Lactate Testing and the Science of Running Performance

Podcast - System Based Training
Optimized Training for Each Athlete

First Question:Do you want to run faster?

Second Question: What do you mean by faster?

What does the term faster mean? This is not a silly question, and the answer to it is the secret to an optimal physiological performance in a race. It usually means who can get to the finish line in the shortest time. That depends on whether the finish line is 200 m away, 1,500 m away, 10,000 m away, 26.2 miles away for a runner or 140.6 miles for an Ironman length triathlon race. The fastest over 200 m will almost certainly not be the fastest over 1,500 m and may not even be able to finish a race of 10,000 m, let alone a marathon. The following discussion will illustrate what is obvious to everyone but which is rarely considered when preparing for a competition. If it sounds a little technical, bear with it because it is actually fairly simple.

The primary physiological objective of training is to maximize the rate of energy release for the event that the athlete is preparing. Just as a fast car depends on how much fuel/energy it can burn per second, so a runner depends on how much energy it will use per second. We emphasize rate because it is the ability to sustain a high rate of energy production per unit of time over the entire event that is important, not the maximum capacity for producing a short burst of energy or the ability to seemingly go on forever.

Let's look at two very different runners, a good sprinter and a good marathoner. First, have them race each other at 200 m. The sprinter will beat the marathoner over 200 m fairly easily because the sprinter is able to sustain a higher rate of energy production for 200 m. The typical person would say the sprinter is faster.

comparison of two different types of runners for a 200 m race

comparison of two different types of runners for a 200 m race

For a longer race the situation is reversed. The marathoner will beat the sprinter over 10,000 m because the marathoner is able to sustain a higher rate of energy production for 10,000 m. The time we estimated for the sprinter over this long distance is optimistic since it is unlikely he will be able to even finish the race.

comparison of two different types of runners for a 10 k race

comparison of two different types of runners for a 10 k race

The typical person would say the marathoner is not necessarily faster but has better endurance. In fact the marathoner is faster over the 10,000 m course. But why? Why can't the sprinter keep up the high rate of speed he exhibited in the 200 m race? We all intuitively know what happens because we have all sprinted and then had to slow down.  But what does this difference mean for training or for a race?

What is it about the metabolism of the marathoner that enables the higher rate of sustained energy production for a 10 k race? A typical response has been that the marathoner has a higher VO2 max. But is this true? And if true, is this the answer? Notice even the marathoner has to slow down considerably when running 10,000 m versus his sped in the sprint race.

comparison of two
different types of runners for a 200 m and 10 k race

comparison of two different types of runners for a 200 m and 10 k race

All this is obvious but what has it to with how one reaches an optimal performance for a particular race? In each situation the winner was able to sustain a higher rate of energy production per unit of time for the length of the race. In each race both runners were using their aerobic and anaerobic systems to produce the energy.

So what is it about these energy systems that leads to
different performances by a sprinter and a marathoner over different distances?

Most would say that the reason marathoners do better in the 10,000 m is because they have better aerobic systems than the sprinters. This may or may not be true. World-class sprinters often have aerobic systems that are as strong as top marathoners. Runners in the 400 m Olympic finals almost assuredly have extremely high aerobic capacities. So why do marathoners do so much better in longer races?

The main reason marathoners can run
faster than sprinters over 10,000 m
is not that they have stronger aerobic
systems but weaker anaerobic systems.

This last sentence may be one of the most important factors for successful training yet few have ever heard this before. Have you?

To say that someone is faster because they are weaker seems to be a contradiction. We have been conditioned to think that if runners are faster, then they are stronger. But this apparent paradox is key for successful training of most runners, for whatever distance. It will be discussed in more detail below. We will show that in longer races the anaerobic system is the gateway to the use of the aerobic system. For shorter events such as longer sprints (over 40 seconds) and middle distance running, the aerobic system returns the favor and becomes the gateway for the use of the anaerobic system.

To illustrate this even further, consider three elite runners, a sprinter, a middle-distance runner and a long-distance runner. We ask each to run their best in three different races, 200 m, 1500 m, and 10,000 m. We then see who is fastest by measuring the pace for each race (meters per second). We also measure the VO2 max for each runner and find that the middle-distance and distance runner have almost identical aerobic capacities. The sprinter is surprisingly fairly high too.

The following chart illustrates how each athlete does at each distance. Two things pop up and each is obvious. (1.) Each athlete wins easily at his preferred distance. (2.) The speed for each event goes down as the distance for the event increases, for all runners.

comparison of three different types of runners
for three different races

comparison of three different types of runners for three different races

But why should this happen if VO2 max is the same, at least for the middle and long-distance runners? Why can’t the middle-distance runner do as well as the marathoner in the 10 k race and why is the marathoner not as fast as the middle-distance runner in the 1500 m race? Why does the middle-distance runner beat the marathoner so easily at 200m? It cannot be VO2 max because the athletes are the same on this criterion. The answer to this is what is behind performance at any distance. Namely, it is the interaction of the aerobic and anaerobic systems. It is anaerobic capacity that is driving the speed at which the athlete can complete any race if the VO2 max is the same. But the anaerobic system plays a very different role in short races than it does in long races.

