Getting Tested Part 2: How to Interpret your Test Results


Okay, you’ve taken your test and gotten your grade. But what does it mean? And where do we go from here?

One advantage to paying professionals to test your blood lactate or metabolic efficiency is that they should explain what the results mean in terms of your training. But for the DIY’ers out there, or for anyone who felt a little fuzzy on their lab technicians’ explanation of the results, here is a basic look at what your results in these tests might mean. Hopefully by covering some of the basics, along with some of the common results we see and what these types of results imply, we can help you come up with some solid decisions about where to make gains in your training.

Gas Exchange Test Results

In the following three tests the vertical axis shows the percentage of overall calorie contribution from fats (blue line) and carbs (red line). The horizontal axis is measured in heart rate. Where the lines cross (the Cross Over Point) corresponds to where fat and carbs each contribute 50% of the total calories. This corresponds very closely to the aerobic threshold. It indicates the maximum intensity you can exercise at while fat is still the dominant energy source. This is the maximum capacity of your aerobic system to produce work before becoming overwhelmed by the output of the anaerobic system.

Moving the Cross Over Point to the right (improving metabolic efficiency/increasing aerobic capacity) needs to be the first training goal of every endurance athlete. 


This graph is from a very well trained Ultra-Runner with a high aerobic capacity/high metabolic efficiency. The contribution from fat to overall energy needs is very high at low intensities, and the Crossover Point occurs around 88-90% of maxHR. Note that even at very high intensities fat still contributes significantly to total calories.


This sort of graph is what we see when athletes train “ by feel” rather than observing their actual metabolic response to exercise. For them it feels good to push their pace right up to their endurance limit in almost every workout. They regularly run at a pace they can just comfortably maintain for the full duration of the workout. This pace feels good, feels like training, gives a flood of happy hormones after the workout and satisfies a compulsion that they must finish each workout tired in order to have gotten any benefits. Time constrained athletes gravitate toward this type of workout. Note the low Crossover Point and low contribution of fat for all exercise intensities. They are leaving a lot of endurance on the table as they try to short cut their way to fitness.

We often see this sort of graph when testing athletes who use low volume/high intensity interval training programs. Even at the lowest of intensities fat never contributes the majority of the caloric needs. These individuals often exhibit no Crossover Point. This type of athlete relies on anaerobic metabolism for virtually all exercise, even long duration, which should be low intensity “aerobic” workouts. These folks need to eat often during most exercise sessions. Through poor diet and training, this person has reduced the aerobic capacity to insignificance. Essentially, half the endurance engine has been deactivated.

If you find yourself with test results that look like the first graph, With a high Aerobic Threshold, then you are to be congratulated for your grasp of the most basic and most important of all endurance training principles. You should continue what you have been doing and will probably benefit from the judicious use of higher intensity training specific to the event you are training for.

If your test looks like a variant of either the second or third graph, (low Aerobic Threshold) you have a case of Aerobic Deficiency Syndrome (ADS).  Don’t despair. While it can be disappointing to see such a result, there is good news for you: There is a lot of upside potential for you and with proper training you will respond positively to the training and diet modifications we are going to talk about next.  For most folks finding themselves in this predicament, the biggest hurdle to overcome will be a mental one. It is going to require a paradigm shift in the way you view your training.  You have arrived in this sorry state by the choices you have made in your approach to training and possibly diet.

The nutshell for the aerobically deficient:
  • Get on a well-designed training plan that targets the development of your aerobic base.  This is job number one. This is not rocket science.  There are numerous options for these plans and coaching here: Training Plans
  • You are going to be much more successful in your training if you have a plan
  • Get a copy of Training for the New Alpinism Read and comprehend the physiology and methodology chapters.  Design your own plan using the book’s guidance.
  • At the very least, use the following UA articles to give you additional information:

David Goettler and Ueli Steck Put Low-Intensity Training to the test in the Khumbu

What Enables Endurance?

Train to Burn Fat

  • Do all your aerobic training BELOW your aerobic threshold.  Yes, this is going to be painfully slow if you have ADS. We know that.  You will probably feel like you are wasting your time. How can such low intensity be doing anything for you?  We’ve heard it all a hundred times.  Bear in mind that you are moving so slowly because that is all the power your puny aerobic system is capable of delivering right now.  There’s only one way to improve that: Train high volumes at this low intensity.  No amount of high intensity will have the desired effect.  In fact; ANY high intensity training done while trying to increase the aerobic base capacity will negate some of your aerobic base work.

These training methods work and work very well as we have documented in hundreds of cases. They only require consistency and patience. Below is a before-after training comparison of metabolic efficiency  from an endurance mountain athlete:

Above is a real world test result of a professional high altitude mountaineer who came to us for coaching. His first test, shown by the dashed lines (blue=fat, red=carbs) demonstrates poor fat adaptation and poor aerobic capacity. In the first test, the cross over point occurs at a 11% grade (constant speed of 3mph). This athlete needed to eat an energy gel or bar each hour he was exercising. The second test (solid line), done a few months later, shows a dramatic increase in aerobic capacity. The cross over point has moved up to 21% (at 3mph). This represents a big increase in aerobic work capacity that will transfer directly to his climbing.