Fitness and Metabolic Health
Optimize Lactate Levels for More Energy and Better Fitness
Here’s why resting lactate levels and hyperlactatemia matter and how to address them carefully and diligently.
As part of our survival mechanism, lactate is an indirect energy source produced during intense exercise or physical work when the muscles lack adequate oxygen. It is a metabolite produced by the body during exercise and stressful situations. It is also a signaling molecule for growth.
I wrote about energy sources like glucose, ketones, and triglycerides before. They are produced through different metabolic activities and in different pathways. In this post, I focus on lactate which energizes the body during stressful times. Muscles, the heart, and the brain can use it.
During my studies, lactate looked like a double-edged sword, similar to the paradoxical nature of sugar and fats. It can serve as an alternative energy source during physical stress, but high levels might cause adverse effects, and chronically elevated levels indicate severe health conditions.
Optimizing resting lactate levels can have powerful benefits like more energy, fitness, and overall health. Preventing and treating chronic conditions like hyperlactatemia and lactic acidosis is vital for survival.
This article aims to give a high-level overview of lactate, highlight the related health conditions for elevated levels, and provide practical tips to improve lactate threshold and optimize resting lactate levels.
What is lactate, and why does it matter?
This paper in Nature used the metaphor of an “ugly duckling” to explain lactate metabolism and its importance. The authors liken it to a beautiful swan having the potential to reshape the field of energy metabolism.
I reviewed many more papers about lactate metabolism and how the brain uses it. I will cover the scientific reviews in another paper. In this section, I aim to clarify this misunderstood molecule and its process in the body. I will summarize the key points from the growing literature in simple language to make it easy for you.
First, lactate is not a bad molecule, as perceived by some people on social media. Lactate is part of our survival system. It is a necessary and valuable molecule with a potential energy source made up of glucose molecules produced during exercise and other physical activities.
Glucose at the highest level contains six carbon atoms. During physical activity, one unit of glucose molecule is converted into two sets of pyruvate molecules, each containing three carbon atoms.
In the absence of oxygen, pyruvate is converted into lactate by adding a hydrogen ion during intense exercise. This process is called lactate production (anaerobic glycolysis).
During aerobic metabolism, glucose is broken down into pyruvate, which is then further broken down into carbon dioxide and water in the mitochondria, producing energy in the form of ATP.
However, during anaerobic metabolism, when there is insufficient oxygen supply to the muscles, pyruvate is converted into lactate through lactate fermentation. This allows the muscles to continue producing energy even without oxygen.
So lactate is formed when glucose is broken down to produce energy in the absence of sufficient oxygen. This process is called anaerobic glycolysis. Lactate was once thought to be a waste product of this process. However, it is now considered a critical fuel source for the body, particularly during intense exercise.
Lactate can act as a signaling molecule, stimulating the production of the growth hormone. It can also enhance endurance performance by improving the body’s ability to buffer acidosis and maintain pH balance during exercise.
Difference Between Lactate and Lactic acid
Understanding the difference between lactic acid and lactate is essential. Lactate and lactic acid are sometimes used interchangeably, but they are different.
“Lactic acid was discovered in sour milk in 1780 by Swedish pharmacist Carl Wilhelm Scheele and identified in blood during shock by the German physician Johann Joseph Scherer in 1843.”
Lactic acid is a molecule produced during intense exercise when the body needs to produce energy quickly and the oxygen supply to the muscles is limited. The lactic acid build can cause muscle fatigue and soreness.
During intense exercise, the body produces more lactic acid than it can immediately clear, which causes a buildup of lactic acid in the muscles and can contribute to muscle fatigue.
However, this lactic acid is quickly converted into lactate, which can be used as an energy source or transported to the liver to be converted into glucose. Lactate can be converted into glucose in the liver via gluconeogenesis.
So, lactate is a molecule formed when lactic acid donates a hydrogen ion in solution. Muscles and other organs can use lactate as energy during exercise and even at rest.
Within the context of lactate and lactic acid, the term “ion donation” refers to the dissociation of the molecule into its constituent parts (lactate and hydrogen ion).
When lactic acid is produced in the muscles during intense exercise, it rapidly dissociates into lactate and hydrogen ions. The enzyme lactate dehydrogenase catalyzes this process.
The hydrogen ions produced during this process contribute to the development of muscle fatigue and acidosis.
The lactate can be transported to tissues and organs like the liver, brain, and heart, where it can be used as a source of energy or converted back into glucose via the liver through a process known as the Cori cycle.
Conversion in the liver, mitochondria, and the brain
The good news is that the liver can convert lactate to glucose, giving more energy to the body. The critical point is the necessity of oxygen in the conversion process.
Since lactate molecules are made of pyruvate, mitochondria can use it to generate ATP, which is the energy currency for the cells.
