The purpose of this study is to compare the change of energy substrates during 40, 80, km road race cycling. Subjects consisted 15 college cyclists. Their physical characteristics were age 19.2±1.66 year, height 173.2±3.71 cm, body mass 70.11±3.42 kg , play carrier 4.87±0.99 year. The blood sample drawn to pre-road cycling 20, 40, 80, 100km of road cycling by collected about 6ml in the antecubital vain. We measure the blood glucose, blood lactate, K, N, Hb, Hct, RBC, TG, TC, HDL, LDL, of each subject. The results were as follow; 1) The concentration of glucose was signigicantly decreased until 40, 80 km race as compared with pre-exercise(p<.01). 2) The concentration of lactate, K, Na, was signigicantly increased until 80km road race as compared with pre-exercise(p<.01). 3) The concentration of RBC, Hb, Hct was signigicantly increased until 80km road race as compared with pre-exercise(p<.01). 4) The concentration of TG, TC, was signigicantly increased until 80km road race as compared with pre-exercise(p<.01). 5) The concentration of HDL LDL was signigicantly increased until 80km road race as compared with pre-exercise(p<.01). 6) The concentration of Total protein was signigicantly increased until 80km road race as compared with pre-exercise(p<.01). 7) The concentration of albumin was no signigicantly increased until 80km road race as compared with pre-exercise.