Sarah Jane Parker

What is lactic acid and what does it have to do with running? We’re exploring everything you need to know about lactic acid, lactate threshold training, and why it matters for running (along with self tests to determine your lactate threshold!)

When you hear the words lactic acid you might be thinking about certain ingredients in food. While some foods do contain lactic acid, the kind we’re referring to isn’t an ingredient in your snack: it’s a metabolic byproduct in your body.

Lactic acid is a natural product of strenuous anaerobic exercise, and your lactate threshold can help determine when you start to fatigue when you exercise hard.

We’re going to explain what lactic acid is, what a lactate threshold is, and how it affects your running.

What is lactic acid?

Lactic acid is natural byproduct of metabolic processes in your body called cellular respiration. Cellular respiration is provides the energy you need for daily life and exercise.

During daily living and submaximal exercise (exercise that is not difficult to maintain a steady pace), your body converts glucose and oxygen into energy with aerobic respiration. Byproducts of aerobic metabolism are heat and carbon dioxide.

When exercise intensity increases and the amount of oxygen your muscles demand to keep moving can no longer be met, your body switches gears to anaerobic respiration that doesn’t require oxygen, but the byproduct of anaerobic respiration is lactic acid.

Lactic acid inhibits energy production when it build up in your muscles. When your muscles produce more lactic acid than can be removed, lactic acid begins to accumulate, causing fatigue.

Once your oxygen consumption returns to normal, lactic acid is then converted to other compounds by your liver to use in regular aerobic respiration.

Fatigue can be caused by a variety of other reasons, too, but fatigue from lactic acid buildup is more likely the cause if you’re exercising at an intensity above aerobic capacity.

Takeaway: when your body’s oxygen consumption exceeds demands, lactic acid is produced, resulting in fatigue.

Scientists have also discovered that different muscle fibers produce different amounts of lactic acid as well, so it’s not just cellular respiration/metabolism that comes into play.

Fast twitch muscle fibers (the ones used in activities like sprinting) produce more lactic acid in the muscle cells than slow twitch fibers do (slow twitch muscle fibers are the ones that are used mostly for longer and slower endurance exercise.

So activities that use more fast twitch muscle fibers than slow twitch muscle fibers will result in more lactate buildup. Another reason sprinting causes fatigue faster than an easy jog!

Lactic acid and muscle soreness

It’s interesting to note the ideas surrounding the relationship of lactic acid and muscle soreness like DOMS (delayed onset muscle soreness).

People used to believe that muscle soreness was caused by residual lactic acid that didn’t leave the muscles adequately.

But new science shows that muscle soreness is actually caused by micro-tears in your muscles and has little to do with lactate build up at all.

If you’re sore, it can be helpful to do gentle movement to help increase blood circulation and speed healing of muscle tissue, but it doesn’t necessarily move lactic acid out of sore muscles as once believed.

What is lactate threshold?

Lactate threshold is the point where lactic acid begins to accumulate in your muscles – your body switches from aerobic respiration where lactic acid is easily moved out of the muscles, to anaerobic respiration where lactate builds up.

During exercise, we’re never really in just one type of cellular respiration, there’s always a little bit of anaerobic metabolism going on along with aerobic metabolism, but it’s usually pretty small.

Once we reach our lactate threshold, the majority of our cellular respiration switches to the anaerobic kind that doesn’t use oxygen and we start to fatigue.

On average, regular people reach lactate threshold at 50-60% of their VO₂ max, recreational athletes reach lactate threshold at about 65-80% of their VO₂ max, and elite endurance athletes reach their lactate threshold at 85-95% of VO₂ max (source).

Why does lactate threshold matter for runners?

Lactate threshold matters to runners because, similar to VO₂ max, the higher your lactate threshold, the better your running economy, speed, and exercise recovery.

Less conditioned runners or exercisers have a lower lactate threshold. So a person who is new to exercise will fatigue faster than someone who is well conditioned.

The well conditioned runner will be able to run at a higher intensity with less fatigue than their less conditioned counterpart (barring things like medical conditions). So increasing your lactate threshold through strategic planning can help you become a faster and more efficient runner!

How to test your lactate threshold

Knowing what your lactate threshold is can help your training for a couple of reasons:

1. It allows you to develop a strategic training plan that helps you train smarter
   
2. You can track your progress over time

When you exercise above an easy and resting level, your body goes through a couple different ventilatory thresholds (times when your breathing noticeably changes): the first ventilatory threshold (V1) and the second ventilatory threshold (V2).

V1 occurs when your breathing rate increases and you can’t talk comfortably, but you can still put several words together while exercising.

