Managing Post-Viral Fatigue

At present there is no known cure or treatment for Post Viral Fatigue. There is unfortunately no quick fix and a return to normal health can take time. The best way to manage Post-Viral Fatigue is through awareness, pacing and lifestyle changes. Understanding fatigue and how it affects you will allow you to have better control. In addition, by recognising what exacerbates or triggers your fatigue will allow you to be able to better manage this.


The first step to managing fatigue is being aware of its cycle. Typically, people with Post-Viral Fatigue will follow a pattern known as the BOOM BUST Cycle.

The BOOM BUST cycle is detrimental to your recovery. As the cycle repeats itself, your overall capacity for activity becomes less, meaning your recovery may take longer. During the BUST phase, you usually experience a period of prolonged rest and inactivity which can lead to
deconditioning. Deconditioning can include a reduction in strength, stamina, exercise tolerance, bone density, motor control, flexibility and overall energy production in the body, meaning that daily, routine activities will require increasingly more energy. Recognising your own individual pattern of BOOM BUST can help you to break it.

This is an example of a typical BOOM BUST week:

Post-Exertional Malaise (PEM)

During a BUST phase you may experience what is known as Post-Exertional Malaise (known as PEM) which is a flare-up of symptoms. PEM is the cardinal symptom of fatigue and tends to occur when you have exceeded your current capacity and/or energy expenditure.

PEM tends to be delayed and usually presents itself around 24-48 hours after exertion. It will often require several days of recovery (BUST). 

It is important to try to minimise Post Exertional Malaise, as much as possible, as BUST periodsoften include prolonged periods of inactivity leading to further deconditioning.

The best way to minimise PEM is by staying within what is called your energy envelope.

Your Energy Envelope

A healthy person will usually have unlimited daily energy levels, however for a person with post-viral fatigue, energy levels may be significantly less than before.

Your ‘energy envelope’ is the amount of energy you have available to use per day – this will be different for everyone.

There are several different analogies which can be used to explain what is meant by the term ‘energy envelope’:

  • Money  – Picture your energy as money! Each day you get a set “allowance” to spend. Any over-spending will put you into debt meaning you will be borrowing from tomorrow.  
  • Fuel – Think of a car – it’s engine can only run if the fuel tank has enough petrol in it! When it runs out of petrol it will break down. 
  • Battery Power  – When you buy a brand new iPhone, the battery tends to last all day. When it gets a bit older however, or it gets damaged, the battery will run out more quickly and it will constantly need to be re-charged. 
Analogies can be useful for a person with fatigue when thinking about managing daily energy expenditure. Where can you or make savings? How can you keep your tank from becoming empty? What can you do to re-charge your battery? You can find your own energy envelope, and baseline level of activity, by using an Activity Diary.

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