The brain can use lactate as an energy source during periods of high energy demand or low glucose availability. Lactate is transported across the blood-brain barrier by the monocarboxylate transporter.
Indication of Lactate Levels
In general, lactate levels can indicate the intensity of physical activity. The levels can provide information about our stress, fitness, and metabolic health. Lactate can play a role in muscle recovery and adaptation to exercise.
Resting lactate levels can indicate the body’s ability to produce energy efficiently. Elevated lactate levels during exercise can indicate an increased risk of fatigue or decreased exercise performance.
As documented in this government source, normal lactate levels are less than 1.0 mmol/L in all age groups.
Lactate levels greater than 2.0 mmol/L represent hyperlactatemia and should be reviewed by a clinician with experience managing deteriorating patients, and treatment should start as advised.
A lactate of 4.0 mmol/L significantly increases the risk for both morbidity and mortality and requires urgent treatment and escalation through the health service organization’s rapid response system.
This meta-analysis examining 150 reports on lactate concludes that “lactate monitoring is critical in risk mitigation in critically ill patients. It is a resuscitation endpoint that improves outcomes. This warrants randomized controlled studies on the efficacy of lactate-directed therapy.”
Monitoring
We can measure and monitor lactate levels with affordable devices.
They are usually palm-sized test meters that quickly measure lactate from a small blood sampling. Some are integrated into blood glucose monitors, and some are linked to mobile phone apps showing graphs.
Monitoring lactate levels can help us design and adjust exercise programs and assess overall health and fitness.
However, lactate levels are just one piece of the puzzle. This measurement must be considered with other factors like heart rate, perceived exertion, and other markers of health and fitness.
You might be wondering if lactate is a valuable molecule and energy source, so what is the big fuss about it, and why do people worry about it?
I will answer this question in the next section.
Hyperlactatemia and Lactic Acidosis
If you are healthy, like your liver works well and mitochondria are functional, lactate molecules or lactic acid production does not pose a risk.
Elevated lactate levels can lead to fatigue, muscle soreness, and cramping. Chronic elevation of lactate levels has been linked to the development of metabolic disorders such as insulin resistance, metabolic syndrome, and type II diabetes.
I reviewed numerous papers about the health impact of abnormal lactate levels. For example, this paper explains the difference between hyperlactatemia and lactic acidosis. I will summarize the key points.
“The build-up of lactate in stressed muscle and ischaemic tissues has established lactate’s reputation as a deleterious waste product.” But this is not the central issue. The real concern in medical communities is hyperlactatemia, leading to lactic acidosis.
Hyperlactatemia is a condition where there is an abnormally high level of lactate in the blood. The body produces lactate as a byproduct of anaerobic metabolism serving as a buffer for hydrogen molecules. It is typically cleared from the blood by the liver and kidneys.
However, in hyperlactatemia, lactate accumulates in the blood, indicating an imbalance between its production and clearance. There might be numerous factors for it. I will list them below.
Well-known reasons for hyperlactatemia are liver disease, lung disease, heart problems, accelerated glycolysis, mitochondrial disorders, congenital disorders, thiamine deficiency, toxins, sepsis, extracellular alkalosis, anemia, and the side effects of some drugs.
Mild hyperlactatemia may not show symptoms. However, severe cases can cause nausea, vomiting, abdominal pain, muscle weakness, and confusion.
If left untreated, hyperlactatemia can progress to lactic acidosis, a more severe condition that can lead to multi-organ failure and even death.
Acidosis results when excess hydrogen ions cannot be utilized by aerobic metabolism or neutralized by lactate, bicarbonate, and other body buffer systems.
The treatment of hyperlactatemia depends on the underlying cause. Switching to an alternative medication may be sufficient if the condition is due to medication side effects. Most treatments might involve addressing underlying medical conditions like liver dysfunction and sepsis.
If hyperlactatemia progresses to lactic acidosis, treatment might involve intense or supportive care, like fluid and electrolyte replacement, and the use of dialysis in severe cases.
How to Improve Lactate Threshold
The lactate threshold is the point during exercise where lactate production exceeds its clearance rate, leading to an accumulation of lactate in the bloodstream.
This lactate accumulation can lead to fatigue, decreased performance, and a burning sensation in the muscles. However, with proper training, the lactate threshold can be increased. It can improve endurance performance.
Two viable approaches are to decrease the rate of lactate buildup and increase the rate of lactate clearance.
Clearance of lactate or lactic acid is quick for healthy people. The body has several mechanisms, such as utilization by muscle fibers, the energy demand of the brain, and the conversion of it to glucose by the liver.
To decrease the rate of lactate, the viable approaches are to use short bursts movements and high-intensity workouts, tempo runs, and strength training. So increasing the lactate threshold requires consistent and specific training adaptations.
