Posted: June 19th, 2022

I need help with a homework problem

INSTRUCTIONS ATTACHED BELOW.
sciencekinesiology
ATTACHED FILE(S)
KINS 4137
Effect of Ergogenic Aids on
Performance/Exercise/Physical Activity/Recovery Assignment
Guidelines for your Journal Article Summary
Below are guidelines for selecting your Journal Article and writing the summary:
1. Find 1 (one) original, peer-reviewed journal article that relates to the topic/question.Here are some guidelines to decide if an article meets the requirement:
A. Published in a common refereed (peer-reviewed) journal.Here are some examples:
· Medicine and Science in Sports and Exercise
· Journal of Strength and Conditioning Research
· Journal of Physical Activity and Health
· Research Quarterly for Exercise and Sport
· Journal of Applied Physiology
· Journal of Physiology
B. The study must have a set number of participants with descriptions included in the study and NOT a review article!
C. At a minimum, the article must have an Introduction, Methods, Results, and Discussion sections.
D. Articles from newspapers, health magazines, and the internet are NOT typically acceptable.
2. A type-written response (in your own words) to the following is required:
A. Describe the research question and why the question is important.
B. Describe the methodological approach.Basically, describe how the researchers executed the study.Include a description of the population they used.
C. Discuss the findings of the research and any practical applications.
D. Discuss the strengths and limitations of the research.
3. Students must include the entire journal article with the assignment.Simply providing the abstract is NOT acceptable.
1
DUE: 6/14 (1 PAGE)
You have one article attached for a reference. You need to find one more reference for the paper. PLEASE follow his instructions and answer the questions he provided in the instructions.
Effect of Creatine and Weight Training on
Muscle Creatine and Performance
in Vegetarians
DARREN G. BURKE1, PHILIP D. CHILIBECK2, GIANNI PARISE3, DARREN G. CANDOW2,
DOUGLAS MAHONEY4, and MARK TARNOPOLSKY4
1Department of Human Kinetics, St. Francis Xavier University, Antigonish, Nova Scotia, CANADA; 2College of
Kinesiology, University of Saskatchewan, Saskatoon, Saskatchewan, CANADA; and 3Department of Kinesiology and
4Department of Medicine, McMaster University, Hamilton, Ontario, CANADA
ABSTRACT
BURKE, D. G., P. D. CHILIBECK, G. PARISE, D. G. CANDOW, D. MAHONEY, and M. TARNOPOLSKY. Effect of Creatine and
Weight Training on Muscle Creatine and Performance in Vegetarians. Med. Sci. Sports Exerc., Vol. 35, No. 11, pp. 1946 –1955, 2003.
Purpose: To compare the change in muscle creatine, fiber morphology, body composition, hydration status, and exercise performance
between vegetarians and nonvegetarians with 8 wk of creatine supplementation and resistance training. Methods: Eighteen VG and
24 NV subjects (19 –55 yr) were randomly assigned (double blind) to four groups: VG � creatine (VGCr, N � 10), VG � placebo
(VGPl, N � 8), NV � creatine (NVCr, N � 12), and NV � placebo (NVPl, N � 12). Before and at the end of the study, muscle biopsies
were taken from the vastus lateralis m, body composition was assessed by DXA, and strength was assessed using 1-RM bench press
and leg press. Subjects participated in the same 8-wk resistance-training program. Creatine dosage was based on lean tissue mass (0.25
g·kg�1 LTM·d�1 � 7 d; 0.0625 g·kg�1 LTM·d�1 � 49 d). Results: Biopsy samples indicated that total creatine (TCr � free Cr �
PCr) was significantly lower in VG compared with NV at baseline (VG � 117 mmol·kg�1; NV � 130 mmol·kg�1; P � 0.05). For
Cr subjects, there was a greater increase in PCr, TCr, bench-press strength, isokinetic work, Type II fiber area, and whole-body lean
tissue compared with subjects on placebo (P � 0.05). Vegetarians who took Cr had a greater increase in TCr, PCr, lean tissue, and
total work performance than nonvegetarians who took Cr (P � 0.05). The change in muscle TCr was significantly correlated with initial
muscle TCr, and the change in lean tissue mass and exercise performance. These findings confirm an ergogenic effect of Cr during
resistance training and suggest that subjects with initially low levels of intramuscular Cr (vegetarians) are more responsive to
supplementation. Key Words: LEAN TISSUE MASS, DUAL-ENERGY X-RAY ABSORPTIOMETRY, MUSCLE FIBER AREA,
BIOELECTRICAL IMPEDANCE
I
ngestion of creatine monohydrate (CM) has been shown
to enhance adaptations to resistance training by aug-
menting changes in lean tissue mass, muscle fiber area,
strength, and resistance to fatigue (4,17,21,30 –32). These
improved exercise adaptations with creatine supplementa-
tion may be due to an increased anaerobic work capacity
resulting from an increased rate of phosphocreatine resyn-
thesis (14) or buffered energy depletion during exercise
bouts (30), allowing one to train at higher volumes
(6,29,32).
