Metabolic And Neurocognitive Responses To An Exercise Challenge In Chronic Fatigue Syndrome (CFS)

Abstract

A comprehensive view of CFS patients during conditions of post-exertional malaise can provide an integrated perspective on the pathophysiology the illness. PURPOSE: To compare the metabolic responses and neurocognitive consequences of a maximal exercise challenge between CFS and control subjects. METHODS: Twenty (n=20) women with CFS and twenty (n=20) sedentary control subjects performed a graded exercise test to maximal exertion. Cardiopulmonary analysis was performed during the exercise test. Blood samples for plasma lactate and glucose were collected before and after the test. Nasal acoustic rhinometry (NAR) was used to measure nasal cross-sectional area and volume on both nostrils before and after the exercise test. Neurocognitive function was measured before and after the exercise test using the CalCap computer program. RESULTS: Multivariate analysis of cardiopulmonary variables found a significant difference between groups; Wilks' λ = 0.053, F = 6.393 (7, 20), p>0.01. Follow-up univariate tests with alpha levels adjusted to account for inflation of the error term indicated that CFS patients scored significantly lower on measures of peak workload (116±19 vs. 176±26 Watts), peak ventilation (70±22 vs. 102±16 L), peak VO2 (23.4±6.4 vs. 32.0±4.5 ml/kg/min), and VO2 and workload at anaerobic threshold (9.7±2.3 vs. 17.3±3.9ml/kg/min and 42±12vs. 75±21 Watts respectively). For the CalCap, a group by test (2X3) factorial MANOVA with dependent variables; simple reaction time (SRT) and three levels of choice reaction time (CRT), produced a significant main effect for group; Wilks Lambda = 0.85, F=4.76 (4, 105), p=0.001. Follow up discriminant function analysis indicated that the CRT measures were more important in differentiating CFS than was SRT. The CFS group was slower on all measures. CONCLUSION: These results indicate that exercise performance and neurocognitive abnormalities exist in CFS. The lack of any significant differences in lactate, glucose or nasal rhinometry precludes clear explanation for these differences.