V2 occurs when lactate begins to accumulate faster in your body than can be removed, and V2 threshold is considered your lactate threshold. Breathing becomes rapid and heavy, and you can no longer speak during exercise.

Traditional testing of lactate concentration in your blood was pretty invasive: doing blood draws at intervals during an exercise test. No thanks! But there are ways to estimate your lactate threshold without the blood draws.

Doing your own lactate threshold testing

There are a few different ways that you can determine your lactate threshold (LT) without going to a lab for testing:

1. Using an online pace calculator to estimate your LT based on your fitness level and recent race times (this is the easiest method).
   
2. Estimate your LT using your heart rate and the Karvonen formula
   
3. Complete a 30 minute time trial to estimate your lactate threshold

There was once a device called the BSX Insight that promised to read lactate concentrations through your skin, but this device is discontinued and no longer on the market.

Estimating your LT using heart rate

If you know your resting heart rate, you can use the widely recognized Karvonen formula. This formula is helpful if you haven’t done a maximal exercise test to already determine your max heart rate, this helps to estimate it for you using your resting heart rate and age.

THR = [ (MHR – RHR) x % intensity] + RHR

MHR = 208 – (0.7 x age)

• THR = Target heart rate
• MHR = Max heart rate
• RHR = resting heart rate

Heart rate training zones in percentages:

• Recovery zone or aerobic training: 50-70% MHR
• Tempo and threshold runs: 71-85% MHR
• Intervals: >85% MHR

So if you’re a 25 year old person with a resting heart rate of 70 bpm and you want to do lactate threshold training at 80% MHR, here’s how that formula would look:

MHR = 208 – (0.7 x 25) = 190.5

THR = [ (190.5 – 70) x 80%] + 70

THR for 80% MHR training in estimate LT training zone = 166

30-minute time trial

You can also estimate your lactate threshold by doing a 30 minute time trial. Ideally you’d do this time trial when you’re not fatigued by heavy exercise the day before. Use a level track, level road, or a treadmill set at 1% incline and use a heart rate monitor.

Start by doing some light cardio activity for 10 minutes, like walking or an easy jog, to warm up your body and prepare it for exercise. Gradually Increase the intensity of your warm up.

Once you’re warmed up, start running at the fastest speed you can maintain for 30 minutes. This needs to be a steady pace over the course of the 30 minutes: make sure you don’t start out too fast and taper off as you get tired.

Measure your heart rate at 10 minutes into your run.

Continue your run and stop at 30 minutes and measure your heart rate.

Add your heart rate at 10 minutes to your heart rate at 30 minutes and divide by 2 to find the average. This is an estimate of your lactate threshold heart rate.

For example: if your heart rate after 10 minutes is 130, and your heart rate after 30 minutes is 170, then your LTHR (lactate threshold heart rate) would be 150 bpm.

Using your LTHR, you can determine training zones (remember, LTHR is not the same as max heart rate in these training zones!):

• Recovery Zone (Zone 1) = 65-85% LTHR
• Long endurance (Zone 2) = 85-90% LTHR
• Intense Endurance (Zone 3) = 90-95% LTHR
• Lactate threshold (Zone 4) = 95-102% LTHR (or same heart rate as time trial)
• Maximal/power training (Zone 5) = 102-110%

How to increase your lactate threshold

One great thing about your lactate threshold is that you can improve it over time with training, much like you can improve your VO₂ max with strategic training.

There are 2 ways to improve your lactic acid threshold and how efficiently your body removes lactic acid from your muscles:

1. Continue your aerobic steady state training
2. Add in lactate threshold training 1-2 times a week

Continuing with your regular steady state aerobic training runs is important for lactic acid clearance because your body adapts to this type of exercise by increasing the number and density of mitochondria in your muscle cells.

Mitochondria are your cells power generators so to speak and where your cellular respiration takes place. The more mitochondria you have, the better your body becomes at using oxygen during exercise (meaning less lactic acid buildup at the same heart rates as before).

Another way to increase your lactate threshold is to add LT training 1-2 times a week into your training program. LT training sessions are higher intensity, so don’t do them too frequently and keep them fairly short, 20-30 minutes long.

The goal with lactate threshold runs is to keep your pace pretty steady throughout the run meeting that heart rate goal or pace goal consistently.

LT training is generally a bit below race pace and should be comfortably hard. They should be challenging but not maximal intensity like VO₂ max training. This is where the pace calculators are handy since they help you determine at what pace you’d likely be LT training based on recent race times.

Now that you know how to determine your lactate threshold and how to improve it, you should be able to make improvements in your race times with these strategies!

