In my podcast episode with Dr. Bryan Jasker, a renowned sports scientist, we explored the science of lactic acid, or lactate, and its significance as a biomarker in athletic training. Lactate, commonly associated with muscle fatigue, is actually a valuable indicator of metabolic health and training progress. Dr. Jasker explained how tracking lactate alongside power output and heart rate can guide training intensity, assess metabolic adaptation, and help athletes achieve peak performance.

Lactate is produced when muscles break down glucose for energy, especially during high-intensity exercise when oxygen levels are lower. Contrary to popular belief, lactate itself doesn’t cause muscle soreness or fatigue. Instead, it acts as a fuel source and a signaling molecule, helping muscles meet energy demands and recover during intense activity.

Dr. Jasker explained that by monitoring lactate levels, coaches and trainers can observe how efficiently an athlete’s body produces and clears lactate. This efficiency is key to metabolic health and endurance, as it reflects the body’s ability to sustain higher intensities for longer periods.

In Dr. Jasker’s approach, lactate levels are measured alongside heart rate and power output to create what he calls the “lactate curve.” This curve provides a visual representation of how lactate levels change relative to power output over time. Testing the lactate curve at regular intervals allows trainers to track adaptations in an athlete’s metabolic fitness.

The goal is to shift the curve to the right and make it flatter, which indicates improved lactate tolerance and a more efficient metabolism. As Dr. Jasker put it, “What we always look for is that lactate curve to move rightward and flatten. For us, that’s the metabolic health benefit.” A rightward, flatter curve shows that an athlete can handle more work at a given lactate level, meaning their body can sustain higher intensities with greater ease.

Using the lactate curve as a feedback tool, coaches can fine-tune training programs to optimize intensity. Dr. Jasker explained that they “close the feedback loop” by adjusting training based on the data collected in each test. Within three weeks, they might see initial changes in an athlete’s curve, with more substantial shifts appearing in 12 to 16 weeks. These adjustments help ensure that training intensity aligns with the athlete’s unique physiological markers, making training both more personalized and effective.

Dr. Jasker’s method involves comparing metrics over time, not just looking at lactate levels alone. For instance, he examines heart rate and power output relative to lactate from one test to the next. Improvements show up when, for example, an athlete’s heart rate at a certain lactate level is lower than in previous tests. This change demonstrates that the athlete is more efficient and better conditioned to handle high-intensity efforts.

For athletes and coaches, using lactate as a biomarker offers a data-driven approach to improve performance and metabolic health. Here are a few takeaways:

1. Regular Testing: Monitoring lactate levels every few weeks helps track metabolic changes and adjust training intensity as needed.

2. Focus on Heart Rate and Power Output: Instead of viewing lactate alone, comparing heart rate and power output at specific lactate levels can reveal more meaningful improvements in efficiency and conditioning.

3. Flatten and Shift the Curve: Aim for a rightward, flatter lactate curve over time. This indicates the body’s improved ability to clear lactate, resulting in better endurance and performance.

Using lactate data to guide training offers a powerful, personalized way to enhance metabolic health and athletic potential, as Dr. Jasker’s work demonstrates.