I tried working out while I had the flu. Here's why you should think twice before doing the same

For the past two days, I've been down with the flu, and yesterday, I decided to do a few jumping jacks. My reason was that I might be sick, but I still needed to keep active while nursing myself back to health. What could a little movement hurt?

Quite a lot, as it turns out.

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A few jumping jacks into my workout, I noticed my heart beating much faster than usual. Panic set in, and I had to stop and take a few deep breaths. I was confused. I'd done this exercise countless times before, so why did my body seem to be struggling with something so simple?

Curious about whether my illness had anything to do with my reaction, I decided to look into it. It turns out that exercising while you're sick can place additional demands on your body, and understanding what's happening physiologically might make you think twice before trying to squeeze in a workout between bouts of flu-induced exhaustion.

So here's more reason why you should avoid working out while you are sick.

Why does your heart beat faster when you're sick?

When you're fighting an infection, your immune system is working to defend your body. This process can trigger inflammation, fatigue and an elevated temperature. If you have a fever, your heart rate may also increase as your body works to regulate its temperature.

Add exercise to the equation, and your heart has to work harder to supply your muscles with oxygen. If you're also dehydrated, eating less than usual or running a fever, the cardiovascular demands can increase further.

This could help explain why an exercise that normally feels manageable suddenly leaves you breathless or with a racing heart. However, a rapid heartbeat shouldn't automatically be attributed to the flu. If it's unusual for you, persists after you've stopped exercising or keeps returning, seek medical advice.

Can exercising while sick make you more ill?

There's an important distinction between feeling slightly under the weather and having an illness that affects your entire body.

If your symptoms are limited to a mild runny nose or sneezing, you may be able to manage gentle movement without difficulty. But if you're experiencing flu symptoms such as fever, chills, body aches, significant fatigue or chest congestion, strenuous exercise is best avoided.

Why? Your body is already dealing with the demands of an infection. Exercising intensely can add to fatigue, increase fluid loss and make it harder to recognise when your symptoms are worsening.

There's also a more serious consideration. Viral infections can occasionally affect the heart muscle, a condition known as myocarditis. It's uncommon, but it can cause chest pain, breathlessness, palpitations and reduced exercise tolerance. This doesn't mean that exercising while sick automatically causes myocarditis; rather, it's one reason not to push through unexplained cardiovascular symptoms during an illness.

Can you sweat the flu out?

We've all heard the idea that a good sweat can help you shake off a cold. Unfortunately, sweating isn't a way to eliminate a viral infection.

Your immune system, not your workout, is responsible for fighting the virus. Exercise can temporarily raise your body temperature, but that doesn't mean you're speeding up recovery. If you're feverish, working out can increase the risk of overheating and dehydration.

Instead, prioritise rest, adequate fluids, nourishing food and sleep. These support your body while it recovers.

When is it safe to return to your workout?

Missing a few training sessions can feel frustrating, particularly when you've worked hard to establish a routine. But a short break is unlikely to undo your fitness progress.

If you've had the flu, wait until your symptoms are improving overall and you've been fever-free for at least 24 hours without using fever-reducing medication before returning to normal activities. You may still be contagious, so consider others before returning to a shared gym.

When you do resume exercise, start with a short, gentle session rather than jumping straight into high-intensity training. Pay attention to how you feel during the workout and afterwards, and increase your activity gradually as your energy returns.

If you've experienced a racing heart that feels unusual, chest discomfort, significant breathlessness or dizziness, get medical advice before resuming strenuous exercise. Chest pain, severe difficulty breathing or fainting warrant urgent medical attention.

Lesson Learnt

My attempt at squeezing in a few jumping jacks while battling the flu taught me that maintaining a fitness routine isn't simply about showing up. It's also about recognising when your body needs something different.

Being consistent doesn't mean exercising through every ache, sniffle or bout of exhaustion. It means knowing when to move, when to modify your routine and when to rest.

Your fitness routine should support your health, not compete with your body's recovery. Sometimes, the most productive thing you can do for your fitness goals is give yourself permission to take a day off.