Post-Exertional Malaise and Its Symptoms and Triggers

Post-exertional malaise (PEM) describes chronic fatigue syndrome symptoms that get worse after physical or mental exertion. PEM can affect you even if the exertion is minor.

With PEM, symptoms typically worsen 12 to 48 hours after activity. PEM can last for days or even weeks. Understanding this hallmark symptom of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) can help you better understand the disease and how to manage it.

This article discusses post-exertional malaise in chronic fatigue syndrome, why it happens, and what you can do to manage it.

What Is Post-Exertional Malaise?

People with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CSF) experience a worsening of symptoms after exercise or mental exertion. The presence of post-exertional malaise is one of the key differences between ME/CSF and other conditions that cause fatigue.

PEM substantially limits the activity levels of people with ME/CFS and considerably lowers their quality of life. In severe cases, PEM can define a person's entire life.

Many healthcare providers consider PEM to be a key to diagnosing ME/CFS. PEM is also the reason why a 2015 Institute of Medicine report suggested changing the name "chronic fatigue syndrome" to "systemic exercise intolerance disease."

PEM Symtoms

PEM symptoms usually appear 12 to 48 hours after activity and can persist for days or weeks. People with ME/CFS say post-exertional malaise feels like a "crash" or a "collapse."

PEM can range from moderately stronger-than-normal symptoms to completely disabling. In a mild case, a person may have extra fatigue, achiness, and cognitive dysfunction. In a severe case, PEM can bring on intense flu-like symptoms, extreme fatigue, pain, and brain fog strong enough that it's hard to form a sentence or follow the plot of a television show.

The range of PEM symptoms can include:

• Flu-like symptoms including headaches, sore throat, muscle aches and weakness, chills, and swollen glands
• Nausea and loss of appetite
• A heavy feeling in the limbs or body
• Increased sensitivity to sound, light, or smell
• Loss of stamina and an increase in fatigue
• Dizziness
• Feeling too cold or too hot
• Ringing in the ears
• Muscle weakness, trembling, or instability
• Heart palpitations
• Burning sensations on the skin
• "Brain fog" or difficulty concentrating, focusing, and thinking
• Speech and word-finding problems
• Sleep disruptions including insomnia, nightmares, or sleeping too much
  

What Triggers Post-Exertional Malaise?

Post-exertional malaise is triggered by exercise or mental exertion. The exertion needed to trigger PEM is different for everyone.

Triggering activities don't necessarily need to be strenuous. Some people can experience PEM after minor physical exertion such as cooking, cleaning, showering, or walking. In extreme cases, PEM can be triggered after very minor activity, such as sitting up in bed for a few hours.

Mental activities that require concentration or mental calculation can also trigger PEM. Some people may even be triggered by things like:

• Social interaction
• Emotional experiences
• Sensory input such as noise or bright lights
• Changes in the weather
• Certain foods
• Stress or anxiety
  

Post-Exertional Malaise Treatment

Treating PEM begins with treating your ME/CFS. Even treatment that isn't aimed at PEM specifically may help reduce its severity.

Most people with ME/CFS say rest is the only treatment that can help manage and improve symptoms of PEM. Generally speaking, it is better to prevent PEM than to try and manage its symptoms.

Preventing Post-Exertional Malaise

If you have ME/CFS, it's important to understand your limits and triggers. Plan your activities according to what you know you can tolerate, and don't try to push yourself. It can be helpful to keep a journal that records all your activities and symptoms and how they seem to affect each other.

If your ME/CFS symptoms improve, talk to your healthcare provider about increasing your activities. They will likely suggest slow, closely monitored increases in both physical and mental activities. Exercise may be helpful for some people but not for others. Don't try to add exercise to your routine without first talking to your healthcare provider.

PEM Research and Controversy

PEM is extremely disabling, yet some healthcare providers remain skeptical that it exists. This may be in part because ME/CFS itself is a controversial diagnosis.

Activity levels can change significantly after the onset of the disease, and it can take a long time to receive a diagnosis. This further complicates the understanding of PEM.

Current diagnostic criteria require symptoms lasting at least six months. This can lead to a significant decrease in activity and physical deconditioning. Many people wait much longer than six months for a diagnosis, however.

A person who has been unable to tolerate exercise for months or years is likely to become significantly out of shape. When this person sees a healthcare provider, they may be dismissed as someone who needs to change their lifestyle rather than someone who needs to be evaluated for a chronic fatigue condition.

What the Research Says

Early research showed no significant difference in physical fitness between those with ME/CFS and healthy, deconditioned people. Later, we learned that the bodies of people with ME/CFS appear to have problems with oxygen consumption the day after exercise, which a 2015 study linked to a metabolic problem.

Some healthcare providers also say that the fear of exertion displayed by many people with ME/CFS is an irrational fear of exercise called kinesiophobia. The research in this area is somewhat mixed.

Some studies have concluded that kinesiophobia rates are high in people with this condition and that it does play a role. An older study agrees that kinesiophobia is common but states that it does not appear to determine daily physical activity. Another older study found no correlation between fear of exercise and exercise performance.

Many patients and advocates point out that fearing the repercussions of PEM is a rational response rather than a phobia.

Summary

PEM describes a worsening of the symptoms of chronic fatigue syndrome. It is triggered by mental or physical exertion. The exertion doesn't have to be excessive, and in some cases, PEM can even be triggered by something minor like taking a shower. Symptoms can include severe brain fog, flu-like symptoms, pain, and weakness.

It's better to prevent PEM than it is to treat it once it happens. Try keeping a journal of activities and symptoms so you will understand your activity limits. Talk to your healthcare provider before adding exercise to your routine.