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What is Lactate Threshold?

One of the most misunderstood and least utilized pieces of physiological data is an athlete’s lactate threshold (lactate threshold). In the following, I hope to help you better understand what the lactate threshold is and how you can use it in your training.

Historically, athletes have understood the lactate threshold to be the point at which they are becoming anaerobic. Thus, they have believed they are transitioning from aerobic energy metabolism to anaerobic pathways. This is simply not the case and is one of the most misunderstood aspects of the lactate threshold. As an athlete works harder and harder – let’s say as a percentage of max pace – the aerobic system will be doing the bulk of the work of producing energy. As you move up to your lactate threshold and past it, the aerobic system is still working just fine. In fact, it is working as hard as it can, and this is where the anaerobic system – specifically glycolysis – needs to contribute more energy production. You are NOT becoming anaerobic. You are simply beginning to consume or burn more carbohydrates and this process produces more lactic acid. The higher you go above your lactate threshold, the greater the contribution needed by glycolysis. In fact, I can take you all the way to maximal oxygen consumption, and your aerobic system is working just fine all the way to 100 percent VO2max. You just need more energy from glycolysis to perform the work because your aerobic system is a slower energy-producing process. So, myth debunked! Your lactate threshold is not the point at which you become anaerobic. You may well be able to run an entire marathon or international distance triathlon at that pace – probably even faster!

Now that we know what your lactate threshold is and why it shows up, how can we use it in training? The best way to find your lactate threshold is to have an actual lactate profile established. We do this test for runners, cyclists and triathletes at the IRONMAN Sports Medicine Institute. We will put you through an exercise test with increasing paces or workloads. Every three to four minutes, we will take a blood sample, determine your lactate for that workload, and then progress to the next workload. Once we find your actual lactate threshold, training zones and paces can be established which are very precise for your physiological response to exercise. There is no guesswork about HR zones or RPE (perceived exertion) zones or other measures of training intensity. You will know exactly how fast or hard you should run or bike, based upon your lactate response. 

Schedule a lactate threshold test »