French researchers questioned whether past experience of high-level physical activity and/or acute infection might affect the response to exercise in people with CFS.
This case-control study compared data from 43 CFS patients to results from a matched control group of 23 healthy sedentary subjects. 18 had practised high-level sport and severe acute infection had been diagnosed in nine patients. A combination of sport practice and infection was noted in 11 patients.
Tests were performed following a maximal cycling exercise test. The presence of stress factors such as acute infection and high-level sport in CFS patients were found to be associated with severe oxidative stress and the suppression of protective HSP27 and HSP70 responses to exercise.
