When discussing lactate testing, there are two critical thresholds to understand: LT1 and LT2. These thresholds represent how your body processes lactate during exercise.

LT1: Lactate Threshold 1

• Definition: LT1, also known as the “aerobic threshold,” is the upper limit of Zone 2 training.
• What Happens at LT1? At this point, lactate begins to accumulate in the blood, but at a slow, manageable rate. Your body can clear lactate as fast as it’s produced, allowing you to sustain activity over long durations.
• Why It Matters: Training at or just below LT1 builds your aerobic base, enhancing your ability to exercise at moderate intensities for extended periods. This is crucial for endurance athletes like marathon runners, cyclists, and triathletes.

LT2: Lactate Threshold 2

• Definition: LT2 is what most people think of when they hear “threshold training.” It marks the intensity level where lactate begins to accumulate more rapidly in the blood.
• What Happens at LT2? Beyond this threshold, lactate production exceeds your body’s ability to clear it and you experience rapidly increasing fatigue.

Why It Matters: A higher LT2 allows you to perform at faster speeds or higher intensities for longer without hitting the wall. Training near LT2 improves your lactate threshold, making it a critical metric for endurance athletes seeking peak performance.