The Lactate Threshold ? Reality or Fallacy?

For many years exercise science has perpetuated the concept of a lactate threshold - a point during exercise where a sudden, sharp increase is noted in the concentration of lactate in the blood. This phenomenon is supposedly noticed when blood samples are taken from subjects performing incremental to max exercise tests much the same as a VO2 max test. Traditionally, it has been noted that when concentration of lactate is plotted against running speed (or %VO2 max) on a graph, as the individual runs faster the quantity of lactate in the blood remains constant up to a certain speed, after which a sudden inflection in the gradient occurs. This inflection point has been dubbed the lactate threshold - the point during intense exercise where the muscles become increasingly anaerobic, generating vast quantities of lactate. Therefore, this phenomenon has also become known as the anaerobic or ventilation threshold.

As discussed in an earlier article on lactate featured on this website, early exercise scientists (and even some present day ones) attributed the increasing amounts of lactate in the blood during exercise to a lack of oxygen supplied to the muscles. This theory holds that the cardiorespiratory system must be inefficient at matching blood (oxygen) supply to the muscles and exercise intensity. Therefore, as the intensity of exercise increases, the muscles have to rely increasingly on "oxygen independent" (anaerobic) metabolism and its associated lactate generation. What these researchers failed to understand, or were unaware of was that as the intensity level (power output) of exercise progressively increases, there is a corresponding increase in the dependence of the glycolytic energy system. It is now universally accepted that energy systems are exercise intensity dependent. As explained in the previous article on lactate, this accumulation of lactate is a necessary consequence to maintain the increased flow of energy through the glycolytic pathway.

Tim Noakes at the University of Cape Town, South Africa states that it is highly unlikely that the muscles ever become truly anaerobic. He provides some powerful evidence to back up this statement and quite possibly the most convincing might be what he calls the "lactate paradox". In his studies of the results of several research papers on Everest climbing expedition experiments, Noakes noted that lactate accumulation in the blood actually decreased as attitude increased. This finding is the exact opposite of what one would traditionally expect since as altitude increases, the ambient barometric pressure decreases, as does the relative availability of oxygen in the inspired air. Therefore, one would suspect that near the peak of Everest, the exercising muscles must be truly anaerobic and generating large amounts of lactate but as mentioned previously, this does not occur. Professor Noakes explains that at such an extreme altitude, some internally regulated factor (possibly the brain) severely limits the intensity of exercise to protect the heart therefore also limiting the amount of lactate production. Additional research, has demonstrated that even at rest under more than adequate oxygen availability, muscles generate lactate. Furthermore, other researchers have failed to find conclusive evidence that muscles become anaerobic at exercise intensities approaching the lactate threshold or even during maximal exercise. Therefore, Noakes prefers to refer to anaerobic metabolism as "oxygen independent" metabolism since in his astute opinion there exists no such thing as anaerobic muscle.

Noakes dismisses the probability of a sudden increase in lactate concentration. He explains that if too few blood samples are taken - say for every three or four kilometers per hour increase, then when the rise in lactate is actually observed, it may indeed show a precipitous "jump" from the one observation to the next. If samples are taken more frequently however, say at every speed increment, then the increase is much more gradual, producing a smoother logarithmic or hyperbolic curve. Dr. Noakes indicates that lactate buildup during increasingly intense exercise is the result of its production rate exceeding its clearance. As mentioned in our article,Lactate is NOT the Culprit!, Brook's lactate shuttle is purported as being responsible for assisting with the transport, utilization and clearance of lactate during exercise. At lower exercise intensity levels, the rate of lactate clearance is able to match the rate of production. However, as exercise becomes increasingly more intense and more muscle mass is recruited, proportionately large quantities of lactate are produced, but it is unlikely that clearance via the shuttle will be able to maintain pace. Therefore, there exists a speed or intensity level at which the production of lactate surpasses its clearance and the blood concentration begins to steadily increase. This point is what Noakes prefers to call for lack of a better word ? the "lactate turnpoint" and that it occurs at an intensity/speed where the concentration of lactate in the blood is approximately 3.0 mmol/L. If the individual were to run at this constant speed, this would be called running at the subjects "lactate steady state". In theory this is the fastest speed that can be maintained by the exerciser for extended periods of time such as marathon running.

