Lactate Threshold 1, or LT1, is the stage at which blood lactate begins to increase beyond what is normal. It indicates the transition at which the body moves from relying on aerobic energy to taking energy from both aerobic and anaerobic sources, but at an intensity you are able to sustain.
This level of training assists in determining various levels of training and is commonly associated with Zone 2 or Zone 3 of a five-zone system. Training at or under LT1 assists in developing stamina and efficiency and is thus significant for endurance athletes. It is commonly determined through laboratory tests, blood lactate tests, or heart rate or pace measurement in the field over a period of time.