This unconventional explanation for the marathoner’s success at longer distances and the middle distance runner’s success at shorter distances is at the heart of these discussions. This website and this section on running in particular will hopefully change your understanding of the physiology behind a peak performance, show why the rate of energy production is key to achieving a peak performance, and help you see why the rate that lactate is produced and consumed is at the heart of maximizing the rate of energy production during a race. Once this link is made, then the usefulness of lactate testing for reaching a optimal performance becomes obvious.

One last question about these athletes is, do they have similar lactate responses to running? The answer is no. The middle distance runner and the marathoner will be similar but be very different from the sprinter. The chart below shows what happens to lactate in the blood as each type of athlete runs faster and faster. But notice that at every speed the sprinter generates more lactate in the blood and at higher speeds the middle distance runner will generate more lactate than the marathoner.

lactate curves for sprinter, middle distance and marathoner

lactate curves for sprinter, middle distance and marathoner

Third Question: How do you get faster?

The answer is appropriate training. But what is appropriate? One way to get appropriate training is to use a professional for your training or the training of your athletes. A second way is to do it yourself. We have advice on both of these approaches. Before we start with specifics, it is necessary to understand one important distinction. That is the difference between testing and training. Most coaches are mainly interested in how to train their athletes. They use their experience on what has worked before. They are usually ex athletes. As one high level coach said to us (he was a world champion), he does not want to confused by the facts. He has his way of training and didn't want lactate tests interfering with his recommendations.

Testing is often an annoyance for many coaches. Lactate testing is not magic but it nearly always tells the coach the actual conditioning level of the athlete. It is a window into how well the athlete is trained and will guide the coach or the athlete to the best training practices to get the athlete more optimally trained for his or her event.

But what the coach and athlete really want is how to train to reach this optimal performance. We advocate a process called the Steering Principle and is described in detail here on our website. Basically, the steering process is a continuous monitoring of the athlete and whether the prescribed training is working or not and will work with any training approach.*.

Steering to a optimum performance through constant testing to ensure continued success

*We are indebted to Jan Olbrecht for introducing us to this principle. It is fairly standard practice amongst high level coaches and sports scientists in Europe. His book, The Science of Winning is probably the best training book in the world.

Using a professional

One of the most sophisticated practitioners of the training of runners using science in the US is Shannon Grady. Shannon has a masters degree in exercise physiology, was once one of the top 1500 m runners in the US, has worked for the Olympic committee training runners and has performed over 10,000 tests on runners over the years. She has an impressive record of improving her athlete's performance, especially with young runners.

Shannon's organization is Go Athletics and to see her website click here.

Here are a sample of some of Shannon's blog posts on using science in the training of runners.

There are others but Shannon is one of the most systematic sports scientist in the US and has good results. You can follow Shannon on Twitter.

Steering to a optimum performance through constant testing to ensure continued success

Doing it yourself

Many coaches and athletes do the testing themselves. They have experience with it from courses they have taken in their education and accreditation process. Many of the coaches have been tested when they were athletes. The following is a simple approach to lactate testing.

This website also has a list of typical questions with answers that athletes and coaches have about lactate testing. It might be good to review this if any of the terms used here are unfamiliar. FAQs about lactate testing.

There are two kinds of lactate tests:

One way to use lactate measurements to set training paces is to determine a baseline lactate for the athlete (usually between 1.3- 2.0 mmol/l) so that the coach and athlete know whether the athlete is training too fast or too slow.  This might require 2-3 additional measurements beyond those needed to find a V4 level (the V4 is the speed during a test that generates 4 mmol/l of lactate.) It may not be necessary for the recreational triathlete, but the literature suggests that most athletes at all levels train too hard. Harder than what is best for their development.  It is difficult to tell am athlete that he is training too hard if his lactate for a particular set is 2.5 mmol/l and the effort feels easy. But this might be a very inappropriate training level if his baseline is 1.5 mmol/l and that is where most of his training should take place.

Here is a running SLTP for a beginning athlete that measures the baseline as well as the V4. The initial running pace was 7:00 min for 1200 m, or quite slow. But this was the first time for the coach so it was a way to make sure the athlete could easily handle the test. Each 1200 m was increased 15 seconds till the athlete generated 4.6 mmol/l at 6:00. This test could be one of the running workouts the athlete might do in the week. He covered 6 kilometers in this testing, which should be considered part of his training for the week. Next time the athlete could start at 6:30 and not have to complete each of these steps. Also after the last step the coach took two samples to make sure he recorded the highest lactate level from the step.

