In ten men whose blood lactate had been raised to 3.9 mmol/L by repeated 5-min runs at 90% VO2max, active recovery cleared it faster than passive recovery, and faster the nearer it came to the lactate threshold: 80-100% of threshold intensity gave shorter time constants and higher peak clearance rates than 40% or passive recovery, with the maximum close to the threshold itself. From the abstract

Menzies and colleagues asked which recovery intensity clears accumulated blood lactate fastest. Ten men did repeated 5-min running bouts at 90% of VO2max, which raised blood lactate from 1.0 ± 0.1 to 3.9 ± 0.3 mmol/L, and then recovered at intensities from 0 to 100% of their lactate threshold.

Repeated blood samples showed lactate falling faster with active than with passive recovery, and faster at 60-100% than at 0-40% of the threshold intensity. Curve and rate analysis showed shorter time constants for clearing 67% of the lactate and higher peak clearance rates at 80-100% than at 40% or with passive recovery.

When the men chose their own recovery intensity, higher chosen intensities also cleared more. The authors conclude that clearance depends on intensity and is fastest with active recovery near the lactate threshold.

n = 10 men (young adults by MEDLINE indexing). Training status, VO2max and threshold values are not given in the abstract.