How to Build an Engine - Endurance Training Demystified

Looking to achieve new endurance performance peaks? Don’t leave gains on the table by not knowing how your body functions during your training session. Understanding the main thresholds and intensity domains can be a game-changer. As a coach, I believe in empowering athletes through education, and I want to share the same knowledge with you. Let's explore the concepts of lactate threshold, critical power, and intensity domains, to build a well-structured training program for lasting progress. Don't miss out on this opportunity to revolutionize your approach to endurance training!

Part 1: Understanding Your Threshold - Lactate Threshold and Critical Power/Maximal Lactate Steady State

When it comes to optimizing your training program and improving your endurance, it's essential to have a solid understanding of concepts like lactate threshold and critical power. These two thresholds play a crucial role in determining your training intensity. Understand this, and you’ll be able to get a lot more results from your training program. Let's dive into what these terms mean and how using this info can impact your performance.

Lactate Threshold:

The lactate threshold refers to the point at which the production of lactate in your muscles exceeds its removal rate. During exercise, your muscles produce lactate as a byproduct of energy production. However, at lower exercise intensities, your body can efficiently clear lactate, limiting its accumulation. As the intensity increases, lactate production surpasses its removal rate, leading to a buildup in your system.

This lactate buildup is often associated with a burning sensation and fatigue, which couldn't be farther from the truth. Lactate accumulation is something that happens at the same time as other factors…you use more fast-twitch muscle fibers, you start shifting to carbohydrates for energy production, etc. These factors will influence your ability (or lack of) to keep working, lactate is just a way to identify the situation. The lactate threshold is an essential indicator of your endurance capacity and represents the intensity at which you can sustain for a prolonged period without fatiguing quickly. The higher your lactate threshold is, the faster you can go without getting fatigued.

Critical Power:

Critical power and Maximal Lactate Steady State can be used somewhat synonymously here. They represent the highest sustainable power output or intensity that you can maintain without fatiguing completely. Critical power is often expressed as a percentage of your maximal aerobic capacity or VO2 max (80-85%). What is cool about it is that you can calculate it using a few different performance tests; this makes it very practical for performance coaching.

To determine critical power, you need a few data points of your performance at various intensities. This information helps establish your power-duration relationship, allowing you to identify your critical power and even figure out how long you have before exhaustion.

Knowing your lactate threshold and critical power enables you to structure your training program effectively and optimize your endurance training. You can then determine your intensity domains and eventually your training zones.

Let's take a look at the intensity domains.

Part 2: Understanding the Intensity Domains

Now that we have a grasp of the lactate threshold and critical power, let's explore the different intensity domains and how they explain what's going on under the hood during a training session. Yep, you get it, knowing this allows you to target specific intensity domains and elicit specific physiological adaptations to build a well-rounded capacity profile.

1. Moderate Intensity Domain:

The moderate intensity domain forms the foundation of your training program. It involves exercising at an intensity that isn’t so hard to recover from, yet very useful to elicit cardiovascular and endurance adaptations. Some of the important characteristics you build here are mitochondrial density and capillary density. This stuff is extremely important to build the foundation of your endurance pyramid. They are also crucial if you want to make the most out of your high-intensity training.

Training Tip: To incorporate moderate intensity work, aim for one to infinity (almost not kidding) hours per week. As we discussed this is low intensity, so your body should tolerate it pretty well, and the adaptations are very important. Your schedule will dictate how much you can do here. Start at 30 mins twice per week if you don’t do any and build slowly from there. The best would be to do it as a stand-alone session, but you can include it during skill work or allocate it before or after lifting sessions if you are short on time. Choose a lower-impact modality if possible, especially if you are new to running or have limited running experience.

PS: I’m sure you know about Zone 2 training…this is what we are talking about here.

2. Heavy Intensity Domain:

When training in the heavy domain, you are now above the lactate threshold. Here, the goal is to sustain an effort that you can hold for a while, we would normally describe it as comfortably hard. Think half-marathon pace, but probably slower than your 10km run pace. One of the important things you will develop here is to improve your body's ability to recycle lactate as fuel…which is pretty important stuff. By performing intervals or continuous work at that pace, you will also stimulate adaptations that improve your lactate threshold and endurance capacity.

Training tip: Incorporate heavy intensity work once or twice a week, depending on your goals and training schedule. As competitions approach, consider increasing the volume of heavy intensity training if the pace is specific to your event duration.

3. Severe Intensity Domain:

The severe intensity domain takes you above Critical Power; this is when things get very demanding. The severe domain is characterized by unsustainable work rates and heavy reliance on fast-twitch muscle fibers and carbohydrates for fuel. In this domain, your time to exhaustion is now calculated in minutes and not hours…the faster you go, the less time you have.

Training tip: Training here typically involves shorter intervals at a pretty fast pace. Training her will help you push that boundary between sustainable and unsustainable higher. Training in the severe intensity domain should be done once per week at most at first, depending on your individual capacity and goals. Remember that the total time spent in this domain is relatively low due to the high metabolic demands and high recovery cost that follows. You need to balance this stuff with the easier work.

4. Extreme Intensity Domain:

If you keep pushing the pace, you’ll end up in the extreme intensity domain. At this point, you are going to make acquaintance with the most popular threshold: VO2Max. This means that your body is using the maximal amount of oxygen it can to get the job done. When you get to that point, you really can’t go for very long.

Training tip: This type of training involves short-duration, high-power output work. It is focused on pure power training rather than endurance. Sprinting and all-out efforts lasting a few seconds or up to a minute are examples of training in this domain. Remember, training in the extreme intensity domain requires minimal volume compared to the other intensity domains, try one session per week at very low volumes to start.

A few notes on program design

Creating an effective training program involves understanding your current capacity, weaknesses, and goals. Start with a conservative amount of training volume, particularly in the moderate intensity domain, and gradually increase it based on your response and recovery.

The majority of your training volume should come from the moderate intensity domain, while the heavy, severe, and extreme domains should make up a smaller portion.

Periodize your training based on competition proximity (if you have one); the closer you get to race day, the more race-specific work you need to perform. The further you are from competition, the more you can dedicate time to the moderate intensity domain, strength training, plyometrics, and improving the parts of your engine that are lacking for you.

By understanding lactate threshold, critical power, and intensity domains, you can develop a comprehensive and targeted training program that enhances your endurance, improves your performance, and ensures long-term progress. I’m obviously biased but you should consider working with a coach to tailor your training program specifically to your needs, abilities, and competition schedule.

In any case, if you are still reading, you clearly are interested in this stuff…hit me up with any questions you may have; it’s always a pleasure to talk shop.

PS: If you want me to dive deeper into program design, you may be able to convince me!

-LPCB 👊