Running Primer – Part 5

ByJarin Satterlee

One of the terms I mentioned in Part 4 of this primer was Lactate Threshold. As this is a term you will frequently see in training plans and in conversation with runners, I thought it important to give this topic it’s own part in the primer.

Keep in mind that as a beginning runner, you should be familiar with this term but not overly concerned with absolute accuracy in determining your personal threshold. If you decide to become more serious about competitive running, you can focus more attention to finding a more precise LT/LTP later.

Lactate Threshold (LT) is a critical concept in endurance sports like running, cycling, and swimming. It represents the exercise intensity at which lactate (a byproduct of anaerobic metabolism) begins to accumulate in the blood faster than it can be cleared. This threshold is important because it reflects a point where your body shifts from primarily aerobic energy production (using oxygen) to anaerobic energy production (without oxygen). Training at or near the lactate threshold can help improve endurance performance, as it allows you to sustain higher intensities for longer periods without fatiguing.

Lactate Threshold Pace (LTP) is the fastest pace a runner can maintain without producing more lactic acid than their body can use.

Why Lactate Threshold is Important:

  1. Performance Indicator: LT is a better predictor of endurance performance than VO2 max (the maximum amount of oxygen your body can utilize during exercise). Athletes with a higher LT can maintain a faster pace for a longer time.
  2. Efficient Energy Use: Training at LT helps your body become more efficient at using oxygen and managing lactate, which delays the onset of fatigue.
  3. Personalized Training: Knowing your LT allows you to tailor your training intensity, helping you to maximize performance gains while minimizing the risk of overtraining.

Determining your Lactate Threshold (LT) can be done in several ways, ranging from laboratory testing to field-based assessments. Here are the most common methods:

1. Laboratory Testing:

This is the most accurate method but requires specialized equipment and professional supervision.

  • Blood Lactate Test:
    • Procedure: During this test, an athlete exercises on a treadmill while their blood lactate levels are measured at regular intervals (usually every few minutes). The intensity is gradually increased, and the point at which lactate levels start to rise significantly indicates the LT.
    • Advantages: Provides a precise measurement of LT, often including data like heart rate and power output at LT.
    • Disadvantages: Expensive, requires a lab and professional staff, and may not be easily accessible.

2. Field Testing:

Field tests are more accessible and can be performed with minimal equipment, often using heart rate or perceived exertion.

  • 30-Minute Time Trial:
    • Procedure: After a proper warm-up, perform a 30-minute all-out effort (running, cycling, etc.) where the goal is to maintain the highest sustainable pace. For the most accurate LT estimate, record your average heart rate over the final 20 minutes of the test.
    • Advantages: Simple, can be done without special equipment, and provides a good estimate of LT heart rate.
    • Disadvantages: Requires a strong understanding of pacing and the ability to push yourself at a challenging effort.
  • Conconi Test:
    • Procedure: This involves gradually increasing your exercise intensity (speed or power) while recording your heart rate. The point where your heart rate no longer increases linearly with the exercise intensity is considered an approximation of your LT.
    • Advantages: Easy to perform and doesn’t require any invasive procedures.
    • Disadvantages: Less accurate than blood lactate testing and can be influenced by external factors like fatigue or hydration.

3. Using Wearable Technology:

Some advanced sports watches can estimate LT based on your heart rate data and exercise intensity during training.

  • Software/Device Estimations:
    • Procedure: Devices like Garmin or other smart wearables can analyze your heart rate, pace, and other metrics during certain types of workouts (like steady-state runs) to estimate your LT.
    • Advantages: Convenient and easily integrates into regular training.
    • Disadvantages: Less precise than lab testing, and the accuracy can vary based on the device and quality of the data input.

4. Perceived Exertion and Talk Test:

For those without access to advanced testing, perceived exertion and a simple talk test can help gauge LT.

  • Procedure: Your LT pace is usually the intensity where you can no longer hold a full conversation but can still speak in short sentences. This corresponds to a “comfortably hard” effort—usually around a 7-8 out of 10 on a perceived exertion scale.
    • Advantages: Very simple and requires no equipment.
    • Disadvantages: Highly subjective and less accurate than other methods.

Time Trial Example:

If you choose to use the 30-minute time trial method for running:

  1. Warm-up: 10-15 minutes of easy running.
  2. Main Test: Run at the fastest pace you can maintain for 30 minutes. Record your heart rate continuously.
  3. Data Analysis: Calculate the average heart rate for the last 20 minutes of the run. This is an approximation of your LT heart rate.

Using Race Data to Estimate Lactate Threshold:

  1. Choose an Appropriate Race:
    • The race should be long enough to require sustained effort but not so long that fatigue significantly lowers your intensity. Ideal races for estimating LT are typically in the 10K to half-marathon range for runners, or a time trial of 30-60 minutes for cyclists.
    • The effort should be close to maximum sustained intensity, meaning you’re pushing hard throughout but not sprinting. This pace typically corresponds to your LT.
  2. Analyze Your Heart Rate:
    • If you wore a heart rate monitor during the race, look at the heart rate data. The average heart rate sustained during the bulk of the race (excluding the first few minutes and the final sprint, if applicable) can be a good approximation of your LT heart rate.
    • For shorter races (like a 5K), consider using the average heart rate from the second half of the race, as the intensity might be slightly above LT.
  3. Calculate Your LT Pace:
    • Determine your average pace or power output (for cyclists) over the race distance. This can give you a rough estimate of your LT pace or power.
    • For runners, your LT pace is typically close to your 10K race pace or the pace you could sustain for an hour.
    • For cyclists, your LT power (often referred to as Functional Threshold Power or FTP) is the highest power you can sustain for approximately one hour.
  4. Consider Perceived Exertion:
    • Reflect on how the race felt. If you were able to sustain a “comfortably hard” effort throughout the race without hitting a wall, this pace likely represents your LT.

Example:

Let’s say you recently ran a 10K race:

  • Race Time: 45 minutes
  • Average Pace: 7:15 per mile
  • Average Heart Rate: 165 bpm

In this case:

  • Your LT pace could be estimated around 7:15 per mile.
  • Your LT heart rate would be approximately 165 bpm.

This method gives you a practical and race-specific estimation of your LT, which can be very useful for planning your training intensities.

Considerations:

  • Race Conditions: Factors like terrain, weather, and your condition on race day can influence your race performance, so consider these when interpreting your LT estimation.
  • Distance Considerations: If the race was very short (e.g., 5K), your pace might be above your LT, while in longer races (like a marathon), your pace might be below it. Adjust your expectations accordingly.
  • Multiple Races: If possible, analyze data from multiple races to get a more accurate and reliable estimate of your LT.

Using race data is a practical way to estimate your LT, especially if you don’t have access to formal testing. This approach integrates real-world performance, giving you a personalized measure that reflects your current fitness level.

Summary:

  • Lab Testing: Most accurate, measures blood lactate directly.
  • Field Testing: Practical and accessible, uses heart rate or pace.
  • Wearables: Convenient, integrates into everyday training.
  • Perceived Exertion: Simple, no equipment needed, but less precise.

Choosing the best method depends on your resources, access to equipment, and how precise you need the measurement to be.

How to Increase Lactate Threshold:

  1. Threshold Training: Also known as tempo runs or steady-state training, these workouts involve exercising at or just below your lactate threshold pace. This intensity is challenging but sustainable, usually around 80-90% of your maximum heart rate. Typical threshold workouts last between 20-60 minutes.
  2. Interval Training: Involves short bursts of high-intensity running followed by recovery periods. This type of training improves both aerobic and anaerobic capacity, pushing your LT higher over time.
  3. Long, Steady Runs: Long-duration workouts at a moderate intensity (slightly below LT) help build aerobic capacity, which indirectly raises your LT by improving your ability to clear lactate.
  4. Consistent Training: Regular training, with a mix of intensities, is crucial. Gradually increasing the volume and intensity of your workouts helps your body adapt and raise the LT.

Training Up to But Not Over the Threshold:

  1. Pacing: Begin with a warm-up to gradually increase your heart rate. During threshold training, maintain a steady pace that feels “comfortably hard”—challenging but sustainable. Monitor your heart rate or perceived exertion to stay near the threshold.
  2. Heart Rate Monitoring: Use a heart rate monitor to keep track of your intensity. If your LT is at 85% of your maximum heart rate, for instance, aim to stay within a few beats of this during your workout.
  3. Perceived Effort: While heart rate monitors are useful, training by feel is also effective. During a threshold workout, you should be able to talk in short sentences but not hold a full conversation.
  4. Avoiding Overtraining: Training just below the LT helps you avoid accumulating too much lactate, which can lead to premature fatigue. Overtraining can occur if you frequently push too far above your LT, so it’s important to include recovery days in your training plan.

Example of a Threshold Workout:

  • Warm-up: 10-15 minutes of easy jogging or cycling.
  • Main Set: 20-30 minutes at your lactate threshold pace.
  • Cool Down: 10-15 minutes of easy jogging or cycling.

As you progress, you can extend the duration of the threshold segment or break it into intervals (e.g., 3 x 10 minutes at threshold with short recovery periods in between).

The inclusion of intervals here is a major source of why tempo/threshold workouts are sometimes called other things and fuel disagreements from some as to whether or not tempo/threshold training is steady-state or interval.

Understanding and training around your lactate threshold can significantly enhance your endurance performance, allowing you to race faster and more efficiently.

Next Topic…

In part 6 of this series I will cover the various ways of tracking your run effort. That will include Heart Race Zones, Run Pace Zones and Perceived Effort.