Lactic acid threshold: what is it and why is it important for every athlete?

Lactic acid threshold: what is it and why is it important for every athlete?

The other day we decided to try out magnesium powder rather than tablets. We were used to see magnesium combined with various salts, such as malate, but we had not yet come across the combination with lactate. When you paid attention during biology lessons you'll know our body produces lactate itself as an energy source, just like it can produce glucose, ribose, creatine and ATP.
However, contrary to these other sources, lactate has a bad reputation due to the association with 'hitting a wall' when you are pushing yourself so much that your body is no longer able to deliver oxygen and energy to your muscles fast enough so you are literally out of breath.

If you are even superficially interested in endurance sports like running or cycling, you will probably have heard about the term 'lactate threshold' or 'anaerobic' threshold and may have heard about excessive lactic acid production.

Which brings us to two questions: what's the difference between lactic acid and lactate and why is it important for every athlete?

The difference between lactic acid and lactate

There's a lot of confusion about the difference between lactate and lactic acid. One fitness article even vehemently claimed our body doesn't produce lactic acid, period. Nothing could be further from the truth.
Lactate and lactic acid are often used interchangeably, at least that is the case in the Dutch language when we literally speak about the 'lactic acid threshold' (melkzuurdrempel) instead of the lactate threshold.
Yet there's an important distinction between those two substances. So what is the difference and when does the body produce those compounds?

Lactic acid is a compound that is produced during anaerobic respiration. This type of respiration occurs when the body doesn't have enough oxygen to produce ATP using aerobic respiration. When lactic acid accumulates in the muscles, it causes a tightening of your muscles and fatigue.

Lactate is a product of aerobic respiration. Aerobic respiration takes place in the presence of oxygen, and produces more ATP than anaerobic respiration. Lactate is produced as a result of this process, and it can be used by the body for energy. In fact, lactate is the body's preferred fuel. You can’t overdose on it.

When you exercise, you get about 1/3 of your total carbohydrate energy from lactate; the rest is from blood glucose and muscle glycogen.

To use lactate as fuel for muscles, you can either "burn" it directly, or turn it into glucose and then burn it.
In untrained athletes about 75% of the lactate used is directly oxidized. In athletes who have intense training regimens, about 90% is directly oxidized. Trained athletes also burn significantly more lactate overall. This shows that endurance training stimulates adaptations to use more lactate, and to use it more efficiently. In trained athletes , lactate has been shown to be the preferred substrate over glucose.

Who uses lactate?

Lactate is used as fuel by all athletes, but it is especially beneficial for endurance athletes. Endurance athletes need a fuel that can be used over long periods of time, and lactate fits the bill perfectly. It's also important for sprint athletes, who need a quick burst of energy to make them competitive.

Lactic acid has a bad reputation in the athletic world, but it's actually not all bad! In fact, lactic acid plays a role in athletic performance. It's responsible for the "burn" you feel in your muscles during exercise, and it's also responsible for fatigue. Lactic acid causes pain and fatigue because it accumulates in the muscles and interferes with muscle contraction. However, this accumulation also signals the body to stop producing lactic acid. So, while lactic acid may cause a tightening of muscles (pain) and fatigue, it's also responsible for signaling that it is time to end your workout.

Lactic acid and lactate are closely related to each other, but have different effects. Your body's acid concentration increases as you produce lactic acid. Lactic acid is split into lactate and hydrogen ions. H+ or hydrogen ions, is the acid part in lactic acid. Lactate is an extremely fast fuel that is preferred by the heart and muscles during exercise. Lactate is vital for ensuring your body gets a steady supply of carbohydrates. H+ (hydrogen ions), the other half of lactic acid is bad news, but only when the acid concentration exceeds the body's ability to flush these ions out of your body.
This is when your muscles tighten up and you just can't keep running, swimming or cycling, at the same pace. You're done!

Is there a method to prevent the build-up of lactic acid?

Yes, you can by raising your lactate threshold. The higher your lactate threshold, the further you’re able to push yourself without accumulating a high amount of lactic acid in your muscles. This is also known as anaerobic threshold, and it's what separates aerobic from anaerobic exercise. For example, if running at a certain speed causes you to accumulate lactic acid quickly (because you're over your lactate threshold), then training at or slightly below this pace will increase the speed at which you reach that point where your body starts producing large amounts of lactic acid.
As a result, once it does occur during exercise, there won't be nearly as much buildup because you've trained your body to handle it.

The lactate threshold typically lies at around 80-85% of your maximum heart rate.

If you have not built up your lactate threshold, then you may look to supplement with beta-alanine or carnosine to reduce lactic acid buildup. Beta-alanine is not actually a buffer for lactic acid, but is the rate limiting factor in the production of muscle carnosine in the body, a natural regulator of pH or lactic acid levels in muscle.

Factors that influence lactate threshold

Heart rate is used to track intensity but most people often misunderstand the concept. For instance, if you have a high lactate threshold heart rate, it does not translate to actual performance. Contrary to popular belief, threshold heart rate is not determined by your age so you have nothing to worry about if you are an older athlete.

Threshold heart rate is the maximum heart rate that you can sustain over a long time period like 10 to 60 plus minutes depending on how able you really are as well as your aerobic fitness level. It is also related to the maximum effort or power that you can sustain over the same period of time.

Efforts that go above your threshold are considered extremely intense. As you go above your threshold your blood sugar depletes. This lasts for a few minutes and you can feel it most just before your recovery time. Knowing your threshold heart rate will help you determine your heart rate range.

Heart rate depends on the individual. There are cyclists who have higher threshold than others and this number varies with age. For instance, a 40-year-old can have a heart rate threshold of 180 and a 25-year-old the same.
It is also common to see cyclists in their 40s with a lower heart rate threshold. However, you can increase your heart rate threshold at any age through interval training.

