Hematological Changes Elicited by Prolonged Intermittent Aerobic Exercise

Abstract

The purpose of this study was to compare the acute and chronic effects of a strenuous work task, in a moderately high heat stress environment, upon selected hematological components. Twenty experienced long-distance runners competed in a 24-hr relay, running approximately one mile each hour in relay fashion. Food and fluid intake was allowed ad libitum during rest intervals. Blood samples were secured three times: (T1) within 1 hr prior to the start; (T2) approximately 10 min after the first mile run; and (T3) approximately 10 min after each subject completed his last mile run. Main blood variables of interest were Hb, Hct, total protein, albumin, WBC diff, Na⁺, K⁺, Cl^?, Ca⁺⁺, glucose, cholesterol, T-bilirubin, LDH, SGOT, CPK, BUN, uric acid, and creatinine. Within the limitations of this study, the following main conclusions appear warranted: (a) hemoconcentration changes between T1 and T2 may be the causative factor underlying the moderate, but significant, increases in the majority of other hematological components between T1 and T2. As hemoconcentration did not appear to increase further between T2 and T3, component changes between T2 and T3 may be due to other causative factors; (b) the data from LDH, CPK, SGOT, BUN, uric acid and bilirubin is suggestive of muscle tissue damage and hemolysis.