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Training intensity terminology clarified

Pete’s World

Published: May 23, 2022

My job as a coach hinges on my clients being on the same training page as me. And a big part of that symmetry involves consensus regarding terminology.
This is why I always make it a point to fully explain the meaning of each training term that I use, even if it’s one that seems like a no-brainer because as I’ve learned, some the most commonly used training terms mean one thing to one person, and then something completely different to another.
Yup, training terminology can get pretty confusing for everyone.
And a prime example of such confusion involves terms that are used to define training intensities, So with that in mind, let’s go over some of the more common training intensity terms - along with a plethora of confusing synonyms.
Easy/Fat Burning/Recovery Intensity Zone 1
These terms stress very easy workouts, less than 60% MRH (maximum heart rate). The pace should be talkative, comfortable, and totally mellow. And though this pace doesn’t really promote cardiorespiratory fitness it does help boost blood flow and nutrients to sore, tired muscles. This is the go-to intensity when I want to stress recovery.
Endurance/Long Distance/Aerobic Threshold Intensity Zone 2
Here are terms that apply to what I call an endurance workout, primarily because the effort should feel easy during the full training session - somewhere between 60% to 70-plus % MHR.
Now though this intensity level might sound too much like zone 1 recovery intensity, it’s definitely not. It’s higher, and actually so important that it should make up the largest chunk of one’s training time. That’s because endurance pacing helps to build a stronger, injury resistant body. What’s more, that lower intensity prevents an athlete from incurring undue training stresses on both the body and mind while still pushing the heart muscle to get stronger and more efficient.
Tempo/Stamina Intensity Zone 3
These intensity terms are notorious for meaning different things to different people. Now for me, tempo, aka stamina, should be performed at 70% to 80-plus % MHR, and therefore at a higher intensity level than endurance…but not by a ton. Unfortunately many people tend to perform tempo/stamina on the “too high” side. So remember, this is a pace that can be sustained for an extended time, usually 10 to 15 minutes for beginners and 90 minutes or longer for really fit athletes.
Anaerobic Threshold/Lactate Threshold/Threshold Intensity Zone 4
This kind of intensity can be sustained for upwards of 60 minutes, but it’s typically performed via 2- to 30-minute interval reps with a short recovery period in between. We’re talking about an intensity that’s anywhere from 75% to 90+% MHR. Why such a large span in the percentages here?
It’s because lactate/anaerobic threshold MHR percentages are based on the caliber of the athlete. For example, a newbie runner might perform threshold pacing that’s about 10 to 15 seconds/mile slower than his/her 5K race pace, a pace that might shake out to 75% to 80% MHR. Conversely, an elite runner’s threshold pacing might be about 25 to 30 seconds/mile slower than his/her 5K race pace, a pace that might correspond to 85% to 90-plus % MHR. Heck, some athletes attain thresholds that top out at around 92% MHR.
The take-away here is that threshold pacing needs to be done at an intensity where the concentration of lactic acid in the blood begins to rise exponentially - and this intensity typically coincides with one’s cardiorespiratory fitness. Now the benefits of threshold workouts are that they help athletes develop the ability to perform at a higher intensity level for longer periods of time. Therefore you can continue to bump up your threshold as a percentage of MHR by getting fitter.
VO2 Max/Anaerobic Intensity Zone 5
Once you go above threshold intensity, those blood lactate levels rise big time, to the point where the production of lactate exceeds its rate of removal. And the greater the intensity of exercise above threshold, the greater the rise in blood lactate levels. Exercising above threshold can only be sustained for several minutes at a time at the low end of VO2 Max, and only for several seconds at the high end of VO2 Max. Either way fatigue sets in and causes you to slow down.
So there you are, training intensity terminology for the five HR training zones - Zone 1 thru Zone 5. Now we’re all on the same page.