Considered by many to be the gold standard for determining disability, cardiopulmonary exercise testing (CPET) uses objective measures to accurately assess an individual’s capacity for work. It is therefore applicable to any condition where fatigue and reduced physical functioning are significant symptoms. CPET can also assist in diagnosing a variety of medical disorders including myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and fibromyalgia. The 2 day testing protocol is particularly helpful in documenting post-exertional malaise (PEM) and symptom exacerbation following physical activity. Testing is performed on a stationary bicycle with resistance added incrementally to keep tests approximately 8-12 minutes. Because CPET results are virtually impossible to fake, they can be a valuable adjunct to any medical and/or legal argument.