Which of the following symptoms is NOT typically associated with chronic fatigue syndrome (CFS)?

Chronic fatigue syndrome (CFS) is characterized primarily by severe fatigue that is not improved by rest and may worsen with physical or mental activity. Symptoms associated with CFS include incapacitating exhaustion, which is one of its hallmark features, along with muscle and joint pain, and sometimes fever. Rapid heart rate can occur but is not a common or defining symptom of CFS.

The correct option — rapid heart rate — typically does not align with the core symptoms recognized in current CFS diagnostic criteria. Alternative conditions or disorders might present with rapid heart rate as a symptom, but it is less characteristic of CFS itself. In contrast, fever, incapacitating exhaustion, and muscle and joint pain are all frequently reported by individuals diagnosed with CFS, making those symptoms more closely associated with the condition.