The purpose of this study was to confirm the usefulness of the %ΔHR_<30>(the rate of decrease in heart rate for 30s after exercise)as an index of the condition of athletes, compared with various other indices of athletic physical condition. Furing camp training, daily changes in the %ΔHR_<30> and HR in a field test(jogging for 4 min), nocturnal urinary vloume, HR and body mass in the morning, and total running distance ware recorded in 15 college male endurance athletes. The %ΔHR_<30>, urinary volume, and morning HR and body mass correlated significantly with the running distance for the previous day(r=-0.708, P<0.001;r=-0.508, P<0.05;r=0.520, P<0.05;r=-0.623, P<0.01, respectively). The correlation coefficient of the %ΔHR_<30> with running distance was significantly larger than those of the morning HR or urinary volume. The correlation coefficient of the %ΔHR_<30> was also larger than that of body mass in the morning, although the difference was not statistically significant. The %ΔHR_<30> did not correlate significantly with the HR during exercise. These results suggest that the %ΔHR_<30> is a sensitive index which can reflect the physical conditions of athletes, i.e.physiological fatigue.