Lactate Threshold is one of the useful measures for determining exercise intensity for training and racing in endurance sports. It can also be used to track fitness gains over time.
Your muscles produce lactate all the time, even at rest (baseline level is between 0.8-1.5 mMol/L). During power exercises such as sprinting, when the rate of demand for energy is high, lactate levels rise. There are two levels that occur when lactate levels rise above the baseline, Aerobic and Anaerobic Threshold, as explained in more detail below.
Aerobic-type training will not help with lactic acid tolerance, however it increases an athlete’s Lactate Threshold. In other words, the body will build a better tolerance to the effects of lactic acid over time during training. Anaerobic training improves the muscles’ alkaline reserves, allowing the muscles to work in the presence of increased lactic acid. Training at or slightly above the intensity where this occurs improves the Lactate Threshold.
This is sometimes defined as the exercise intensity at which blood lactate concentrations rise above rest levels. AeT is the exercise intensity at which aerobic energy pathways start to operate, considered to be around 65-85% of an individual’s maximum heart rate.
Some have suggested this is where blood lactate reaches a concentration of 2 mMol/liter. Body fat is the predominant fuel source used at or below the Aerobic Threshold. Endurance athletes train to increase their AeT because body fat is an unlimited fuel source for all practical purposes.
Anaerobic Threshold (AnT)
Also called Lactate Threshold (LT), is the exercise intensity beyond which blood lactate concentration is no longer linearly related to exercise intensity, but increases with both exercise intensity and duration. Some testers approximate the Lactate Threshold by using the point at which lactate reaches a concentration of 4 mMol/liter.
The blood lactate concentration at the anaerobic threshold is called the “maximum steady-state lactate concentration” (MLSS). Some highly trained endurance athletes clear lactate at levels much higher than at 4 mMol/liter and therefore require a different testing procedure to determine their accurate MLSS.
