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89
Molecular and Cellular Biochemistry 244: 89–94, 2003.
© 2003
K
l
uwer Academic Publishers. Printed in the Netherlands.
Effects of creatine supplementation on
performance and training adaptations
Richard B. Kreider
Exercise and Sport Nutrition Laboratory, Center for Exercise, Nutrition and Preventive Health Research, Department of
Health, Human Performance and Recreation, Baylor University, Waco, TX, USA
Abstract
Creatine has become a popular nutritional supplement among athletes. Recent research has also suggested that there may be a
number of potential therapeutic uses of creatine. This paper reviews the available research that has examined the potential
ergogenic value of creatine supplementation on exercise performance and training adaptations. Review of the literature indi-
cates that over 500 research studies have evaluated the effects of creatine supplementation on muscle physiology and/or exer-
cise capacity in healthy, trained, and various diseased populations. Short-term creatine supplementation (e.g. 20 g/day for 5–7
days) has typically been reported to increase total creatine content by 10–30% and phosphocreatine stores by 10–40%. Of the
approximately 300 studies that have evaluated the potential ergogenic value of creatine supplementation, about 70% of these
studies report statistically significant results while remaining studies generally report non-significant gains in performance.
No study reports a statistically significant ergolytic effect. For example, short-term creatine supplementation has been reported
to improve maximal power/strength (5–15%), work performed during sets of maximal effort muscle contractions (5–15%),
single-effort sprint performance (1–5%), and work performed during repetitive sprint performance (5–15%). Moreover, crea-
tine supplementation during training has been reported to promote significantly greater gains in strength, fat free mass, and
performance primarily of high intensity exercise tasks. Although not all studies report significant results, the preponderance of
scientific evidence indicates that creatine supplementation appears to be a generally effective nutritional ergogenic aid for a
variety of exercise tasks in a number of athletic and clinical populations. (Mol Cell Biochem 244: 89–94, 2003)
Key words: sport nutrition, ergogenic aids, exercise, training, phosphocreatine
Introduction
An ergogenic aid is a technique or practice that serves to
increase performance capacity, the efficiency to perform
work, the ability to recover from exercise, and/or the quality
of training thereby promoting greater training adaptations. [1]
When evaluating the potential ergogenic value of a proposed
aid, it is important to evaluate the theoretical rationale, the
scientific evidence that the proposed aid affects exercise
metabolism and/or performance, whether studies have incor-
porated an appropriate research design (e.g. double blind,
placebo controlled, randomized clinical trial), and the reli-
ability of the experimental methods employed. It is also im-
portant to examine whether a proposed ergogenic aid is safe
for a given population. Based on a thorough analysis of the
literature, it is then possible to make conclusions regarding
the ergogenic value and safety of a proposed aid [1].
In the case of creatine, it has been well established that in-
creasing dietary availability of creatine serves to increase total
creatine (TC) and phosphocreatine (PC) concentrations in the
muscle [2–9]. Moreover, that availability of creatine and PC
play a significant role in contributing to energy metabolism
particularly during intense exercise. For example, creatine
supplementation (e.g. 20 g/day 5 days) has been reported
to increase muscle TC and PC typically by 15–40% [10–12].
Theoretically, increasing the availability of PC would en-
hance cellular bioenergetics of the phosphagen system that
is involved in high-intensity exercise performance [7, 11, 13]
as well as the shuttling of high-energy phosphates between
the mitochondria and cytosol via the creatine phosphate shut-
Address for offprints: R.B. Kreider, Exercise and Sport Nutrition Laboratory, Center for Exercise, Nutrition and Preventive Health Research, Department of
Health, Human Performance and Recreation, Baylor University, P.O. Box 97313, Waco, TX 76798-7313, USA (E-mail: Richard_Kreider@baylor.edu)
90
tle that may enhance both anaerobic and aerobic capacity [14,
15].
