Lactate Testing: A Key Pathway to Higher Performance

In part one of this series, “Lactate Explained From a Physiological Perspective,” I discussed what lactate is, how it is generated and its physiological implications on endurance sports performance.

In part two, we’ll cover the benefits of lactate testing as a pathway to achieving greater insights into the effects of exercise intensity and duration on how our body processes fuels to generate energy. These insights lead to a greater appreciation of how to use this testing metric to improve coaching methods and, ultimately, an athlete’s endurance performance.

What’s Better? VO2 Max or Lactate Threshold

For endurance athletes, the term VO2 max, or maximal oxygen uptake, is a widely recognized marker associated with performance. Even among those who do not know the textbook definition often know it has something to do with absorbing oxygen into the body. It is further accepted that a direct correlation exists between higher oxygen uptake and greater fitness.

Well, no argument here. That is a scientifically sound and well-established statement. No doubt, having a high VO2 max will positively translate to improved aerobic athletic performance. 

However, its influence on achieving podium finishes is greater in more intense, shorter races, such as the 800 meters or mile. Success in long-distance races relies heavily upon the ability to sustain a high percentage of one’s VO2 max. 

Thus, given two athletes with the same VO2 max values, the athlete who can sustain the highest percentage of VO2 max the longest before reaching a metabolic threshold (e.g., lactate or ventilatory) will potentially be the first to cross the finish line.

With proper training, built upon the data of a lactate threshold test an athlete can expect a rise in their lactate threshold. The significance of this is not an increase in running speed, but an increase in stamina, the speed that an athlete can sustain throughout the distance of the race or training session. A key factor in achieving high performance outcomes in endurance sports is the ability to combine speed with stamina.

Lactate Presence Relative to Exercise Intensity and Metabolic Fuel

As exercise intensity increases, the body shifts from using primarily fat for fuel to using primarily carbohydrate for fuel. This shift occurs because there is a higher demand for energy, but an inadequate amount of oxygen to produce energy quickly enough from fat. As such, one of the primary goals of endurance training is to train the body to become more efficient at using fat for energy. With respect to maintaining and/or increasing the level of intensity, the contribution of glycolysis (carbohydrate utilization) increases. This leads to an increase in lactate production. 

While the body can store an abundance of fat, it stores a limited amount of carbohydrate (as glycogen). For an athlete to maintain intense effort for an extended amount of time, they need to fuel with carbohydrates. This is why coaches and athletes should always take into consideration the length and intensity of training or racing to determine fueling needs.

Lactate: A Performance Testing Metric

Lactate levels are a prime indicator of aerobic performance and metabolic conditioning. Assessing lactate accumulation via lactate testing provides key information on the effectiveness of training methods in the development of the physiological adaptations that drive endurance performance. It is an important metric in designing endurance training programs.

During a metabolic performance test, not only is an athlete’s oxygen uptake measured, but so is the amount of carbon dioxide expelled. When the generation of carbon dioxide increases suddenly, it is indicative of insufficient oxygen. 

As a review, lactate is formed from pyruvic acid when there is insufficient oxygen to contribute to the generation of ATP during glycolysis. When lactate cannot be cleared faster than it is generated, the cellular environment can become too acidic. This results in a loss of muscle function — glycolytic enzyme impairment and a reduction in muscle tension development — and ultimately, decreased performance.

A higher lactate threshold ultimately means better performance. A lactate test is a way to monitor an athlete’s current fitness and performance ability, and it can help guide coaches in program design. Lactate tests can also be repeated, providing an excellent metric to track.

Lactate Profile Test Benefits Include: 

• Assessing the effectiveness of an endurance training program in increasing the contribution of lipids to the generation of ATP.
• Gaining awareness of accelerated muscular fatigue onset due to increased muscle acidity.
• Raising fuel economy leading to reduced demand for fuel supplements during races or training sessions.
• Using lactate as a metric to design training programs to produce higher sustainable exercise intensities for improved endurance performance.
• Lactate markers strongly correlate with ventilatory data, enhancing identification of training thresholds. Plus, lactate testing can be used as a suitable alternative to cardiopulmonary exercise testing.
• Gaining greater insight into optimizing training intensity to enhance development of Type II-A and Type II-B muscle fibers.

Final Thoughts

A results-based training program depends on adapting one’s physiology to the challenges encountered in competition. Understanding the intrinsic mechanisms that drive the adaptations is fundamental to the desired performance outcome. However, you cannot assess what you cannot measure. Fortunately, with lactate testing, the endurance coach and athlete have access to reliable, accurate and practical means to measure lactate.

Michael D. Weiss, M.S., ACSM: EP-C, EIM, is a former university professor of exercise science. He is an exercise physiologist, endurance sports consultant, running coach and an avid endurance athlete engaged in trail running, cycling and cross-country skiing. Michael’s professional interests include the human responses and adaptations to exercise in environmental extremes, with emphasis on heat and altitude conditioning. Additionally, via his own business, he combines his background in cardiometabolic conditioning with his practical skills in performance testing to develop high-performance training programs for endurance athletes.

Please visit Alta Health and Performance Solutions to learn more about Michael Weiss and performance testing.