Objective To assess the immediate effects of loaded running exercise on immune parameters.Methods Seven female university students were asked to do running exercise under different loaded conditions（with or without an additional load of 5% of their body mass weight）.The running protocol was:warm-up running speed 3.0 km/h

gradient 1%;after 3 min of warm-up running

the formal experiment began

initial running speed 4.0 km/h

gradient 1%

with an increment of 1 km/h every 3 min until the subject became exhausted.About 4 m L of venous blood was collected before running and immediately after running

3 m L of which was used for blood routine test and 1 m L was used to determine the blood lactate level.Results In both groups

the post-running total count of white blood cells（WBCs） was significantly higher than those before running（P<0.05）;the WBC differential counts were also significantly higher than their pre-running values in both groups（P<0.05）

except that the lymphocyte and eosinophil counts remained unchanged in the non-loaded group（P> 0.05）.Besides

the post-running lymphocyte count in the non-loaded group was significantly higher than the standard value（P<0.05）

and meanwhile the post-running lymphocyte count in the additional loaded group was significantly lower than that in the non-loaded group（P<0.05）.In both groups

the post-running neutrophil percentage was decreased while the lymphocyte percentage was increased as compared with their pre-running values（P<0.05）;the post-running neutrophil percentage in the additional loaded group was significantly higher while the lymphocyte percentage was significantly lower than those in the non-loaded group（P< 0.05）.In the post-running setting

positive correlations were observed in both groups between respiratory quotient and lymphocyte count;maximal heart rate and WBC

neutrophil

lymphocyte

and basophil counts;blood lactate level and WBC

neutrophil

and lymphocyte counts（P<0.05）;a negative correlation was noted between respiratory quotient and neutrophil percentage in both groups（P<0.05）;a positive correlation was found between respiratory quotient and lymphocyte percentage in the non-loaded group（P<0.05）.Conclusion It seems that loaded running exercise has an impact on human immune function

manifested as an increase in peripheral WBC count

mainly lymphocytes;and exercise intensity mainly affects lymphocytes and neutrophils.