The aim of the present study was to compare the effects of exercise at 85% VO2max (30min) with prolonged exercise at a lower work rate (60% VO2max for up to1.5 h) on blood leukocyte count and the percent blood leukocyte subsets in young men athletes. Fifteen athlete male university students (mean ± SD age 22.3±2.6 yr, weight 65.5±5.72 Kg and height 174.2±3.64 cm) participated in this study. After physical examinations, subjects performed Running on an electrically treadmill at 85% VO2max (30 min). On another occasion, separated by at least one week, subjects performed exercise on the same treadmill at 60% VO2max for 1.5 hour. Blood samples were collected from a peripheral arm vein before and immediately after exercise sessions, and served for determination of total and differential leukocyte counts. The acquired data were analyzed by MedCalc software and using t-tests. Statistical significance was set at P < 0.05. Both exercise bouts caused significant (p<0.05) elevations of the blood leukocyte count. Mean blood leukocyte count were increased from 6.4±0.79 to10.26±3.3 and 6.32±0.75 to 9.85±2 (×106/ml) after exercise at the 60% VO2max (1.5 h) and 85% VO2max (30min) respectively. After exercise at the lower work rate for a longer duration, blood monocytes (1.25%) and neutrophil percent (11%) were significantly higher and blood lymphocytes (11.75%) were significantly lower than those observed at 80% VO2max. However, No significant differences were observed in the blood monocytes percent after the both exercise bouts (p<0.05). The results showed that when exercise is very prolonged, the diminution of innate immune function is greater, than or at least as great as that observed after fatiguing exercise at higher work rates. The sum of acute responses observed in this study may exert a protective effect against sickness and may be used to improve health and lifespan in athletes.