Over the last several years, a number of reviews were pub-
lished examining the potential ergogenic value of creatine
supplementation [6, 7, 10–13, 16–19]. These reviews gener-
ally concluded that creatine supplementation serves to in-
crease muscle TC and PC content. In addition, that creatine
may improve performance primarily during short-duration,
high intensity exercise. However, there was less evidence that
creatine supplementation enhanced exercise performance
during moderate to high-intensity prolonged exercise. In
addition, there were some questions whether results observed
in laboratory settings would transfer to performance on the
field, whether performance changes observed would enhance
training adaptations, and whether long-term creatine supple-
mentation was safe. Since these reviews, a number of research
studies have been published evaluating the effects of creat-
ine supplementation on performance and training adaptations
in a variety of populations. The purpose of this paper is to
examine the most recent research that has examined the ef-
fects of short-term creatine supplementation on exercise
performance and whether creatine supplementation during
training can serve as a safe and effective ergogenic aid for
athletes.
Effects of short-term creatine
supplementation on performance
Numerous studies have examined the effects of short-term
creatine supplementation (5–7 days) on exercise perform-
ance. As described in a number of reviews, the majority of
initial studies suggested that creatine supplementation can
significantly increases strength, power, sprint performance,
and/or work performed during multiple sets of maximal ef-
fort muscle contractions [6, 7, 10–13, 16, 20]. More recent
studies have supported these initial observations. For exam-
ple, Volek et al. [21] reported that creatine supplementation
(25 g/day for 7 days) resulted in a significant increases in the
amount of work performed during five sets of bench press
and jump squats in comparison to a placebo group. Urbanski
et al. [22] reported that creatine supplementation (20 g/day
5 days) increased maximal isometric knee extension strength
and time to fatigue. Tarnopolsky et al. [23] reported creatine
supplementation (20 g/day 4 days) increased peak cycling
power, dorsi-flexion maximal voluntary contractions (MVC)
torque, and lactate in men and women with no apparent gen-
der effects. Moreover, Wiroth et al. [24] reported that creatine
supplementation (15 g/day 5 days) significantly improved
maximal power and work performed during 5 10-sec cy-
cling sprints with 60-sec rest recovery in younger and older
subjects. These findings and many others support prior re-
ports indicating that creatine supplementation can improve
performance when evaluated in controlled laboratory and
testing settings.
Some have criticized this type of early creatine research
suggesting that although performance gains have been ob-
served in controlled laboratory settings, it was less clear
whether these changes would improve athletic performance
on the field [17, 19]. Since then, a number of studies have
attempted to evaluate the effects of creatine supplementation
on field performance. These studies have generally indicated
that short-term creatine supplementation may improve high
intensity, short-duration performance in various athletic tasks.
For example, Skare et al. [25] reported that creatine sup-
plementation (20 g/day) decreased 100-m sprint times and
reduced the total time of 6 60-m sprints in a group of well-
trained adolescent competitive runners. Mujika et al. [26] re-
ported that creatine supplementation (20 g/day 6 days)
improved repeated sprint performance (6 15 m sprints with
30-sec recovery) and limited the decay in jumping ability in
17 highly trained soccer players. Similarly, Theodorou et al.
[27] reported that creatine supplementation (25 g/day 4
days) significantly improved mean interval performance
times in 22 elite swimmers. These recent preliminary find-
ings and many others suggest that creatine supplementation
can improve performance of athletes in a variety of sport-
related field activities [28–41].
Since creatine supplementation may affect shuttling of
high-energy phosphates between the cytosol and mitochon-
dria, some have suggested that creatine supplementation may
affect performance during more prolonged exercise bouts.
