Abstract
Background: The chronic fatigue syndrome (CFS) is characterised by a limited exercise capacity. Studies have reported reduced muscle oxidative capacity in CFS, evidenced by abnormal acidosis during exercise and reduced aerobic capacity and exercise endit ranee.
Objective: To compare physiological responses to walking exercise in CFS subjects, sedentary controls, and clinically improved CFS subjects.
Design: Age- and sex-matched pairs, with repeated measures.
Subjects: Sixteen subjects diagnosed with CFS and 16 age- and sex-matched sedentary controls.
Measurements: Heart rate (HR), oxygen uptake (V02) ventilation (VE) and relative perceived exertion (RPE) responses to incremental walking exercise to volitional exhaustion.
Results: CFS subjects reached significantly lower HRpeak (P = 0.023) and achieved nonsignificantly (P > 0.05) lower TO2penk than control subjects. Despite no differences in submaximal exercise responses, CFS subjects reported higher RPE scores than controls (P = 0,003) at submaximal workloads. RPE scores correlated with symptomatic scores for emotionality (r = 0.642) and general fatigue (r = 0.568). Symptomatic recovery in six CFS subjects was associated with nonsignificant increases in HRpeak, VO2peak and VEpeak and nonsignificant decreases in RPE scores at submaximal workloads.
Conclusions: These data suggested that the limited exercise capacity in CFS subjects may be explained by deconditioning due to the sedentary lifestyle necessitated by the condition, coupled with an increased perception of exertion, potentially linked to psychological symptoms associated with CFS.