Lactic Acid Present in Blood

What is it, why do we care, and how do we measure it?

One of the ways to measure running intensity is by testing for the amount of Lactate found in the Blood. This page is going to step a little deeper into the topic and help a new coach or athlete understand some physiology basics.

We’ll use the abbreviation BLa (Blood Lactate) for the rest of this page.

For runners, BLa test is done DURING the exercise session - a spike in BLa is present in blood within a few seconds of exercise. If you were to drive to a lab and ask for a BLa test, they may laugh at you and the result would be pretty much useless. You would get a low BLa that would not tell you much / correlate to your training efforts.

This form of intensity measurement requires the athlete to provide a small blood sample during exercise. The results are given in “millimoles of lactate per liter of blood.” That term may be overwhelming for you - forget about it until you go to grad school for physiology.

• A low BLa reading is about 0.8 and you may see that after measuring somebody while they are hanging out at home.

• Now, go to the Olympic finals of the 800 meters and test an athlete at the finish line - you will eventually get a very high BLa reading near 20.0. This is one of the most intense events in sports and 20.0 is a very high BLa.

  • Depending on the sprint or intensity of the race, the reading may actually be higher if you wait a minute, or even a few minutes, vs testing at the moment of the finish.

  • The physiological changes in the body is one reason why the 800m is such a great / favorite / tactical event for so many athletes and fans. The athletes are flying around the track and the hydrogen ions (and BLa - more on that later) begin to pile up very quickly after 350 meters. With 200 meters to go in the race, athletes get taken out by the muscle-seizing, hydrogen ion laden acid - one runner at a time. Sometimes, the person in last place with 200m to go is the only one able to hang on with their speed mostly intact until the finish. You will even see athletes seize up with 15 meters left in the race and stumble to a loss. It is competitive and captivating to watch.

    • https://www.youtube.com/watch?v=LLBAaD8FbYM This is a link to a popular example of the last place runner catching everyone else and earning an Olympic spot. Watch the guy in last place the entire race for much of the race. The 2nd place guy passed four people in the last 75 meters to earn another spot on the team.

  • A very slight miscalculation of energy distribution costs the athlete a meter or two… and the race. Other factors, such as current nutrition and hydration, along with overtraining - may cause a premature BLa / Hydrogen ion spike and the athlete to lose another meter or two as well.

Note: We’ve somewhat misled you to believe that BLa is the “problem.” Blood Lactate is NOT the problem and NOT what actually causes muscles to seize up and stop working. Hydrogen ions are acidic and are the cause of the painful problems with muscles during exercise.

• Basically, we use glucose or glycogen as the “fuel” for most types of physical activities / muscle movements. When this fuel is “burned” in the body’s muscles, it leaves behind Lactate (measurable as BLa) and Hydrogen ions.

• Light Bulb Moment: Hydrogen ions are the real problem. However, we cannot easily / accurately / cheaply measure the presence of hydrogen ions during exercise. So… we measure the corresponding product - BLa. BLa is easily measurable - see my pictures and video above - and gives us an accurate-enough measurement of effort.

• Lactate is an energy source. It is not “bad.” It is just not an efficient or sustainable energy source at max speeds for an extended period of time (that is why we get so exhausted in an 800m race). It is a great source for medium efforts for about 90 minutes… then, it begins to falter and get real interesting - study or experience marathon bonking to explore that challenge.

Understanding Energy Sources: We’ve talked a little about energy sources for humans, we’ve mentioned glycogen, and we’ve also introduced the by-products of hydrogen ions and lactate that result from humans burning energy while running.

• Rockets use an RP-1 Kerosene derivative and liquid oxygen as an energy source. It’s an explosive energy source that is much faster than humans. A rocket would really hand us a devastating loss in an 800m race. However, the advantages of the thrust / speed of a rocket come at a cost as well - it requires up to 200,000 gallons to get a rocket about 60 miles away into space. If you are calculating the cost of miles per gallon - not cheap.

In physics - and physiology - we are often trying to maximize energy sources and efficiency for the vehicles we use (human body, planes, cars, rockets).

• Various types of Chemists and Engineers work together to get the mechanical, electrical, and fuel systems to work toward the desired performance outcome of a vehicle.

• Likewise, various types of Biologists, Doctors, Physiologists, and Coaches work together to figure out how to make humans run faster.

For running races, coaches and athletes are simply testing and experimenting with dozens of training methods to make the most out of our fuel systems. We study the race and determine the fuel that our body needs for that event. Then, we train that energy system to make the most out of the fuel and the engine (body) for that event.

• That is why 100m sprint training is much, much different than marathon or ultra training - it is arguably a completely different sport. The required energy system is different and the fuel is different.

Hopefully, if you have made it this far you are starting to understand BLa. Here are some example measurements to help you understand how a BLa reading may feel. We’ll discuss RPE (Rated / Relative Perceived Effort… or feeling) later, but eventually you’ll be able to synthesize all of these forms of intensity measurement.

