Evaluation of immune response after moderate and overtraining exercise in wistar rat

Objective(s): The effect of prolonged overtraining on cytokine kinetics was compared with moderate exercise in the present study. Materials and Methods: Male Wistar rats were randomly divided into control sedentary (C), moderate trained (MT), (V=20 m/min, 30 min/day for 6 days a week, 8 weeks), overtrained (OT) (V=25 m/min, 60min/day for 6 days a week, 11 weeks) and recovered overtrained (OR) (OT plus 2 weeks recovery) groups, (n=6 for each group). Immediately, 24 hr and 2 weeks (in OR) after last bout of exercise blood samples were obtained. The plasma concentrations of TNF alpha, IL-6, IL-10, IL-4 and IFN gamma were measured by ELISA method. Results: Immediately after last bout of exercise the following findings were observed; IL-6, IL-10 and TNF alpha concentrations increased in OT and OR groups compared with control (P<0.05-P<0.001). Serum level of IL-4 decreased (P<0.01) but IFN gamma increased (P<0.05) in MT group vs. control. In addition, circulatory levels of TNF alpha, IL-6, IL-10 and IL-4 were higher but the IFN gamma concentrations were lower in OT and OR groups than MT group (P<0.05-P<0.01). The IFN-gamma/IL4 ratio was significantly increased in MT (P<0.01) while it decreased in OT group. There were not statistical differences in TNF alpha, IL-6, and IFN gamma levels between different time intervals after exercise in MT, OT and OR groups. Conclusion: These data confirm a positive effect of moderate exercise on immune function and a decrease in susceptibility to viral infection by inducing Th1 cytokine profile shift. However, prolonged and overtraining exercise causes numerous changes in immunity that possibly reflects physiological stress and immune suppression.