Lactate Threshold Testing
What exactly is lactate threshold (LT)? What does it mean to you as an endurance athlete? How do you determine your LT and what do you do with it? Let’s look at some definitions before you run the necessary tests to determine your LT.One goal in endurance training is to identify your ideal training zones; obviously your goal races and distances will mean different training protocol. If you are a sprint or Olympic distance athlete, you are going to push faster and shorter than, say, an Ironman athlete. For an Ironman athlete, you are going to train a little slower, a little longer and you will need to identify your “forever” pace, the pace that you could train at all day with the right amount of nutrition and hydration. Regardless of your distance and goals, measuring your LT will provide you with the information you need to set training zones with far more accuracy and predictability than heart rate training. But how does it work?
What will I need?
The only tools needed for the tests we are going to perform are a bike and a heart rate monitor with a lap function. And running shoes. You should run with shoes on.
What is lactate/lactic acid?
Lactate, also commonly referred to as lactic acid, is an important substance for endurance athletes to understand. Lactate often gets a bad rap, the common misconception is that lactic acid is inherently negative, probably because of its historic connection with the “burn”. This is a bit of a misnomer, though, as increased lactate production during high-intensity exercise is natural. Lactate is produced and utilized by the organs as a metabolic fuel, even at rest. In fact, endurance athletes should pay particular attention to the way in which the liver utilizes lactate, to produce glucose, which is then released back into the blood stream and used as fuel everywhere. Glucose is mother’s milk, right? What, then, is the problem with lactate? The problem lies in the bottleneck that occurs when lactate production exceeds the body’s ability to remove it from the bloodstream. During intense training or especially in high stress, high paced race situations, when the rate of demand for energy is high, lactate is produced faster than the ability of the tissues to remove it and lactate concentration begins to rise. That is what is known as the burn and that is the problem.
Can the body be trained to utilize lactate more effectively?
Endurance training affects lactate metabolism in two fundamental ways:
First, it lessens the production of lactate in all slow and some fast twitch fibers (those which have aerobic capability). Endurance athletes are slow twitch athletes. I am looking at this from an Ironman’s perspective, but the science applies. If you are like me and your athletic background is a history of fast twitch activities, don’t despair. Over time, extensive endurance training will convert many of the fast twitch fibers that have almost no aerobic capacity to slow twitch fibers.
Second, endurance training speeds up the process of moving lactate around the muscles and the body, a process called clearance. Endurance training causes adaptations that speed up clearance. Clearance is the process that helps us to avoid a lactic bottleneck where muscles cannot process lactate as fast as the body produces it, leading to the inevitable and painful bonk. The faster this clearing process happens, the better you will perform for a longer period of time. When you hear the expression, “building an endurance base”, the changes described above are some of the implications of that expression. The longer these fibers can contract the faster your race and the longer you can stave off the bonk.
When you stress the aerobic system in a training or race setting, your body adapts in several ways. Oxygen can move more quickly to each muscle. Oxygen is necessary to produce the maximum amount of energy possible. Also, endurance training over time will literally alter the physical composition of your muscles, by increasing the density of cells, increased capillaries, efficiency of lactate usage, and most of all, tying all of this together to more efficiently and quickly produce the energy you need to keep going faster and longer.
What is my lactate threshold?
Lactate threshold (LT) is the best indicator of performance known in endurance athletics. Scientifically, a working definition of LT is the point during training or racing at which blood lactate begins to accumulate above resting levels, where lactate clearance is no longer able to keep up with lactate production. For our purposes, LT is the upper limit of your forever zone. As mentioned above, this is the pace that you could maintain all day (theoretically) if nutrition and hydration were kept at a steady state. You will conduct field tests to determine your LT and then work backwards to create training zones that maximize training time and push the upper limits of your LT.
What tests can I use to determine my lactate threshold?
The best tests for LT are conducted in a laboratory or at least with equipment that literally measures the blood lactate levels by drawing blood. This can be cumbersome, expensive, and not readily available for many of us. In the place of these scientific tests, you will conduct field tests using time trials on the bike and run. Swimming can be more difficult to gauge, so it must be handled differently. The objective of these tests is to determine your heart rate training zones as a measure of LT. There is an old formula that has been used since the invention of Jazzercise, probably before. That formula for determining your maximum heart rate is 220-Your Age formula. If you all you want is a quick, simple formula, this works. However, there are dozens, it not hundreds of variables that render this inaccurate and somewhat useless. Leave this formula to the treadmill set. Approach your training from a more practical, comprehensive standpoint. By taking field measurements you can determine the exertion level at which you reach lactate threshold and thus identify your ideal training zones.
To make this as easy as possible, you will use a 30 minute time trial (TT) on the bike and run. From these time trials you can determine the correct training zones.
Bike Test Protocol
Warm up for 15 minutes. Take your time, get thoroughly warmed up, spin through your gears, get yourself ready. This is going to be a challenge.
Once warmed up thoroughly you are ready to begin. Find a flat-ish course, preferably one you have done before and definitely one with no stoplights, stop signs, or obstacles that will slow you down during the test. This TT will be a 30 minute test. Pace yourself – you don’t want to explode halfway through but you also don’t want to finish the thing knowing you could have gone significantly faster or farther. Metering your effort equally over the whole test. Begin in a gear that you can spin at 90-95 RPM. (note this gear mentally because you are going to want to test this over and over throughout your training and want to keep things equal). At 10 minutes, hit the Lap (Split) button on your heart rate (HR) monitor. Your heart rate over the next 20 minutes will be the average heart rate you will use. This is the number you are working towards, the objective of this test. This is, for your purposes, your LT.
Finish with an easy cool down.
Run Test Protocol
You should repeat a similar test, on a different day, for the run. 15 warm up, 30 minute test, hitting the Lap button 10 minutes into the test and recording average heart rate for the final 20 minutes of the test.
Swim Test Protocol
Heart rate is a useful, effective determinant of LT on the bike and run, but not so much in the pool. In the pool you will use pacing.
Bike and run training efforts are based on heart rate zones and perceived exertion. For swimming you will use pacing, because it is easier than trying to take heart rates in a pool. Can you use heart rate? Of course, if you want to stop every 100 meters and take a 6 second count, then multiply by 10. I prefer to test by pacing and feel in the pool, and I like to use 10 x 100 as the baseline test for my clients. After a thorough (~500 meters) warm up, you are going to push yourself hard for a set of 10 100 meter sprints. You know yourself, you know the pace that is not so exhausting that you might drown, but not so easy that you are smiling. Bottom line, if you feel like you might just vomit but you don’t actually vomit, you hit it just right. Record these times. Ideally they are all within ~5%-10% of each other. A larger differential sheds doubt on the results and we probably need to question the accuracy.
What do I do with all of these numbers?
Now you have a baseline. You have performed basic LT testing, but in a controlled environment, eliminating as many mitigating variables as possible. Now you test and retest. Monthly testing fits nicely as part of a 4 week periodization paradigm. Every month has an “easy” week, what better time to retest? Each time we retest, recreate the original test as well as possible (same course, same climate, same diet-what did you eat or not eat before your original test, same state of mind, same equipment, etc. etc). This is spoken from the point of view of an Ironman training plan; 30 minute time trials may not fit into everyone’s definition of an easy week, but short, explosive TT’s make a nice training session once per month regardless.
By establishing these numbers, by implementing them into an intelligent, thoughtful training program, and by constantly retesting yourself, you we are putting yourself into the best position to train well and race successfully.
Written by Brian Melekian