Four factors that affect your rate of lactic acid accumulation

There are several factors that end up changing the rate at which lactate is produced in your body and it is important that you are aware of them.

Exercise intensity

When it comes to exercising, the harder you work out the more lactate you will produce. Since the muscles are responsible for lactate production, you are likely to produce more when your muscles are more engaged.
As you age, however, your muscles decline which is why strength training is more important to help build the muscles such that when you get on your bike you are able to ride for a long time before your legs begin burning due to the acid build-up.


As you grow older, you need to be more careful about what you eat. For one, your muscles and bones are declining and as such you need to eat a diet that restores and strengthens them. When it comes to lactate build-up, what you eat matters as well.
If your glycogen stores are low in the body, you won’t be able to engage in high-intensity training for long.


With proper training, you are able to lower your rate of lactate accumulation. A higher density of mitochondria means that lactate re-synthesis increases. A higher level of fat burning prevents that build up. This is because naturally, your body will burn fat and not glycogen hence preserving the glycogen that will be used as a source of fuel when exercising.


When you have high muscle mass and are exercising out at moderate intensity, you tend to produce less lactate than someone with small muscle mass working at a higher intensity.

The lactate threshold is one of the greatest predictors of performance endurance. That means that if you want to be faster, you need to increase your lactate threshold.

Four ways of raising your threshold

The functional threshold power is the power output that you can steadily maintain over an extended time period. This power output is important as it will determine how fast you get fatigued when exercising. Normally, if your threshold is higher, you will be able to go faster. Threshold training is both physically and mentally draining but it’s what makes it effective.

Let's suppose you are a cyclist wanting to raise your lactate threshold

Spending more time

Spend more time on your bicycle. By increasing your cycling duration, you end up getting better at cycling especially if you are a beginner. However, this does not mean pushing yourself too hard beyond what your body can handle. Start at an easy pace and then work on increasing your cadence.

Interval training

Three 10-minute or one 30-minute interval training session once or twice a week is effective at improving your cycling performance. The intervals can be built in different ways depending on what you are comfortable with. You can start three 10-minute intervals with a recovery time of five minutes and move on from there. If you happen to handle one 30-minute interval, then you are good to go.


One other way of improving biking performance that is often overlooked by a majority of people is cadence. As such, you are likely to focus on force rather than cadence. If you like spinning on high 70 to 80 rpm, then it is best if you use moderate cadence or a high cadence for efforts of 90 to 100 rpm.


If after different threshold intervals you can’t seem to increase your threshold, mix up the training. As you grow older, you will realize that you take longer to recover. Give yourself a few days to recover by using those days for easy endurance training that does not exceed 75% maximum heart rate.

Training to raise your lactate threshold

Just like anything else that is related to your body, your lactate threshold is genetic, but it doesn’t mean that you can’t train. By pushing your limits systematically, you can enable the body to become way more efficient at buffering and clearing lactic acid that builds up.

The goal is to reach a point where you can comfortably ride for whatever hours and then sustain a few minutes before your legs burn. Before you start lactate threshold training, it is important that you establish plenty of mile bases as well as have some speedwork. Your results will depend on how big your aerobic engine is when you are beginning.

As such, there are drills that are meant to increase your lactate threshold. The only thing to remember is that you have to choose one exercise per work out and ensure that you don’t do LT training more than twice a week. If at all you do it, ensure that you don’t do it on consecutive days.

Steady state intervals

To do this you need to warm up and ride for 10 minutes at a steady pace and effort, all this time keeping your heart rate below your lactate level about three to five beats. Stop and give yourself 10 minutes to recover. If you feel comfortable with the 10-minute level, do two more repeat efforts of 20 minutes each stopping to recover every 20 minutes in between. In the end, work out to a 30-minute routine as this is the only way you can increase your LT power effectively.

Up and down intervals

This interval blends the ability of your body to process oxygen in order to stimulate the amount of effort that you need to race up a hill where you need to push your LT for short surges and then clearing the acid and recovering quickly. First, you need to warm up and then pick up your LT heart rate and hold the intensity for about 5 minutes or so. Push yourself three to five beats more above your LT level for one or two minutes and then drop it back down. Do this interval for about three cycles which is equivalent to 18 or 20 minutes to determine what you can comfortably handle.

Tolerance Interval

Most mountain bike riders have to elevate their suffering and lactate threshold because that kind of cycling requires them to push past their LT and holding it there for extended bursts. Through intensity training whereby your body can not clear lactate, you will in the process boost the ability to keep cycling even in the case of high lactate levels. Start with a thorough work out after which you will increase your effort five beats above your lactate threshold heart rate. Hold there for about 3 to 5 minutes then reduce the effort for about 60 to 90 seconds just long enough to feel like you have recovered though not ready to go again. Repeat this interval three more times.


How much of lactate threshold training should you engage in?

The right duration each week should be about 25 minutes of lactate threshold training and you are bound to see the results increase in a few weeks.
The most important thing, however, should be to go with your pace. Don’t push yourself too hard and always give yourself enough time to recover especially when you are just starting out.
Just like any other training., different people will respond in different ways to tempo training and in this case, their optimum level will tend to slightly vary. You are able to maximize the benefits if your lactate threshold training is about 15 to 25% of the total time spent cycling.

Closing words

Entire books have been written on improving yourself in just about any sport. In case you don't like reading books on how to improve your cycling skills I can whole-heartedly recommend the YouTube channel Live Slow Ride Fast and more specifically the series 'Beter worden'. Yes it is in Dutch, but it can be subtitled in English.

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