Recording form - the coach or athlete should have a recording form that he or she uses during the testing. A simple form that we have seen used is the following.

form for collecting information during lactate testing

Here is the form filled out for our recreational athlete.

form filled out for a recreational runner during a lactate testing session

Here is the data plotted. We used Excel to make these charts.

lactate curve for running for a recreational athlete

So what does this mean for this athlete? What does he do with the chart? First and most important, if the athlete had done a similar test previously, he will have a way to evaluate the training since that test and adjust it for the next cycle of training. This is the “Steering Principle” referred to above. You train, you test, and then you adjust the athlete's training based on what the testing shows. For this athlete the testing is simple and the objectives are simple: train to raise aerobic capacity which will generally be revealed in the test results if the V4 keeps moving to a higher pace.

This is not a very fast runner and probably should not run anything more than a 10k till the coach sees how he does. If he has been training for awhile, he will probably run a marathon between 4 to 4 1/2 hours. Here is how he compares to other runners including some of the world's best. He is the runner to the far left on this chart.

comparison of runners of different capabilities using lactate testing

Let's look at a second runner. Here is the form that recorded his test. Notice that heart rate was also recorded and the test was done on a treadmill and measured in kilometers per hour.

form filled out for a recreational runner during a lactate testing session

Here is the chart for this runner. The V4 is approximately 15.6 km/h or about 4.3 m/s. This would place him just a little bit faster than the recreational runner in a chart of runners above.

lactate curve for running for a recreational athlete

Here is a chart for a runner that was tested and then re-tested about 6 weeks later. It is using a sub-maximal protocol that stops when the athlete has generated 4mmol/l of lactate. The V4 for the first test is approximately 3.75 m/s in September and about 3.9 m/s in November. This indicates that this runner will be somewhat faster in a distance race and that his training is working if he is preparing for a distance race such as a half marathon. This protocol can be improved if an all out effort was included. This usually takes place about 15 minutes after the last step of the sub-maximal protocol.

lactate curve for running for a recreational athlete

Control Test

A simple control test for this last athlete might be to take a lactate reading about a half hour into a training run in which he maintained a constant heart rate. For example, suppose after the November test, his coach wanted this runner to maintain less than 2 mmol/l lactate levels during most of his distance runs. The coach told the athlete to run at a heart rate of about 150 bpm or a little less.

If the lactate reading during the run was 2.5 mmol/l then the runner was going too fast and the coach would tell him to adjust his heart rate to about 145.

Anaerobic system

We have mentioned nothing about the anaerobic system and how if affects race performance. We have several questions about the anaerobic system on our Questions page

How does the anaerobic system affect performance in distance events?

The anaerobic system is one of the main determinants of the lactate threshold, which is key to performance in a distance event such as a marathon, a triathlon, a road cycling race and any other event over 15-20 minutes. See See lactate threshold.

The anaerobic system has been engaged to a level that lactate and other metabolites will continue to increase unless the athlete slows down to an effort below this threshold. So when one is discussing the lactate threshold, one is really referring to the level of output of the anaerobic system. Here is what we say on the lactate threshold page about anaerobic capacity and endurance races.

  • First, , anaerobic capacity helps determine aerobic power and thus the lactate threshold, because it interacts with aerobic capacity. Briefly, the anaerobic system limits the body's use of the aerobic system by putting out more lactate and hydrogen ions than the aerobic system can absorb, inhibiting muscle contraction. We refer to this as the gate-keeping effect, which is discussed in detail on the CD-ROM and elsewhere in the triathlon site. If the anaerobic capacity is too high the athlete will be slowed down by the excess acidosis that accompanies lactate production. So for endurance events it is necessary to train the anaerobic capacity down. The lower it is the more the aerobic system can be utilized before acidosis occurs.   But, it can’t be TOO low because you need some anaerobic capacity for speed....

  • Second, anaerobic capacity affects performance by determining the total amount of carbohydrates available for the aerobic system during competition. Unless the anaerobic system is generating enough carbohydrate fuel for the aerobic system, the aerobic system will have to use more fats, which metabolize slower and slow the athlete down. Thus, if the anaerobic capacity is too low, the athlete will be driven to less effective fat metabolism. This is why an athlete will consume glucose supplements as the race progresses so that he/she can utilize more of faster metabolizing carbohydrate fuels.

Essentially the stronger the anaerobic system is the more it will slow a runner down for an endurance race such as a 10K, half marathon or marathon. But it has to be strong for a shorter race such as a 800 m or 1500 m race in order to make the runner faster. Training can either suppress anaerobic capacity or build it up depending on what is desired for the runner's primary event.


We are in the process of developing this section but in the mean time, see our webpage on training for the triathlon which includes recommendations that are appropriate for running as well.

(Again, this page is under development and will be continually updated)