Recent studies also provide some support this contention. For
example, Earnest et al. [42] reported that creatine supplemen-
tation (20 g/day 4 days and 10 g/day 6 days) improved
cumulative run time to exhaustion in two runs lasting approxi-
mately 90-sec each. Smith et al. [43] reported that creatine
supplementation (20 g/day 5 days) increased work rate dur-
ing exercise bouts lasting between 90–600 sec primarily at
the shorter, more intense exercise bouts. Nelson et al. [44]
found that creatine supplementation (20 g/day 7 days) de-
creased submaximal heart rate and oxygen uptake (VO
2
),
while increasing ventilatory anaerobic threshold (VANT) and
total time to exhaustion during a maximal exercise test in 36
trained adults. Rico-Sanz et al. [45] reported that creatine
supplementation (20 g/day 5 days) increased time to ex-
haustion (29.9 ± 3.8 to 36.5 ± 5.7 min) while reducing am-
monia levels (a marker of adenine nucleotide degradation)
when cycling at 30 and 90% of maximum until exhaustion.
Finally, Preen et al. [46] evaluated the effects of ingesting
creatine (20 g/day 5 days) on resting and post-exercise TC
and PC as well as performance of an 80-min intermittent
sprint test (10 sets of 5–6 6-sec sprints with varying recov-
ery intervals). The authors reported that creatine increased
resting and post-exercise TC and PC, mean work performed,
91
and total work performed during 6 6-sec sets with 54- and
84-sec recovery. In addition, work performed during 5 6-
sec sprints with 24-sec recovery tended to be greater (p =
0.056). Collectively, these findings support contentions that
creatine supplementation may provide ergogenic benefit for
more prolonged exercise bouts involving both anaerobic and
aerobic energy systems.
However, as with previous creatine research, not all of the
recent studies have found that creatine supplementation en-
hances exercise performance. For example, McKenna et al.
[47] reported that creatine supplementation (30 g/day 5
days) did not affect 5 10-sec sprints with rest intervals of
180, 50, and 20-sec in 14 untrained subjects. Gilliam et al.
[48] found that creatine supplementation (20 g/day 5 days)
did not affect isokinetic knee extension performance during
5 30 MVC in 23 untrained subjects. Deutekom et al. [49]
reported that creatine (20 g/day 6 days) increased body
mass but did not affect muscle activation, fatigue, and/or
recovery from electrical stimulation of the quadriceps or
maximal exercise performance during sprint cycling in 23
well-trained rowers. Similarly, Edwards et al. [50] reported
that creatine (20 g/day 6 days) did not affect running fa-
tigue to exhaustion following performing 4 15-sec sprints
in 21 moderately active subjects. However, ammonia levels
were lower following creatine supplementation suggesting
that may have lessened the degree of adenine nucleotide deg-
radation and improved metabolic efficiency. In another study,
Op’t Eijnde et al. [51] reported that creatine (20 g/day 5
days) did not enhance stroke performance or 70-m agility
sprint performance in well-trained tennis players. Finally,
Finn et al. [2] reported that although creatine supplementa-
tion (20 g/day 5 days) increased TC content and 1-sec rela-
tive peak power in 16 triathletes, no significant effects were
observed in repetitive cycling sprint performance (4 20-sec
sprints with 20-sec rest recovery).
In my view, when one examines all of the available litera-
ture on creatine supplementation, the following conclusions
can be drawn. First, although some intra-subject variability
has been reported, the vast majority of studies available to
date (> 90%) indicate that short-term creatine supplementa-
tion significantly increases TC and PC content as determined
by assessing muscle biopsies, urinary whole body creatine
retention, and/or magnetic resonance spectroscopy (MRS) [4,
6, 9, 10, 12, 52, 53]. Consequently, it is clear that creatine
supplementation enhances the potential to perform high in-
tensity exercise much like carbohydrate loading enhances the
potential to perform endurance exercise to exhaustion. Over-
all, approximately 70% of short-term studies on creatine sup-
plementation report some ergogenic benefit particularly
during high- intensity, repetitive exercise [10, 12]. These ben-
efits have been primarily found when performing laboratory
tests that have good test-to-test reliability [23]. However, as
described above, a number of recent studies have indicated
that creatine supplementation can also improve performance
in field type events like running, soccer, and swimming. It is
also interesting to note that over the last few years, the per-
centage of studies reporting ergogenic benefit from creatine
supplementation has risen to 80–85% presumably due to a
greater understanding of how to properly design studies to
assess the ergogenic value of creatine supplementation. Ben-
efits have been reported in untrained, trained, and diseased
children, adolescents, adults, and elderly populations [10, 12,
54]. Studies reporting no significant effects of creatine sup-
plementation have generally observed small but non-signifi-
cant improvements in performance (i.e. 1–7%). It should be
noted that no study has reported a statistically significant
ergolytic (negative) effect from creatine supplementation.
