This article was originally published in the December/January 2023 issue of UltraRunning Magazine. Subscribe today for similar features on ultra training, racing and more.
We have a fantastic physiology lab at our home office in Colorado Springs, CO. It’s been privy to hosting over 1,000 physiological tests on all different levels of runners, cyclists and triathletes. It’s also a venue for our coaches to learn how the training they prescribe affects athletes’ physiology. As athletes gear up and recalibrate their training during the fall and winter months, it’s a good time to use physiological testing as a window into your strengths and weaknesses to help make training decisions. Below I’ve provided some context on physiological testing and considerations to take into account alongside the arsenal of information you already have at your fingertips. To narrow the scope of this article and improve its practicality, I am going to mainly focus on lactate threshold testing using a standard graded exercise test (a test where the intensity gradually increases, normally in 3-4 minute increments) where both oxygen uptake and lactate are being measured. While I recognize there are a host of other tests including FatMax testing, Running Economy testing, biomechanical evaluations and the like, full coverage would be outside the scope of this article and could encompass an entire (albeit boring) issue of UltraRunning Magazine.
As athletes gear up and recalibrate their training during the fall and winter months, it’s a good time to use physiological testing as a window into your strengths and weaknesses.
Do you even want to test?
Taking a lactate test does not magically make you faster. And many times, the information is not all that insightful. So, before you run out and schedule a lactate test, consider the following points. Although the initial picture might seem bleak, don’t let the initial barrage of weak selling points fool you, physiological testing can be enormously insightful to the training process.
The main reason you would want to do physiological testing is to use the information derived from the test to help drive training decisions. This means that the lab has to have the proper equipment and also the expertise to help you interpret your results (more on both of those later). It also means that you actually want to logically design your training utilizing different intensities at different times of the year depending on your goals and physiology.
If you have all of the aforementioned in your favor, your next step will be to implement the information from the test into your training. This might mean setting training ranges (via heart rate or pace) rearranging your overall training structure to work on different strengths or weaknesses or even changing your whole race plan or timeline. Be prepared to utilize all or none of these based on the results of the testing.
All of this being said, if you want to get tested for sheer entertainment purposes, be my guest. We see many people in our lab who just want to compare their VO2max numbers to Eulid Kipchoge or their favorite running star. That’s fine if that’s your goal. Entertainment value is in the eye of the beholder.
How to Find a Lab
One of the bigger points of consideration when determining testing is who is doing the test, what equipment they use and who is doing the interpretation (many times the lab technicians are not the same people as those analyzing the results). Below are some guidelines I use when trying to find a lab for athletes.
Blue Chip Equipment
There is a large range of testing equipment in the marketplace. The equipment can range from $20K for a gold standard metabolic cart like a Parvo Medics, to just a few thousand dollars for a cheap knockoff typically found at your local gym. For my buck, I only have athletes test on gold standard equipment to ensure the accuracy and precision of the test and the reliability that the testing environment will be consistent from test to test. This type of equipment is typically found at universities and only a small handful of commercial labs (our lab at CTS being one of them). The accuracy and precision of the equipment is important, particularly if you are coming back season after season for repeat tests. For most trained athletes, improvements in lactate threshold and VO2max are in single-digit percentages. This means that having precision is paramount as the signal you are seeking (improvement in any number) has to be bigger than the noise (precision of the instrument).
Expert Interpretation
Your next point of consideration is who is giving you the results of your test and if they can apply them to your training. While it’s one thing to go over the numbers and raw data, it’s another thing entirely to take that information and decide what to do with it. In my experience, while lab technicians are well intended in this area, many fall short of providing such expert interpretation. This is where a skilled coach can come into play. Coaches (at least the ones that look at lots of testing data) can look at your previous training, match that up with interpretation from the tests and fuse those elements together to come up with a plan. At the very least, the person interpreting your lab results should ask for an overview of your recent training in order to have the necessary context of your fitness coming into the test.