Creatine supplementation has been found to result in
significant increases in muscle creatine (Cr), phosphocre-
atine (PCr), and total creatine (TCr � free Cr � PCr)
concentrations (13,16). However, large interindividual dif-
ferences in baseline resting TCr content and responsiveness
to CM supplementation are evident (24,31). Because some
individuals do not experience any significant change in
cellular creatine or phosphocreatine or improved exercise
performance with short-term creatine ingestion, it has been
suggested that there is a range of individual responsiveness
to creatine supplementation (14,18). One feature common to
most studies that directly measure intramuscular creatine
and phosphocreatine is that those subjects with the lowest
initial total creatine experience the greatest increase after
creatine supplementation (5,14,16,18). After 5–7 d of crea-
tine loading, most individuals experience an increase of
20 –25 mmol·kg�1 dry mass (dm) in total creatine of which
about 30% is in the form of phosphocreatine (16). A few
vegetarian subjects included within mainly omnivorous
study populations have demonstrated the greatest increase in
muscle total creatine concentration after acute loading
(14,16), and a recent study demonstrated that improvements
in anaerobic exercise performance were greater for vegetar-
ians than nonvegetarians who supplemented with creatine
(26). Lukaszuk et al. (23) demonstrated that 3 wk of a
lacto-ovo-vegetarian diet reduced muscle creatine content in
omnivorous subjects, which when followed up with creatine
Address for correspondence: Darren G. Burke, Ph.D., Department of Hu-
man Kinetics, St. Francis Xavier University, P.O. Box 5000, Antigonish,
Nova Scotia, B2G 2W5, Canada; E-mail: dburke@stfx.ca.
Submitted for publication February 2003.
Accepted for publication June 2003.
0195-9131/03/3511-1946
MEDICINE & SCIENCE IN SPORTS & EXERCISE®
Copyright © 2003 by the American College of Sports Medicine
DOI: 10.1249/01.MSS.0000093614.17517.79
1946
supplementation resulted in greater, though nonsignificant,
increases in total creatine as compared with placebo.
The purpose of this study was to compare the change in
muscle TCr content, fiber morphology, body composition,
hydration status, and exercise performance between vege-
tarians and nonvegetarians with 8 wk of creatine supple-
mentation and resistance training. It was hypothesized that
vegetarians would have lower baseline intramuscular crea-
tine and phosphocreatine concentrations compared with
nonvegetarians. As well, it was hypothesized that the veg-
etarian subjects would experience the greatest change in
total creatine, muscle fiber area, body composition, and
exercise performance during creatine supplementation as
compared with placebo.
METHODS
Subjects and study design. Forty-nine subjects (19
vegetarian, 30 nonvegetarian) volunteered for the study and
had a muscle biopsy taken from the right vastus lateralis
muscle. Forty-two of the original subjects (18 vegetarians,
24 nonvegetarians) agreed to take part in an 8-wk resistance-
training and CM supplementation study and were randomly
assigned (double-blind) to receive creatine or placebo in
stratified blocks based on whether they were vegetarian (3
vegan, 15 lacto-ovo) or nonvegetarian and gender. Subjects
were recreational athletes, and all participated in a minimum
of 20 –30 min of exercise (walking, jogging, swimming,
cycling, and/or weight lifting) 3–5� wk�1. All subjects had
some resistance training experience (� 1 yr but � 5 yr), but
no subject performed only weight-lifting exercise as his or
her only activity. No subject had supplemented with creatine
within the previous 6 months, which is longer than the time
it takes muscle creatine levels to return to baseline after
creatine supplementation (11). Subjects were self-described
as vegetarian or nonvegetarian; however, 3-d food records
were completed and used for confirmation. Subjects were
considered vegetarian whether they were lacto-ovo or vegan
and were required to be vegetarian for a minimum of 3 yr.
All subjects were measured at the beginning and end of the
training and supplementation period for muscle fiber mor-
phology and metabolite concentrations, body composition,
hydration status (Bioelectrical Impedance Analysis), and
exercise performance. This study was approved by the uni-
versity’s ethics committee for biomedical research involv-
ing human subjects, and written informed consent was ob-
tained from each subject. Subject characteristics (mean �
SE) are presented in Table 1.
Supplementation. The supplementation protocol for
this study was based on the results obtained from a prelim-
inary study that indicated a creatine dose of 0.25 g·kg�1 of
lean tissue mass resulted in minimal excretion of creatine in
the urine during the acute loading phase (unpublished find-
ings). Because there is about a 4:1 ratio between the amount
typically consumed during loading compared with mainte-
nance (14,18,30), an individualized maintenance dose of
0.0625 g·kg�1 lean tissue mass was selected. Therefore,
subjects in the creatine group consumed 0.25 g of creatine
per kg lean tissue mass (LTM) per day of creatine (0.0625
g·kg�1 LTM, 4� d�1) for 7 d as a loading phase. This was
followed by 0.0625 g of creatine per kg LTM per day
(0.0625 g·kg�1 LTM, 1� d�1) for an additional 49 d. The
average absolute daily dose of creatine for subjects during
loading and maintenance was 16.8 � 0.7 g·d�1 and 4.2 �
0.2 g·d�1, respectively. Subjects in the placebo group con-
sumed the same amount of supplement as the creatine
group; however, the supplement only included maltodextrin.
