There is a wide body of literature reporting red blood cells (RBC) hemolysis as occurring after various forms of exercise. Whereas the trauma associated with footstrike is thought to be the major cause of hemolysis after running, the influence of insole materials on hemolysis during running has not been thoroughly addressed. The purpose of this study was to investigate the influence of insole cushioning on hematological responses during running. Eight male students completed a 10-km run on a paved road (75-85% heart rate max) wearing either normal (N) or soft (S) insole in the same running shoes in random order one month apart. Running time and total steps during the 10-km run were recorded, while RBC, hematocrit, hemoglobin, haptoglobin, lactate concentrations, and creatine kinase (CK) activities were measured immediately before (pre), immediately after (post), and 1 and 24 hrs after the 10-km run. There were no significant differences in running time, total steps during the 10-km run, and in blood lactate concentrations before and after the 10-km run between N and S insole trials. Plasma haptoglobin concentrations tended to decrease 1 hr after the 10-km run and to go back to the pre values in both trials. Although a significant (p<0.05) decrease was found in N trials 1 hr after the 10-km run compared to the pre values, no significant change was found in S trials. RBC, hemoglobin concentrations, and hematocrit increased immediately after the 10-km run, and fell progressively less than the pre values. In N trials, a significant (p<0.05) decrease was observed 24 hrs after the 10-km run compared to the pre values in either hemoglobin concentrations or hematocrit, but did not change significantly in S trials. In all of these hematological parameters no significant difference was observed between N and S insole trials. The 10-km run in this study, irrespective of insole type, showed a significant increase (p<0.001) in CK activities 24 hrs after the run compared to the pre values, with no significant differences between different types of insole.
　These results suggest that, whereas general circulatory trauma to RBC associated with running may result in some exercise-induced hemolysis, insole cushioning reduces mechanical trauma associated with footstrike and attenuates hemolysis during running.

DESCENTE SPORTS SCIENCE Vol.25/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE