If you’ve ever experienced that intense burning sensation in your muscles during a sprint or a tough workout, you’re likely familiar with terms like “lactic acid” and “lactate.”  But what exactly is happening inside your body during these moments?  Let’s clarify these concepts and see how understanding them, especially the concept of lactate threshold, can help you elevate your training and performance.

 

Lactic Acid vs. Lactate: What’s the Difference?

 

First, it’s crucial to distinguish between lactic acid and lactate, as they are often used interchangeably but represent different stages of a process:

 

• Lactic Acid: During high-intensity exercise, your body requires rapid energy.  When oxygen is insufficient, your muscles use glucose anaerobically, resulting in the production of lactic acid (cite).  This accumulation of lactic acid is commonly associated with the burning sensation in your muscles.  It indicates that your body is pushing its limits and producing energy in an oxygen-deprived state.
• Lactate: Once lactic acid enters your bloodstream, it dissociates into lactate and hydrogen ions.  Unlike lactic acid, which often contributes to muscle fatigue, lactate serves an important function.  It is transported to the liver, where it converts back to glucose through a process known as gluconeogenesis (where “gluco-” means glucose, “neo-” means new, and “-genesis” means creation)¹.  This newly formed glucose can then re-enter the bloodstream for your body and muscles to use as an energy source. Thus, lactate is not merely a waste product; it plays a critical role in sustaining energy during intense exercise¹.

 

Lactate Threshold Explained

 

Now that we’ve clarified these terms, let’s explore lactate threshold—a concept crucial for athletes looking to improve their performance and endurance.

 

The lactate threshold, also known as the anaerobic threshold, marks the exercise intensity at which lactate accumulates in the bloodstream faster than the body can clear it².  This threshold varies with individual fitness levels but typically occurs at higher intensities for well-trained athletes³.  It represents a critical transition point where the body shifts from primarily relying on aerobic metabolism—where oxygen supports energy production—to relying more on anaerobic metabolism, which does not require oxygen².  This shift increases the production of lactate and hydrogen ions, leading to greater muscle acidity and eventual fatigue.

 

• Measurement: Lactate threshold tests involve incremental exercise (such as running on a treadmill or on a stationary bike) with blood samples taken at various stages to measure lactate levels². Alternatively, using performance metrics like pace or heart rate during progressively intense workouts can help you estimate your lactate threshold².
• Physiological Impact: When you reach your lactate threshold, your muscles begin producing lactate at a rate that exceeds your body’s ability to clear it². This leads to increased acidity in the muscles, which contributes to the burning sensation and eventual muscle fatigue.  By improving your lactate threshold, you can perform at higher intensities for longer periods before experiencing significant fatigue².

 

Why Does Lactate Threshold Matter?

 

Understanding and improving your lactate threshold can have a profound effect on your athletic performance.  By training at or near this threshold, you encourage your body to adapt to elevated levels of lactate, which can lead to several performance benefits².  Specifically, you can enhance your endurance, allowing you to sustain higher intensities for longer periods before experiencing fatigue.  Additionally, you’ll improve your speed by recovering more quickly and maintaining higher speeds or power outputs.  Moreover, better management of lactate helps optimize energy use, reducing discomfort during high-intensity efforts and ultimately boosting your overall athleticism.

 

How to Improve Your Lactate Threshold

 

Several effective strategies can improve your lactate threshold, each targeting different aspects of your training.  High-intensity interval training (HIIT) involves short bursts of intense exercise followed by recovery periods, helping your body adapt to higher lactate levels and improving lactate clearance efficiency².  Tempo training, where you run or cycle at a steady, challenging pace just below or at your lactate threshold, conditions your body to sustain efforts near this level and gradually raises your threshold².  Consistent moderate-intensity training below your lactate threshold enhances endurance and delays fatigue by improving lactate management without overloading your system, as training above the threshold is unsustainable.  Adequate recovery prevents overtraining and excessive lactate buildup, which can hinder performance.  Proper nutrition and hydration also play a crucial role by providing necessary energy and supporting efficient lactate clearance².

 

Putting It All Together

 

Next time you feel that intense burn during a workout, remember it’s not just about lactic acid causing discomfort; lactate is actively helping you sustain energy, and improving your lactate threshold can make a significant difference in your fitness level.  By understanding these concepts and incorporating targeted training strategies, you can push through tough moments, enhance your endurance, and achieve new levels of performance.

Keep challenging yourself, stay informed, and embrace the science behind your workouts.  With the right knowledge and training, you’ll be well on your way to reaching your athletic goals.

 

 

References

1. San I. What is Lactate and Lactate Threshold. Trainingpeaks.com. Published July 17, 2014. Accessed September 8, 2024. https://www.trainingpeaks.com/blog/what-is-lactate-and-lactate-threshold/
2. Quinn E. Lactate Threshold Training for Athletes. Verywell Fit. Published February 19, 2008. Accessed September 8, 2024. https://www.verywellfit.com/lactate-threshold-training-3120092
3. Garmin. Lactate Threshold. www.garmin.com. Accessed September 8, 2024. https://www.garmin.com/en-US/garmin-technology/running-science/physiological-measurements/lactate-threshold/