Training Your First and Second Lactate Threshold: A Guide for Runners and Triathletes

When it comes to endurance sports like running and triathlon, optimising your lactate thresholds can have a profound impact on your performance. Whether you’re striving to improve your 5k time, tackle a marathon, or finish strong in a triathlon, understanding and training both your first and second lactate thresholds is key to maximising your potential. In this article, we’ll explore the concept of lactate thresholds, why they’re important, and how you can implement targeted training to enhance your endurance, speed, and race-day performance.

What Are Lactate Thresholds?

Lactate thresholds are the points during exercise at which lactate, a byproduct of anaerobic metabolism, begins to accumulate in the blood. The two main lactate thresholds are the first lactate threshold (LT1) and the second lactate threshold (LT2). Both thresholds are essential markers for endurance athletes to understand and train.

First Lactate Threshold (LT1)

LT1 is typically referred to as the aerobic threshold. It represents the intensity at which your body can still clear lactate from the bloodstream as it is produced [1]. Below LT1, the body can efficiently clear lactate, and your muscles can rely primarily on aerobic energy sources (fat and oxygen) for fuel. Training at or near LT1 enhances aerobic capacity and allows you to perform at higher intensities without fatiguing as quickly.

Second Lactate Threshold (LT2)

LT2, also known as the anaerobic threshold, occurs at a higher intensity. At LT2, lactate starts to accumulate exponentially, and the body’s ability to clear it becomes overwhelmed [2]. This threshold is a critical point where your body transitions from primarily aerobic energy system use to an increased contribution of anaerobic energy systems. Training at or near LT2 increases your ability to sustain efforts at high intensities, improving your endurance in races that involve sustained high-intensity efforts.

Why Are Lactate Thresholds Important?

Your lactate threshold serves as a crucial marker of endurance capacity. The higher your lactate threshold, the better your body can handle sustained efforts at higher intensities without accumulating harmful lactate. In simple terms, improving your lactate threshold means you can run or cycle faster for longer without feeling fatigued.

For runners and triathletes, a higher lactate threshold means you can race at a faster pace without hitting a wall. Whether you’re looking to improve your 5k time or achieve a personal best in a triathlon, understanding and working to improve your lactate threshold can make a significant difference.

Coach Jack in action administering a Lactate Threshold test to a former PGC1 athlete and Hyrox Worlds Qualifier Amy Aldridge

The Benefits of Threshold Training

Training both LT1 and LT2 offers numerous benefits, whether you're a runner, cyclist, swimmer or triathlete. Here are some of the key advantages:

• Improved Endurance at Higher Intensities: The higher your LT1 and LT2, the longer you can maintain higher intensities before metabolites accumulate in your muscle and fatigue sets in. This allows you to sustain faster speeds in races and training sessions. Whether it's completing a 5k, marathon, or a triathlon, you’ll have the endurance to push for the duration of the race.

• Enhanced Fatigue Resistance: By training at and around your lactate thresholds, you’ll increase your resistance to fatigue. This is especially important for long-duration events, where the ability to maintain a steady pace without slowing down is crucial for a successful performance.

• Better Recovery: Improving your LT1 and LT2 also improves your body’s ability to recover during and after high-intensity efforts. Therefore, during a race, you are able to bounce back from an effort more rapidly, leading to an improved performance. You are also better able to react to accelerations that may occur during training and races. Enhanced post-exercise recovery reduces fatigue, enabling you to train harder and race better.

• Training Adaptation: When you train your LT1 and LT2, your body adapts by improving its ability to clear lactate, increasing aerobic capacity, and enhancing fatigue resistance. This results in a stronger, more efficient cardiovascular system.

• Pacing Strategy: Knowing where your lactate thresholds lie enables you to pace yourself more effectively during races. This includes, for example, being able to judge how hard to push up hills and when to surge during a race. Training within these thresholds helps you understand the effort levels required and to know when to conserve energy or start that final push to the finish line.

Mental Toughness: Threshold training is physically and mentally demanding, forcing you to work hard at intensities that challenge your body. Over time, this builds mental toughness, allowing you to push through discomfort in races and hard training sessions.

In Jack's next blog he will go into detail on how to implement threshold training along with why coaches aim to enhance it!

This blog was written by Jack Bond, MSc in Physiology from Loughborough University, BSc in Sport and Exercise Science from Exeter University and currently studying for a PhD at Loughborough University on thermoregulation and training adaptation. Jack is the Head Triathlon Coach at PGC1-Coaching and has coached athletes to GB age group competitions at both European and World level. Jack alongside his triathlon coaching helps inform training practice within PGC1, offers lactate testing to athletes and coaches runners on a 1-2-1 basis.

References

[1] Wasserman, K., Whipp, B.J., Koyl, S.N. and Beaver, W.L., 1973. Anaerobic threshold and respiratory gas exchange during exercise. Journal of applied physiology, 35(2), pp.236-243.

[2] Kindermann, W., Simon, G. and Keul, J., 1979. The significance of the aerobic-anaerobic transition for the determination of work load intensities during endurance training. European journal of applied physiology and occupational physiology, 42, pp.25-34.