If you have ever run a race, pushed yourself through a set of heavy squats on leg day, or done a workout of all-out 400-meter repeats, you can probably conjure up the intense burning sensation in your legs that many commonly attribute to “lactic acid buildup.” What naturally follows is wanting to figure out how to get rid of lactic acid.
Although we used to think the burning and fatiguing feeling in the muscles during intense exercise was due to lactic acid, the notion of lactic acid buildup causing muscle pain is actually false.
So, what exactly is going on? If it’s not “lactic acid buildup,” what causes the burning sensation in your legs when you’re running fast or pushing your body to the max? More importantly, we want to know how to get rid of lactic acid or whatever that burning sensation is.
In this guide, we will discuss how to get rid of lactic acid in the legs by addressing the real root cause and then examining potential strategies to reduce “lactic acid” in the legs to run harder and recover faster.
In this article, we will cover:
- Does Lactic Acid Make Your Muscles Burn When You Run or Work Out?
- What Is Lactate?
- Does Lactate Buildup Cause Burning In Your Legs?
- What Causes Burning In Your Legs When Working Out?
- What Is Lactate Threshold?
- How To Get Rid Of Lactic Acid In Your Legs
Let’s get started!
Does Lactic Acid Make Your Muscles Burn When You Run or Work Out?
The short answer is no. Lactic acid is not the culprit or cause of the burning sensation and intense fatigue in your muscles when exercising at a high intensity.
Historically, exercise physiologists and other researchers thought that lactic acidosis, or the overabundance of lactic acid accumulating in the muscles, was the cause of the burning sensation felt during intense exercise.
Lactic acid is a molecule formed when a hydrogen atom (also known as a single proton) bonds with the lactate molecule.
However, subsequent research elucidated the fact that lactic acid as a molecule cannot really exist in its intact form in the body because the pH of human blood is too high.
In other words, the pH of our blood is too alkaline, or not acidic enough to sustain the bond between the hydrogen ion and the lactate molecule.
As a result, “lactic acid” in the body freely dissociates into the freestanding lactate molecule and lone hydrogen ions.
Therefore, there is no buildup of lactic acid in your legs during intense exercise, and lactic acid is clearly not the cause of muscle burning and fatigue during hard workouts and races.
What Is Lactate?
When you are running fast or doing a hard set of burpees or weighted step-ups, your muscles need energy to do work and enable your movement.
Our muscles can produce cellular energy (adenosine triphosphate (ATP)) through several different metabolic pathways, depending on the availability of fuel sources (carbohydrates, fats, etc.) and oxygen, as well as the type of muscle fiber (Type II “fast-twitch” fibers or Type I “slow-twitch” fibers).
When you are exercising at a very high intensity, such that you are breathless or nearly so, ATP must be made through anaerobic metabolism (without oxygen). This is primarily accomplished through a process or pathway known as glycolysis.
Without getting into the weeds of biochemistry, glycolysis essentially is a set of chemical reactions that breaks down the glucose molecule (simple sugars from the foods we eat).
The end result of glycolysis is the production of four ATP molecules, of which two are the net energy yield. Your muscles can then use these energy molecules to power your running stride, deadlift, or any other vigorous exercise you are doing.
In addition to ATP, anaerobic glycolysis produces lactate. Therefore, during heavy exercise, the concentration of blood lactate increases.
Does Lactate Buildup Cause Burning In Your Legs?
So, if lactic acid doesn’t exist in the body and lactate levels increase during intense exercise, the natural next question is whether or not lactate, rather than lactic acid, causes the burning sensation and fatigue in your legs when you’re sprinting the last quarter mile of a 5k or trying to bang out a set of heavy squats.
Research indicates that lactate is not responsible for muscle burning during vigorous exercise or delayed-onset muscle soreness (DOMS) after a workout.
While the blood lactate concentration can be used as a biomarker or indicator of exercise intensity and glucose breakdown, the lactate molecule itself does not cause muscle fatigue or discomfort during or after exercise.
In fact, research suggests that lactate is actually beneficial to the body during and after exercise in numerous ways. For example, lactate can be used directly by the brain and heart for energy or converted into glucose in the liver or kidneys, which can then be used by nearly any cell in the body for energy.
