Four female distance runners and 4 female race walkers were examined to assess the validity of OBLA (onset of blood Lactate accumulation) as a criteria of endurance training. They performed both the incremental treadmill exercise test and submaximal exercise test at the intensity of OBLA. OBLA was determined as blood lactate reached at a rigid value of 4 mM during the incremental treadmill exercise test. The values of OBLA in distance runners and race walkers were 49.4±1.6 ml/kg/min (91.3±1.4% VO₂max) and 44.5±4.0 ml/kg/min (86.8±4.5%,VO₂max), respectively.
　At the point of OBLA, blood lactate/pyruvate ratio has already been increased, indicating the elevated lactate production by mass action effect. When the subjects performed submaximal exercise at the intensity of OBLA, blood lactate increased significantly to the predicted value, although VO₂, was well agreed with the predicted value.
　It is suggested that maximal steady state for blood lactate during the submaximal exercise would be necessary to obtain OBLA during the incremental treadmill exercise test.

DESCENTE SPORTS SCIENCE Vol.9/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE