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Yes. Something called “post exertional malaise” which can be tested via the Stevens Protocol.

In short, given the same exercise test two days in a row, normal people behave the same (slightly better even) but CFS patients degrade substantially.

A variety of other tests such as tilt table tests, Cardio Pulmonary Exercise Tests (CPET) and Advanced Invasive CPET are also able to diagnose physical symptoms, and sometimes even treatable sub-sets of the condition.