Studies that have reported no significant benefit of creatine
supplementation often have low statistical power, have evalu-
ated performance tests with large test-to-test reliability, and/
or have not incorporated appropriate experimental controls.
Consequently, it is my view that the preponderance of evi-
dence indicates that short-term creatine supplementation
enhances performance in a variety of laboratory and on-field
exercise tasks.
Effects of creatine supplementation on
training adaptations
Theoretically, increasing the ability to perform high-intensity
exercise may lead to greater training adaptations over time.
Consequently, a number of studies have evaluated the effects
of creatine supplementation on training adaptations. For ex-
ample, Vandenberghe et al. [55] reported that in comparison
to a placebo group, creatine supplementation (20 g/day 4
days; 5 g/day 65 days) during 10-weeks of training in
women increased TC and PC, maximal strength (20–25%),
maximal intermittent exercise capacity of the arm flexors
(10–25%), and fat free mass (FFM) by 60%. In addition, the
researchers reported that creatine supplementation during 10-
weeks of detraining helped maintain training adaptations to
a greater degree. Kelly et al. [56] reported that 26-days of
creatine supplementation (20 g/day 4 days; 5 g/day 22
days) significantly increased body mass, FFM, three repeti-
tion maximum (RM) on the bench press, and the number of
repetitions performed in the bench press over a series of sets
in 18 power lifters. Noonan et al. [57] reported that creatine
supplementation (20 g/day 5 days; 100 or 300 mg/kg/day
of FFM 51 days) in conjunction with resistance and speed/
agility training significantly improved 40-yard dash time and
bench press strength in 39 college athletes. Kreider et al. [58]
reported that creatine supplementation (15.75 g/day 28
days) during off-season college football training promoted
greater gains in FFM and repetitive sprint performance in
92
comparison to subjects ingesting a placebo. Likewise, Stone
et al. [38] reported that 5-weeks of creatine ingestion (~ 10
or 20 g/day with and without pyruvate) promoted signifi-
cantly greater increases in body mass, FFM, 1 RM bench
press, combined 1 RM squat and bench press, vertical jump
power output, and peak rate of force development during in-
season training in 42 Division IAA college football players.
Volek et al. [8] reported that 12-weeks of creatine supple-
mentation (25 g/day 7 days; 5 g/day 77 days) during
periodized resistance training increased muscle TC and PC,
FFM, type I, IIa, and IIb muscle fiber diameter, bench press
and squat 1 RM, and lifting volume (weeks 5–8) in 19 resist-
ance trained athletes. Peters et al. [59] reported that creatine
monohydrate and creatine phosphate supplementation (20 g/
day 3 days; 10 g/day 39 days) during training significantly
increased body mass, FFM, and 1-RM bench press in 35
resistance-trained males. Kirksey et al. [60] found that creat-
ine supplementation (0.3 g/kg/day 42 days) during off-sea-
son training promoted greater gains in vertical jump height
and power, sprint cycling performance, and FFM in 36 Di-
vision IAA male and female track and field athletes. Pearson
et al. [61] reported that creatine supplementation (5 g/day
10 weeks) during resistance training promoted greater gains
in strength, power, and body mass with no change in percent
body fat in 16 Division IA college football players during
summer conditioning. Moreover, Jones et al. [32] reported
that creatine (20 g/day 5 days; 5 g/day 10 weeks) pro-
moted greater gains in sprint performance (5 15-sec with
15-sec recovery) and average on-ice sprint performance (6
80-m sprints) in 16 elite ice-hockey players. Becque et al.
