By Jaclyn Mullick B.S.
The onset of muscle fatigue has hindered many athletes from achieving
their maximum performance. Over the years we have been taught that it
is the build-up of lactic acid that is the downfall of muscle fatigue
and soreness. This is only partially true; there is a little more to it
than what we have been told. I hope that this article provides you with
a possible short-term remedy and does not confuse you more but rather
makes you more aware of what is going on when your muscles become fatigued.
During short term (anaerobic) exercise, ATP and creatine phosphate (CP)
are used up within the first 7 seconds of training. This signals the metabolism
of glycogen to produce energy for your body. This process is known as
glycolysis. During glycolysis, glycogen (muscle sugar) is broken down
to produce more CP. The breakdown of CP releases energy, which catalyzes
a reaction to produce ATP. The production of more ATP allows movement
of the muscle to continue. Lactic acid is a product of glycolysis created
by the breaking down of pyruvate.
Lactic acid is then disassociated to produce lactate. When lactic acid
(C3H6O3) releases a hydrogen ion (H+), the remaining compound binds to
a sodium ion (Na+) or a potassium ion (K+) to form a salt. It is this
salt that is lactate. Now the cell contains a lactate compound and a free
H+ for each compound of lactic acid that is produced. It is this increase
in cellular H+ that causes the pH to decrease, becoming more acidic. The
acid in the muscle causes the fibers' calcium-binding capacity to decrease,
thus limiting muscle contraction. This is the cause of muscle fatigue.
Some of the lactate seeps out of the cell into the bloodstream where it
is sent to the liver to be used to synthesize glucose. The remainder of
the lactate must be eliminated in the cell. Oxygen and cellular lactic
acid act together to resynthesize ATP via anaerobic metabolism.
The question many athletes want answered is how can I prolong my muscle
fatigue? Theoretically, if you can decrease the amount of acid build-up
produced in the muscles, then you can delay the onset of muscle fatigue.
One method of decreasing acid build-up is by buffering it with a base
compound.
The most significant buffer compound found in human blood is bicarbonate.
Other buffering agents are also present, including proteins and organic
acids, but they are present in much smaller concentrations. When the pH
in the blood falls due to the increase of H+, the bicarbonate-carbonate
acid equilibrium shifts toward more acidic. At this same time the carbonic
acid loses water (H20) to become CO2. The CO2 produced is lost in the
lungs through exhalation. When blood pH increases, more bicarbonate is
formed and more CO2 is taken from the lungs to be used in the blood for
conversion to carbonic acid. Acidosis is a disturbance in the blood buffer
system resulting in a pH as low as 7.1, where the normal blood pH is 7.4.
The normal treatment of acidosis is an injection of sodium bicarbonate.
This process sparked the idea that the consumption of sodium carbonate
could prolong acid build-up causing muscle fatigue.
Some research has shown that the consumption of sodium bicarbonate (an
alkalizing agent) helps to buffer the lactic acid concentration in the
bloodstream. The decrease in blood acidity would in turn allow the acid
within the cells to enter the blood stream via the concentration gradient.
Bicarbonate is not able to enter the cells; therefore it must act in the
bloodstream.
In an attempt to kick start the body's natural bicarbonate process, some
sprinters will try hyperventilating shortly before a race with the hope
that it will help reduce acid build-up. This increases the pH of the blood
slightly, making it better able to deal with the short-term build-up of
lactate and acid during the sprint.
According to Mc Naughton et al. (1997), research found that the consumption
of sodium bicarbonate in athletes competing in short events (1-7 minutes)
improved their performance by 1-2%. This means that if you were Kevin
Herlihy of the UCSB men's swim team and you increased your performance
in the 200m freestyle (1:40.81) by 2%, you could potentially decrease
your time by about 2.02 seconds.
The effective dose of sodium carbonate is 135mg/lb of body weight (0.3g/kg
of body weight). Doses above 20gm have been shown to cause vomiting and
diarrhea. Athletes who have performed in the experiments (Mc Naughton
et al. (1997)) took the bicarbonate substance 60-90 minutes before exercising.
Not everyone reacts the same to supplementation, and it is for this reason
that the research on sodium bicarbonate is conflicting. For every study
done that gives positive results there is another giving the opposite.
It is for this reason that experimentation is done. If you are able to
stomach the sodium bicarbonate, you just might get the results you are
looking for. Bicarbonate supplementation would not be advantageous for
endurance athletes, since they do not accumulate as much lactic acid in
their muscles as do sprinters.
WARNING: (http://www.rxlist.com)
Sodium bicarbonate is incompatible with acids, acid salts,
ammonium chloride, lime water, ephedrine hydrochloride, and iron chloride.
It is used to treat acidosis (e.g., in renal failure). Orally it is used
as an antacid, although its effectiveness for this purpose is questionable.
Externally, it is used as a mild alkaline wash. It is also used as a component
in many laboratory reagents, such as various buffers, microbiologic media,
and control materials.
Solutions containing sodium ions should be used with great care, if at
all, in people with congestive heart failure, severe renal insufficiency
and in clinical states in which there exists edema with sodium retention.
In people with diminished renal function, administration of solutions
containing sodium ions may result in sodium retention.
The intravenous administration of these solutions can cause fluid and/or
solute overloading resulting in dilution of serum electrolyte concentrations,
over hydration, congested states or pulmonary edema.
If you have any questions or comments regarding this article or have any
article ideas, please feel free to contact jaclyn@issaonline.com.
References:
Voet, D., Voet, J., Pratt, C. (1999). Fundamentals of Biochemistry. p.
37, 667.
Mc Naughton, L.R., Dalton, B, Tarr, J., Buck, D. (1997). Neutralize Acid
to Enhance Performance. Sportssciences Training & Technology. http://www.sportssci.org/traintech/buffer/lrm.htm
Williams, Alun. Sodium Bicarbonate: Research suggests it may boost performance
in short events, but it can have nauseating side effects. http://pponline.co.uk/encyc/0086.htm
http://www.rxlist.com
