Ergogenic Aids
by Leesa Nacht
of J&M Consulting
Providing Information for the Equine Industry
Your horse is at the top
of his game. What can you do to get just a little bit more? There
are a number of products now available on the market today that
are classified as ergogenic aids. The term ergogenic is
derived from the Greek word "ergon", meaning work,
and "genic", meaning producing. Work producing aids
are any factor which can increase or improve work production
resulting in increased speed, endurance or strength. Sounds tempting,
especially since these products are generally easy to administer,
by just adding them to the feed tub.
There are a number of factors that can affect performance in
a horse. These are classified as psychological factors, mechanical
or biomechanical factors (shoes, ground surfaces), pharmacological
agents, physiological improvements, and nutritional supplements.
What we are going to examine in this article are the nutritional
supplements that claim to boost performance and how they do it.
Ergogenic Class Supplements
Nutritional supplements can work on the body in a variety of
manners. In order to fall into this ergogenic classification,
the supplement must have one of the following effects on the
horse:
o improve coordination and/or the recruitment of muscle tissue
o provision of supplemental fuel sources
o increased levels of stored energy
o improved ATP/ADP homeostasis in muscle tissue
o decreased substrate depletion
o decreased end product accumulation
These nutritional supplements must also show absorption from
the gut, along with adequate uptake to the target tissues. They
should also show an improvement in tissue function and improved
performance. Definitely a tall order to fill. There is a great
lack of scientific evidence that some of these products work,
and what is often found is anecdotal or taken as known from work
in species other than horses.
Another issue that comes under scrutiny is that of the ethics
involved in the use of these products. What is allowable and
what should be allowable? Is an ergogenic aid simply an advance
in feeding strategies or is it a prohibited substance? And most
importantly, how are the decisions made to classify these products?
Has safety data been properly gathered and are the products manufactured
under proper controls? The International Olympic Committee
has issued a fairly clear statement as to their stance: "Any
physiologic substance taken in abnormal quantities with the intention
of artificially and unfairly increasing performance should be
construed as doping, violating the ethics of sport performance."
As far as racing rules go, some ergogenic aids are banned, while
others are not, but testing is on-going and could result in reclassification
at any time. The best bet is to check with your Racing Commission
for up-to-date rulings before administering any substance. With
that in mind, let's take a look at the situation of supplementation
with fat, a common practice in performance horses today. Compare
fat with an ergogenic aid, creatine. Both are not normal components
of a horse's diet. What then is the deciding factor between feed
supplement and doping agent, when both are known to improve performance?
A tough question to answer.
By adding fat to the diet, improved performance can result from
increased mobilization of free fatty acids (FFA's) into the muscle,
increased speed of uptake of FFA's, a glycogen sparing effect,
and an increased capacity for high intensity exercise. Of course,
this change in diet has to be accompanied with the appropriate
training.
Keeping these ethical questions in mind, the following are the
categories that ergogenic aids are divided into. Those with the
ability to: 1. Improve the availability of stored glycogen. 2.
Boost oxidative metabolism. 3. Modulate cellular acid-base regulation
Glycogen is an energy source that is stored in the muscle cell
and utilized during exercise. Oxidative metabolism refers to
the oxygen capacity of the muscle, as oxygen is vital in order
for aerobic exercise (as opposed to anaerobic exercise) to be
maintained. Cellular acid-base regulation is important because,
as horses exercise, there is an accumulation of lactic acid in
the muscle, dropping the pH (increasing the acidity). This results
in the muscle becoming fatigued. Let's take a more detailed look
at these three catagories.
1. Glycogen loading is something we are all probably familiar
with. Typically we hear about marathon runners who eat vast amounts
of carbohydrates prior to the race. Though this has been proven
to work in humans (they can actually double the glycogen content
of muscle with the proper combination of diet and exercise),
scientists have been unable to prove a similar response in horses.
In trials, there was no change in the rate of muscle glycogen
synthesis, nor in the final levels reached after exercise and
after a recovery period.
