Exercise

Exercise is any movement or activity considered to contribute to general health and well-being. Exercise may be recommended as part of a wellness regimen in chronic illness. However, exercise intolerance is a central feature of ME/CFS, and patients show multiple documented abnormal responses to exercise. Rather than increase health and well-being, ME/CFS patients report that increased activity has reduced their physical and cognitive capacity over time, sometimes permanently.

Physiological effects of exercise
Exercise causes a variety of temporary physiological changes in healthy people. This includes an increase in respiratory rate, heart rate, and blood pressure in order to keep up with higher energy demands. The chemical reactions that break down nutrients -- glycolysis, the citric acid cycle, and the electron transport chain -- move more rapidly to liberate energy, and blood flow to muscles should increase. In healthy individuals, the amount of oxygen and carbon dioxide present in the blood should not alter significantly.

Immune system
In healthy people, exercise induces a variety of temporary changes to immune markers. Immediately after exercise, natural killer cell activity is decreased and Leukotriene B4 (LTB4) increase, along with the LTB4/PGE2 ratio. Exercise elevates levels of prostaglandin E2 (PGE2) for up to five days.

Infection
Several studies of a mouse model of Coxsackie B3 myocarditis have found that exercise increases the virulence of the infection and results in poorer outcomes.

Neurotransmitters
Acetylcholine, an important neurotransmitter that regulates immune response and muscle strength, decreases during exercise.

Post Exertional Malaise


ME patients who exercise are likely to experience Post-exertional malaise, a worsening of symptoms following physical, cognitive, or sensory exertion.

Read the main page: Post-exertional malaise.

Pain threshold
Pain thresholds, or the point at which a stimulus becomes painful, drop in people with CFS (as per the Fukuda criteria) after graded exercise. In healthy controls, pain thresholds rise. This phenomenon has been attributed to a dysfunction of the central anti-nociceptive mechanism in CFS patients.

Immune System
Histamine, a chemical that is released in response to cellular damage and inflammation, is released during exercise in healthy individuals. The histamine dilates blood vessels in order to deliver nutrients to working muscles. However, patients with ME may experience increased histamine release due to increased mast cell populations at baseline.

Microbiome
A small study of ten CFS patients found significant changes in the composition of the microbiome and increased bacterial translocation (movement from the intestine into the bloodstream) following exercise. The study found increased Clostridium in the blood fifteen minutes after exercise and increased Bacilli 48 hours later.

Musculature
Exercise has also been found to induce both early and excessive lactic acid formation in the muscles with reduced intracellular concentrations of ATP and acceleration of glycolysis. Several studies have found abnormal increases in plasma lactate following short period of moderate exercise that cannot be explained by deconditioning. There is evidence of abnormalities in pH handling by peripheral muscle, and possible evidence of an increased acidosis and lactate accumulation.

There is also evidence of loss of capacity to recover from acidosis on repeat exercise.

Finally, there is evidence of abnormalities of AMPK activation and glucose uptake in cultured skeletal muscle cells in ME/CFS patients.

Gene expression
There is evidence of increased expression of certain genes following muscular exertion. A 2011 study found that moderate exercise in CFS increased the expression of 13 genes (sensory, adrenergic and 1 cytokine) for 48 hours, and the increases correlated with fatigue and pain levels (see graph at right).

Second day exercise test
The seminal study on the response by CFS patients to a 2-day cardiopulmonary exercise test was published by Mark VanNess, Christopher Snell and Staci Stevens in 2007: "Diminished Cardiopulmonary Capacity During Post-Exertional Malaise". While people with CFS responded similarly to healthy controls on a first test, on a follow-up 24 hours later, they were unable to replicate their original normal results. Instead, they had significantly lower values for VO2 peak and AT; these differences could be used to identify the CFS patient over 90% of the time. A repeat study in 2013 confirmed these results.

In a confirmation study, Doctor Betsy Keller also found that patients could not repeat their performance on a second cardiopulmonary exercise test performed a day after the first.

A review by Nijs et al. found that multiple studies showed reduced peak heart rate, reduced endurance, reduced peak work rate, reduced peak oxygen uptake, lower blood lactate values, and an increased respiratory exchange ratio in people with ME, ME/CFS, or CFS; see 'Oxidative impairment' below.

