In 2012, exercise scientist Dr. Stephen Seiler coined the term “80/20 Training” and a few years later “introduced” the endurance world to Seiler’s Hierarchy of Endurance Training Needs, based on his extensive study of the training patterns of the world’s best athletes in endurance sports. His conclusion? The old saying, “No Pain, No Gain” was WRONG.

His ground-breaking research, since verified by many other researchers around the world, showed that the VAST majority of an athlete’s training should be done in “Zone 2”, according to the endurance sports media. Until others claimed that they shouldn’t. People chimed in on social media with tales of glory and tales of woe. Influencers influenced. And here we are today, with as many variations of “Zone 2 Training” as there are of opinions.

We at Breath Runner are big fans of Dr. Seiler and the other researchers who have done the hard work to help us understand the dynamics of a quality training program. Here’s a short - and woefully incomplete - explanation of what all these Zones are about, and what we at Breath Runner have settled on for a balanced training program.

Is It 3 Zones, 5 Zones, or 7 Zones?

The answer is: Yes. And there’s even more models out there. These are representative of the three most popular currently in use (in a very generic form; not for actual use).

These three models have two things in common: Heart Rate (as expressed as a percentage of Heart Rate Reserve, or the difference between one’s resting heart rate and their maximal sustainable heart rate), and Blood Lactate levels (as expressed as millimoles per liter per kilogram of body weight).

What’s important to understand is that what each of these is attempting to do is put a numerical value on an effort level, in order to help us better understand the intensity of our training and the effects of those efforts and intensities.

Things they all have in common

Something that all these models have in common is a point known as VT1 and VT2, or Ventilatory Threshold 1 and 2. Ventilatory Threshold is a key term in endurance sport. VT1 refers to the point at which the demands of exercise begins to cause a buildup of lactate in the bloodstream. Why is this important?

If we’re exercising below VT1 (sometimes referred to as LT1, or Lactate Threshold 1; they’re basically the same thing), then that means we’re operating using the aerobic glycolysis system (also known as Lipid Metabolism) as our primary energy system. The reason that is significant is that aerobic glycolysis is a ten-step process which utilizes stored fat deposits as its primary fuel source, and requires a high volume of oxygen in order to produce the nucleotide Adenosine triphosphate (ATP), which is what our mitochondria use to produce the energy required for muscle contraction. Aerobic glycolysis (also referred to as aerobic metabolism) is a very efficient way for our bodies to generate energy, as the primary waste products are carbon dioxide (CO2), water (H2O), and heat. We can exercise in this realm for literally hours.

Once we “breach” VT1, the glycolytic system (often referred to as simply glycolysis) comes into play in a more pronounced way. Sugar in the form of glucose (the most basic form of sugar) becomes the primary fuel, with fats reduced to a supporting role. At this effort level, one of the by-products of this energy production is a metabolite called lactate. When the demand for both oxygen and ATP exceeds supply, as occurs during intense exercise, lactate production increases. This can be measured in the bloodstream.

Lactate vs Lactic Acid

We have to take a moment to clear something up. Most of us have been taught in middle school science that ‘lactic acidosis’ (lactic acid) is what causes the burning sensation is our muscles when we work out really hard. This is NOT true! The fact of the matter is that it is impossible for a non-diseased living organism to produce lactic acid which exists in the body for more than a few milliseconds.

When energy is produced via glycolysis, an end product is the momentary appearance of the molecule Lactic Acid: C3H6O3 (three carbon atoms, six hydrogen atoms, and three oxygen atoms). But a split-second after it is produced, it sheds one ionized hydrogen atom (H+), becoming Lactate: C3H5O3- (three carbon atoms, FIVE hydrogen atoms, and three oxygen atoms).

It’s the accumulation of the ionized hydrogen ions in the bloodstream which causes the burning sensation in the muscles. Part of lactate’s job is as a buffer to minimize the hydrogen ion buildup by acting as a supplemental fuel source. When this buffering process can’t keep up, that’s when our muscles start to burn. If glycolysis did not produce lactate, muscle fatigue and blood acidosis would occur more quickly, and exercise performance would be even more severely impaired. It’s important to remember that the body's inability to clear excess blood lactate is caused by an inadequate supply of oxygen down to the mitochondria. Training helps “teach” the body how to lower the production of lactate for a given effort level, and thereby allows more work to be done at a lower metabolic cost.

Back to the Zones

The point of this entire discussion is this: Our bodies don’t care what model you choose to use.  They only know Effort, Effect, and Time.  Our bodies know what amount of effort is being asked for in the moment.  Our bodies know the effect of the cumulative efforts, and the amount of time at various efforts - in the moment, in the day, over the course of the past several days, and over the course of the past several weeks.  Our bodies strive for homeostasis, the state of equilibrium.  They want everything to be on an even keel, so to speak.  Our bodies are rapacious accountants; they keep a rolling inventory of every molecule of resources available, spent, and required.  If denied the resources needed, our bodies will make do with what they have, in whatever way they need to do it.  For example: Under-fueled?  Our bodies will find the fuel, even if it means scavenging body parts.  Work at too high of an effort for too long, and the body will start shutting down sectors in order to meet demand, until there is nothing left.  Injury, illness, or worse are the result.

So HOW does one stay at an appropriate level of effort in a way that allows the body to do what it does best, which is simply keeping everything operating in a harmonious manner?  We at Breath Runner believe it’s by using our breathing as a way to modulate effort.  Our breath is a primary, direct indication of the level of strain our bodies are experiencing, in real time.  If we “assign” our effort levels to be regulated by syncing our locomotive efforts to our respiratory abilities, we have given our bodies the ability to control the controllable.  Over the weeks and months and miles of training, the balanced efforts of a LOT of low to moderate effort running with the occasional bouts of high intensity, our bodies acclimate and strengthen in response, and become ever more efficient at the movements.

And that’s the whole point of training, isn’t it?

Speaking of which, Breath Runner Training Plans are now available on TrainingPeaks!  More to come!  Stay tuned!