1. Running Head: EFFECTS OF CREATINE
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Effects of Creatine Monohydrate Supplementation
Combined With Resistance Training on Muscular
Strength and Endurance.
Matthew R. Summers-Johnson
Humboldt State University

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Abstract
Effects of creatine monohydrate supplementation combined with resistance training on muscular
strength and endurance. The purpose of this investigation was to determine if creatine
monohydrate supplementation increases an individual’s muscular strength by testing one rep
max on bench press, leg press, and arm flexor. Studies include Herda, et al., 2009; Kreider, et
al., 1998 & Becque, et al., 2000. Minimum one year training experience required for
participants, could not have taken any supplements thirty days before experiment. Double blind,
placebo controlled design. Placebo group consumed 4g of cellulose per day and the creatine
group consumed 5g of creatine monohydrate per day. Testing took place pre- and post-
supplementation separated by and average of thirty days. In each study, individuals showed a
significant difference in one rep max for bench press, leg press, and arm flexor (p<0.001).
Placebo group demonstrated no significant difference in muscular strength from pre- to post-
supplementation. Creatine supplementation combined with resistance training, lead to greater
increases in bench press, leg press, and arm flexor one rep max from pre- to post-
supplementation.
Literature Review
Creatine monohydrate has been the most studied supplement since the early 1990’s on
the effect it has on an individual’s muscular strength (Gutierrez-Sancho, Moncada-Jimenez,
Salazar-Rojas, & Robinson, 2006). According to The Journal of Strength and Conditioning
Research (2010), supplementation of creatine monohydrate has also been the most common
supplement individuals consume. In a study of 229 physically active men, it was reported that
69% of the subjects consumed a mean of 12.25 grams of creatine on a daily basis (Volek, et al.,

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1999). Creatine is primarily found in meat and fish but can also be consumed via
supplementation. It has been shown that creatine users show an increase in muscular strength
and endurance when combined with a resistance-training program (Gouttebarge, Inklaar, &
Hautier, 2012). It is known that consuming creatine monohydrate increases phosphocreatine
levels in the skeletal muscle, therefore increasing the rate of adenosine triphosphate (ATP),
which plays an important role in muscular contraction (Becque, Lochmann, & Melrose, 2005).
Since the availability of phosphocreatine stored in the skeletal muscle influences how much
energy is produced, it has been hypothesized that increasing the amount of creatine content in the
body may increase the availability of phosphocreatine and permit for an accelerated resynthesis
of ATP during short, high intensity exercise (Demant & Rhodes, 2009). It has also been
hypothesized that individuals who consume creatine monohydrate supplementation will improve
their muscular strength and endurance when combined with a resistance-training program. In the
present paper, the effects of creatine monohydrate supplementation on muscular strength and
endurance are investigated. The following three literature reviews attempt to support the
previous hypotheses. The purpose of this paper was to investigate and determine if the effects of
creatine monohydrate supplementation improves an individuals muscular strength and
endurance. Google scholar was the primary source for information used for this literature
review. I searched from year 2000 to present for literature related to creatine, muscular strength,
muscular endurance, and effects of creatine. Additional literature was acquired through cross-
referencing references of articles obtained through the searches.
In a research article by Herda et al. (2009), muscular strength and endurance tests were
performed to support their hypothesis. They hypothesized that creatine supplementation greatly
increases an individuals muscular strength. Fifty-eight healthy men (mean +/- SD: age, 21 +/- 2

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years; height, 176 +/- 6 cm, body mass, 75 +/- 14 kg were used in this study. Subjects had to
have a minimum of one-year weight training experience. This study was a double-blind placebo
controlled experiment. Subjects were tested on muscular strength and endurance by performing
bench press and leg press. Bench press was conducted on a standard free-weight bench with an
Olympic bar. Subjects were instructed to lower the bar to their chest and then press the bar up
till forearms were fully extended. Leg press was conducted on a hip sled device set at a 45-
degree angle. Subjects were instructed to lower the platform until their knees were at 90 degrees
of flexion then fully extend their legs. Both pre- and post-tests were conducted separated by 30
days. In order to test for muscular strength, a one rep maximum was determined by
progressively loading weight until the subject could not complete the lift. To test for muscular
endurance, subjects took 80% of their one rep maximum and had to complete as many repetitions
as possible until failure. (Kreider, et al., 1998)
The group who consumed the creatine monohydrate supplementation showed a
significant difference in bench press from pre- to post-supplementation. During pre-
supplementation, the mean for one rep max on bench press was 164.6 kg and the post-
supplementation one-rep max for bench press was increased to 177.7 kg. Thus, indicating a
significant increased on muscular strength (p<0.001) (Herda, et al., 2009). During pre-
supplementation testing for leg press the mean for one rep max was 524.6 kg then increased to
576.9 kg, which was also a significant difference in strength (p<0.001) (Herda, et al., 2009). The
placebo group remained unchanged and showed no significant difference in muscular strength
pre- to post-supplementation. In a study that Kreider, et al. (1998) conducted, similar findings
related to improved muscular strength after creatine supplementation were also found.
The creatine monohydrate group also showed a significant difference in muscular

