The aim of this study was to analyze the effects of exercise mode on the validity of onset of blood lactate accumulation (OBLA—3.5-mM fixed blood lactate concentration) to predict the work-rate at maximal lactate steady state (MLSS work-rate ). Eleven recreationally active males (21.3±2.9 years, 72.8±6.7kg, 1.78±0.1m) performed randomly incremental tests to determine OBLA (stage duration of 3min), and 2 to 4 constants work-rate exercise tests to directly determine maximal lactate steady state parameters on a cycle-ergometer and treadmill. For both exercise modes, the OBLA was significantly correlated to MLSS work-rate , (cycling: r=0.81 p=0.002; running: r=0.94, p<0.001). OBLA (156.2±41.3W) was lower than MLSS work-rate (179.6±26.4W) during cycling exercise (p=0.007). However, for running exercise, there was no difference between OBLA (3.2±0.6ms −1 ) and MLSS work-rate (3.1±0.4ms −1 ). The difference between OBLA and MLSS work-rate on the cycle-ergometer (r=0.86; p<0.001) and treadmill (r=0.64; p=0.048) was significantly related to the specific MLSS. We can conclude that the validity of OBLA on predicting MLSS work-rate is dependent on exercise mode and that its disagreement is related to individual variations in MLSS.