This is a term that we occasionally hear in reference to training, but what exactly is it and why should we be bothered?? . I’m not going to lie, the complexities of lactate threshold, or lactate and lactic acid, can be a bit daunting for the beginner runner. However, if we break things down very simply and avoid discussion of the more scientific terms, it can be easily understood to the point where you can appreciate its application to your training.
What is lactate or lactic acid?
While lactic acid contributes to why we hurt at the end of races, lactate is actually a source of energy. Your body breaks down glucose for energy and a by-product of this process is lactate. During easy running, your body reconverts and recycles this lactic acid back into energy and efficiently expels the waste products. Therefore, the production of lactate will remain relatively constant while running at an easy aerobic pace, which doesn’t require a huge demand for energy.
As you continue to run faster and demand more energy, the production of lactic acid will slowly increase. At some point, whether it be too fast a pace or holding a steady pace for too long, the production of lactic acid will soar and your body will no longer be able to convert lactate back into energy and expel the waste products. This point is commonly referred to as your lactate threshold. The lactic acid then floods into system, muscle power is diminished and you begin to slow down. Ultimately, lactic acid is one of the largest contributors to why you slow down as the race goes on. So, in short, your lactate threshold is defined as the fastest pace you can run without generating more lactic acid than your body can utilize and reconvert back into energy. This pace usually corresponds to 10 mile or half marathon race pace. Therefore a tempo run or threshold run is basically a workout that is designed to have you running at just below or at your threshold pace.
But why is this important?
By running just below your lactate threshold you can begin to decrease (or improve, depending on how you look at it) the pace at which you begin to produce too much lactic acid for your body to manage.
For example, at the beginning of a training plan for the marathon, your threshold might be 10 minutes per mile. This would mean you could run a 10 mile or half marathon race at this pace. As you do more tempo runs, your body gets stronger, adapts to the increased production of lactic acid, and decreases the pace per minute mile. Now, since your threshold is lower, you are able to run faster with less effort, which for the marathon means you can burn fuel more efficiently – saving it for the crucial latter stages of the race.