The individual anaerobic threshold (IAT) is the highest metabolic rate at which blood lactate (LA) concentrations are maintained at a steady state during prolonged exercise. The purpose of this study was to compare the effects of active and passive recovery on the determination of the IAT before and after an endurance training program. Both before and after an 8-wk training program, nine subjects did two submaximal, incremental cycle exercise tests (30 W and 4 min per step) until LA was greater than or equal to 4 mmol.l-1. Blood was sampled repeatedly during exercise and for 12 min during the subsequent recovery period, which was passive for one test and active (approximately 35% VO2max) during the second test. An IAT metabolic rate and power output were calculated for the passive (IATp) and active (IATa) recovery protocols. On separate days, before and after training, five of the subjects exercised for 30 min at either the IATp or the IATa. Before training, IATa occurred at a higher (P less than 0.05) power output and absolute and relative VO2 compared to IATp. After training, VO2max and the power output and VO2 at IATa and IATp increased significantly; as a percent VO2max, IATp but not IATa increased. During the pretraining 30-min IAT rides, LA was higher during the IATa than the IATp test, but LA values did not change during the last 20 min of exercise. LA was similar for both 30-min IAT rides after training and did not change from 5 to 30 min of exercise. The LA steady-state concentrations ranged from 1.3 to 6.8 mmol.l-1.(ABSTRACT TRUNCATED AT 250 WORDS)