Flu symptoms after exercising

Dr. Jen Tan

19 August 2014

Exercise and the immune system

We hear it all the time: we should exercise more if we want to stay healthy; exercise strengthens our immune system; and it helps us to maintain a healthy weight.

How does it feel, then, when you finish a workout feeling worse than before? Experiencing flu symptoms after exercise is not uncommon, but can be very disconcerting.

Causes of flu symptoms after exercise

There are several reasons why we may experience flu-like symptoms after exercise, including:

Human Growth Hormone – this is a hormone released during exercise to repair muscle and encourage tissue growth. This hormone is vital for proper functioning of our muscles. However, it can make us feel nauseous, and after an intense training session, excess amounts of this hormone are released, making us suffer this symptom.

Dehydration – even if we keep drinking plenty, it is easy to become dehydrated when we exercise, as we lose fluid through sweat and our breath. Dehydration can cause our muscles to feel weak and can result in a headache and dizziness.

Poor nutrition – what you eat feeds your muscles and organs. This means that if you haven’t eaten enough of the right type of food before exercising, then you may struggle to fuel your body during exercise. This can leave you feeling nauseous, fatigued and dizzy.

Flu virus – the flu is caused by the influenza virus, not by exercise. However, a very intense out-of-the-blue bout of exercise may cause your immune system to temporarily weaken, as energy is diverted from it to muscle function. If your symptoms persist and worsen, it may be that you have been hit by a virus

Chronic Fatigue Syndrome or Fibromyalgia– if you experience fatigue and other flu-like symptoms every time after exercise, even if it is only mild, then this may be an indication of a more serious health concern such as Fibromyalgia or Chronic Fatigue Syndrome. Persistent symptoms like this should be checked by a doctor.

Tips to reduce flu symptoms after exercise

Finding the cause of your flu-like symptoms after exercise is the first step towards finding an effective treatment. After a doctor has ruled out any underlying health concerns, often a few simple changes will help to minimise these symptoms.

When you exercise, micro-tears occur in your muscles, and when your body repairs these tears, certain toxic substances are released. These substances can cause aching muscles and other flu like symptoms. Look after your muscles by ensuring you have a proper warm up and warm down when exercising, and if possible try to work in a massage if you are training hard as this will help to reduce micro-tearing and subsequently reduce flu-like symptoms.

Although some people prefer exercising on an empty stomach, remember that doing too much without proper nutrition and hydration can leave you feeling weak. You do not want to eat a huge meal before going for a jog, but allowing a light meal of carbohydrates to settle is often recommended as this gives you slow-release energy. It is also important to eat enough protein for muscle function. Taking a bottle of water with you when exercising (and drinking from it) will help to keep your muscles hydrated throughout your workout.

If you are going to embark on an intense exercise programme, and want to boost your immune system so that you do not pick up bugs, taking a herbal supplement such as Echinacea may help to support your immune system. This herb will also help you to recover more quickly from colds and flu enabling you to get back to exercising as soon as possible.



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  • Dot's photo avatar
    Dot — 28.02.2018 22:06
    Hi I am having problems of cold and flu symptoms after doing aerobic exercises,and horse riding when I have been working hard. Is there anything I can do to stop these symptoms please


    • Jen Tan's photo avatar
      Jen Tan — 01.03.2018 08:11
      Hello Dot. The tips on this page should give you a starting point. In addition, you could be deficient in magnesium and you might also wish to try a supplement such as the A.Vogel Balance Drink which many find useful for recovery after exercise.https://www.avogel.co.uk/food/products/balance-mineral-drink/


    • thulani's photo avatar
      thulani — 20.03.2018 17:25
      I just started exercising in few weeks and I caught flu afterwards my worry is that I'm positive. What could be the cause because I'm taking my treatment well?


    • Jen Tan's photo avatar
      Jen Tan — 21.03.2018 13:36
      Hello Thulani. Exercise, if the body is not used to it, can depress the immune system temporarily. If you are more prone to infection as a result of other causes, exercise might exacerbate the situation. One reason might be that you have another underlying infection depressing your immune system. Your doctors should be able to help you work out the precise factors, in your specific case.


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