Lactate Curve Types
If you decide to undertake a lactate threshold test, there are a few prototypical lactate curve shapes that can unfold. While not every test will mirror these prototypes exactly, you can at least draw some conclusions and drive training decisions depending on the shape. We can certainly overcomplicate each shape with their endless real-life mutations. However, the framework below is distinct enough that a markedly different training direction can be taken from the results of the test. After all, the point of testing is to inform training decisions. If you have a broad direction of where to take your training, you can expect the training to be more impactful as it addresses your strengths and weaknesses more accurately.
Normal Curve
In every freshman-level physiology textbook, there is a lactate threshold example that looks like this one. It is how things are “supposed” to look if an athlete is well trained, the test starts at the right intensity and there are no other mitigating factors like the athlete being on a low carbohydrate diet or fasting going into the test. For purposes of simplicity and because we are not a very creative lot, we are going to call this lactate curve “normal.” This curve will serve as the basis for comparison with the other curves that are normally seen. I have also denoted the curve with the first and second lactate turn points (LT1 and LT2) which many (but not all) labs will denote. Somewhat ironically and hilariously, this “normal” curve is rarely seen in real life and in particular, in our lab at CTS. Take that color commentary for what it’s worth.
What the normal curve tells you:
- There are no overwhelming strengths or weaknesses.
- The athlete is well trained.
What you should do with a normal curve:
- Proceed as planned with training.
Linear Curve
The oxymoronic linear curve appears when an athlete is relatively unfit and/or has not been training much. The initial increases in workload cause a disproportionate amount of carbohydrate to be oxidized and therefore lactate accumulates quickly. Usually, this test ends quickly and the subject will reach volitional exhaustion within the first few stages. Sometimes this curve appears if the starting stage is set too fast by the technician. But, since you’ve chosen a high-quality lab, you won’t run into that problem, right? In all seriousness, this is why it is important to be honest about your current fitness levels with the lab.
What the linear curve tells you:
- The athlete is relatively unfit or new to training.
- There is very little physiological resilience at low intensity.
- The aerobic system is undertrained.
What you should do with a linear curve:
Start doing low-intensity work. Anyone with a linear-shaped curve should spend at least three months doing nothing but low-intensity aerobic runs. There is no need for higher-intensity work until the aerobic engine is sufficiently built. Higher-intensity work will not be all that productive.
Steep Curve
A steep curve normally happens when an athlete has developed a robust aerobic engine through a steady diet of low-intensity running over many months and years. In most ways, this is the ideal curve for ultramarathon athletes as it demonstrates the athlete’s ability to oxidize fat as a fuel source through a wide range of intensities. However, once a sufficient intensity is reached, lactate accumulation increases dramatically. Training at higher intensities has probably been limited with athletes demonstrating a steep curve. We also see this curve with athletes who adopt a low-carbohydrate diet.
What the steep curve tells you:
- The athlete is well-trained, particularly at low intensities.
- The athlete has little resilience at intensities beyond his/her lactate threshold. This is normally reinforced by training copiously at lower intensities.
What you should do with a steep curve:
Start doing high-intensity work far away from your goal race. While low-intensity running will still be the majority of the training diet, athletes who demonstrate a steep curve can improve tremendously with some high-intensity work early in the season.
Final Say
Lactate testing was once confined to elite-level athletes with big budgets and copious amounts of time to train. That’s no longer the case. Commercial labs and universities willing to test subjects now dot the landscape and make it more accessible for everyday athletes to procure a physiological test. And there’s a reason for the increased proliferation and interest: with the right equipment, protocol and interpretation, lactate testing (and other physiological testing) can greatly inform training. And it’s immediately impactful as the training you do in the weeks after the test can look markedly different pending the results. So, if you are considering adding some sophistication to your training process next year, consider a lactate threshold test. At the very least, it tells you your training has been working and at the most, it gives you a clear direction of what you should work on for both the short and long term.