3 Levels Versus 5 Zones for Training

Today we are exploring a continuation of the conversation around effort gradations with aerobic and anaerobic training. The recent article “Chiming in on the Zone 2 Discussion” generated a significant amount of much-appreciated community feedback. Feel free to refer back to that piece as a reference that may help you to put everything in context.

The 5-Zone intensity classification has been a cornerstone of aerobic/anaerobic training models, particularly in endurance athletics. As we discussed in the aforementioned article, the Zones are based on percentages of maximum heart rate, lactate threshold, VO2max, or functional threshold power. We commonly use this 5-Zone system in The Lifetime Athlete App in our Training Tribe platform and it is a cornerstone of program design for the endurance sport specialists in our community.

However, many athletes and fitness enthusiasts – primarily those who are not dedicated endurance sport specialists – generally find the 5-Zone intensity model to be a bit too complex for the majority of their needs. Consequently, in many cases we can simplify. By recognizing the potential for overlap of intensity in Zones 1-2 and 4-5, and their corresponding (general) percentages of max output, we can stratify intensity of training by reducing it to only three levels. 

I’ve learned that many Lifetime Athletes find this a welcome and refreshing way to look at effort. Having only three choices makes life a bit simpler by removing excess complexity and potential for confusion. In general, intensity can be classified as either low, medium, or high. Each of those descriptors corresponds to Level I, II, and III, respectively. This is depicted in the following table. [We intentionally use Level for our 3-tiered example to differentiate between the 5-Zone model.]

Let’s discuss intensity a bit more by comparing the 3-Level system above with the classic 5-Zone distribution of effort. In a 5-Zone model, Zones 1-2 represent primarily aerobic training, in which the effort lies at or below the first ventilatory threshold and training in this effort region emphasizes development of the aerobic system. One can make the argument that there is a difference between Z1-2 but in reality it is indeed a fairly small difference, both in terms of training effect and in perception of effort. When I ask most athletes if they can really feel the difference between a 58.7% output and one at 64.3% (these are arbitrary figures based on what they are capable of in the moment, not necessarily a percentage of maximum heart rate, etc.), we tend to agree that low intensity is low intensity. It feels “pretty easy” and doesn’t require much concentration. The mind can wander and you can carry on a reasonable conversation. The human body can tolerate and absorb a considerable volume of low intensity training.

With medium intensity training, this effort focuses most workouts into tempo territory, often referred to as “sweet spot” training. This is the region between the first and second ventilatory threshold which represents the balance limit for lactic acid production and clearance. Many athletes and coaches describe this effort as “comfortably hard” and, in our example, Level II is essentially synonymous with Z3. Medium intensity training develops the oxygen utilization and lactate clearance mechanisms which allow an athlete to perform at a higher percentage of MHR and VO2max before escalating acidosis (which is inevitable with increasing effort) leads to fatigue and output reduction. Put simply, training near or just below the second threshold tends to, over time, raise the threshold itself. Zone 3 or Level II is indeed a moderate effort that needs some attention to maintain, yet it can be sustained continuously for 20 to as much as 60 minutes for most athletes. You can communicate in short phrases but you don’t have the breath, or cognitive space, for lengthy exchanges.

But once we go above this middle range of output, effort is high and training is hard. You’re producing lactate more rapidly than it can be cleared and this becomes the rate-limiting factor that eventually leads to shutdown. In exercise physiology terms we generally recognize training above Zone 3 or Level II as the onset of blood lactate accumulation (OBLA), which typically occurs at an approximate (there is some individual variability) blood lactate level above 4.0 mmol/L. This is also known as the Lactate Turn Point (LT2/AnT). Once you’re out of Zone 3 or Level II, and into Z4-5 or LIII, a maximum amount of concentration is demanded and there’s barely room for little, if any, conversation or deep thought. It’s all about the big effort, right NOW!

Also as we discussed in the previous article, there are differences between Zone 4 (VO2max and anaerobic capacity) and Zone 5 (neuromuscular power and lactate tolerance) in terms of effects, but those are consistent with effort and they are time-dependent. It’s simply how long you are sustaining output in your reps. Zone 4 intervals are generally conducted for several minutes while true Zone 5 work is only for seconds. 4 minutes at 88% is potentially just as “hard” as 20 seconds at 95%, at least in terms of the total amount of focus and systemic strain involved. So in some ways, hard is hard, no matter how you slice it. Going as hard (or nearly) as you can for several minutes is a different kind of hard than giving all you’ve got for 10 seconds, but both are hard as hell (if you’re doing it right and not “fluffing” the session).

