Lactate is a commonly used term in endurance training, and generally, we use the term lactate when referring to “threshold” training or super hard efforts.
Measuring the lactate concentration in our blood can give us insight into how physically demanding a task is. The lactate concentration in our blood acts as a proxy for the rate of anaerobic metabolism occurring in the working muscles.
I feel bad for the lactate molecule because everyone blames it for being bad, but it’s trying to help you. Lactate removes positively charged hydrogen ions from your muscles cells to maintain the pH, or acid/base balance, so you can maintain normal function.
Lactate Threshold is Important
The lactate threshold is an important physiological reference point because it represents the transition between heavy and severe exercise intensities (Figure 1. Jones 2019).
Severe exercise is at no point steady-state and therefore the duration you can exercise above your lactate threshold is limited to the rate lactate is accumulating. However, below your lactate threshold, you can reach a steady-state and exercise for prolonged periods. If we know your threshold, we can easily define unsustainable and sustainable pace/power outputs. Knowing your sustainable outputs is particularly important for endurance events around 1-5hrs.
The "Step Test" is Great BUT...
Traditionally, lactate testing has been done via a “step test”. A step test measures your lactate concentration at increasing speeds or power outputs. Usually, each step is 4-5min long and will start at an easy pace/power and progress until you cannot hold the pace/power for the entire 4-5min. Using the data from a step test, we can plot your “lactate curve” and determine your “lactate threshold”. If you do these step tests every couple of months, you can track your fitness by looking at how sharp your curve is and the pace/power of your threshold.
While the step test is good for looking at many different outputs in one single test, generally, we’re only interested in one metric; your lactate threshold. Trying to find your lactate threshold on a curve plotted from 5 or 6 points can often lead to error.
The maximal lactate steady-state test is an alternative to the lactate step test for determining your lactate threshold. Not only is the MLSS test a more accurate method of testing, bu