Subjects mixed their supplement with ~300 mL of a fruit
drink each time it was consumed. Fruit juice was used
because it has been found that carbohydrate increases cre-
atine uptake into skeletal muscle (13). The creatine and
placebo supplements were identical in taste, texture, and
appearance. All supplementation was double blind, in that
an individual who was not involved in any other aspect of
the study prepared the creatine and placebo supplements and
did not reveal the code for subjects on creatine and placebo
until the completion of the study. Subjects were given
enough of their respective supplement to last for 5 d, after
which they had to return their empty packages to receive an
additional 5-d supply.
Body weight, body composition, and hydration sta-
tus. Body weight was measured before the study and again
at the end of the study on a scale accurate to the nearest
0.1 kg (Toledo Scales, Toledo, OH). Subjects were weighed
in a T-shirt, shorts, and socks and at the same approximate
time of day. The scale was calibrated at the beginning and
end of the study to ensure accuracy in body weight mea-
surements. Before the study and again at the end, subjects
were measured for body composition using dual energy
x-ray absorptiometry (DXA) to determine lean tissue mass
and percent body fat. Whole body scans were performed on
a Hologic QDR-2000 (Hologic, Waltham, MA) in array
mode. All scans and regional assessments were made by the
same technician using system software version 7.1. The
coefficient of variation for the DXA measurement of lean
TABLE 1. Subject characteristics for those vegetarian and nonvegetarian subjects who participated in 8 wk of resistance training and supplemented with either creatine
or placebo.
Group N � M/F Age RT Exp Height (cm) Weight (kg) %Fat
VGCr 5/5 31 � 2.2 1.8 � 0.4 169.9 � 2.8 67.5 � 2.5 19.5 � 2.6
VGPl 3/5 34 � 4.2 2.0 � 0.6 168.1 � 2.9 66.7 � 4.3 20.7 � 2.2
NVCr 7/5 33 � 2.6 1.4 � 0.3 170.6 � 2.5 69.6 � 3.9 21.1 � 2.0
NVPl 5/7 32 � 2.4 1.9 � 0.5 172.3 � 2.6 71.7 � 3.1 22.9 � 2.6
VGCr, vegetarian creatine; VGPl, vegetarian placebo; NVCr, nonvegetarian creatine; NVPl, nonvegetarian placebo; vegetarian, lacto-ovo or vegan; N � M/F, number of male/female; RT
Exp, years of resistance training experience; N � 42 subjects; values are mean � standard error.
CREATINE AND VEGETARIANS Medicine & Science in Sports & Exercise� 1947
tissue mass using this unit was determined by the measure-
ments of 12 subjects twice and found to be 0.54%.
For hydration status, total body water, extracellular water,
and by deduction, intracellular water content (total body
water minus extracellular water) was measured before the
study and again at the end of the study using a dual fre-
quency (5 kHz and 200 kHz) bioelectric impedance analyzer
(BodyStat, Tampa, FL). Two surface electrodes were placed
on the right foot and the right hand, and connected through
four separate 3-m leads to the base of the impedance unit.
This unit was calibrated at the beginning of each testing
period. Coefficients of variation using this device were
determined by measuring 10 subjects twice in one day and
found to be 0.22% for total body water and 0.25% for
extracellular water.
Muscle biopsy and metabolite assays. Percutane-
ous needle biopsies were obtained from the distal third of
the vastus lateralis muscle using a 5-mm Stille needle (Mi-
crins, New York, NY) under local anesthetic with 1% lido-
caine (Smith-Kline Beecham, Toronto, ON) and with suc-
tion applied via a 60-cc syringe (10). Pre- and postbiopsies
were taken from the lateral portion of the same leg, with the
first sample taken 15 cm proximal to the knee joint and the
second sample 3–5 cm proximal to the first incision (15).
The sample was obtained when the needle was inserted
approximately 1 cm below the fascial resistance to control
for possible variations in fiber type distributions from su-
perficial to deep (28). The same physician performed all
biopsies. Immediately after the muscle sample was excised,
it was mounted onto cork, embedded with optimum cutting
temperature (OCT) medium, and exposed to the room air for
60 s. The mounted sample was then submerged for 30 – 40
s in isopentane cooled by liquid nitrogen. Samples were then
quickly wrapped (~1–3 s) in aluminum foil and stored in
liquid nitrogen until being moved to �80°C refrigeration.
In lots of four at a time, samples were removed from
ultra-low refrigeration and placed inside a microtome cut-
ting chamber and warmed to �20°C for about 5 min. Four,
7-�m cross-section cuts were taken from each mounted
muscle sample and prepared for their respective staining
treatment (described in detail later). The remaining tissue
was immediately dissected free of the cork and OCT, placed
into plastic vials, and frozen in liquid nitrogen. These sam-
ples were then lyophilized overnight and stored at �80°C
until subsequent analysis.
