Our body relies on three primary macronutrients that provide us with a constant source of essential energy. These macronutrients, or macros for short, include carbohydrates, proteins, and fats. As we’ve discussed in the past, different macronutrients will offer varying levels of caloric energy. While both carbs and proteins have four calories of energy per gram, fats have nine.
Much like a car burns fuel for energy, we burn these calories for energy whether we’re sitting or running down the block. And we’re even more like the automobile’s fuel system than you might assume.
Of the three macronutrients we utilize for energy, carbs act as the primary source because they’re broken down into a usable substance called glucose. And much like a car produces emissions when it burns fuel, our body produces a byproduct of its own when burning glucose. We call that substance lactate, or lactic acid.
A substance commonly associated with exercise intensity, lactic acid is produced as the body processes glucose, and it often causes muscle soreness as it builds up in the blood.
Yet despite all the pain lactic acid may cause, it can actually be used as fuel if we remain within our lactate threshold. So what is this threshold exactly? And how can we train it? Let’s take a closer look at the benefits of the lactate threshold.
What Is Lactic Acid?
Before we can jump into the benefits of training our lactate threshold, let’s take a step back and discuss lactic acid, or lactate, in greater detail.
Imagine for a moment what it feels like to go for a long, intense run. Heart rate is elevated, breathing is heavy, and the body’s muscles are growing sore. We press on despite the pain, enduring this high intensity exercise because of the countless benefits.
As we’re suffering on the surface, glucose is being turned into energy deep within our cells through a process known as glycolysis. And as energy is made in the form of ATP, our body produces a substance called lactic acid that’s deposited into the blood as a waste product.
Normally our body can manage these blood lactate levels and utilize lactic acid as fuel. But if we happen to push our pace too hard or run at a steady pace for a long time, eventually our lactic acid levels will rise.
At some point, our body won’t be able to convert the waste product that is lactic acid back into energy. This is when we’ve reached our lactate threshold. At this point, lactic acid will flood the body via the blood and negatively impact muscles, diminishing strength and causing soreness.
So, What Is Lactate Threshold?
Lactate threshold is the fastest pace we can run without creating more lactic acid than our body is capable of using for fuel. And because this pace often falls near our 10K or half marathon pace, we can perform exercises like interval training that utilize training zones as a means of improving our lactate threshold. Many training programs will incorporate endurance training that’s designed to make us run just below or at our threshold pace.
Why Is Lactate Threshold Important?
So why is this sore and tiring response to blood lactate accumulation so important in the first place? In reality, it’s because running at or below the pace where we begin producing excess lactate can actually increase our lactate threshold over time.
We can train our body to respond differently to lactate by performing physical activity that reaches the threshold. Elite athletes or endurance sport athletes (such as cyclists and triathletes) often utilize training plans and blood samples that provide an accurate measurement of blood lactate concentrations and thresholds. But the rest of us must figure out our lactate threshold on our own.
Determining Our Lactate Threshold
There are two principal ways by which we can determine our lactate threshold.
The most concrete yet expensive way to do this is by taking a series of blood samples while exercising at increasing intensity. This test would take place at an exercise physiology laboratory that houses expensive equipment and is, therefore, not readily available to the general public.
During this lactate threshold test, athletes exercise on a treadmill or stationary bike while increasing exercise intensity at precise intervals until exhaustion sets in.
Doctors or researchers take a blood sample during specific stages of the test. . And from there, blood lactate levels are measured at various speeds and power outputs. Results are then plotted to illustrate lactate levels during these specific moments in time.
Yet what makes our lactate threshold so fascinating is the notion that it can change. If we live a sedentary lifestyle and measure our lactate threshold, chances are it will be rather low (meaning our threshold is low).
But if we participate in endurance exercises for the next few months, a new reading will produce a higher threshold. This means it will take more effort for our body to max out and pass the threshold.
The other tests we can administer aren’t nearly as sophisticated or expensive as the blood test. One test utilizes VO2 max to identify a training pace that will maintain lactate threshold.
For instance, if an individual can run a 6:49 mile pace, their VO2 max will be 42 and their lactate threshold will be 7:52. This means lactate will be reused as energy above a 7:52 pace, but will spill over into our blood if we run quicker than this pace. Consider utilizing a VDOT (VDOT is shorthand for “V-dot-O2 max”) chart for more information.
Another test we can utilize is called the Conconi test. During this test, a heart rate monitor will record our heart rate every five seconds as we begin running. We’ll then increase speed every 200 meters.
The goal isn’t to maintain a constant speed, but to continue increasing the pace until it becomes extremely challenging. When we plot our heart rate against our speed, the point on the graph at which our heart rate goes beyond our speed will roughly correlate to the lactate threshold.
A final method that sports medicine encourages is called the 30-minute test. During this test, a 30-minute flat out time trial takes place, and this is one of the most accurate tests that doesn’t require expensive equipment.
Start this test with a warm up before running on a track at the fastest sustainable pace. Obtain a heart rate reading 10 minutes into the test, and then again after the test has ended. Adding the recorded heart rate at the 10-minute mark and the 30-minute mark will produce the lactate threshold heart rate. Average pace for the entire test is considered the lactate threshold pace.
Who Benefits From Lactate Threshold Testing?
Understanding the dynamics of lactate threshold testing is by no means reserved solely for the endurance athletes and triathletes of the world. We can all increase athletic performance by way of lactate threshold training to ensure our bodies are operating in peak physical shape. And for those who compete in endurance events such as triathlons or ultramarathons, understanding lactate threshold levels may be the key to athletic success.
Lactate Threshold Testing: It Isn’t Just for the Pros
Lactate is a misunderstood character. While it’s true that high levels of lactate can impact our endurance, lactate can also provide us with a deeper understanding of how well-adjusted our body is to regular activity.
Our Lactate threshold is an indicator of our current state of health and can always be improved upon should we seek an opportunity to lead a healthier life. When we incorporate lactate threshold training into our workouts, we can improve both endurance and well-being along the way.