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endurance (p<0.001). Pre-supplementation repetitions performed on bench increased from a
mean of 9.5 to 12.1 repetitions. Repetitions performed on leg press increased from 13.8 to 18.3
pre- to post-supplementation, which is also a significant difference in repetitions (p<0.001)
(Herda, et al., 2009). The placebo group also showed a significant difference in repetitions
performed pre- to post-supplementation. A similar study that was conducted by Gouttebarge, et
al., 2012 found that creatine supplementation increased muscular endurance the same amount as
the placebo group.
The findings from this study exhibited significant increases from pre- to post-
supplementation for bench press and leg press one rep maximum only for the creatine
monohydrate group. Additionally, these findings showed significant increases from pre- to post-
supplementation for muscular endurance for both the creatine monohydrate group and the
placebo group. The findings from this study support the hypothesis that creatine monohydrate
supplementation combined with a resistance training program increases an individual’s muscular
strength and endurance. Additionally, muscular endurance was increased for both placebo and
creatine group, therefore creatine supplementation increases your muscular endurance just as
effective as consuming no creatine supplementation.
In a research article by Kreider, et al. (1998), one main question was addressed for
guiding this study. Does creatine supplementation increase an individual’s overall lifting volume
after a resistance-training program? The focus of this study was to determine if creatine
supplementation significantly increases an individual’s overall lifting volume. Lifting volume
was determined by adding the results from each assessment together. Twenty-eight NCAA
division 1A football players who were undergoing off-season training were used in this study.
The average age, weight, and height of these football players were 19.9 years, 97.2 kg, and 183

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cm respectively. Half of the subjects consumed placebo, and the other half consumed creatine
monohydrate supplementation. Subjects were instructed to consume either the placebo or
creatine monohydrate supplement immediately after their workout everyday. Pre-
supplementation assessments included bench press, back squat, and power-cleans. Subjects who
consumed the creatine monohydrate supplementation increased from 502.2 kg to 708.1 kg in
total lifting volume from pre- to post-supplementation, which is a significant increase (p<0.005)
(Krieder, et al., 1998). Subjects who were given the placebo showed no significant increase in
total lifting volume.
These findings support the hypothesis that creatine supplementation combined with
resistance strength and conditioning program increases and individuals total lifting volume from
pre- to post-supplementation. The findings from these studies also support the hypothesis that
increasing the total amount of creatine levels in your body allows your skeletal muscle to
produce more ATP thus allowing faster muscle contraction. Similarly, Herda, et al. (2009) also
reported that creatine supplementation significantly increases total lifting volume after a
resistance training program.
In a research conducted by Becque, et al. (2000), the main purpose of the study was to
investigate the effect of creatine supplementation on arm flexor strength. Twenty-three healthy
males with the mean age of 21.5 years were used in this study in a double blind placebo
controlled design. The strength test was conducted one week prior to supplementation of the
creatine and then after a six-week resistance-training program. To determine the strength of the
arm flexor, subjects performed a one-rep max with a wide-grip lifting bar on a preacher curl
bench. Weight was progressively added to the bar until the subject could no longer complete the
task. The one rep max for the creatine group significantly increased from pre- to post-

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supplementation after a resistance-training program (p<0.001) (Becque, Lochmann, & Melrose,
2005). The placebo group showed no significant increase from pre- to post-supplementation.
The discoveries from this study support that creatine supplementation significantly increases arm
flexor one rep max from pre- to post-supplementation.
One of the most major findings in these studies is that creatine supplementation increased
muscular strength when combined with a resistance-training program. Findings from these
studies also indicate that creatine supplementation produces the same results as the placebo
group for muscular endurance. The findings from the three research studies suggest that creatine
monohydrate supplementation should be combined with a resistance-training program in order
increase an individual’s muscular strength and endurance (Herda, et al., 2009; Kreider, et al.,
1998; Becque, et al., 2000). In Herda, et al’s. (2009) study, subjects showed a significant
increase in muscular strength whereas the placebo group remained unchanged and showed no
significant increase in strength. A similar study done by Percario, et al. (2012) concluded that
creatine supplementation combined with a resistance-training program resulted in a significant
increase in muscular strength and endurance. Each study also suggests that you see a greater
increase in muscular strength in the creatine monohydrate group, not in the placebo group. Even
though muscular endurance was significantly increased in the creatine group, a significant
increase in muscular endurance for the placebo group was reported as well. Studies suggest that
creatine monohydrate supplementation has the same effect on muscular endurance as not
consuming creatine monohydrate supplementation (Earnest, Snell, Rodriguez, Almada, &
Mitchell, 2000). Since muscular strength is determined by a one-rep max, it is considered a
short, high intensity exercise. Creatine plays an important role in the production of ATP for
short, high intensity exercise, which in essence is considered strength. Since muscular endurance

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is longer lasting that muscular strength, creatine does not play an important role in the production
of ATP (Rawson, Gunn, & Clarkson, 2001).
Each of the three studies used a double blind placebo controlled design, with one group
taking placebo and the other group consuming creatine monohydrate supplementation.
Additionally, the typical assessments for muscular strength and endurance are bench press and
leg press. In order to ensure the assessments were reliable, each study reported test-retest for the
bench press, leg press, and arm flexor one rep max. The correlation coefficients for the bench
press, leg press, and arm flexor one rep max were 0.98, 0.98, 0.95 respectively along with no
reports of a significant differences between the means of one rep max scores for test versus retest
(Haykowsky, Quinney, Rosalind, & Thompson, 2007).
Additional research needs to be done on how creatine monohydrate supplementation
works, research demonstrates that creatine supplementation works but does not demonstrate how
creatine works and how its absorbed in the body. Secondly, future research should evaluate
creatine supplementation compared with training volume and training intensity. There have been
very few studies on the use of creatine for a longer period of time; future research needs to focus
on the potential health problems creatine supplementation can cause.
Based on research, creatine has been the most studied ergogenic aide since the early
1990’s. Creatine monohydrate supplements are the most common used supplements among
physically active individuals among the United States. Studies demonstrate that the higher levels
of phosphocreatine in your skeletal muscle, the better ability you have to produce ATP during
short, high intensity exercises. It has been hypothesized for several years that creatine
monohydrate supplementation increases an individual’s muscular strength and endurance when
combined with a resistance-training program.

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