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Aerobic Fitness: An Introduction to Training

One of the most important aspects of fitness in any regard is Aerobic Fitness. I'll say that again for the people in the back. It does NOT matter what you do in an athletic sense, if you are a boulderer, a mountaineer, a cheerleader, or a bodybuilder training aerobic fitness WILL improve your game.

In this post, I am going to share with you some fundamentals of Aerobic training including; how many hours you should be training to start, what those hours should look like, how to measure at home, and what intensity you should be training at. For a more detailed and scientific description of what I am alluding to here please read the following three articles on the Summation Athletics Blog before moving on.

Okay, now that you are here I will assume that you either skipped the articles and don't care or are here and will understand the rest of the jargon I throw at you.

How do I know what my heart rate zones are?

First and foremost you are going to need a way to accurately (or somewhat) measure your heart rate. This can be done with most smartwatches, heart rate chest straps, or other systems like that of a Whoop. Do a couple of practice runs just to make sure your straps are calibrated and reporting. Then you are going to perform what we at Summation Athletics call a Critical Intensity test. Note: These are field tests so they are not the most accurate way but they are the cheapest and will do for all but the most extreme athletes.

Critical Intensity Test Protocol: This test should be performed at least 3 days after any hard efforts and will require maximal output so you need to be physically and mentally ready. You can do this either on a steep treadmill (15% incline) or a steep hill. Somewhere it is easy to modulate your intensity and somewhere that has a consistent grade. The test will take approximately 30 minutes. You will want to be well-fueled prior to testing. Make sure you ate your most recent meal at least 90-120 minutes pre-testing and ideally top up with a light carbohydrate-focused snack of about 100 calories within 30-45 minutes of beginning the test.

  • Step One: Make sure the heart rate monitor is working and ready to record the whole workout.

  • Step Two: Do a 10-15 min warm starting easily and gradually building the effort until you break a sweat. Ease into this warm-up so that your aerobic system is fully online.

  • Step Three: As soon as you are done with the warm-up continue immediately into the test. Once you start, go as hard as you can sustain for the full 30 min.

  • Step Four: Pace yourself so that you don’t blow up in the first 5 minutes of the test.

  • Step Five: Note your average heart rate for the 30-minute test. This will be your CI Heart Rate.

Calculating Your Zones: Now that you have your average CI Heart Rate we are going to use a formula from the Triathalon legend Joe Friel. His protocols have been used by triathletes for a long time and his book on training for triathlons is an amazing resource for periodizations, annual training plans, workouts, and more. I have made a Google sheet that you all can access via the link HERE. You will enter your CI Heart Rate in the box and it will auto-calculate your zones. Below you will find a screenshot for a CI Heart Rate of 165 and what that means in terms of training zones.

Don't get too caught up in the different zone types at this level. The biggest takeaway here is the green, yellow, and orange zones. Their general function in training is listed to the right in order of stress induced to the body during the said zone. They are Recovery, Aerobic Base Building, Lactate Threshold/Functional Threshold Heart Rate (FTHR), and Anaerobic/Critical Speed Zones.

Training Load and Distribution (The Beginning): Depending on your training history with cardio or endurance activities you may start with a higher training load but for most everyone a solid 8 weeks of training is the minimum I would suggest for a structured aerobic plan. The way I approach aerobic training personally is that it never stops. No matter what I am training for the minimum to which I will train aerobically is 3 hours per week and I think this is a good base for most people for the first 2-3 weeks, with slight increases in workload after 2 weeks and beyond.

As the Summation Athletics (SA) articles by Scott eluded you will spend about 70-80% of your time in the Aerobic Threshold or Aerobic Base Building Zones, this is the zone below your CI Heart Rate or FTHR. You will spend about 10-15% of your time in the Anaerobic or Critical Speed Zones (the zones at the highest levels) and only about 5% of the time will be spent in between those zones (the orange). This is a polarized model of training that has worked very well for our athletes, myself, and even in other avenues of training which we will get into more in later segments of Mountain Talk.

What does this look like in practice for someone who is just starting out with Aerobic Training? Well, something like this... at 3 hours a week.

  • Monday:

  • Tuesday: 45:00 Aerobic Base Building Run

  • Wednesday:

  • Thursday:45:00 Aerobic Base Building Run

  • Friday:

  • Saturday: 1:00:00 Aerobic Base Building Run (Optional: Tempo to finish)

  • Sunday: 30:00 Recovery Run/Walk

Note: Tempo Finish means in the last, and I mean the very last bit of your long run (5% or less) continue to increase your pace until you are finished with the run, something like a jog, to run, to sprint. But only do this if you are feeling VERY GOOD and probably only after the first 4-6 weeks.

I would continue this for a minimum of two weeks before increasing 15 minutes a week or so. I like the 4 days week blocks until you are doing something like 45/1/1.5-2/45 on the same protocol. Then after that, we would reevaluate or retest your CI.

All in all, this is just the tip of the iceberg when it comes to training but should give us a solid foundation to build from moving forward. Next up in the Aerobic Fitness discipline, I will share with you all what gear I use for all of my sub 2.5-hour runs, so look out for that.

This essay was originally posted on my Patreon. If you enjoy the content think about donating to my venmo @george-bieker or if you want to engage, ask questions, give feedback or anything at all contact me via email, Facebook, or Instagram @georgebieker


  • #1 After taking a hit of acid each, Alex and I ran back and forth on a beautiful beach in Oregon until we hit something like 13 miles, barefoot, on the sand the entire time. This was my first 6-month aerobic-only training program when I was training for the Cassin. August 2020.

  • #2 Classic Aerobic base build run, 2 hours with Alex in the Southern California foothills of Mount Laguna, east of San Diego, CA. September 2020. Sans acid.


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