2. The best way to increase the oxidative capacity of muscle
is through training, but of course, nutritional supplements have
been used to try and push this edge even further. Some of them
are:
Q10 - a.k.a. ubiquinone. This compound has a role in the electron
transport within the cell. Theoretically, if you could increase
this 'shuttle', you could increase the energy. Most research
shows that though Q10 has a vital role, it seems in no way to
be limiting to oxidative metabolism in well-fed, healthy animals.
Studies in rats and humans have failed to show any effect on
performance. There are no studies showing uptake from the gut
into the muscles of horses, and again, no effect on physical
performance.
L-carnitine. This is a co-factor for the transport of fatty acids
within the cells. L-carnitine has also been suggested to be a
limiting factor in performance. So far, this is unsubstantiated.
What may be a factor is the possible role in carbohydrate oxidation.
This provides a valuable source of energy during the early stages
of high intensity exercise. The horse must synthesize L-carnitine,
as research shows that it is poorly absorbed in the horse when
supplemented orally. Prolonged oral supplementation showed no
changes in muscle content and there was no effect when administered
intravenously.
DCA - Dichloroacetate. This compound is a component of the energy
producing cycle within the cell. It is said to limit lactic acid
accumulation in muscle tissue when fed orally. There has been
positive results seen in greyhounds, but no trials have been
conducted in horses. (A dog does not a racehorse make!)
DMG/TMG - Dimethylglycine/Trimethylglycine. These related compounds
are reputed to prevent lactic acid build-up during exercise.
This would decrease overall muscle fatigue. They are both said
to increase oxygen utilization. Though DMG has shown some effects
in humans, equine trials have shown no response. TMG was tested
and showed that it was able to lower lactic acid levels in untrained
horses, but had no effect on fit horses. While this may be a
beneficial training tool, it can not be considered an ergogenic
aid because peak performance is not improved.
3. Acid-base regulation and buffering (the reduction of acidity)
is a key area of interest in working horses. The natural by-products
of exercise are lactic acid and hydrogen ions, both of which
make muscles acidic, causing fatigue and cramping. Amino acids,
inorganic and organic phosphates (such as phosphorylcreatine)
and carnosine do normal cellular buffering. Carnosine accounts
for up to 30% of the buffering capacity of the body.
BCAA - Branched Chain Amino Acids. These supplements are available,
but data in both humans and horses is contradictory. Some trials
report that these amino acids increase alanine synthesis (see
below), and lower glycogen utilization during exercise, but other
trials show no response.
Alanine/L-Histidine. These amino acids limit the availability
of carnosine, which as mentioned, has a big role in buffering
in the muscle cells. They are well absorbed by horses, but to
date, there have been no ergogenic trials performed on horses.
The drawback of administering these amino acids is that they
can cause parasthesia (paralysis) in heart and skeletal muscles,
even at low doses.
Phosphorylcreatine. This is a natural compound that is synthesized
by the liver, pancreas and kidneys. The concentration of creatine
correlates to the glycolytic capacity of the muscles, or the
ability of the muscles to store and utilize glycogen. Supplementation
can increase the capacity for sustained or intermittent hard
exercise. Creatine is low in plant materials and, therefore,
low in herbivore diets and would need to be supplemented. While
readily absorbed in humans and dogs, tests show poor absorption
in horses, and evidence of an effect in performance horses is
lacking.
Sodium Bicarbonate. For a time, this was used widely to affect
the acid/base balance in athletes. There were mixed results in
trials, mostly due to the differences in dosage and time administered.
Though performance was seen to be enhanced in endurance events
i.e. one mile in racing, sodium bicarbonate is illegal for use
in competition horses.
In conclusion, there is still a lot of work to be
done in studies with horses to prove both safety and efficacy.
The ethical issues need to be resolved. Can feeding creatine
and carnitine be any different from feeding vitamins, minerals
and carbohydrate supplements? For now, until clearer guidelines
are set forth, yes, it is different, and continues to be regulated
as such.
Republished
with permission from Canadian Thoroughbred
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