Also, a common point that needs to be clarified with many athletes is that heart rate is a valuable metric with Z4 training, but it is less so with Z5. This is because there is a slight delay in heart rate response with all-out (or very near) efforts. If you’re only going balls-out or full ham for say, 20 seconds…heart rate probably won’t peak until after your rep is finished. Consequently, during very high, yet brief efforts, RPE trumps HR. In a Z5 episode, there may not be enough time for HR to stabilize (and be a useful metric) like it will in a Z4 rep. Z5 is all about peak speed, pace, and power and we really want to look at that in terms of meters per second, specific pace/speed splits, or watts. 

Because we use this descriptive terminology in workout programming, when an athlete sees Level III, he/she automatically knows the intensity will be high and the specific parameters of the session will determine exactly what kind of training is to be performed, as well as what metric we will monitor during the session. If desired, we can be selective and identify if the Level III workout contains Z4 or Z5 objectives. But, there’s another way to think about these bouts. Just go as reasonably hard as you can for the duration or distance specified. It’s self-selecting and time-dependent. Give your best effort for 4 minutes or your best effort for 20 seconds. The latter will be faster/higher than the former but your body will recognize each as nearly equally hard. 

High intensity training drives the greatest adaptation in the human organism, but the dose makes the poison. In other words, you’ve gotta be smart and careful in the application of high intensity. That statement drives our discussion to the total volume of training, and most importantly the relative amounts or ratios between Levels I, II, and III for the Lifetime Athlete. Volume is dependent on an athlete’s ability and experience (also known as training age) as well as goals and current focus. The more advanced or serious you are about your training, the more of it you’ll tend to do. But the distribution between Level I, II, and III requires deeper consideration.

Many of you are probably familiar with the work of Steven Seiler, PhD. Dr. Seiler has published extensively on the training habits of elite endurance athletes, especially those in cross-country skiing, cycling, and running. There are numerous articles, podcasts, and videos available relating to Seiler’s work that you can, and perhaps should, take a look at. But for the sake of brevity, forgive me for respectfully paraphrasing. Most elite endurance athletes, particularly during the off-season, use a method of preparation Seiler describes as Polarized Training. Basically, they either do workouts that are relatively easy…or those which are quite challenging. And not too much in the middle – the gray area we typically color code yellow and call Z3/LII (although strategic amounts of this type of training are still performed). 

Interestingly, most of the athletes and coaches of this elite caliber actually use 5-7 Zone models in their program design. But when Seiler (and others) examined their training data, he recognized that it can be classified using a 3-tiered system. He uses Zones 1-2-3 and those are essentially the same as the Level I-II-III we are talking about here. Again, I went with Levels to create a distinction and minimize any potential confusion. 

Basically, elite endurance athlete training patterns boil down to this: they do most of their workouts (approximately 80%) very easy at Level I, and the rest of their training (the other 20%) at Level II and III, with most of that being quite hard in Level III. Thus, Polarized Training is also known as 80/20 training. It’s not the only model out there but it is popular in the athletes Seiler studies. 

My convention is that if 3 Levels (or Zones if you prefer) are good enough for the pros, the same approach is probably entirely adequate for the rest of us. However, I think we should talk about this a little more. 

While humans are similar we are not all the same. Each of us is a unique and special snowflake, so to speak. At least when it comes to what we think and feel based on our individual personalities. Some people like complexity and they prefer to have more data to analyze and manipulate. Others gravitate toward the simplicity of a traffic light with only three choices (green, yellow, red). That’s totally fine and there’s no judgement. Whatever floats your boat or as one of my professors used to say, “whatever blows your hair back!.” I think I was still rocking the mullet back in those days.

The critical perspective is that you should select the training system (3 Levels or 5 Zones in our paradigm but in reality this applies to every training methodology) which appeals to you most. That’s because it will serve as a motivator to give your workouts more meaning and consequently you’ll be more engaged and consistent. This is where results come from. It doesn’t matter if I tell you that easy is easy and hard is hard. If you want to split hairs and micromanage (but not being condescending here) intensity, you should do exactly that. As Tom Petty sang “You believe what you wanna believe” and that’s the key. It matters less how we quantify training and more that we stratify it.

This is what I’ve seen with thousands of Lifetime Athletes. Those who consider themselves to be serious about endurance sport performance and who equally thrive on detailed, organized systems like the 5-Zone model for aerobic/anaerobic training. These are people who want to ask themselves “Hard? Yes…but exactly how hard?” They expect that in their programming and they achieve outstanding results with this method.

Equally, many of us like and deserve to use a solid and proven approach to our training, but we really only want or need the basic stuff. Just the facts, ma’am. Keep it simple, silly. Stuff like that. “Go easy? Ok, got it.”

There’s a place for everyone at TLA. Three Levels. Five Zones. It’s all good and The Lifetime Athlete App can help you…to do YOU!