For almost a hundred years, athletes and exercise physiologists have
blamed lactic acid (LA) as the primary culprit for fatigue during
strenuous exercise. They referred to it as a metabolic waste product
that, if allowed to accumulate to certain levels in muscle tissue,
would cause cessation of exercise. New research has now shown that LA
is not the cause of muscle fatigue but actually helps prevent it.
If lactic acid is not the villian for muscle burn then what is? To
understand muscle fatigue, you must understand the pH scale which tells
you how acidic or alkaline (basic) the body is on a scale of 1-14. It
is based on numbers of hydrogen ions, with pH readings of less than 7
being acidic (more hydrogen ions) and readings greater than 7 being
basic (less hydrogen ions).
The human body is slightly alkaline with a pH of 7.4. If you
perform an all out sprint your muscles and body will become more acidic
with a major drop in pH to about 6.5. A burning feeling sets in the
working muscles which become fatigued and eventually unable to contract.
Since LA isn't responsible for the drop in pH from sprinting what
is? The answer lies in the fuel sources we use during high intensity
activities-carbohydrates in the form of glucose and glycogen (glycogen
is stored in the muscle and glucose is already floating around in the
blood stream). When glycogen and glucose are broken down for use as
energy, they release hydrogen ions. This rapid release of hydrogen ions
drastically lowers pH, causing the burning and fatigue associated with
exercising in an acidic environment. In summary, it's the hydrogen ion
production and increased acidity that cause muscle fatigue, not LA.
LA is actually a hero.It has been found to assist in removing the
hydrogen ions from the working muscle cells which helps buffer the
acidic environment, bringing the muscle cell back to it's normal pH.
After close to 90 years, the villian reputation of LA has finally been
put to rest.
About the Author
Dr. Lanny Schaffer is an Exercise Physiologist and the President of The
International Fitness Academy. For more cutting edge training
information go to http://www.aerobic-exercise-coach.com
