Post exertional malaise is a familiar to many individuals with ME/CFS, and for those who have had this disease for several years or longer, it is likely to be a facet of the disease which is very disabling. Some of us have learned to live within the confines of this symptom of ME/CFS, however it does pose many unseen limitations to how an individual may participate in their activities of daily living (housework, for example) personal activities of daily living (personal care).
Malaise is the term used by the Canadian Consensus Document to describe the onset of exacerbated signs and symptoms of ME/CFS, including cognitive function deterioration, and increased pain and fatigue. The term malaise is described in most literature as a vague feeling of general unwellness. Encyclopedia.com states that malaise is a 'medical term for a general condition of unease, discomfort, or weakness' (Retrieved 10 February 2010), and the Oxford Nurses Dictionary, (4th ed.), defines malaise as 'the general feeling of being unwell. The feeling may be accompanied by a feeling of physical discomfort, and may indicate the presence of disease' (McFerran, 1998).
Individuals with ME/CFS identify this 'malaise' as the onset of exacerbated signs and symptoms of the disease, following a period of physical or mental exertion. For individuals with ME/CFS, it is common for this feeling to follow active physical exertion, such as going for a walk, hanging out the washing, cooking a meal, etc. Post exertional malaise typically lasts 24 hours or more following an activity or exercise.
For the purposes of this post, I will be using the word activity, and delineating it from the word exercise. I will use the word 'activity' to describe the engagement of the body or the mind in tasks associated with daily living, as opposed to 'exercise'; the engagement of physical training to develop fitness and improve health. I will not be addressing exercise or aerobic training.
There are physical signs associated with the symptom of post exertional malaise, which can be demonstrated by comparing an individual with ME/CFS with a healthy individual after participating in physical activity. An individual without ME/CFS will often experience anti depressant effect as a result of physical activity. This is caused by the increase of oxygen-carrying blood to the whereas individuals with ME/CFS show a decrease in oxygen and blood to the brain, which contributes to the feeling of malaise (van de Sande, 2009). Individuals with ME/CFS demonstrate hypo-profusion of blood through particular areas of the brain, which means a decreased blood flow through the brain tissue, which is further decreased as a result of physical activity (van de Sande, 2009). This is the opposite of the effect of physical activity on the brain tissue of an individual who does not have ME/CFS (van de Sande, 2009). Body temperature normally increases with physical activity, however individuals with ME/CFS demonstrate a decreased body temperature after exercise (van de Sande, 2009). A table of this can be found on page four of the Canadian Consensus document.
Although on average individuals with ME/CFS have an elevated resting heart rate, they typically demonstrate a significantly reduced heart rate when they are participating in an activity at their maximum workload. Individuals with ME/CFS also demonstrate 'an inability to reach the age-predicted target heart rates (van de Sande, 2009). Van de Sande, (2009), refers to a study completed by De Becker, et al (2000) which demonstrated that the maximum oxygen uptake and maximum workload attained by individuals with ME/CFS was approximately half that of sedentary controls. This could be attributed to autonomic dysfunction and/or heart dysfunction, which means that it is advisable for individuals who have ME/CFS not to try to attain age-predicted heart rates(van de Sande, 2009). Other dysfunctions which are common for individuals with ME/CFS to experience after physical activity include impaired cognitive function, orthostatic intolerance and gait disturbance (van de Sande, 2009).