Blood Lactate Levels for Common Races

• Resting BLa: 0.8 - 1.5 mmol/L

• Basic movement and warm-ups with rest periods BLa: 1.2 - 1.5 mmol/L (Kawczynski, IJPAS, 2015)

• After a 100m Sprint: 6.7 - 9.3 mmol/l (Women / Men) within 60 seconds of sprint. The level actually rises after a few more minutes. I like to think of the delayed rise as, the athlete stunned the body and the body needed time to react. (Kawczynski, IJPAS, 2015)

• After a 400m Race: 24 mmol/L

• After an 800m Race: 20+ mmol/L

• After a 1500m / Mile Race: 15 mmol/L

• VO2Max Pace Work (2 Mile Pace): 11 mmol/L

• After a 5000m Race: 9 mmol/L

• After a 10000m Race: 7-8 mmol/L

• Lactate Threshold / Tempo Run Pace: 2.5 - 3.5 mmol/L

• Jogging / Aerobic Threshold Pace: 1.8 - 2.2 mmol/L

Here is a real kick-in-the-pants piece of information: You may be incapable of getting your BLa to 20.0! An athlete may lack the neuromuscular coordination to allow the body to produce enough force and use enough energy to reach that 20.0 BLa point.

• Think back to the rocket engine example. If 99% of the rocket is able to handle the thrust necessary to get to space… the scientists have a BIG problem - the 1% that is NOT ready. Rockets can explode if the wrong 1% is not able to handle the application of the force.

• Likewise, a runner may lack the hip mobility to create the stride length necessary to run really fast. ALL / EVERY SINGLE running race is won by the athlete who dominates the combination of Stride Frequency x Stride Length. The runner may lack one of several necessary requirements to run that fast.

  • If I don’t have the hip mobility, the aerobic capacity, the aerobic power, or the muscular strength I may not be able to even get to a 20.0 BLa. Or, in theory, I would reach 20.0 BLa way to soon and lose the race because I am unfit, in every sense of the word.

  • This is one reason we have medical exams for athletes prior to the season. We are looking for that 1% of the body that may be broken / weakened with the athlete. The athlete may break under the high stress of training or racing. That break, if it is in the cardiovascular system, may lead to death. Read this document to dig a little deeper into that discussion.

Time Under Tension

I purposefully misuse the term “Time Under Tension,” but it seems to make sense to me and our teams. In the case of BLa, it refers to the length of time you can maintain a specific BLa - How long can you cook your blood at that painful level?

Training Density: I also refer to it as training density (my term). TD, to me, is the finicky combination of volume and intensity when building a training plan.

• Most athletes can function with the pain of a 3.0 mmol/L… BLa measurement.

• However, once the blood is cooking (my term as well) at that 3.0 level, there is a time limit that the body can tolerate it (about 45-60 minutes). At that point, most athletes will “blow up” and must stop or slow down.

• If an 800m runner tries to run the entire event at 300m race pace, he / she will blow up, stumble, and collapse well before 800 meters.

• Our individual metabolic system places limitations on the amount, and time it takes, to clear acids from the muscles and blood.

• Therefore, one of the talents of a talented runner, may simply be that they have an advantage in the metabolic arena. This may be one partial way to explain the 9th grade runner who runs a 4:35 mile just 10 weeks after he starts running track. His body may be naturally exceptional at moving hydrogen ions away from the muscles.

Final Words on BLa, Speculation, & My Guesses / Questions

When you exercise, your body is stunned. It scrambles to create more energy to keep the exercise going - but it cannot continue indefinitely. There is a cost to creating this extra energy. Fuels are extracted from the blood, muscles, and liver. The heart rate rises. Breathing intensifies. We sweat. At some point, the body’s systems are overwhelmed and the athlete must ease up or stop. If the athlete refuses mentally to stop, the muscles may seize up and cause the body to collapse, vomit, or go Frankenstein (rigidity / cramping / spasms).

Arguably, the reason we train all year for our sport is to improve the body and mind’s ability to tolerate, move, and use Blood Lactate efficiently / provide the unimpeded energy we need to race well.

You’ll eventually hear the terms lactate tolerance, lactate buffering, and lactate shuttling.

• Some of these running advantages take 5+ years of endurance training in order to near-maximize the body’s ability.

• Equally exacting, elite sprinters spend years working on drills, strength, and mobility just so their body (rocket) can tolerate the massive amount of force applied in the short amount of time of the sprint. If my body was forced to copy what Usain Bolt was able to do in the sprints, my hamstrings would literally snap in half because I have not done the necessary work.

Coaches may say that training physiology is overrated and unnecessary. Then, the same coach will prescribe a plan that has worked for them (training physiology) in the past. The moment you utter a phrase about good training you are dabbling with science / physiology.

Athletes and coaches will compare the BLa measurement to heart rate and try to paint a better picture or fitness profile of the athlete. This method is still imperfect.

• The athlete may produce slightly different values of lactic acid or have a distorted heart rate due to hydration levels, nutrition, weather, and fatigue. As the relationship grows, the coach and athlete learn to detect, account for, and manage these small differences - all while doing the work to run faster.

Interestingly - just because you have the supplies and time to administer blood lactate testing - you will not guarantee success. There is discussion about the level of relative, or actual, impairment experienced by a specific athlete at a specific blood lactate measurement.

• Basically, 4.0 mmol/L may be very painful and slow me down after 20 minutes, but the same measurement may not feel the same to another athlete, and he / she may keep going. Are they just tougher and used to it, or are their pain sensors actually different, shut off, or numb…

As stated at the onset of our training pages, there are outliers that make us question our understanding of the physiology. The general recommendations are designed to get most people to a high level by following proven methods.

Feel free to email any physiology errors to Rob@ColoradoTrackClub.com and you may earn a t-shirt.