Purpose: This investigation assessed the effects of training intensity and ground surface type on hemolysis, inflammation, and hepcidin activity during running.
Methods: Ten highly trained male endurance athletes completed a graded exercise test, two continuous 10-km runs on a grass (GRASS) and a bitumen road surface (ROAD) at 75%-80% peak VO2 running velocity, and a 10 x 1-km interval running session (INT) at 90%-95% of the peak VO2 running velocity. Venous blood and urine samples were collected before, immediately after, and at 3 and 24 h after exercise. Serum samples were analyzed for circulating levels of IL-6, free hemoglobin (Hb), haptoglobin (Hp), iron, and ferritin. Urine samples were analyzed for changes in hepcidin expression.
Results: After running, the IL-6 and free Hb were significantly greater, and serum Hp was significantly lower than preexercise values in all three conditions (P < 0.05). Furthermore, IL-6 levels and the change in free Hb from baseline were significantly greater in the INT compared with those in the GRASS (P < 0.05). There were no differences between the GRASS and ROAD training surfaces (P > 0.05). Serum iron and ferritin were significantly increased after exercise in all three conditions (P < 0.05) but were not different between trials.
Conclusion: Greater running intensities incur more inflammation and hemolysis, but these variables were not affected by the surface type trained upon.