Lactic acid itself isn’t responsible for the muscle fatigue that causes you to do the skeleton dance at the end of a race.
Despite what you might be tempted to believe after scanning the headlines of your favorite running magazines, there’s no one secret workout that will guarantee you set a new personal best at your next race. As experienced runners know, it’s the right mix of workouts and consistency over time that brings long-term and steady results. With a seemingly endless variety of workouts to choose from, picking the most effective workout to accomplish your racing goals takes a little research.
Luckily, coaches and exercise scientists alike understand the specific metabolic demands placed on the body during long distance events. As such, they know what type of workouts will be the most effective for success at each particular race distance. Specifically, coaches and exercise scientists realize the important role of lactate during long distance running — how the body produces it, how the body utilizes it as a source of energy, and how lactate contributes to slowing down.
Therefore, it’s no surprise that most training schedules include a steady diet of threshold runs, particularly in the form of tempo runs or tempo intervals. However, when we take the time to examine exactly how lactate works, both as a fuel source as well as how the body clears it, many coaches have come to realize that straight tempo runs might not be the best way to improve your body’s use of lactate.
Instead, many coaches and exercise scientists are beginning to understand that the goal of threshold training isn’t to produce less lactate — as has been traditionally thought — but to improve the body’s ability to clear lactate from the blood. In essence, you should be training to improve your lactate clearance rate.
In this article, we’re going to debunk some of the faulty science about lactate that still permeates training theory today so you can better understand how to train more efficiently. More importantly, we’re going to look at how adding lactate clearance workouts into your training schedule can help you improve as a runner, Lastly, we’ll show you some specific lactate clearance workouts you can implement right away.
Lactate Is Your Friend
Lactate, or lactic acid as it is commonly known, gets a bad rap thanks to some faulty science from the 1970′s. While an excess accumulation of lactate contributes to why runners slow down at the end of races, lactic acid itself isn’t responsible for the muscle fatigue that causes you to do the skeleton dance at the end of a race. In fact, lactate is actually a source of energy.
Hydrogen ions are the real culprit.
The cause of your muscle fatigue is actually the result of a buildup of hydrogen ions. For each lactate molecule produced by the body, one hydrogen ion is also formed. Hydrogen ions lower the blood pH and make the muscles acidic. This acidity irritates muscle nerve endings and causes that pain, heaviness, and burning mistakenly attributed to lactic acid.
How lactate really works:
As you probably already know, your body breaks down glucose for energy, and a byproduct of this process is lactate. During easy running, your body reconverts and recycles this lactic acid back into energy (through the Cori Cycle) and carries away hydrogen ions with it. Therefore, the production of lactate, and the clearance of hydrogen, will remain relatively constant while running at an easy aerobic pace, which doesn’t require a huge demand for energy.
As you continue to run faster and demand more energy, the production of lactic acid will slowly increase. At some point, whether it be too fast a pace or holding a steady pace for too long, the production of lactic acid will soar and your body will no longer be able to convert lactate back into energy. At this point, lactate can’t grab its hydrogen ion to reduce the concentration of hydrogen in the muscle cell. And, as we learned previously, hydrogen is what causes the muscles to seize up.
How this knowledge changes your approach to lactate threshold training:
Now that we understand how lactate really works in the body, and have discovered the true culprit of our muscle fatigue, how does that change our approach to training? Recent research indicates that the goal of endurance training shouldn’t be to reduce the production of lactic acid but to improve the ability to clear lactate from the blood. Simply speaking, we shift from the idea of increasing our tolerance for lactate production to the idea of increasing how efficiently our body utilizes lactate as an energy source.
The faster we can train our body to reconvert lactate back into energy in the liver, the longer and faster we can run at a given pace. Therefore, the goal of your lactate threshold training shouldn’t be how to reduce lactic acid production, but instead to train your body to use it efficiently. While this shift in thinking is slight, it radically changes how you approach your lactate threshold workouts.
Lactate Clearance Workouts
Of course, traditional tempo runs, tempo intervals, and cruise intervals help increase your body’s ability to clear or reconvert lactate. However, you can implement special lactate clearance workouts into your training to more specifically target this niche of your training. Two of my favorite lactate clearance workouts are the alternating tempo run and, for lack of a better name, what I call the lactate clearance tempo run.
Alternating Tempo Runs
I first learned about alternating tempo runs from my college coach, John Gregorek. We used alternating tempos in the early phase of our cross country training when we were developing our endurance and establishing a base for the long season ahead. I find them particularly effective for half marathon and marathon training, although you can scale them down to 10K or 5K training as well. It’s a good way to mix in some speed while also doing threshold training.
The goal for the workout is to run a specific distance (even numbers work best) and alternate the pace between marathon pace and either 10K or half marathon pace, depending on the distance of your run and your fitness level. The shorter your tempo run, the closer you can get to 10K pace during the “fast” portion, while during longer alternating tempo runs these “fast” portions are better done near half-marathon pace.
The goal is to spike lactic acid production with the faster mile and then train your body to efficiently process the lactate while still running at a more reasonable pace (marathon pace). This will help make you more efficient at reconverting lactate into energy on race day.
For a 3:30 marathon runner, the workout might look something like this to start:
* 1-3 mile warmup, 6 miles continuous at 8:00, 7:25, 8:00, 7:25, 8:00, 7:25, 1-2 mile cool down.
As you get more fit, you can increase the distance of the run to 8-12 miles, depending on your normal workout volume.
This workout is also a good way to hone your pacing skills. Changing paces so often is difficult, but it can happen in races.
Remember, the “slow” mile is designed to teach your body how to become efficient at processing lactate. Running faster just because you can reduces the effectiveness. Remember: Faster is not always better.
Start with the slow mile if you’re new to the workout and start with the fast mile first once you’ve become more seasoned.
Lactate Clearance Tempo Run
The purpose of the lactate clearance tempo run is the same as the alternating tempo — to flood the muscles with lactate and then teach your body how to reconvert that lactate back into energy efficiently while running fast.
The lactate clearance workout is a great tempo effort for runners training for 5K or 10K. It allows you to run at or near goal pace for part of the workout and still get the benefit of a threshold run. Likewise, marathoners and half marathoners can use it to add a little speed to a training plan that might be full of marathon-paced miles.
The objective is to run the first mile or two of a tempo run at about 10K pace and then back off the last mile or two miles to half marathon or marathon pace. Here’s how the workout might look for a 3:30 marathoner:
* 2-mile warmup, 2 x 3 miles (first 2 miles at 7:20, last mile at 7:50 pace) w/3 min rest between reps, 1-mile cooldown
If you’re a beginner, you can slow the “recovery” pace down to marathon pace or do one fast mile with two “slow” miles. To increase the total length of the workout, you can break the tempo into two or three 3 to 4 mile sessions. This will allow you to keep your volume high without going overboard with the workout.
This workout serves as good practice for those runners who can’t control their pace early in a race. This will help you “recover” if you go out too fast.
Doing more than 4 miles in one “set” is difficult. Keep the sets to 3 or 4 miles.
Again, don’t run the entire 3-4 miles at 10K pace even though you might be able to do so. That is not the point of the workout.
With your new understanding of how lactate works, try implementing these workouts into your schedule to spice things up and improve your lactate clearance rate.