What Is Lactate Threshold? Simply Explained

Why it matters

Understanding and improving your Lactate Threshold is crucial for runners because it directly dictates the highest intensity you can maintain for extended periods without experiencing severe fatigue. A higher LT means you can run faster for longer distances, significantly impacting your race performance and training adaptations. For instance, a runner with a higher LT can complete a half-marathon at a faster average pace before "hitting the wall."

How it works

During exercise, muscles produce lactate as a byproduct of anaerobic metabolism, especially at higher intensities. Simultaneously, the body clears lactate through various mechanisms, including converting it back into glucose in the liver (Cori cycle) or using it as fuel by other muscle fibers and the heart. The Lactate Threshold occurs when lactate production surpasses clearance. While there isn't a single simple "formula" for LT itself, it's typically identified through physiological testing (e.g., graded exercise test with blood lactate sampling) by finding the exercise intensity (pace, power, or heart rate) where blood lactate concentration starts to rise exponentially, often defined as a specific lactate level like. A common field test approximation involves finding the highest sustainable pace or heart rate for 30-60 minutes, with the average heart rate from the last 20-30 minutes of a 30-minute maximal effort often used as an estimate for LT heart rate (LTHR).