Increasing running volume elicits hematological changes in trained endurance runners: A case study

Abstract

Background: Endurance running training induces several hematological changes that increase the capture, transport and delivery of the oxygen to the exercising muscles. Objective: This study aimed to verify how a dramatic increase in running volume induced new alterations in several hematological indicators in previously trained endurance runners. Methods: Three subjects (PL: 26 years, 169,5 cm; HP, 27 years, 167,9 cm; MC, 27 years, 180,7 cm) running 10-12 km/day, increased their running volume to prepare the participation in a 100-km ultra-marathon. New training program included 10-12 training sessions per week, totalizing 200-260 km. Average daily running volume was 35.8±6.2 km. The parameters analyzed were: hemoglobin, erythrocytes, hematocrit, mean cell volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), leukocytes, neutrophils, eosinophils, lymphocytes, and monocytes. Results: Erythrocyte count, hemoglobin, and hematocrit decreased 6.5%, 5.1% and 6.7%, respectively for the average of the three runners. Leukocytes, neutrophils, eosinophils, lymphocytes, and monocytes showed different alterations among participants with all the values remaining within normal reference values. Conclusion: Well-trained runners show further hematological alterations when training volume is dramatically increased, which can be seen as the specific adaptation to the new training level. It seems that hemogram is more sensitive than leucogram to the increase in running volume.