[62] found that creatine supplementation (20 g/day 5 days;
2 g/day 37 days) during strength training led to greater gains
in arm flexor muscular strength, upper arm muscle area, and
FFM than strength training alone in 23 resistance trained
athletes.
Additionally, Burke et al. [63] reported that low dose crea-
tine supplementation (7.7 g/day 21 days) during training
promoted greater gains in total work until fatigue, peak force,
peak power, and fatigue resistance in 41 college athletes.
Brenner et al. [64] reported that creatine supplementation (20
g/day 7 days; 2 g/day 28 days) significantly improved
upper-body strength gain and decreased percent body fat in
16 female college lacrosse players during pre-season train-
ing. Larson-Meyer et al. [34] reported that creatine supple-
mentation (15 g/day 7 days; 5 g/day 84 days) promoted
greater gains in bench press and squat maximal strength with
no differences in FFM during off-season training in 14 fe-
male college soccer players. Interestingly, Jowko et al. [65]
recently reported that creatine supplementation (20 g/day
7 days; 10 g/day 14 days) significantly increased FFM and
cumulative strength gains during training in 40 subjects ini-
tiating training. Additional gains were observed when 3 g/
day of calcium beta-hydroxy-beta-methylbutyrate (HMB)
was co-ingested with creatine.
In a very interesting experimental design, Stevenson et al.
[66] evaluated the effects of creatine supplementation (20 g/
day 7 days; 5 g/day 49 days) on volitional and electrical
stimulated training in 18 resistance trained subjects. Subjects
participated in a traditional resistance training program as
well as an electromyostimulation (EMS) training program
(i.e. 3–5 sets 10 eccentric and concentric contractions per-
formed twice per week on one leg). The researchers found
that creatine supplementation did not affect mechanical or
hypertrophic responses to the EMS training. However, mag-
netic resonance imaging (MRI) determined cross-sectional
area of the traditionally trained but non-electrically stimulated
leg was significantly greater in the creatine group. Finally,
Willougby et al. [9] recently reported that in comparison to
controls, creatine supplementation (6 g/day 12 weeks)
during resistance training (6–8 repetitions at 85–90%; 3
weeks) significantly increased total body mass, FFM, and
thigh volume, 1 RM strength, myofibrillar protein content,
Type I, IIa, and IIx myosin heavy chain (MHC) mRNA ex-
pression, and MHC protein expression. This study provides
strong evidence that creatine supplementation during in-
tense resistance training leads to greater gains in strength
and muscle mass.
In my view, after evaluating the available data on the ef-
fects of creatine supplementation on training adaptations, the
following conclusions can be drawn. Studies that evaluated
the effects of creatine supplementation on muscle TC and PC
stores described in the present review as well as the majority
of previous studies reviewed elsewhere indicate that creat-
ine loading increases TC and PC. Creatine supplementation
during training is typically associated with a 0.5–2 kg greater
increase in body mass and/or FFM. Although it has been
hypothesized that the initial weight gain associated with crea-
tine supplementation may be due to fluid retention, a number
of studies indicate that long-term creatine supplementation
increases FFM and/or muscle fiber diameter with no dis-
proportional increase in total body water. These findings
suggest that the weight gain observed during training appears
to be muscle mass. About 90% of long-term training studies
report some ergogenic benefit with gains typically 10–100%
greater than controls. Improvements have been reported in
untrained and trained adolescents, adults, and elderly pop-
ulations. No clinically significant side effects have been re-
ported in these studies even though many of them involved
intense training in a variety of exercise conditions. These
findings suggest that creatine supplementation during train-
ing serves to enhance training adaptations. Moreover, these
beneficial changes may offer some therapeutic benefit for a
variety of pathologies involving muscle weakness and/or
muscle wasting.
93
Conclusions
Creatine appears to be an effective and safe nutritional ergo-
genic aid to improve high intensity exercise performance and/
or training adaptations in a variety of sports. Although more
research on the potential ergogenic value of creatine for spe-
cific athletic populations may be useful, it is my view that
the most promising area of future research will be to examine
potential therapeutic benefit for various clinical populations.
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