Pain, fatigue and malaise after exercise are hallmarks of ME/CFS, and their very presence greatly helps to distinguish ME/CFS from, say, major depressive disorder. Many of these symptoms can be explained by the actions of the immune system in response to over-exertion, but is there good scientific evidence to back this up?
Prof Jo Nijs and his team at Vrije Universiteit Brussel, who have received ME Research UK funding for several studies in the past, have just completed a systematic review of the scientific literature (see report) on exercise-induced immunological changes in ME/CFS patients. In total, they found 23 relevant case control studies which had addressed the issue using standardized exercise protocols in a laboratory setting.
Overall, compared to the normal immune response to exercise in healthy people, ME/CFS patients had more pronounced responses in 3 key areas. First, they respond to strenuous exercise with a slow but stronger increase in blood complement C4a levels – and 2 independent studies have confirmed the relationship between an altered complement response and post-exercise malaise. Next, there is accumulating evidence that oxidative stress following exercise occurs earlier and lasts longer in ME/CFS patients, as our studies at the University of Dundee have shown. Last, there is some evidence of post-exercise increases in immune cell gene expression (specifically in interleukin-10 and Toll-like receptor genes).
A biological signature or clinical thumbprint for ME and CFS is the holy grail, and post-exercise immune changes could well be an key component.
Source: Altered immune response to exercise in patients with chronic fatigue syndrome/myalgic encephalomyelitis: a systematic literature review. Nijs J, et al. Exerc Immunol Rev, 2014; 20: 94-116. Read more (full text).