Freeze-dried muscle samples were powdered in a con-
trolled environment, with 15–30% relative humidity to pre-
vent rehydration of the muscle sample. Powdering was done
manually using 7-cm curved tissue forceps, and all connec-
tive tissue and fat was dissected away from the powdered
muscle. After powdering, 5–10 mg of tissue was weighed
and placed into a 2-mL vial (VWR Canlab, Edmonton, AB)
for extraction with perchloric acid.
Muscle metabolites were extracted with 0.5-M perchloric
acid containing 1 mM of EDTA at a ratio of 800 �L to every
10 mg of powder for 15 min on ice, while periodically
vortexing. Samples were then centrifuged in a precooled
centrifuge (4°C) for 5 min at 15,000 rpm. The supernatant
was weighed into another 2-mL vial and neutralized with
2.2-M KHCO3 added at a volume equal to one-fifth the mass
of the extract supernatant. The subsequent metabolite assays
were performed using methods previously described
(15,25). Neutralized extracts were prepared for spectropho-
tometric determination of ATP, phosphocreatine, and free
creatine using a Hitachi F2500 spectrofluorometer
(Chromabec, Montreal, PQ) at an excitation wavelength of
340 nm and an emission wavelength of 445 nm. Coefficients
of variation for the ATP, phosphocreatine, and free creatine
assays using this machine were determined using the re-
peated measurement of 100 samples and found to be 2.05%,
3.78%, and 3.08%, respectively.
Histochemical staining and image analysis. Serial
muscle tissue cross-sections from the same individual pre- and
posttraining were placed together in the same preincubation
mediums and stained for myosin ATPase at pH 4.2, 4.6, and
pH 9.4 (2). After staining, sections were mounted and the area
positively stained was analyzed using Image Pro Plus Version
4.0 software (Media Cybernetics, Silver Spring, MD). First,
each slide was viewed under 200� magnification (Olympus
BX60, Tokyo, Japan). Then, three to four pictures were taken
per slide (Spot Diagnostic Instruments Inc, Sterling Heights,
MI) and immediately saved as a JPEG file into a Dell Dimen-
sion XPS R450 (Dell Computer Company, Austin, TX). Ap-
proximately 100 –150 muscle fibers were used for determina-
tion of mean fiber area.
Urine collection. Twenty-four-hour urine was col-
lected in 4-L plastic containers (Fisher Scientific, Edmon-
ton, AB) five times during the study: one day before sup-
plementation, the first day of supplementation, the third day
of supplementation, the fifth day of supplementation, and
after the last day of supplementation. Total 24-h urine out-
put volume was recorded, and then an aliquot was removed
and stored at �20°C until the end of the study, when all
samples were analyzed together.
Creatine and creatinine were determined using the Jaffe
method (19), which results in the formation of an orange-red
alkaline creatinine picrate complex that can be measured for
optical density spectrophotometrically. The following pro-
cedure as adapted from Jaffe (19) was performed for each
urine sample: 100 �L of urine was mixed with 600 �L of
water, 100 �L of 10% sodium tungstate, and 200 �L of
0.67-N sulfuric acid. This mixture was vortexed for 10 s and
centrifuged for 10 min. After centrifugation, a 300-�L ali-
quot was pipetted off and added to 2700 mL of water. In an
ice bath, 1 mL of 0.04-M picric acid followed by 1 mL of
0.75-N sodium hydroxide was added to this solution. This
solution was then vortexed for 10 s and placed in a 20°C
water bath for 20 min. Samples were read in a Hitachi
U2010 UV-vis spectrophotometer (Chromabec) at 520 nm
immediately upon removal from the water bath, which pro-
vided a measure of creatinine concentration. To determine
urinary creatine, the same steps were followed up to and
including the addition of picric acid; however, after the acid
was added, the solution was then heated at 100°C for 1 h.
After heating, the sample was removed and cooled in ice for
5 min. Then 1 mL of 0.75-N sodium hydroxide was added.
1948 Official Journal of the American College of Sports Medicine http://www.acsm-msse.org
The solution was then vortexed for 10 s and placed into a 20°C
water bath for 20 min. The sample was again read in the same
spectrophotometer at the same setting immediately upon re-
moval from the water bath. Heating in acid for 1 h converted
all creatine to creatinine, and the second optical density mea-
sure subtracted from the first optical density measure of cre-
atinine for the same sample gave the amount of creatine
present. Samples were prepared in duplicate for both creatinine
and creatine measurements. The coefficient of variation be-
tween duplicate samples for creatinine (and indirectly creatine)
determination using this machine was 6.82%. Because the
purpose of the urine collection was to monitor changes in
creatine and creatinine excretion associated with creatine sup-
plementation, only the urine from those subjects who supple-
mented with creatine were analyzed.