Curious about what is VO2 max and how it affects your exercise performance? We give you the scoop on VO2 max, how to measure it yourself, and ways to increase it so you can go harder, and run faster.

Chances are if you’ve been running for a while or have been involved in any type of endurance sport, you’ve heard the term “VO₂ max” before.

VO₂ max is often referred to in fitness circles, but not very well understood, especially if you’re a beginner to exercise.

In this post, we’ll explain what is VO2 max, how it affects your running, and ways to improve VO2 max to run faster and more efficiently.

Once you begin to focus on your running performance – for example, when in marathon training – it can be beneficial to focus some of your training on VO2 max improvements.

So, what is VO2 Max?

VO₂ max is defined as the maximal oxygen consumption of your body during a specified time, usually during intense exercise. Essentially, it’s the maximum amount (Volume) of oxygen (0₂) your body can take in and actually use during maximal fitness efforts.

Some people refer to VO₂ max as a measurement of aerobic power and our aerobic ceiling, and it’s measured in milliliters per minute per kilogram of bodyweight (ml/kg/min).

Your body’s VO₂ max capacity is largely dependent on 1) cardiac output and 2) the ability of your muscles to use the available oxygen your heart and lungs are providing them.

Let’s get geeky for a minute. Here’s the scientific formula for VO₂ max:

VO₂ = SV x HR x (a-v O₂ diff)

• SV = stroke volume (the volume of blood your heart is moving with each stroke)
• HR = heart rate
• a-v O₂ diff = arteriovenous oxygen difference (how much oxygen the body is actually utilizing)
• SV x HR = CO (cardiac output)

So our VO₂ max is determined by our stroke volume, our heart rate, and the amount of oxygen that our body actually uses from our blood.

What does VO₂ max mean for running or fitness?

VO₂ max is one of the many measurements in our fitness and endurance toolbelt (along with things like lactate threshold and exercise economy) that tell us where our fitness level is, where we can improve, and a way to track progress over time.

If you can improve your VO₂ max, you can run farther, faster, and with more intensity. The same goes for any other cardiorespiratory activity like cycling, swimming, etc.

With proper training, you can increase your VO₂ max and improve your running speed and endurance by increasing the elements of VO₂ max :

• Your stroke volume (strengthening your heart muscle)
  
• And the oxygen uptake of your muscles (training your muscles to use oxygen more efficiently).

How is VO₂ max measured?

Measuring VO₂ max is a great way to measure your aerobic capacity. In a lab setting, VO₂ max is usually measured with participants wearing a mask that measures incoming and outgoing air.

Participants are placed on a piece of cardio equipment like a stationary bike, treadmill, etc. and exercise is gradually increased until reaching a maximal tolerated level of exercise and physiological measurements (like heart rate) reach a plateau. All the information is collected and calculated into your VO₂ max.

Doing formal lab tests for VO₂ max can be really helpful if you’re going to test training programs and check for improvement or to establish a baseline. The VO₂ max tests are also fairly accessible and available at many university fitness centers and cost about $100.

But these tests may not be practical for the average person who isn’t a competitive athlete. But there is a way to do your own version of a VO₂ max yourself for free (more on that in a bit).

If you do get a VO₂ max test done (or you do your own test), you can check your place in VO₂ max norm charts by gender and age. But the best way to use a VO₂ max test is to use the data to measure progress over time to make sure that your training program is working like it should.

How to do your own VO₂ max tests: VO2 Max Calculators

If you don’t want to do a formal lab test for VO₂ max, you can do your own tests to estimate your VO₂ max. These self-tests have a margin of error and are not as accurate as a lab test, but are still helpful in estimating your VO₂ max.

There are a variety of tests available that people can do, but we’re listing the protocols for 2 of the easiest tests to complete on your own. We’ll include both the maximal 1.5 mile run test and the submaximal 1 mile jogging test below so there are 2 options for different fitness levels.

For a few other test types, this helpful compilation of tests also includes a submaximal jog test and the Rockport walking test.

1.5 mile run test (maximal test)

The 1.5 mile run test is a maximal test and is suitable if you are conditioned to run at maximal effort. Avoid this test if you have heart problems or or contraindications (like joint problems) that would prevent you from running at your highest effort.

On a level running surface, run 1.5 miles as fast as possible. Try to run at an even pace near the end (like you would in a race), and you can do a trial run prior to the run test to get a sense of the pace you’ll be at.

Record your time to complete the 1.5 mile run in minutes and seconds, and your heart rate at the end of the test. Use the formulas below to estimate VO₂ max.

