[This is a case study on graded exercise. You can read the full report here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1280066/pdf/11220065.pdf]
Source: Sharma A, Oyebode F, Kendall MJ, Jones DA. Recovery from chronic fatigue syndrome associated with changes in neuroendocrine function. J R Soc Med. 2001 Jan;94(1):26-7. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1280066/ (Full article)