Ergogenic Effects of Glycerol
HKIN 262: Performance-Enhancing Substances
Professor: Dr. Daniel Kane
Friday, December 2nd, 2011
Stephen MacLeod (200902441)
Ergogenic Effects of Glycerol
There are a wide variety of supplements that can either result in an increase or
decrease in ergogenic effects in humans. Some may react differently to certain substances
then other people. Glycerol is a three-carbon molecule, which is similar to alcohol. “It
occurs naturally in the human body as a component of stored fat; a small amount is also
present in body fluids as free glycerol. When ingested, it is absorbed and increases the
concentration of the fluid in the blood and tissues” (Robergs, R.A., 1998). This
metabolite historically shows to be a safe and effective hyperhydrating agent that may be
beneficial to the performance of athletes (1). In this paper, I will elaborate on two studies
that analyzed the ergogenic effects glycerol has on athletic performance in tennis and
mountain biking.
The first study was performed at the School of Human Performance and
Recreation of the University of Southern Mississippi. The purpose of this study was to
compare glycerol and water hyperhydration on tennis related skill and agility
performance. This experiment consisted of eleven male subjects that had to complete two
counter-balanced, double blind trials. The trials all consisted of three important phases.
In the first phase, the subject would begin with a hyperhydration phase. The
hyperhydration either contained 1.0 g*kg -1 glycerol or none at all. The second step was
the exercise process. This consisted of 120 minutes of playing tennis, which is known as
an exercise-induced dehydration (EID). Finally, in the last phase, the subjects are
rehydrated with or without the glycerol sample included. This phase takes place during
the 90 minutes after the exercise was performed. (Wingo et al., 2004)
The eleven advanced level male tennis players that volunteered had an average
age of 27 years old, an average body weight of 77.4 kg, and an average body fat of
12.3%. Before being tested, each subject completed a health history questionnaire, had
their blood pressure measured, and many other health and physicality tests. Performances
such as speed, agility, and serves. The performance was evaluated by different
technologies for each test. The tests were performed three times each to collect more
accurate data. (Wingo et al., 2004)
After all tests and information were analyzed, the results showed some positive
and negative effects. During and after the experiments, none of the subjects experienced
any nausea or vomiting. The study showed that the subjects who were given samples
containing glycerol improved hydration status as well as expand their plasma levels. This
shows that water-containing glycerol can make you more hydrated then water on its own.
Although hydration is increased with the consumption of glycerol, the performance
evaluation had different results. Results show that “tennis-related agility and skill
performance was not affected”(Wingo et al., 2004) by the glycerol. It was also
demonstrated that just a small amount of hypohydration negatively influences anaerobic
performance by less then 3%. Therefore, in this case, this substance shows ergolytic
effects on athletic performance. (Wingo et al., 2004)
In the second case I will be reviewing, the subjects are required to race mountain
bikes in a high heat area. This case had 12 subjects who took part in 3 treatments. These
treatments outlined what the sample contained and when it is consumed. In the first
treatment, water was consumed before the race and no water during the race. This is
called a no water during exercise (NE) treatment. The second treatment (G) is a mixture
of glycerol and water prior to the race and was allowed to consume water during exercise.
The third treatment (W) was simply consuming water before and during the race. (Magal
et al., 2003)
The objective of this case was “to determine if pre-exercise hydration with and
without glycerol differentially affects physiologic and performance responses during
mountain-bike races in the heat”. (Magal et al., 2003) Each subject was responsible for
completing numerous measurements and an Environmental Symptoms Questionnaire.
The subjects had an average age of 24.5 years old, an average body fat percentage of
14.3, an average mass of 76.9 kg, and an average height of 179 cm. (Magal et al., 2003)
In the study itself, the subjects (who are all experienced mountain bikers) had to
race around three 10-mile (16 km) loops of rough terrain. Each was allowed to rest for
eight minutes after each loop so that the data could be collected for each stage. Each of
the three treatments described above were flavored with sugar-less powder that would
mask any potential taste or texture of glycerol. Once the professionals working on this
experiment analyzed all the information, similar information to the first case was found.
(Magal et al., 2003)
Results show that after the exercise was performed, the G treatment subjects were
not as thirsty as the subjects who received the NE and W treatments. This shows, just as
we seen in the first case, that water containing glycerol appears to increase hydration
more then the water itself. Again, just like the first case, because of water retention, the
plasma volumes were expanded. Although the G trial performed 5 minutes faster on loop
three than the W and NE trials, it is not significant enough to show much improvement.
The final conclusion of this case showed that glycerol mixed with water before an intense
mountain bike race in high heats did not show any increase in ergogenic effects. (Magal
et al., 2003)
Prior to reading these two articles, from what I already knew about glycerol, I
suspected there to be some ergogenic effects due to the fact that it increased the subjects
hydration. These case studies prove that although it may increase hydration and expand
plasma volumes, glycerol does not improve athletic performance. In fact, as I stated
earlier, in some cases, the substance may be slightly ergolytic. This shows that with the
information provided, we can state that glycerol is probable to not provide any ergogenic
effects.
Bibliography
Magal, M., Webster, M., Sistrunk, L., Whitehead, M., Evans, R., Boyd, J., 2003.
Comparison of Glycerol and Water Hydration Regimens on Tennis-Related Performance.
Pp. 150-156.
Wingo, J., Casa, D., Berger, E., Dellis, W., Knight, J., McClung, J., 2004. Influence of a
Pre-Exercise Glycerol Hydration Beverage on Performance and Physiologic Function
During Mountain-Bike Races in the Heat. Pp. 169-175.
Robergs, 2011) CITETHIS SHITTTTTTTTTTT