Abstract
PURPOSE:
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.
METHODS:
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% CI. Effects were pooled using a random-effects model and corrected for small-sample bias to generate mean [INCREMENT]. Multi-level regression modeling adjusted for nesting of effects within studies. Moderators identified a priori were diagnostic criteria, fibromyalgia comorbidity, exercise factors (intensity, duration, type) and measurement factors.
RESULTS:
Seven studies examining 159 people with ME/CFS/SEID met inclusion criteria, and 47 fatigue effects were derived. The mean fatigue effect was [INCREMENT] = 0.73 (95% CI = 0.24, 1.23). Fatigue increases were larger for people with ME/CFS/SEID when fatigue was measured four or more hours after exercise ended rather than during or immediately after exercise ceased.
CONCLUSIONS:
This preliminary evidence indicates that acute exercise increases fatigue in people with ME/CFS/SEID more than 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.
