Why is lactate important?

There are several energy systems that contribute to your body’s ability to exercise but only two are major ones: aerobic metabolism and anaerobic metabolism. Latin for “with air”, aerobic metabolism utilizes oxygen and is the strongest, most efficient energy system, producing the majority of energy consumed during endurance exercise. While aerobic metabolism is efficient because it utilizes long, slow pathways, it is not always able to create all the energy necessary for exercise.

When our bodies require more energy than our aerobic metabolism can provide, the anaerobic metabolic system provides the difference. Using shorter pathways, energy is quickly delivered to the working muscle and lactate is produced as a by-product. By measuring the concentration of lactate in the blood, we can see the strength of your aerobic metabolism and how well your anaerobic metabolism works.

The Lactate Curve

By measuring lactate and other variables during an exercise test, a detailed picture can be painted of your physiology. The concentration of lactate is graphed versus a constant, such as power, speed or pace; and a “lactate curve” is created.

Within the lactate curve, there are normally two inflection points that break the curve into three parts. The lactate threshold (LT), also known as the aerobic threshold, marks the point at which the anaerobic system begins to play a more significant role in the production of energy and lactate levels begin to rise above resting levels. At and below this point, exercise intensity can be maintained for long periods of time.

The onset of blood lactate accumulation (OBLA) is the point before lactate levels begin to rise at an uncontrolled rate. This point correlates with the highest intensity that can be maintained for a significant amount of time, such as a 40k cycling time trial or 10k run, which is why it is also known as the maximal lactate steady state (MLSS).

One of the best uses of lactate testing is the ability to determine training thresholds from the curve. By measuring several physiological variables at different intensities, training zones may be determined with exceptional accuracy. Unlike training zones determined from some programs that use formulas, lactate testing can determine exactly what types of workouts are needed to accomplish your goals in the shortest amount of time. While most formulas rely on a single variable (i.e. max heart rate) to determine training zones, LT is one of the most influential variables throughout training and can only be accurately found through testing.

Field vs. Lab Testing

Field testing is an excellent resource for many reasons. Primarily, it can act as an excellent benchmark and motivator; but, lab testing has distinct advantages that warrant its use as a tool for athletes of every ability. Lactate testing, in particular, has many advantages over field testing:

1. Control - Sustained constant efforts can be difficult in the field; using a trainer or treadmill can provide greater control.
   

2. Environment - In a controlled, indoor setting, results are less likely to be affected by environmental conditions (hot, cold, wind).
   

3. Repeatability - A strength of any test is the ability to repeat it to track changes and improvements; replicating the exact conditions with a field test is nearly impossible.
   

4. Comprehensive - Lab testing offers a more complete view of your training needs and performance capabilities by taking you through the entire range of intensities.