title: Effect of Acute Exercise on Fatigue in People with ME/CFS/SEID: A Meta-analysis.
abstract: A prominent symptom of myalgic encephalomyelitis, chronic fatigue syndrome, or systemic exertion intolerance disease (ME/CFS/SEID) is persistent fatigue that is worsened by physical exertion. Here the population effect of a single bout of exercise on fatigue symptoms in people with ME/CFS/SEID was estimated and effect moderators were identified.
  
  
  
  Google Scholar was systematically searched for peer-reviewed articles published between February 1991 and May 2015. Studies were included where people diagnosed with ME/CFS/SEID and matched control participants completed a single bout of exercise and fatigue self-reports were obtained before and after exercise. Fatigue means, standard deviations, and sample sizes were extracted to calculate effect sizes and the 95% confidence interval. Effects were pooled using a random-effects model and corrected for small sample bias to generate mean Δ. Multilevel regression modeling adjusted for nesting of effects within studies. Moderators identified a priori were diagnostic criteria, fibromyalgia comorbidity, exercise factors (intensity, duration, and type), and measurement factors.
  
  
  
  Seven studies examining 159 people with ME/CFS/SEID met inclusion criteria, and 47 fatigue effects were derived. The mean fatigue effect was Δ = 0.73 (95% confidence interval = 0.24-1.23). Fatigue increases were larger for people with ME/CFS/SEID when fatigue was measured 4 h or more after exercise ended rather than during or immediately after exercise ceased.
  
  
  
  This preliminary evidence indicates that acute exercise increases fatigue in people with ME/CFS/SEID more than that in control groups, but effects were heterogeneous between studies. Future studies with no-exercise control groups of people with ME/CFS/SEID are needed to obtain a more precise estimate of the effect of exercise on fatigue in this population.
authors.affiliation: 1Department of Neurology, Oregon Health and Science University, Portland, OR; 2Department of Kinesiology, University of Georgia, Athens, GA.
authors.forename: Bryan D
authors.initials: BD
authors.lastname: Loy
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: O'Connor
authors.forename: Rodney K
authors.initials: RK
authors.lastname: Dishman
mesh_terms: D015444:Exercise / Q000502:physiology; D005081:Exercise Therapy; D015673:Fatigue Syndrome, Chronic / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans