Lactate Inflection Point for Advanced Runners

For elite athletes, every detail counts to improve performance. In order to improve, advanced runners must understand their lactate inflection point (LIP). In this article, we will explore what the lactate inflection point is and how it can be determined. We will also talk about how elite athletes can use this knowledge to enhance their training.

What is the Lactate Inflection Point?

The lactate inflection point is also known as the lactate threshold or anaerobic threshold. It is the point where the production of lactate in the muscles surpasses the body’s ability to remove it. This results in a rapid increase in blood lactate levels. It’s so important to runners because it is the boundary between sustainable aerobic efforts and unsustainable anaerobic efforts.

What Happens at the Lactate Inflection Point?

Let’s say you’re pushing your limits during a high-intensity workout. As you work harder, your muscles require more energy. At first, your body relies on oxygen to produce this energy, fueling your muscles. However, as the intensity increases, your muscles need more energy faster than your aerobic system can supply it.

At the lactate inflection point, lactate production accelerates. This causes a spike in blood lactate levels. It is important to note that your body does not switch entirely to anaerobic metabolism at this point. Rather, it signifies the shift towards a more pronounced anaerobic contribution to energy production. When you’re working at lactate threshold, you’ll feel it. It’s what athletes often refer to as “comfortably hard“.

Testing Your Lactate Threshold

The gold standard for identifying your LIP is through lactate threshold testing. During a threshold test, you’ll undergo a controlled and systematic increase in intensity. At each step up in intensity, you’ll measure your blood lactate levels.

Here’s how it works:

1. Baseline Measurements: The testing begins with baseline measurements of your resting lactate levels, as well as heart rate. This will be helpful benchmarking later for your heart rate zones.
2. Incremental Intensity: From here, we will gradually increase intensity. A common protocol would be intermediate distances at progressively faster intervals. For example, you could conduct 6×1,200m intervals with 60 seconds of rest. Each rep being 15-20 seconds per mile faster than the last rep, ending with an all out sprint.
3. Regular Blood Sampling: After each interval, a small blood sample is drawn from your fingertip or earlobe. These samples are immediately analyzed for lactate concentration by a lactate device.
4. Identifying the Lactate Inflection Point: As you continue to exercise, your blood lactate levels will start to rise. The LIP is identified as the intensity point at which there is a significant, sustained increase in lactate concentration. This is usually expressed as a specific heart rate, power output, or pace at which the lactate threshold occurs.
5. Zone Determination: The intensity corresponding to your LIP is critical for establishing personalized training zones. These zones allow you to target specific physiological adaptations and optimize your training program.

Sample Track Workout at Threshold

1. Warm-Up (15 minutes): Begin with a warm-up of easy jogging, dynamic stretches, and light drills to prepare your muscles for the workout.
2. Progressive Intervals: Perform the following intervals on the track, focusing on gradual intensity increments:
   • 800 meters: Start with a comfortable, sub-threshold pace. This should be an effort level you can maintain without significant discomfort.
   • 400 meters: Increase the pace to just below what you perceive as your lactate threshold. You should feel a moderate increase in effort.
   • 400 meters: Push the intensity further, aiming to reach your lactate threshold. This is where you believe your body transitions into an anaerobic state.
   • 200 meters: Sprint at maximum effort. This is a benchmark to gauge your anaerobic capacity.
3. Rest Periods: Take a brief 1-2 minute active recovery jog or walk between each interval. This will allow you to partially recover and prepare for the next intensity increment.
4. Repeat the Cycle: Repeat the entire cycle of intervals (800m, 400m, 400m, 200m) at least two more times. This repetition will help confirm the consistency of your LIP.
5. Cool Down (10-15 minutes): After completing the interval cycles, cool down with an easy jog and static stretching to aid recovery.

Summing It Up

The lactate inflection point is a powerful tool for advanced runners. It gives us valuable insights into training optimization, pacing during races, and overall performance enhancement. By determining your Lactate Inflection Point through lactate threshold testing and incorporating zone-based training, you can elevate your training.