse effect on the immune system. People who exercise excessively are not protected and can experience more infections. So, there is a sweet spot with exercise. 

Risks of Working Out While Sick 

Exercising while you’re sick can lead to several problems that may make your illness worse. First, intense exercise can suppress your immune system temporarily, making it harder to fight infection and may prolong illness. Moreover, in those with serious infections, exercising while sick can lead to severe complications, such as myocarditis (inflammation of the heart muscle) in the case of viral infections. Finally, when you’re not feeling well, your coordination and focus can be compromised, increasing the risk of musculoskeletal injury during exercise. A prime example would be suffering from a severe knee injury while playing football or netball because your coordination is impaired. 

When working out while sick is ok vs when it’s not

Doctors often use the “neck rule” when deciding when someone sick can exercise.

Light to moderate exercise is generally considered safe if your symptoms are above the neck, such as a runny nose, nasal congestion, or a mild sore throat. Walking, gentle yoga, or a light jog can help boost your immune system and improve your mood without overtaxing your body. However, it is critical to listen to your body and rest more if you feel unwell. 

However, it’s best to skip the workout if your symptoms are below the neck, including chest congestion, a hacking cough, stomach issues, or fever. Engaging in physical activity under these conditions can worsen your symptoms and lead to complications such as pneumonia or myocarditis, which could potentially be life-threatening. 

Examples of symptoms that require you to rest include the following:

  • Persistent fever above 38 degrees 
  • Severe muscle aches or weakness
  • Chest congestion or a productive cough
  • Difficulty breathing or chest pain
  • Gastrointestinal issues like vomiting or diarrhoea
  • Extreme fatigue
  • Feeling faint or dizzy 

So, using this simple “neck rule”, you can safely navigate exercise while sick. 

 
young lady who is running while sick with a temperature

Tips to Keep Healthy When Working Out While Sick: 

Listen to your body

First and foremost, it’s essential to listen to your body. If you feel too tired, it’s a sign that you should rest. Exercise puts additional stress on your body, and if your body is already fighting an illness, adding more stress can prolong your recovery time.

More sleep is essential

Sleep is crucial for your immune system to function effectively. Make sure to get adequate rest. Generally, you need more sleep when you are unwell to assist in your recovery. 

Keep well hydrated and eat healthily

Drink plenty of fluids, such as water, herbal teas, and clear broths, to stay hydrated and flush out toxins. Focus on nutrient-dense foods that can provide your body with the vitamins and minerals it needs to fight off the infection. Use over-the-counter medications such as decongestants, paracetamol, or ibuprofen, but don’t excessively consume these products if you’re exercising. 

Reduce exercise intensity and duration 

Most doctors suggest reducing the duration and intensity of exercise while you’re unwell. Generally, you should reduce both duration and intensity by 50% while you have an acute infection. As you feel better, you can increase duration first before increasing intensity. However, you should keep listening to your body and be prepared to step back if you’re feeling tired or more unwell. 

Prevention is Better Than Cure: How to Keep Healthy While Exercising 

Generally, exercising keeps us healthy by boosting our immune system. However, there are a few tips to keep us well while exercising. 

First, you should avoid sudden increases in intensity and duration of exercise. Generally, you should avoid increases of greater than 10% per week. Gradually increasing your exercise or sport will keep your immune system functioning, fight off infections, and reduce the risk of tendon, muscle or joint injuries. Second, allow adequate time for rest and recovery between intense workout sessions. Overtraining can weaken your immune system and increase the risk of infections and other health issues. Finally, practice good hygiene by washing your hands regularly, wiping down gym equipment before and after use, and avoiding touching your face during workouts.

Other Frequently Asked Questions about Working Out While Sick:

Can I exercise if I have a fever? 

Generally, we suggest you avoid exercise when your temperature is above 38 degrees (104 F). Fever elevates the heart rate and dehydrates the body, making exercise more risky as it leads to more stress on your heart and other organs. Keep well hydrated, take soothing temperate baths, and take over-the-counter medications such as paracetamol or ibuprofen. Avoid aspirin, especially in children or teenagers, as there is a link between taking aspirin and a rare and severe liver inflammation called Reye’s syndrome. 

Can you get a fever from working out?

A workout does not typically cause a fever, but it can lead to conditions that may result in a fever. Heat exhaustion and heat stroke occur while exercising in hot and humid environments. 

Is running safe when you’re sick?

We use the “neck rule” to decide whether you can run while sick. For symptoms above the neck, you can run at about 50% of your usual intensity and duration. However, you should avoid running if you have symptoms below the neck, such as fever, diarrhoea, nausea, vomiting, muscle aches, or extreme fatigue. 

Why do I get a cold after working out? 

Intensive exercise can temporarily suppress your immune system for 24 hours. So, an intensive workout such as a HITT class or interval running can leave you susceptible to infections, including colds. To prevent infection, take precautions after an intense workout, including keeping warm and washing your hands. 

Can you exercise while on antibiotics?

The primary consideration is the illness for which you are taking antibiotics. If your body is fighting a bacterial infection, rest might be more beneficial than exercise, especially in the early stages of recovery. Light exercise can sometimes be helpful if your symptoms are mild and you feel up to it, but strenuous activities should be avoided.

Also, different antibiotics can have varying side effects, affecting your ability to exercise. For example:

  • Tetracyclines (e.g., doxycycline) can cause photosensitivity, increasing the risk of sunburn. If you exercise outdoors, use sun protection or avoid exercising in the middle of the day when the sun is hottest. 

Final Word from Sportdoctorlondon on Working Out While Sick

Deciding whether to exercise when unwell requires careful consideration of your symptoms. Use the “neck rule” to help you decide. Light exercise might be beneficial if you have mild, above-the-neck symptoms. However, rest is crucial when dealing with more severe illnesses or symptoms below the neck. Sometimes, the best exercise you can do is to rest and allow your body to heal.

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