Muscle performance measures. Muscular strength
and total work performed during 50 isokinetic knee extension
and flexion repetitions at 180°·s�1 were measured at the be-
ginning of the study and again after 8 wk of supplementation
and training. Strength was assessed by 1-RM for bench press
and leg press. Before the leg press, a warm-up consisted of the
modified hurdler’s stretch held twice on each leg for 20 s
followed by 10 repetitions of leg press (Hammer Strength, Life
Fitness, Franklin Park, IL) using a weight determined by each
subject as an appropriate warm-up weight. Before the bench
press 1-RM test, a warm-up consisted of 20 push-ups; two
static stretches of the chest musculature against a wall, held for
8 s each; and 10 repetitions with a comfortable starting weight
as determined by each subject. For bench press, subjects were
positioned on the bench (Pulse Fitness Systems, Winnipeg,
MB) with both feet flat on the floor and the handles of the press
at the level of their nipples. Subjects were not allowed to lift
their buttocks off the bench or arch their backs during a lift.
After warm-up, for both leg press and bench press testing,
subjects selected a weight they felt they could complete three
repetitions with. At this weight, they only performed one rep-
etition. Subjects then selected a weight they felt would be their
1-RM and attempted one repetition with this weight. After
successful attempts, weight was increased by 2–5 kg for sub-
sequent 1-RM attempts. The 1-RM was usually reached in less
than six sets, including the warm-up set. There was 3-min rest
between attempts, and two assistants changed the weight be-
tween attempts. Reproducibility of the bench press and leg
press was determined on two separate days in 10 subjects. The
coefficients of variation for bench press and leg press were
3.6% and 3.0%, respectively.
Total work performed during 50 repetitions was mea-
sured in the right knee extensors and flexors, using an
isokinetic dynamometer (Biodex System 3, Biodex Medical
Systems Inc., Shirley, NY). The dynamometer was set in the
concentric mode for knee extension/flexion, at an angular
velocity of 180°·s�1 (20). Range of motion consisted of
movement from 90° to 170° of knee flexion (internal angle).
Subjects sat against a back support, producing an angle of
85° of hip flexion. Stabilizing belts were placed over the lap,
across the chest, and across the distal one-third of the tested
leg thigh. The rotational axis of the dynamometer was
positioned to be coaxial with the knee axis (lateral condyle)
during testing. Subjects were given two practice trials of 10
repetitions where they were told to perform knee extension
and flexion as fast and hard as possible. After the practice
trials and 10-min rest, subjects performed the test trial,
which consisted of 50 repetitions of knee extension and knee
flexion at maximal effort. Torque on the machine attach-
ment was corrected for the effects of gravity on the lower
leg and the dynamometer’s resistance pad. The torque out-
put on the dynamometer was checked with a calibration
weight on a weekly basis throughout the study duration.
Reproducibility of the total work measurements was deter-
mined on two separate days in 12 subjects. The coefficients
of variation for knee extension and flexion total work were
4.93% and 8.31%, respectively.
The order of tests was the same each time: muscle biopsy,
then 24-h later leg press, bench press, and isokinetic knee
extension/flexion, with at least 15 min of rest between each
test.
Exercise program. All subjects followed the same
high volume, heavy load (�70% 1-RM), resistance-training
program for 8 wk (1). This program was designed to in-
crease lean tissue mass and strength and had been previously
found to yield these results (3). In this program, subjects
self-select a weight that permits completion of the required
number of sets and repetitions for each exercise and to reach
failure by the last repetition each time. This typically takes
a subject two to three sessions to find the appropriate weight
to use for each exercise but allows for individual progres-
sion throughout the program. The program involved a 3-d
split routine using whole body musculature. Day 1 was for
chest and tricep musculature and included the following
exercises in order: bench press, incline bench press, flat
bench dumbbell flyes, incline dumbbell flyes, cable tricep
extensions, rope reverse tricep extensions, and french curls.
Day 2 was for back and bicep musculature and included the
following exercises in order: chin-ups, low row, lat pull-
downs, alternate dumbbell row, standing EZ-curls, preacher
curls, and alternate dumbbell curls. Day 3 was for leg,
shoulder, and abdominal musculature and included the fol-
lowing exercises in order: leg press, leg extensions, ham-
string curls, standing calve raises, military dumbbell press,
upright row, shrugs, deltoid flyes, and abdominal crunches.
Day 4 was rest and recovery. These four days were consid-
ered one cycle, and the cycle was repeated continuously
throughout the duration of the study. The program was
broken into seven blocks of two cycles or 8 d, for a total of
56 d. Block 1 consisted of three sets of 10 –12 repetitions,
with 1-min rest between sets. Block 2 consisted of three sets
of 8 –10 repetitions, with 1.5-min rest between sets. Block 3
consisted of four sets of six to eight repetitions, with 2-min
rest between sets. Block 4 consisted of five sets of four to six
repetitions, with 3-min rest between sets. Block 5 consisted
of four sets of six to eight repetitions, with 2-min rest
between sets. Block 6 consisted of three sets of 8 –10 rep-
etitions, with 1.5-min rest between sets. Block 7 consisted of
three sets of 10 –12 repetitions, with 1-min rest between sets
(3). Subjects trained with at least one partner and adjusted
their exercise load accordingly to permit completion of the
CREATINE AND VEGETARIANS Medicine & Science in Sports & Exercise� 1949
desired repetitions. A personal trainer supervised and as-
sisted with all training sessions.
