Essentials of Creatine in Sports and Health

255 Pages·2008·21.42 MB·English

by  Jeff S. Volek PhD

ESSENTIALS OF CREATINE
IN SPORTS AND HEALTH
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ESSENTIALS
OF CREATINE
IN SPORTS
AND HEALTH
Edited by
R.
JEFFREY STOUT, PhD
DepartmentofHealth andSports Science
University ofOklahoma, Norman, Oklahoma
JOSE ANTONIO, phD
International Society ofSports Nutrition
DeerfieldBeach, Florida
and
DOUGLAS KALMAN, PhD, RD
Division ofNutrition andEndocrinology
Miami ResearchAssociates
Miami, Florida
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Preface
The Dietary Supplement Industry is a booming $21.3 billion dollar
industry in the United States alone. This industry includes vitamins,
minerals, herbs, specialtysupplements,meal replacementpowdersand
bars, as well as sports nutrition and weight loss supplements. There
is perhaps no single ingredient in the history ofdietary supplements
that has been studies more thoroughly than creatine monohydrate. In
a nutshell, creatine works and is safe. A PubMed search of"creatine
monohydrate" alone brings up 234 research articles, and there are cer
tainly many more peer-reviewed publications on creatine that do not
appear on the NLM and NIH databases.
With all of the misinformation regarding the effects of creatine
supplementation on health and sports performance, Essentials of
Creatine in Sports andHealth brings together the information on how
creatine affecs body composition, exercise performance, and health.
Supported by the International Society ofSports Nutrition, this book
is timely and vital for all professionals in the field ofsports nutrition.
Propersupplementationwithcreatinecanimproveperformanceinboth
enduranceandstrength-powersports(seechaptersbyDrs. Willoughby
and Cramer). As far as safety, perhaps no othersingle supplement has
been shown to be extraordinarily safe while still being effective. Dr.
Poortmans' chapter edifies the reader on the safety and health data
regarding creatine.
This text will bring the student, academic scientist, clinician, and
sports nutritionist up to date on the latest science ofcreatine, as well
as dispel the common myths that have pervadedthe mainstream press
regarding this truly remarkable ergogenic aid.
Jeffrey R. Stout, PhD
Jose Antonio, PhD
Douglas Kalman, PhD, RD
v
Contents
Preface v
Contributors ix
1 An Overview ofCreatine Metabolism 1
JeffS. Volek, Kevin D. Ballard,
andCassandra E. Forsythe
2 Creatine Supplementation in Strength-Power Sports 25
Darryn S. Willoughby
3 Creatine Supplementation in Endurance Sports .45
Joel P. Cramer
4 Creatine Supplementation and Woman Athletes 101
Joan Eckerson
5 Creatine Consumption and Health 127
Jacques R. Poortmans andMarc Francaux
6 Clinical Application 173
Joseph Weir
7 Creatine Overview: Facts, Fallacies, andFuture 211
Mike Greenwood
Index 241
vii
Contributors
JOSE ANTONIO, PhD • International Society ofSports Nutrition, Boca
Raton, Florida
JOEL T. CRAMER, PhD· DepartmentofHealth andExercise Science,
University ofOklahoma, Norman, Oklahoma
KEVIN D. BAllARD, MS • DepartmentofKinesiology, University
ofConnecticut, Storrs, Connecticut
JOAN ECKERSON, PhD· DepartmentofExercise Science andAthletic
Training, Creighton University, Omaha, Nebraska
CASSANDRA E. FORSYTHE, MS • DepartmentofKinesiology, University
ofConnecticut, Storrs, Connecticut
MARC FRANCAUX, PhD· Institut Superieurd'Education Physique etde
Readaption, Faculte de Medecine, Universite Catholique de
Louvain, Louvain-la-neuve, Belgium
MIKE GREENWOOD, PhD • Department ofHealth, Human Performance,
andRecreation. Baylor University, Waco, Texas
DOUGLAS KALMAN, PhD, RD • Division ofNutrition andEndocrinology,
Miami Research Associates, Miami, Florida
JACQUES R. POORTMANS, PhD· Institut Superieurd'Education Physique
etde Kinesitherapie, Universite Librede Bruxelles, Brussels,
