How to calculate your lactate threshold Every runner’s lactate threshold will be different depending on their age, fitness, and experience. There a few different ways to calculate yours. One way to determine your lactate threshold is by using heart rate as the primary metric and performing a 30-minute run. This method will require a watch that can track heart rate or a heart rate monitor. It is important to understand that this heart rate is a range more than an exact heart rate data point. Anot