What Causes Burning In Your Legs When Working Out?
If it’s not lactic acid and it’s not lactate, what is causing your legs to burn when you’re running fast?
The current consensus is that the burning sensation in your muscles during intense exercise is due to the acidic environment, or drop in pH level, in the muscles that occur as a result of the hydrogen ions that have dissociated from “lactic acid” as it became lactate, as well as the phosphate, produced after ATP has been broken down for use by your muscle fibers.
In a nutshell, your muscles produce energy through anaerobic glycolysis during heavy exercise. This metabolic pathway produces usable energy, lactate, and hydrogen ions.
The lactate can actually be further processed and utilized for energy elsewhere in the body while the hydrogen ions are metabolic byproducts that lower the pH in the muscles and blood, causing an acidic environment that yields a burning sensation and intense fatigue in your muscles.
What Is Lactate Threshold?
Up until a certain exercise intensity, you can continue to breathe steadily during your workout, supplying your muscles with oxygen.
This means that the reliance on anaerobic glycolysis to produce energy is minimal because there’s enough oxygen for the muscles to generate energy through aerobic pathways.
Glycolysis is still occurring to some degree, but the body is able to shuttle lactate out of the muscles where it can be converted to glucose or used by the brain and heart as quickly as it is being produced, keeping the blood lactate levels relatively stable.
However, once you start pushing yourself beyond a level where you can breathe steadily and comfortably, your muscles have to keep up with the need for energy by ramping up glycolysis. At this point, the blood lactate levels increase precipitously. This is the lactate threshold.
The lactate threshold can be used as a marker of the point at which hydrogen ions are going to rapidly accumulate and cause the burning acidic feeling in your legs.
How To Get Rid Of Lactic Acid In Your Legs
The good news is you don’t have to do anything to get rid of “lactic acid” buildup or lactate buildup in your legs. The liver takes care of the processing of lactate.
As soon as you drop the intensity of your exercise and start breathing in more oxygen, the pH will increase and the burning sensation will dissipate. That said, there are a few things you can do to help get rid of the burning in your legs from a workout, including the following:
#1: Cool Down After a Hard Workout
This is one of the primary reasons why cooldowns or other forms of active recovery can be so beneficial for your muscles and may reduce the severity of delayed onset muscle soreness.
The low intensity allows you to breathe in plenty of oxygen and you are still moving your body, which keeps circulation to your muscles elevated, allowing the flushing or removal of the hydrogen ions and lactate from your muscles.
#2: Drink Water
Drinking plenty of water to stay hydrated is also thought to help return your body to baseline.
#3: Consider BCAAs
Branched-chain amino acids (BCAAs) are three essential amino acids—leucine, isoleucine, and valine. They have a unique chemical structure that enables them to bypass digestion in the liver and go straight to the muscles where they can be immediately used for energy.
While BCAAs are best known to support muscle protein synthesis, they may decrease lactate production and increase the time to exhaustion.
#4: Take Beta-Alanine and Carnosine
Beta-alanine is an amino acid that increases the levels of carnosine in your muscles. Carnosine helps buffer the pH levels in your muscles, which is key to minimizing the acidic burn from the hydrogen ions.
#5: Try Whole-Body Vibration
There is also some evidence to suggest that whole-body vibration may decrease lactate levels and expedite recovery after vigorous exercise.
Study participants who did whole-body vibration after exercise had a significantly greater decrease in blood lactate levels (93.8% decrease in blood lactate) compared to those in the control group who just rested (32.8% decrease in blood lactate).
Researchers concluded that the vibration stimulates blood vessels in the muscles, much like forms of active recovery like light jogging and walking. The vibrations enhance circulation and oxygenation to muscle tissue and help flush out the acidic byproducts of glycolysis.
#6: Increase Your Lactate Threshold
Finally, through proper training, you can increase your lactate threshold—or the pace you can run before which your body will start needing to produce energy anaerobically. Tempo runs, threshold intervals, and speed workouts can help improve your fitness and increase your lactate threshold.
If you would like to give some of these workouts a try, check out our database of information for workout ideas:
So, even though you don’t need to figure out exactly how to get rid of lactic acid in your legs, you can follow these tips to help get rid of that tough-to-take burning sensation to help make your workouts more enjoyable!