Therefore, from discussions in this and previous articles, it is safe to conclude that lactate production in the body is the direct result of an increased reliance on the glycolytic energy systems, not from a lack of oxygen in the muscles. Paired with this increased use of oxygen independent metabolism is an increase in lactate production. The sudden jump in lactate production simply does not exist; it increases proportionally with the increased exercise intensity or power output. In addition, it should be obvious that the term anaerobic threshold is a misnomer and that perhaps the only appropriate term to refer to this phenomenon is the lactate turnpoint.

References and further reading: more information on the concept oxygen independent metabolism and the lactate turnpoint may be found in Lore of Running ? a classic book in its fourth edition dedicated not only to running performance, but to cutting edge exercise physiology as well.

David Petersen is a Personal Trainer/Certified Strength and Conditioning Specialist and the owner and founder of B.O.S.S. Fitness Inc. based in Oldsmar, Florida. More articles and information can be found at http://www.bossfitness.com

NOTE: You're free to republish this article on your website, in your newsletter, in your e-book or in other publications provided the article is reproduced in its entirety, including this note, author information and all LIVE website links as above.

---

Weight Loss, Bodybuilding, and Exercise Tips ? Keeping Your Body-fat Low: Part 2 of 10

My name is Greg Ryan. I am a fitness expert,... Read More

Basic Abdominal Exercises

If it's six pack abs that you're after, daily abdominal... Read More

How NOT to Return from an Exercise Break

Several sites, including this one, recommend that you take a... Read More

The Power Workout:

Scenario: I really want to get in shape, but I... Read More

What is the Right Home Exercise Program for You?

What do you want to get out of the exercise... Read More

Exercise and Losing Weight for Life ? Avoid the #1 Mistake Everyone Makes!

Do you ever feel like you are working out so... Read More

How to Avoid Using Your Home Gym as a Clothes Rack

So here's the situation?You have a home gym, treadmill, elliptical... Read More

The Many Benefits of Exercise

Health experts encourage us to include exercise as a necessary... Read More

Weight Loss and Exercise in Tough Environmental Conditions

Working out is working out, right?Wrong.Depending on the environmental conditions... Read More

Warning! Lack Of Exercise Could Be Harmful To Your Health

You know it's bad when the Surgeon General issues a... Read More

Core Strength Limits Arm and Leg Power

Core training has become such a hot topic in the... Read More

Exercise - Anxiety & Panic

Yes, all I'm afraid this does play a part in... Read More

The Two Greatest Myths About Abdominal Exercises

If you have ever read a fitness magazine...If you have... Read More

How to Keep Your Body Fit

Fitness is just as imperative as health. As a matter... Read More

How To Gain An Avalanche Of Energy!

For many people out there trying to become more energised... Read More

Discover the Best Weight Loss Exercise Ever!

The Best Weight Loss ExerciseThe exercise the experts are keeping... Read More

Different Exercises Schedule to Combat Diabetes, Arthritis, and Obesity!

Different Health Problems generally do not allow us to do... Read More

How to Start a Walking Program

Did you know that walking is the number one participation... Read More

Six Simple Strategies to Turn Your Walks into Workouts

If You are already fitness walking several times a week... Read More

The Degradation of Fitness Science

The world and our selves evolve and exist in a... Read More

Lance Armstrong, Exercise, and Will Power? Characteristics that Make a Champion!

The Tour De France, arguably may be the hardest sport... Read More

Arthritis Exercise for All Levels

Exercise can be very beneficial for arthritis sufferers, often relieving... Read More

Why Core is Key

Do you currently suffer or have you ever suffered from... Read More

An Introduction to Tennis

Is tennis good for you?Absolutely - tennis is a gentle... Read More

Success Versus Failure in the Exercise Department

Success is what you are prepared to make of yourself... Read More

10 Best Workout Tips

Top Trainers share their secrets to getting slim, toned and... Read More

Core-Principles: The Function of Functional Training

Okay?okay?okay! Enough already!!! It seems like with every new term,... Read More

How to Maximize Your Fitness Results

What I am about to reveal to you can make... Read More

The New Discovery That Makes It Possible To Get An Effective Workout In Less Time

The Art of Multifunctional TrainingPeople often complain about how they... Read More

Have a Detailed Exercise Plan Before Training

You would never build a house without a site plan,... Read More

Arthritis Exercise ? One Way to Relieve Pain & Stiffness in Your Joints (part 2)

Even when you cannot make it out to walk or... Read More

Strength Training After Fifty

Strength training after fifty is no longer for those people... Read More

The Bad Workout: Some Advice for Female Bodybuilders

Bad workouts. We have all had them at some time... Read More