These practices can also improve resting lactate levels which I cover in the next section.
Why and How to Optimize Resting Lactate Levels
Resting lactate levels refer to the concentration of lactate in the bloodstream when the body is at rest.
In healthy people, the resting lactate levels are typically low, usually less than one mmol/L. If the levels are more than two mmol/L, we need to take some action and obtain professional support.
Elevated resting lactate levels may indicate underlying health issues, such as impaired mitochondrial function, metabolic disorders, or chronic inflammation. We can measure them through blood tests.
Optimizing resting lactate levels can have several benefits, such as improved aerobic capacity, reduced fatigue, improved recovery, enhanced performance, and better metabolic health.
Resting lactate levels are an indicator of our aerobic capacity and performance. Optimizing resting lactate levels can improve our ability to utilize oxygen during exercise, enhance our aerobic capacity, and enrich performance during high-intensity workouts.
Based on my reviews and interactions with athletes, I’d like to provide practical tips to improve resting lactate levels.
1 — Increase aerobic exercise and try high-intensity interval training.
Aerobic exercise, like swimming, tennis, running, and cycling, might improve the ability to clear lactate from the bloodstream.
Regular HIIT for healthy people can improve lactate clearance and overall fitness. During HIIT, the body experiences short bursts of intense activity followed by rest periods. This process can increase lactate clearance.
2 — Avoid overtraining.
Overtraining can lead to an increase in lactate levels and a decrease in performance. Balancing training with adequate rest and recovery is essential to avoid overtraining and prevent excessive lactate accumulation.
3 — Manage stress, improve sleep, and oxygenate the body.
Chronic stress can lead to elevated lactate levels, as the body responds to stress by producing lactate as a fuel source. Mindfulness, meditation, yoga, and deep breathing might reduce stress and lower lactate levels.
Sleep deprivation due to causing high stress is linked to elevated lactate levels. Getting enough restorative sleep can help the body to recover and repair, reducing overall stress and lactate production.
Once the exercise is complete, the body can take in more oxygen, converting lactate back into pyruvate. It can produce energy via oxidative phosphorylation in the mitochondria of cells. Breathing exercises can help utilize lactate as a pleasant energy source.
4 — Lower refined carbs and increase healthy fats.
A high-carb diet can increase lactate levels in some people, especially during chronic stress, as excess glucose can be converted into lactate.
Consuming a diet lower in refined carbs and higher in healthy fats might shift the body towards using fat as the primary fuel source, reducing the need for lactate production during stressful times.
5 — Monitor lactate levels during exercise.
Monitoring lactate levels during exercise can provide valuable information about fitness and metabolic health.
We can adjust our training intensity and duration by tracking lactate levels to optimize lactate clearance and improve overall performance.
6 — Get your symptoms checked.
If you have symptoms of elevated lactate during resting time and your blood monitors consistently show high levels, like over two mmol/L, there might be some underlying conditions related to the liver, heart, kidneys, and mitochondria. Thus, obtaining timely professional support is vital.
Conclusions and Takeaways
The body produces lactate to generate muscle energy during intense exercise or physical activities. Glucose is the primary energy source for the muscles, which is broken down through glycolysis to produce pyruvate.
Under normal conditions, pyruvate enters the mitochondria to be metabolized into energy, but during intense exercise or when there is insufficient oxygen, it is converted into lactate.
Lactate serves as a way to regenerate the energy-generating system of muscle cells, allowing them to produce energy even in the absence of oxygen. It also helps maintain the pH balance in the muscle cells by removing excess hydrogen ions produced during exercise.
Improving resting lactate levels can have significant benefits for overall health and fitness. Lactate is a double-edged sword. It can provide the body with an alternative energy source during intense exercise, but high levels can also cause adverse effects.
In moderate amounts, lactate can fuel the body, allowing it to continue exercising at a high intensity. However, when lactate production exceeds the body’s ability to clear it, it can lead to lactate buildup in the muscles and blood, accumulating lactate during rest times.
Lactate accumulation can cause muscle fatigue, burning sensations, and muscle soreness. It can also lead to decreased muscle pH, impairing muscle function and reducing the body’s ability to generate energy.
However, recent research suggests that lactate accumulation may not be entirely harmful. Lactate may actually act as a signaling molecule for growth hormone secretion, triggering adaptations in the body that can improve athletic performance and metabolic health.
Preliminary studies indicate that lactate can increase gene expression in glucose uptake and utilization, potentially improving insulin sensitivity and metabolic health. I will cover them in another article.
By understanding the mechanisms behind lactate production and metabolism, we can optimize our training and nutrition to improve performance and overall health.
The critical point of this article for healthy people is improving the resting lactate levels, which can provide multiple benefits that I covered.
Another critical point is preventing or getting treatment for hyperlactatemia and lactic acidosis, severe health conditions.
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