Diminished Cardiopulmonary Capacity During Post-Exertional Malaise

ABSTRACT. Reduced functional capacity and post-exertional malaise following physical activity are hallmark symptoms of Chronic Fatigue Syndrome (CFS). That these symptoms are often delayed may explain the equivocal results for clinical cardiopulmonary exercise testing with CFS patients. The reproducibility of VO2max in healthy subjects is well documented. This may not be the case with CFS due to delayed recovery symptoms. Purpose: To compare results from repeated exercise tests as indica-tors of post-exertional malaise in CFS. Methods: Peak oxygen consumption (VO2 peak), percentage of pre-dicted peak heart rate (HR%), and VO2 at anaerobic threshold (AT), were compared between six CFS patients and six control subjects for two maximal exercise tests separated by 24 hours. Results: Multivariate analysis showed no significant differences be-tween control and CFS, respectively, for test 1: VO2 peak (28.4 ± 7.2 ml/ kg/min; 26.2 ± 4.9 ml/kg/min), AT (17.5 ± 4.8 ml/kg/min; 15.0 ± 4.9 ml/ kg/min) or HR % (87.0 ± 25.4%; 94.8 ± 8.8%). However, for test 2 the CFS patients achieved significantly lower values for both VO2peak (28.9 ± 8.0 ml/kg/min; 20.5 ± 1.8 ml/kg/min, p = 0.031) and AT (18.0