Training logs detailing the weight used and numbers of
sets and repetitions performed for each exercise were com-
pleted for every workout. Training volume was calculated
(kg � reps) for the entire 8 wk of training and compared
between groups and supplements. As well, the training
volume during the second week (three sets of 8 –10 reps)
was compared with week 7 (three sets of 8 –10 reps) for pre-
to postcomparisons between groups, supplement, and time.
Week 2 and week 7 were compared because the sets and
reps were the same and this exercise cycle represented the
beginning (week 2) and end (week 7) of the study.
Dietary intake. Subjects were asked not to alter their
diet (increase or decrease caloric consumption) for the du-
ration of the study. Three-day food diaries were collected
from each subject at the beginning and end of the study.
Subjects were given instruction about proper portion sizes
and how to accurately record all food or beverages con-
sumed during the 3-d recording in the food diary. Fuel
Nutrition Software 2.1a (LogiForm International Inc., Saint-
Foy, PQ) was used to analyze the food records for total
calories and the amount of energy from each of carbohy-
drate, protein, and fat. This information was collected to
determine whether diet might be a confounding factor in the
study and to confirm vegetarian status.
Statistical analysis. There were two separate analysis
performed in this study. The first analysis involved the
assessment of baseline measurements of muscle concentra-
tions of creatine, phosphocreatine, total creatine, and aden-
osine triphosphate in the muscle biopsies from the initial
subject pool, consisting of 19 vegetarian and 30 nonveg-
etarians. The second analysis involved assessment of
changes in body composition, exercise performance, muscle
metabolite concentration, and muscle fiber area in the sub-
ject population (N � 42; 24 NV; 18 VG) that participated in
8 wk of resistance training and supplementation with either
creatine or placebo.
In the first analysis, muscle concentrations of creatine,
phosphocreatine, total creatine, and adenosine triphosphate
were analyzed by two-way analysis of variance (ANOVA)
for differences between group (vegetarian vs nonvegetarian)
and gender (male vs female). Whenever significance was
evident, Tukey post hoc tests were performed to compare
means. A P value of 0.05 was considered significant.
In the second analysis, results were analyzed using a
group (vegetarian vs nonvegetarian) � supplement (creatine
vs placebo) � time (pre- vs posttraining) ANOVA with
repeated measures on the factor of time. Whenever signif-
icance was evident, Tukey post hoc tests were performed to
compare means. A P value of 0.05 was considered signifi-
cant. All results are presented as means � standard error. As
part of the second analysis, Pearson correlations were cal-
culated for the change in muscle creatine and initial muscle
creatine, the change in muscle creatine and the change in
lean tissue mass, and the change in muscle creatine and the
change in exercise performance variables. A P value of 0.05
was considered significant.
RESULTS
Baseline Measurements
The first purpose of this study was to determine whether
a habitual vegetarian diet resulted in lower creatine, phosph-
agen, and total creatine concentrations. Because males and
females were included in this study, gender was entered as
a factor and assessed for baseline differences in the same
above-mentioned variables. The results demonstrated that
there was no significant difference between vegetarians and
nonvegetarians or males and females for free creatine con-
centration. There were no significant differences between
vegetarians and nonvegetarians or males and females for
phosphocreatine or adenosine triphosphate concentrations.
However, there was a significant difference between vege-
tarians and nonvegetarians for total creatine concentration
(P � 0.05; Fig. 1), with the nonvegetarians demonstrating
higher total creatine concentration. This difference was ex-
pected and was the basis for blocking subjects accordingly
for the 8-wk training study.
Although males and females did not differ in muscle
metabolite concentrations, there were expected differences
between genders (16,24). In those subjects who participated
in the training and supplementation study, males exhibited
significantly higher values than females on all body com-
position variables except percentage fat, hydration mea-
sures, and muscular performance variables. This also was
the basis of blocking subjects according to sex, which re-
sulted in the random assignment of subjects to groups based
on their gender. Numerous published reports indicate that
there is no difference between how males and females
respond to resistance training (7,22,28). Therefore, gender
was not included as a factor in the statistical analysis for the
subsequent training and supplementation study.