Belgium
JEFFREY R. STOU1, PhD· Department ofHealth andSports Science
[/niversity olOklahoma. Norman, Oklahoma
.JEfF S. VOlEK, PhD, RD • Department o/Kinesiology, Universit,v
o/Connecticut, Storrs, Connecticut
JOSEPH P. WEIR, PhD· Physical Therapy Program, Des Moines
University~Osteopathic Medical Center, Des Moines, Iowa
DARRYN S. WillOUGHBY, PhD • DepartmentofHealth, Human
Performance. andRecreation, Baylor University, Waco, Texas
ix
1 Overview ofCreatine Metabolism
JeffS. Volek,
PhD, RD,
Kevin D. Ballard, and
MS,
Cassandra E. Forsythe,
MS
1. INTRODUCTION
Creatine (Cr) was first discovered as an organic constituent ofmeat
some time in the early 1800s. Later in the 1800s, Cr was consistently
detected in muscle tissue extracted from various mammals. It was
noted that foxes killed in a hunt immediately after running, contained
significantly more Cr than normaL providing the first indication that
muscular contraction results in an accumulation of Cr. Around the
same time, a substance called creatinine (Crn) was detected in the
urine and later determined to be a breakdown product of Cr.
Phosphocreatine (PCr) was first isolated from muscle tissue in 1927
and found to play an important role in the transfer ofenergy. Around
the same time, two researchers who consumed large quantities of Cr
noted that a percentage of the Cr ingested could not be accounted for
by excretion in the urine (J). This study was one ofthe first to indicate
that "Cr loading'" in muscle is possible when large amounts of Cr are
consumed. A great deal of research has been done since this early
work to further define the importance ofCrin humans, and the impact
ofCrsupplementation. In this chapter,the basicmetabolism andfunction
of Cr in humans will be overviewed. To what extent and what factors
influence blood- and muscle-Cr levels in response to Cr supplementa
tion will be discussed. Also some of the proposed mechanisms that
account for the ergogenic effects from Cr usage observed in many
studies will be explored.
From: EssentialsofCreatine in SportsandHealth
Edited by: J. R. Stout. J. Antonioand D. Kalman © HumanaPress Inc..Totowa, NJ
1
2 VoleketaI.
Fig. 1.StructureofCr.
2. LITERATURE REVIEW
Cr (Fig. 1), also known as methylguanidino acetic acid, is a term
derived from the Greek work kreas, meaning flesh. Indeed, the highest
quantities (-94%) ofCr are in muscular tissues, such as skeletal mus
cleandheart(2).Crisanexampleofaphysiologicallyimportantnitroge
nous compound synthesized from amino acids. However, because rates
ofCrbiosynthesis are sufficientto maintain normal Crlevels, Cris not
consideredanessentialdietary nutrient. Cris also notconsideredapro
tein, even though it contains nitrogen and is made from amino acids.
Unlike proteins, Cr synthesis does not involve formation of peptide
bonds and its degradation does not involve deamination (removal of
nitrogen) when it is excreted by the kidney. Thus, the concern that Cr
poses a threat to renal function because itrepresents a nitrogen loadon
the kidney is unlikely and has not been substantiated (for more infor
mation, see Chapter5).
2.1. Endogenous Cr Synthesis
In all mammals, muscle tissues do not have the ability to synthesize
Cr, so the compound must be taken up from the blood originating from
endogenous biosynthesis or dietary sources. Synthesis ofCr in humans
occurs primarily in the liver, from the conditionally essential amino acid
arginine, the nonessential amino acid glycine, and the potent methyl
donor, S-adenosyl-methionine(SAM) (2).Thefirst stepinCrbiosynthe
sisinvolvestransferoftheamidinogroupofarginine to glycine, forming
L-ornithine and guanidinoacetic acid. This reaction is catalyzed by the
enzyme L-arginine:glycine amidinotransferase (AGAT). In the next step,
guanidinoacetic acid is methylated by SAM through the action of the