Dramatic Elevations of Interleukin-6 and Acute-Phase Reactants in Athletes Participating in the Ultradistance Foot Race Spartathlon: Severe Systemic Inflammation and Lipid and Lipoprotein Changes in Protracted Exercise

Abstract

Plasma IL-6, the serum inflammatory markers C-reactive protein (CRP) and serum amyloid A (SAA), and the tissue destruction marker-free plasma DNA, as well as the circulating lipid profile, were examined in athletes participating in the ultradistance foot race of the 246-km Spartathlon. SETTING, DESIGN, AND PARTICIPANTS: This race consists of continuous, prolonged, brisk exercise. Blood samples were obtained from 15 male athletes, who finished the race in less than 36 h, taken before, at the end of, and 48 h after the end of the race. IL-6, CRP, SAA, and free plasma DNA levels markedly increased (by 8000-, 152- 108-, and 10-fold, respectively) over the baseline at the end of the race. However, IL-6 levels returned to normal by 48 h, whereas CRP, SAA, and free plasma DNA remained elevated. The mean values of cholesterol, triglycerides, low-density lipoprotein, and apolipoprotein B decreased to a minimum value at the end of the race and remained low 48 h after the race. High-density lipoprotein levels, on the other hand, were mildly increased at the end of the race (P < 0.015) and decreased to normal 48 h after the race. Apolipoprotein AI levels decreased significantly during the time course of the exercise and remained low 48 h after the race (P < 0.001). These observations suggest that continuous, prolonged, moderate-intensity exercise is associated with markedly elevated IL-6 and acute-phase reactant concentrations, peripheral tissue damage, and significant changes in serum lipid levels. The biochemical changes observed during the Spartathlon amount to a potent systemic inflammatory response, which might explain severe cardiovascular events that occur during prolonged exercise in compromised individuals.