Cytokine and oxidative responses to maximal cycling exercise in sedentary subjects.

Introduction: The simultaneous determination of the time course and magnitude of oxidative stress indicators and cytokine changes elicited by maximal incremental exercise has not yet been published for healthy sedentary subjects.

Purpose: The determination of normal exercise-induced changes in oxidant-antioxidant status and plasma cytokine represents a fundamental step before exploring patients suspected of altered biochemical responses.

Methods: Fifteen healthy sedentary subjects performed an incremental cycle exercise until volitional exhaustion with measurement of maximal oxygen uptake (VO2max), two cytokines (IL-6 and TNF-alpha), and three indicators of oxidative stress (plasma thiobarbituric acid reactive substances (TBARS), reduced erythrocyte glutathione (GSH), and reduced plasma ascorbic acid (RAA)).

Results: At VO2max, we noted a significant increase in plasma IL-6 and TNF-alpha concentrations, concomitant with the decrease in plasma RAA level. Besides, the plasma TBARS increase and erythrocyte GSH decrease respectively occurred at the 5th and 10th minutes of recovery. The exercise-induced variations of all blood indicators were completed within the 20th minute of the recovery period. We found significant positive correlations between VO2max and the peak increases in IL-6 (but not TNF-alpha) and TBARS. The corresponding variations of IL-6 and TBARS were also correlated.

Conclusion: This study indicates that blood samples for analyses of changes in both oxidant-antioxidant status and cytokine levels in response to maximal cycling exercise must be performed within the first 20 min of the postexercise recovery period.