The aim of the study was to evaluate the cardiorespiratory parameters at rest and and as the response to very low intensity physical exercise in women with chronic fatigue syndrome (CFS).

A group of 141 women suffering from chronic fatigue synrdrome (CFS) were compared with a control group (C) of 20 women while at rest and during 4 minutes of constant exercise on a cycloergometer with no work load (work load=0 watts).

Significant differences were found during the exercise: respiratory quotient (CFS=0.9±0.09, C=0.8±0.08, p<0.05); the respiratory equivalent for oxygen (CFS=34.6±10.1, C=28.0±3.4, p<0.01) and for carbon dioxide (CFS=37.9±7.7, C=33.4±3.8, p=0.01). Differences were observed in the heart rate during the rest period (CFS=86,8±14,2 beatsmin−1, C=79.8±8.4 beatsmin−1, p=0.03). There were no significant differences in the perception of effort made during rest (CFS=10.3±3.0. C=6.2±0.6, p<0.001) and just after exercise (CFS=12.5±2.8, C=6.8±1.4, p<0.01).

It was concluded that women with chronic fatigue syndrome had less ventilatory efficiency than the controls during low intensity physical exercise. This condition could be improved through specific rehabilitation programs.