Training Study
Body composition and hydration status. There
were no differences between groups at baseline for scale
body weight or lean tissue mass. For body mass, there was
FIGURE 1—Baseline creatine (Cr), phosphocreatine (PCr), total cre-
atine (TCr), and adenosine triphosphate (ATP) concentration for veg-
etarian (VG) and nonvegetarian (NV) subjects. Concentration is ex-
pressed as millimoles per kilogram dry mass. Values are mean �
standard error for N � 49 subjects. * Indicates significant group
difference (P < 0.05). 1950 Official Journal of the American College of Sports Medicine http://www.acsm-msse.org a supplement � time interaction (P � 0.05), with those subjects supplementing with creatine demonstrating a greater increase from pre- to posttraining than those on placebo. For lean tissue mass there was a group � supplement � time interaction (P � 0.05). Vegetarians on creatine expe- rienced an increase of 2.4 kg in lean tissue mass compared with an increase of 1.9 kg for nonvegetarians on creatine (significant interaction, P � 0.05; Fig. 2). Those subjects supplementing with creatine (vegetarians and nonvegetarians) demonstrated a greater increase in lean tissue mass as compared with those groups on placebo (P � 0.05). The change in lean tissue mass was significantly correlated with the change in muscle total creatine (r � 0.61, P � 0.05). Total body water, extracellular water, and intracellular water all increased significantly (time effect) from baseline to post- training and supplementation, and there were no differences between groups or supplements. The increase in total body water, extracellular water, and intracellular water was 35.4 � 1.2 L to 37.0 � 1.2 L, 17.2 � 0.5 L to 17.9 � 0.5 L, and 18.2 � 0.7 L to 19.1 � 0.8 L, respectively (P � 0.05). Muscle metabolites. There were no group, supple- ment, or time main effects or interactions for free creatine content. There was a significant group � supplement � time interaction for phosphocreatine concentration (P � 0.05; Fig. 3) and total creatine concentration (P � 0.05; Fig. 4). Post hoc tests revealed that vegetarians on creatine experienced a significantly greater gain in phosphocreatine and total creatine concentration from pre to post than all other groups (P � 0.05). Nonvegetarians on creatine expe- rienced a significant increase in phosphocreatine and total creatine from pre- to posttest (P � 0.05). There was a significant negative correlation between the change in mus- cle total creatine and initial muscle total creatine for those subjects supplementing with creatine (r � �0.77, P � 0.05). There were no changes in creatine, phosphocreatine, or total creatine for those subjects supplementing with pla- cebo, and there was no effect of supplementation or training on adenosine triphosphate concentration. Muscle fiber area. There were inconsistencies with differentiation of fiber types at preincubation of pH 4.6. Therefore, to ensure accurate calculation of muscle fiber area, results from only those slides at pH 4.2 and 9.4 were reported, which permitted determination of Type I and II fiber area pre- and posttesting (2). There were no differences at baseline between groups for Type I or II muscle fiber area. There were no significant main effects or interactions for Type I muscle fiber area. There was a significant sup- plement � time interaction for Type II fiber area (P � 0.05). Creatine supplementation resulted in a 28% increase in Type II fiber area, which was greater as compared with 9% for placebo supplementation (Fig. 5). Fiber type area and percentages for each group pre- and posttraining are listed in Table 3. Urine. There were significant group differences in urine creatine output at baseline, with nonvegetarians excreting greater 24-h urinary creatine than vegetarians (P � 0.05). Urinary creatine output on day 3 and day 5 of creatine supplementation significantly differed from baseline, and FIGURE 4 —Graph of baseline (BL, first bar on left in each column) and posttraining (Post) measurement of total creatine (TCr) concen- tration. VGCr, vegetarians on creatine; VGPl, vegetarians on placebo; NVCr, nonvegetarians on creatine; NVPl, nonvegetarians on placebo. Values are mean � standard error for N � 42 subjects. * Indicates significant pre- to postchange (P < 0.05). ** Indicates significant group � supplement � time interaction (P < 0.05). FIGURE 2—Graph of lean tissue mass (kg) at baseline (BL) and posttraining (Post) for subjects supplementing with creatine and pla- cebo. VGCr, vegetarians on creatine; VGPl, vegetarians on placebo; NVCr, nonvegetarians on creatine; NVPl, nonvegetarians on placebo. Values are means expressed in kilograms (kg) � standard error for N � 42 subjects. * Indicates significant pre- to postchange (P < 0.05).** Indi- cates significant group � supplement � time interaction (P < 0.05). FIGURE 3—Graph of baseline (BL, first bar on left in each column) and posttraining (Post) measurement of phosphocreatine (PCr) con- centration for those subjects who participated in 8 wk of weight training and supplementation. VGCr, vegetarians on creatine; VGPl, vegetarians on placebo; NVCr, nonvegetarians on creatine; NVPl, nonvegetarians on placebo. Values are mean � standard error for N � 42 subjects. * Indicates significant pre- to postchange (P < 0.05). ** Indicates significant group � supplement � time interaction (P < 0.05). CREATINE AND VEGETARIANS Medicine & Science in Sports & Exercise� 1951 urinary creatine output on day 5 significantly differed from day 3 (P � 0.05). Creatinine output remained unchanged throughout the loading phase of supplementation but was significantly greater at posttest compared with pretest values (time main effect, P � 0.05). After supplementation ended, urinary creatine was not different from baseline. Urine cre- atine output is presented in Fig. 6. Muscle performance measures. There were no dif- ferences in 1-RM bench press and leg press between