Lactate threshold is a better guide than maximum heart rate for heart rate run training because it gives you a more personalized and accurate measure of your aerobic capacity.
As you exercise harder, lactic acid builds up in your muscles and bloodstream.
Lactate threshold is the exercise intensity where this buildup rapidly accelerates.
For most runners, this occurs between 80-90% of maximum heart rate.
The problem with just using max heart rate for training is that it varies widely between individuals based on factors like genetics and fitness level.
So a heart rate that’s 80% max for one runner could be too easy or too hard for another.
Lactate threshold is a more functional measure of your ability to work aerobically.
Knowing your lactate threshold heart rate zone allows you to tailor your training to target the ideal intensity for building endurance – hard enough to challenge your body, but not so hard that you’re wheezing or struggling.
Using lactate threshold for heart rate training helps optimize development of your aerobic system.