Bookmark Website  | Free Registration  | The Team
The Lounge  | Champions  | The Wire |  Schedule |  Audio  |  Arcade  |  The Top Ten  |  Historical  |  Email  |  Video

The Truth About Lactate and Exercise


For years exercise scientists and physiologists have preached that lactate/lactic acid build-up in the muscle is the direct cause of muscle fatigue and a decrease in performance. It is proposed that lactate builds up in the muscle cells during intense exercise and literally "poisons" them, essentially shutting down activity biochemically by reducing the pH or increasing the acidity level. Lactate has therefore been dubbed a metabolic by-product or dead end and as the enemy of human exercise and performance. This may be far from the truth as this article explains.

Unfortunately, the information that gave lactate this unearned reputation is outdated and very questionable since the research on which this theory is based was isolated frog muscle experiments from 1910-1914. The experiments were performed and the lactate theory proposed by A.V. Hill and associates. Basically, these investigators took excised frog muscle and continuously stimulated it with electric shocks until failure and then took lactate samples for analysis. Lactate levels were extraordinarily high, and from this finding the scientists came to the conclusion that lactate buildup must have been the culprit for the fatigue and ultimate failure of the muscle. Hill also concluded that since there was no blood and therefore oxygen supply to the muscle, that this condition must have been the cause of the accumulation of lactate.

These investigations however were highly flawed in their design, since the muscle had been removed from both its nervous and its circulatory (arteries and veins) systems. Since the electrical stimulus was applied at a fixed voltage from an external source, one cannot correlate this with the situation of a live muscle in an animal with a nervous system and brain that regulates nervous and motor input to the muscles. One must account for the possibility of central or nervous fatigue limiting activity. With the absence of a circulatory system, how was the generated lactate supposed to be transported away from the working muscle via the veins? Also, the regulation of metabolism, which is highly dependent on hormonal control, was eliminated with the loss of blood circulation. Clearly, there were big problems with these early experiments, but amazingly the theory in all its weakness has been upheld to the present day!

Few people realize that lactate generation is actually necessary to allow moderate to intense exercise to occur. It is the conversion of a product known as pyruvate to lactate that enables the glycolytic (a fast energy generating metabolic process using glucose) system to continue working at a fast rate. Lactate is formed during moderate to intense exercise, when the human body relies heavily on carbohydrates and the glycolytic system to produce energy. All metabolic processes are highly regulated and only a fixed amount of energy-supplying product or substrate may be used at a time before a backup or "metabolic bottleneck" develops. A good analogy to visualize the regulation of a metabolic pathway is to consider energy substrates as an army of soldiers marching to, and through a tunnel. When the first few soldiers enter, they can move quickly and unrestricted, but as the number trying to enter increases, the process slows down dramatically. The conversion of pyruvate to lactate prevents the excess pyruvate from clogging up the pathway, bringing glycolysis to a grinding halt. This slowing of glycolysis obviously does not occur, because if it did running events such as the 400m would be impossible. As we shall see in another article on this site, the accumulation of lactate in the blood is the direct result of this "redirection" of energy in the body not because of a lack of oxygen in the muscles as Hill proposed. (see The Lactate Threshold - Reality or Fallacy? ). Lactate as will be described below, is actually a useful and readily available source of energy for the body to utilize.

Recent research is supplying some very interesting information concerning the role of lactate and muscle performance. George Brooks at the University of California at Berkeley has dedicated much of his career to exploring the role of lactate during exercise. Brook's investigations indicate the presence of a "lactate shuttle" that allows for the transportation of lactate from one muscle to another. The glycogen (stored carbohydrate) stored in muscle is destined for use in this tissue only, unlike liver tissue, which is able to release glucose into the bloodstream to be used by the rest of the body. The lactate shuttle is proposed as being a means for muscles to be able to "share" and redistribute their glycogen stores to other muscles and tissues in the form of lactate not glucose. For many years it was thought that lactate was a metabolic by-product that to be of any use it had to be transported via the blood to the liver to generate glucose via a process known as the Cori Cycle, but there is evidence to indicate that tissue such as red muscle, heart and brain tissue can directly oxidize the product. Therefore lactate can be utilized by tissue very close to, or even far from the source of generation. The shuttle works via the interaction of the circulatory system and the presence and operation of special transporter proteins located in muscle called mono carboxylic acid transporters (MCTs). These transporters are able to efficiently transport lactate from the blood into adjacent or distant muscles in the body. The inactive muscle can actually store the lactate, thereby further lowering the concentrations in the blood and active muscle. According to Brooks, lactate is far from a metabolic dead-end and may in fact be the most important metabolic fuel used by muscles especially during exercise. Estimates are that approximately 70% or more of the lactate generated during exercise is actually consumed or oxidized while only 19% is converted to glycogen.