VO2 Max Calculator: Fast 1.5 Miles Test

VO₂ max = 88.02 + (3.716 x gender multiplier) – (0.0753 x body weight in pounds) – (2.767 x time for 1.5 miles in minutes and fractions of minutes)

Gender multiplier = 1 for males, 0 for females.

Remember that equations in parentheses are completed first, then the rest of the equation is completed.

Example: if Joe is a 25 year old male that weighs 175 pounds and completes his 1.5 mile run in 12 minutes 15 seconds, his equation would look like this:

VO₂ max = 88.02 + (3.716 x 1) – (0.0753 x 175) – (2.767 x 12.25)

VO₂ max = 88.02 + 3.716 – 13.178 – 33.896

VO₂ max = 44.6 (rounded up)

1 mile jog test (submaximal)

The 1 mile jog test is a submaximal test that is great for people who are not able to complete a maximal run test for a variety of reasons.

Complete a comfortable jog over exactly 1 mile measured distance. It’s should not be fast, so pace should be less than 8 min/mile for men and 9 min/mile for women.

Once the test is completed, immediately record the time and record the heart rate from a heart rate monitor within 5 seconds of completion. If you’re doing a manual heart rate check, check heart rate as soon as possible and count your beats for 15 seconds, then multiply by 4 for your beats per minute at completion.

VO2 Max Calculator – 1 Mile Comfortable Jog Test

Use the formula below for calculating your estimated VO₂ max:

VO₂ max = 100.5 + (8.344 x gender) – (0.0744 x weight in pounds) – (1.438 x mile time in minutes and fraction of minutes) – (0.1928 x heart rate)

Gender multiplier = 1 for male; 0 for female

VO2 Max Chart: Men and Women

The VO2 Max Chart above shows the various VO2 Max ranges for both men and women, sorted by age group.

How to increase your VO2 max

After you learn what is VO2 Max, the next step is figuring out how to improve it!

If you’d like to increase your VO2 max (your maximal oxygen consumption) so you can run faster and more efficiently, there are a few ways to do this. Here’s our recommendations:

Interval training

Studies have shown that high-intensity interval training (HIIT) improves the VO₂ max of young participants by improving oxygen delivery in the body.

To train your VO₂ max with intervals, your hard work intervals segments need to be at or near maximal intensity. Your heart rate during these hard work segments should approach your max heart rate.

More on interval training:

• Interval Sessions Guide for Marathon Training

• How To Perform Hill Sprints: Every Runner’s Secret Weapon

• How To Get Faster With Fartleks

Note that this type of training is not suitable for everyone, especially if you have heart problems. Always check with your doctor about new exercise programs.

Unlike HIIT training, submaximal exercise like moderate jogging appears to improve metabolism, but doesn’t increase VO₂ max. So if you’d like to increase your VO₂ max, make sure you’re adding HIIT interval training into your running workouts!

What Is VO2 Max – Supplements To Improve VO2 Max

I know what you’re probably thinking: it’s not possible to increase your cardio capacity with supplements.

But studies have shown that it is possible to improve your maximal oxygen consumption with certain supplements. It’s believed that some of these supplements (like peppermint mentioned below) work by increasing vasodilation (opening up the blood vessels), and improving lung function which increases oxygen uptake.

Obviously you should never try to replace proper training with supplements, but combining natural, sport safe supplements and nutrition strategy with a solid training routine may help.

Make sure to speak with your doctor before beginning a new supplement!

Here are a few examples of supplements and nutrition strategies shown by scientific studies to be effective for improving VO₂ max:

• Quercetin (a natural plant bioflavonoid) has been found effective at increasing VO₂ max.
  
• Iron supplementation if you have low blood iron levels.
  
• Peppermint essential oil taken by mouth seems to improve VO₂ max and respiratory rate.
  
• Rhodiola and ginkgo combined appear to improve endurance performance and VO₂ max.

Certain supplements like a glucose or caffeine may increase time to exhaustion and mitigate the feelings of exhaustion, but don’t necessarily increase your VO₂ max.

Other considerations

VO2 max is a great thing to work on and improve, but it is not the only thing to consider. VO₂ max isn’t the same thing as lactate threshold, first or second ventilatory threshold (VT1 and VT2), etc.

If you’d like to improve running, here are a few other things to keep in mind along with VO₂ max:

• Lactate threshold (the point at which lactic acid accumulates in the blood faster than it can be removed)
• Mental fitness and psychological readiness for races
• Strength training and conditioning of legs and core for movement efficiency
• Stride length, cadence, and foot strike.