Cytokine Responses To Strenuous Exercise In Elite Athletes And Sedentary Subjects

Abstract

Several pro inflammatory cytokines induce fatigue and somnolence when administered exogenously. The involvement of TNFα and IL6 in modulation of fatigue has been indirectly suggested by several lines of clinical evidence. PURPOSE: Our main objective was to asses changes in plasma IL6 and TNFα as well as in TNFα release from Lipopolysaccharide (LPS) stimulated blood by peripheral blood mononuclear cells (PBMC's) in well-trained cyclists over a strenuous exercise session. Our second objective was to compare plasma IL6 and TNFα as well as the TNFα release from LPS stimulated blood by PBMC's in well-trained cyclists with sedentary subjects. METHODS: Eight well-trained cyclists performed a maximal incremental exercise test followed by a strenuous exercise protocol. Nine sedentary subjects performed a maximal incremental exercise test as well. Blood samples were obtained before, during and after the exercise session. Concentrations of plasma IL6 and TNFα as well as TNFα release from LPS stimulated blood by PBMC's were measured. RESULTS: Plasma IL6 was elevated after the strenuous exercise protocol in well trained cyclists (P = 0.02). The capacity of LPS stimulated PBMC's to release TNFα decreased over the maximal incremental exercise test (P = 0.05) and decreased even further over the strenuous exercise protocol (P = 0.001) in well trained cyclists whereas no changes were observed over the maximal incremental exercise test in sedentary subjects. Basal TNFα release capacity was lower in sedentary subjects compared to well-trained cyclists (P = 0.01). Basal concentrations of TNFα and IL6 were below the detection limit of 3 pg/ml. CONCLUSION: Plasma IL6 and the LPS induced capacity of PBMC's to release TNFα are affected by a strenuous cycling exercise (increased and decreased, respectively) in welltrained cyclists while these responses are absent in sedentary subjects.