What is the lactate threshold?
This is probably one of the more common questions we get. In the scientific literature there are numerous lactate threshold (LT) concepts (25 in a recent review!), which make the topic confusing and difficult for many people to understand.
In everyday practice, the most common use of the term is the intensity at which your body can no longer sustainably keep up with the energy demand. In other words, it is the highest intensity, or the fastest pace, that you could maintain without a steady increase in blood lactate.
At a higher intensity the blood lactate levels would continue to rise and the acidosis associated with that rise would eventually cause fatigue and a decrease in output.
Why does an athlete need to know this?
To train to it of course! Training hard can be beneficial in moderation with the right plan and/or the supervision of a good coach, but the smarter you train the more you will get out of all that hard work. If you know your lactate threshold, through appropriate training it is possible to shift this lactate threshold curve to the right (as seen in the graph below).
A lower blood lactate level at the same intensity indicates improved fitness.
The Benefits of Lactate Threshold Training: A real life example
See the test and re-test results above as an example. In this example, this athlete performed two lactate threshold tests, an initial test (blue) and a post training test (red) with the lactate threshold identified by the respective arrows above.
There was a noticeable improvement due to smart, lactate threshold-focused training. Notice that the lactate threshold shifted from the 250W intensity to the 275W intensity after a few months of focused training. Secondly, at any point along the curve this athlete has a lower blood lactate level for the same intensity indicating that their body has improved its ability to handle that intensity. Intensity, in this example, is measured by power output; whereas, for a running protocol the intensity would be measured by pace and represented as min/mile.
To better understand the illustrated improvement, let’s take a look at 250W on the graph. The pre-LT training blood lactate concentration was 3.5mmol and the post-LT training concentration was 2.3mmol meaning that at 250W intensity the athlete does not have to work as hard as they did previously to achieve the same result.
Additionally, the blood lactate concentration at 250W is the same as the blood lactate concentration at 225W from the first test which is a 25W improvement. In a running example, that would be like saying your pace got 30 seconds faster!
In this example, the entire lactate curve has shifted to the right (higher intensity) indicating an improvement, and ultimately that is the goal of lactate threshold training.
The Results: Improving Your Lactate Threshold
This improvement is often the difference on race day. For example, in the case of two athletes with very similar ability, the athlete with the better LT will almost always outperform the other. Furthermore, lactate threshold’s predictive power makes it a perfect tool for optimizing your training intensities for race day success.
In conclusion: Lactate threshold based training is a great tool to use in the design of a smarter training program that leads to improved performance.