It is important to note that CPET testing oxygen uptake (VO2), carbon dioxide output (VCO2), tidal volume (VT), blood pressure, and oxygen saturation are objective measures, and cannot be invalidated with inadequate effort.

Oxidative impairment
DeBecker et al (2000) and VanNess et al (2003) found low VO2 during exercise testing; Fulle et al. (2000) demonstrated oxidative damage to DNA ; and Wong et al. (1992) showed defects in oxidative metabolism and poor recovery of ATP after exercise.

Graded exercise
Graded exercise therapy, or the incremental increase in physical activity over time, is a controversial treatment for ME/CFS, due to exercise intolerance being a central feature of the disease. See the main page for more.

Talks and interviews

 * 2009, Staci Steven speaking to CFSAC meeting (Staci Stevens)
 * 2010, Slide presentation to CFSAC (Staci Stevens, CFSAC)
 * 2012, Clinical exercise testing in CFS/ME research and treatment (Christopher Snell)
 * 2012, MECFS Alert Episode 32: Staci Stevens, Director of the Pacific Fatigue Lab (Staci Stevens, ME/CFS Alert)
 * 2012, Top 10 Things You Should Know About Post-Exertional Relapse (Staci Stevens)
 * 2013, CFS gene expression after exercise (part 1) (Lucinda Bateman)
 * 2014, Mark VanNess 'Exercise and ME/CFS' at Bristol Watershed. Part One (Mark VanNess)
 * 2015, 72. Gene-expression and exercise / Gen-expressie en inspanning – dr. Lucinda Bateman (Lucinda Bateman, Science for Patients)
 * 2016, Dr. Mark Van Ness, "Expanding Physical Capability in ME/CFS" Part 1 (of 2) (Mark VanNess)
 * 2016, Dr. Mark Van Ness, "Expanding Physical Capability in ME/CFS" Part 2 (of 2) (Mark VanNess)

Notable studies

 * 2011, PACE trial
 * 2011, Tired of being inactive: a systematic literature review of physical activity, physiological exercise capacity and muscle strength in patients with chronic fatigue syndrome (Abstract)
 * 2016, Effect of Acute Exercise on Fatigue in People with ME/CFS/SEID: A Meta-analysis
 * 2016, Cochrane meta-analysis
 * 2017, Neural consequences of post-exertion malaise in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Learn more

 * 2011 - ME/CFS and Exercise: The VO2 Max Based Exercise Program, A Personal View by Dan Moricoli
 * Autumn 2011 - Loss of capacity to recover from acidosis on repeat exercise in chronic fatigue syndrome: a case–control study, an essay for ME Research UK
 * 2014 - ME/CFS and Exercise: VO2 Max Testing with Nancy Klimas M.D. - PREVIEW (this is a preview of a pay-per-view video)
 * May 16, 2014 - Sufferers of chronic fatigue, fibromyalgia have hope in new diagnostic tool by Wendy Leonard for Deseret News
 * Jan 17, 2015 - Dr. VanNess on recent press reports by Sally Burch in Just ME blog
 * Nov 7, 2015 - Deviant Cellular and Physiological Responses to Exercise in Myalgic Encephalomyelitis and Chronic Fatigue Syndrome by Frank N.M. Twisk, and Keith J. Geraghty
 * April 2015 - Objective Evidence of Post-exertional “Malaise” in Myalgic Encephalomyelitis and Chronic Fatigue Syndrome by Frank N.M. Twisk
 * Dec 19, 2015 - Exercise alteration of the CFS Microbiome from CFS Remission blog
 * Jan 2016 - Review Article: Understanding Muscle Dysfunction in Chronic Fatigue Syndrome by Gina Rutherford, Philip Manning, and Julia L. Newton
 * Feb 10, 2016 - Lost in Translation - The ME-Polio Connection and the Dangers of Exercise by Nancy Blake for ProHealth
 * Jul 6, 2016 - Australian metabolomics study of young women with ME/CFS (CCC) by Sasha Nimmo for ME Australia
 * Aug 12, 2016 - Neuromuscular Strain in ME/CFS – Research Study Conclusion in Solve ME/CFS Initiative Newsletter
 * Oct 2, 2017 - For People With Chronic Fatigue Syndrome, More Exercise Isn't Better - by Michaeleen Doucleff for Shots: Health News From NPR