In conclusion, the dubbing of lactate as a metabolic dead-end and as an exclusive cause of muscle fatigue was hasty but may have seemed appropriate at the time. Since then however technological advances in research have provided some quite contradictory evidence to the role of lactate. Amazingly, lactate may in fact be a "super fuel" for the body during exercise sessions that produce large quantities of the product. Exercise science will continue to investigate the role and contribution of lactate to exercise but in the meanwhile runners and athletes alike can rest assured that lactate is not the enemy but may in fact be an ally.

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.


MORE RESOURCES:

Business Insider

An exercise scientist told us the 2 things everyone gets wrong about working out
Business Insider
Everyone out there seems to have ideas in their heads about what works and what doesn't, which is why the best thing you can do is turn to the actual science of how your body works for answers. Recently, we chatted with Rutgers exercise scientist Shawn ...

and more »


U.S. News & World Report

This is what drinking too much water during exercise does to your body
Washington Post
The idea that you should always stay hydrated has been ingrained in many of us since childhood by everyone from Little League coaches to parents. For many athletes that advice has been translated into drinking a lot and drinking often while exercising.
Health Buzz: Is Too Much Water During Exercise a Bad Thing?U.S. News & World Report
Water Overdose: Exercise-Associated Hyponatremia Can KillClapway
Why Is Drinking Too Much Water During Exercise Bad?Youth Health Magzine
News-Medical.net -Pioneer News -Medical News Today
all 119 news articles »


Quad City Times

Exercise helps with more than physical health
Quad City Times
About a month ago, Emily Fall hired a personal trainer and got serious about a regular exercise program. Fall, 26, of Davenport, had twin baby boys six months ago, and some of the extra weight she gained during pregnancy had stayed with her. Throughout ...



SaukValley.com

Freedom: Defend it, exercise it, celebrate it
SaukValley.com
Freedom: Defend it, exercise it, celebrate it. Sauk Valley residents know all about celebrating freedom. They're good at defending it and exercising it, too. We wish you a happy Fourth of July. Published: Friday, July 3, 2015 5:02 p.m. CDT ...



Northern Edge 2015, Alaska's premier joint training exercise wraps up
Arctic Sentry
The exercise brought together nearly 6,000 active-duty, Reserve and National Guard members from all branches of service, including the U.S. Coast Guard, to participate in Alaska's premier joint training exercised designed to practice operations ...



Loop 21 (press release) (blog)

Fit Over 40 3 Key Components of an Exercise Program
Loop 21 (press release) (blog)
Following a regular exercise and nutrition program can bolster your immunity, accelerate weight loss, improve muscle tone, strengthen bones, improve balance, reduce stress, and increase the desire for sex. Plus, those who perform 30 minutes of ...



Kadena, Marine units integrate for large-force exercise
Air Force Link
A HH-60G Pave Hawk from the 33rd Rescue Squadron flies off the coast of Okinawa, Japan, during a large-force exercise June 30, 2015. The exercise, which integrated Air Force and Marine Corps assets on Okinawa, was designed to allow the units to ...



Fox News

Weight-loss surgery better than diet and exercise in treating type 2 diabetes ...
Fox News
A growing body of evidence suggests that weight-loss surgery is more effective than diet and exercise at getting rid of Type 2 diabetes. A small but rigorous randomized trial published Wednesday in JAMA Surgery provides the latest evidence showing the ...
Weight Surgery Treats Diabetes Better Than Diet, ExerciseNewsmax
Weight-Loss Surgery May Be Better Than Exercise And Diets At Fighting Type 2 ...Tech Times
Bariatric Surgery Bests Diet and Exercise Against DiabetesMedPage Today
U.S. News & World Report -NY City News
all 64 news articles »


HealthCanal.com

Guidelines Released for Exercise-Associated Hyponatremia
Medscape
Untreated, the dangerous fluid imbalance can cause brain herniation, noncardiogenic pulmonary edema, and death, according to a statement developed at this year's Third International Exercise-Associated Hyponatremia Consensus Development ...
Drink water only when you're thirsty, experts sayScience Times
Endurance Athletes Should Only Drink When Thirsty, Experts SayDoctors Lounge

all 4 news articles »


Why a professor asks students to exercise in class
Futurity: Research News
While dismissing some common brain science myths that are mainstays of the self-help industry, she also offers her own “brain hacks”—four minute exercises, from doing squats while you brush your teeth to thinking up new uses for a rubber band—to help ...

and more »

Google News


Advertisement



Section Site Map - Submit News - Feedback - Comments - Advertise with Us

Copyright © 2006 Luminati Inc. All rights reserved.