Metabolic and cardiovascular effects of a progressive exercise test in patients with chronic fatigue syndrome

PURPOSE: To evaluate the aerobic power (as maximum volume of oxygen consumed [V̇O₂ max]) of women with chronic fatigue syndrome (CFS). PATIENTS AND METHODS: Twenty-one women with CFS and 22 sedentary healthy controls (CON) were studied at the CFS Cooperative Research Center Exercise Laboratory at the VA Medical Center, East Orange, New Jersey. Performance was measured on an incremental treadmill protocol walking to exhaustion. Expired gases were analyzed by a metabolic system, heart rate was recorded continuously, and ratings of perceived exertion (RPE) were taken at each workload. The groups were divided into those who achieved V̇O₂ max (CFS-MAX and CON-MAX) and those who stopped at a submaximal level (CFS-NOMAX and CON-NOMAX) by using standard criteria. RESULTS: Seventeen CON and 10 CFS subjects achieved V̇O₂ max. The V̇O₂ max (mL/kg/min) of the CFS-MAX (28.1 ± 5.1) was lower than that of the CON-MAX (32.1 ± 4.3, P = 0.05). The CFS-MAX achieved 98 ± 11% of predicted V̇O₂ max. The CFS group had a higher RPE at the same absolute workloads as controls (P < 0.01) but not the same relative workloads. CONCLUSION: Compared with normal controls, women with CFS have an aerobic power indicating a low normal fitness level with no indication of cardiopulmonary abnormality. Our CFS group could withstand a maximal treadmill exercise test without a major exacerbation in either fatigue or other symptoms of their illness.