The purpose of this study was to compare the influence of prolonged continuous (CON) and intermittent (INT) exercises on metabolic and hormonal responses in 8 male college students (age ; 23.0±0.5 yr, weight; 67.7±1.5 kg, VO₂max ; 2.8±0.1 L/min, mean±SE) . Both trials consisted of two 40 min cycling bouts divided by a 5-min rest period. The intensity of INT was alternated every 4 min at low intensity (25% VO₂max) and high intensity (75% VO₂max), whereas the intensity of CON was maintained at 50% VO₂max. Blood samples were collected before, and after 40 and 80 min of exercise, to determine blood lactate, serum glucose, FFA, insulin, plasma adrenaline and noradre-naline. Perceived exertion (RPE) was assessed at 40 and 80 min of exercise using the Borg scale. Although the changes in the concentration of plasma noradrenaline and serum insulin from basal values were similar in INT and CON, the degree of increase in plasma adrenaline during INT was significantly smaller than that during CON (90.5±16.6 vs. 152.8±27.0 pg/ml, p<0.05, after 80 min of exercise) . There was no difference in the change in the serum glucose level between the two trials. However, serum FFA in INT was significantly smaller than that in CON after 40 min (0.28±0.06 vs. 0.10±0.04 mEq/l, p<0.05) and 80 min (0.54±0.08 vs. 0.33±0.07 mEq/l, p<0.05) of exercise. RPE did not differ between the trials. These data indicate that even if performed total work and exercise duration are the same, metabolic and hormonal responses during prolonged intermittent exercise differ from those during continuous exercise.