Aerobic Self-Assessment for Mountain Athletes

AEROBIC THRESHOLD SELF-ASSESSMENT

Assessment of the aerobic system’s capacity for providing the needed energy can run from expensive laboratory tests to formulaic educated guess. In this section we’ll go through the various options for determining your AeT—from least to most expensive and least often to most often accurate—and discuss the pluses and minuses of each one.

MAF (Maximum Aerobic Function) Formula

Longtime endurance coach Phil Maffetone, most famous for coaching Mark Allen to six Kona Ironman Triathlon wins, came up with a simple formula to help people determine the heart rate that corresponds to the top of their aerobic base training zone. He did this through observations of many athletes. The MAF formula is simple to use but is based on a statistical average of a large population. Like any such result, it will give a statistically accurate answer when applied to the group but may or may not be accurate for any one individual. This means that if you apply this formula to 100 people it will have an 85–90 percent chance of predicting the AeT heart rate. The problem is that no individual can know if their personal prediction is correct.

The MAF formula is useful as a quick-and-dirty first stab. When compared to other tests, it tends to give a lower or more conservative AeT heart rate. This is a plus for most people who tend to do most of their aerobic base training at too high of an intensity.

The formula is simple: 180 minus your age. In order to semi-personalize it, you can use the following modifiers:

• If you are recovering from a major illness or on significant medications, subtract 10 bpm from the result.
• If you have been sick or injured and not training regularly, subtract 5 bpm from the result.
• If you have been training consistently for two years with neither a) nor b), use the formula 180 – Age.
• If you have been training consistently for more than two years and seeing improvements with neither a) nor b), add 5 bpm to the result.

MAF Formula Takeaways

Pluses: Simplicity.

Minuses: Besides the statistical shortcoming mentioned above, its narrow window for improvement—only +5 bpm—does not allow for the significant improvement that will come with training correctly. We have seen hundreds of athletes with ADS improve their aerobic threshold by 25–30 bpm over several months to a year.

Rating: 1–2 stars

Nose Breathing/Conversational Test

During the training of high-level endurance athletes, we noticed that the upper intensity limit of their ability to breathe through the nose or carry on a conversation in full sentences corresponded very well with tests for the AeT, such as a blood lactate test. This led us to propose in our earliest writings that we could substitute this simple noninvasive test for the more complex and expensive ones. 

All you need to do is close your mouth during a run and see if you can sustain breathing through your nose for several minutes at a time. Alternatively, see if you can carry on a conversation in medium-length full sentences.

We were not inventing anything new here. Exercise science uses the ventilatory markers rate and depth of breathing for this same purpose when doing a Gas Exchange Test (GET, discussed later), albeit with more accuracy. However, once we began to work with untrained and less well-trained climbers, we discovered that this nice, simple test no longer worked.

Nose Breathing Takeaways

Pluses: Simplicity and real-time feedback. If you have a long history of aerobic training, this test is likely to work for you. It can be used frequently for checks on improvement.

Minuses: If you’re not well trained aerobically, forget it and move on to the next test.

Rating: 0–3 stars

Heart Rate Drift Test

This test has become our go-to test for all our coached athletes. We like it so much that we include it as the first workout in every aerobically based training plan we offer. This article provides a full description of the test, so we won’t repeat the instructions here. We have found it to be well correlated (95+ percent) with Metabolic Efficiency Tests (the gold standard, explained later). 

Simple in concept, this test uses the principle that when you hold an aerobic pace (<AeT), your heart rate will remain nearly constant for as long as an hour. If your heart rate rises more than 5 percent at that steady pace, your starting heart rate was higher than AeT. If the heart rate drift is less than 5 percent, your starting heart rate was below AeT.  

Here is a video tutorial on how to properly conduct a Heart Rate Drift Test.

If you are conducting your Heart Rate Drift test on a running track, be sure to read this very short post to get the most accurate data.

Heart Rate Drift Takeaways

Pluses: The test is free and can be performed frequently to assess improvement.

Minuses: To get an accurate result, you need to follow the directions carefully. It is best performed on a treadmill. While not required, it is helpful to have a TrainingPeaks premium account.

Rating: 3 stars

Blood Lactate Concentration Test

With the advent of relatively cheap portable lactate monitors in the 1990s, it became possible for amateurs to conduct a test previously reserved for exercise science labs. We consider blood lactate testing to be useful for determining AeT if the stages are at least 3 minutes long. Many labs offer this type of test either alone or in conjunction with a Gas Exchange or Metabolic Efficiency Test. We’re not fans of using the blood lactate test to determine the anaerobic threshold (AnT). Read below to see why.

Links to longer articles on this test:
Blood Lactate Test Protocol: Tips and Tricks
Blood Lactate Testing: The Silver Standard

Blood Lactate Test Takeaways

Pluses: Accuracy in determining AeT. You can use this test to confirm the result of your heart rate drift test, and it gives a good idea of your dependence on carbs for fuel.

Minuses: Somewhat complex and fiddly to get good test samples. Expense is considerable, either in a lab or if you buy your own meter. Best if blood samples taken by a partner. Has a learning curve if you are self-testing rather than going to a lab.  Blood lactate is a proxy for intensity.  To determine AnT, why use a proxy when you can do a field performance test as explained below.

Rating: 2 stars

Gas Exchange Test and Metabolic Efficiency Test

A Gas Exchange Test (GET) is conducted in a laboratory and explained in more depth here. You use a treadmill, the angle of which is decided by the event you are training for—flatter for runners and steeper for climbers. You breathe through a mask connected to a sensitive device that measures many parameters, with rate and depth of breathing and the concentrations of oxygen and carbon dioxide in your expired breath being the principal ones of interest to us. 

While this type of test is considered the gold standard for determining AeT, we advise caution in selecting a lab. Not all labs conduct these tests in a manner that will give you the results you need. If the lab calls this test a maxVO2 (or VO2max) test, you will want to ask how long the warm-up is and how long each intensity stage is.

If you can find a lab that will conduct a Metabolic Efficiency Test (MET) then you might want to do this test.  An MET is a special type of GET using the same lab equipment but with a very different test protocol. With an MET, you will get a detailed analysis of your body’s preference for fuel type—carbs or fat—at each of the intensities you are tested at. This is useful and actionable data for all endurance athletes but especially for those taking part in events lasting several hours or more, and for high-altitude mountaineers.

Find out how to locate a testing lab here.

GET and MET Takeaways

Pluses: Accuracy, accuracy, accuracy. You get additional actionable information to guide training decisions. You can use this test result to confirm the result of your heart rate drift test.

Minuses: Expensive (typically $250–$400). Can be hard to find a good lab. The expense and logistical hassle make it less practical for follow-up tests.

Rating: 4 stars