groups at baseline. There was a supplement � time interaction for 1-RM bench press (P � 0.05). Those subjects who supple- mented with creatine demonstrated an increase in 1-RM bench press from 85.1 � 8.5 kg to 101.0 � 9.5 kg, which was greater than the placebo subjects who increased 1-RM bench press from 76.4 � 9.0 kg to 85.1 � 10.1 kg. Leg press increased as a result of training (P � 0.05) with no dif- ferences between groups. The mean increase in leg press was 22.1 � 10 kg. There was a significant positive corre- lation between the change in muscle total creatine and change in bench press (r � 0.62, P � 0.05) and leg press (r � 0.52, P � 0.05) for those subjects supplementing with creatine. The total work performed during 50 repetitions at 180°·s�1 of knee flexion and extension was used as a measure of muscular endurance. There was a significant group � supplement � time interaction (P � 0.05) for total work. Post hoc tests indicated that the comparison of pre to post for vegetarians supplementing with creatine was sig- nificantly greater than all other groups (P � 0.05; Fig. 7). The change in total work performed was significantly cor- related with the change in muscle total creatine for those subjects supplementing with creatine (r � 0.59, P � 0.05). Training volume. There was a significant difference in total training volume between creatine and placebo supple- mentation (P � 0.05), and a significant supplement � time interaction for training volume from week 2 and week 7 (P � 0.05). Creatine supplementation resulted in training vol- umes of 56,702 kg � reps and 65,198 kg � reps for weeks 2 and 7 (three sets, 8 –10 reps), whereas placebo subjects had training volumes of 46,477 kg � reps and 50,105 kg � reps for weeks 2 and 7 (Fig. 8). Diet. There was a significant difference between vege- tarians and nonvegetarians for total calories and calories as protein before and at the end of the study (P � 0.05), with the nonvegetarians consuming higher total calories and cal- ories as protein. The amount of total calories and calories as protein did not change for any group from pre- to posttest. Total calories and macronutrient (protein, carbohydrate, and fat) content of the vegetarian and nonvegetarian subjects are listed in Table 2. DISCUSSION This is the first study to demonstrate that habitual vege- tarians (lacto-ovo or vegan) have lower resting intramuscu- lar concentrations of total creatine as compared with om- nivorous peers. As well, the results of this study are in agreement with previous work indicating that baseline mus- cle creatine concentrations affect the increase in muscle total creatine resulting from creatine monohydrate supple- mentation. The vegetarians supplementing with creatine in this study exhibited a greater increase in muscle concentra- tions of phosphocreatine and total creatine, and also a greater increase in lean tissue mass and total work output. These changes were also significantly correlated with the changes in muscle total creatine concentration. Delanghe et al. (8) and Shomrat et al. (26) found that vegetarians had lower plasma creatine than nonvegetarian FIGURE 6 —Graph of urine creatine output (mg·d�1) for baseline (BL), day 1 (D1), day 3 (D3), and day 5 (D5) of loading (0.25 g·kg�1 LTM·d�1 � 7 d) for vegetarian (VG) and nonvegetarian (NV) subjects supplementing with creatine. Values are mean � standard error for N � 42 subjects. * Indicates significant group main effect (P < 0.05). ** Indicates significant difference from baseline (P < 0.05). *** Indi- cates significant difference from previous measurement day (P < 0.05). TABLE 2. Total calories (kcal�d�1) and macronutrient (g�d�1) content of vegetarian and nonvegetarian subjects at pre- and postexercise/supplement intervention. Energy Vegetarian Nonvegetarian Pre Post Pre Post Calories (kcal�d�1) 2159 (71)* 2213 (78)* 2638 (67)* 2629 (61)* Carbohydrate (g�d�1) 332 (11) 330 (12) 349 (12) 348 (11) Protein (g�d�1) 78 (2)* 80 (2)* 139 (2)* 138 (3)* Fat (g�d�1) 59 (3) 61 (4) 67 (3) 66 (3) All values are mean � (standard error); data are based on the average for 1 d from 3-d food records. * Significant difference (P � 0.05) between groups (vegetarians and nonvegetarians). FIGURE 5—Graph of Type II muscle fiber area (�m2) for creatine supplementing (CM) and placebo supplementing (PL) subjects both at baseline (BL) and posttraining (Post). Values are mean � standard error for N � 42 subjects. Plot demonstrates significant supplement � time interaction (P < 0.05). 1952 Official Journal of the American College of Sports Medicine http://www.acsm-msse.org peers, and Lukaszuk et al. (23) demonstrated that a 3-wk lacto-ovo-vegetarian diet could reduce muscle creatine in omnivorous men. The average plasma creatine concentra- tion is about 30 –70 �M for omnivorous adult males, and the vegetarians in the Delanghe et al. (8) and Shomrat et al. (26) studies had plasma creatine of 9 �M and 11 �M, respec- tively. The urinary analysis in our study supports these results in that vegetarians excreted significantly less urinary creatine than nonvegetarians, which would be expected of a diet that lacks animal meats, and therefore, little ingested creatine. In the only study to date involving creatine sup- plementation in a group of vegetarians, Shomrat et al. (26) gave seven vegetarians 21 g of creatine per day for 6 d and measured anaerobic exercise performance. Vegetarians ex- perienced the same amount of weight gain as nonvegetar- ians, but they had significantly better fatigue resistance on the second of three Wingate anaerobic tests. In the present study, muscle biopsies provided direct evidence that muscle total creatine stores were lower in vegetarians than nonveg- etarians, and after creatine supplementation and resistance training, these vegetarians experienced greater increases in TCr, PCr, lean tissue mass, and total work performance compared with nonvegetarians. These findings are signifi- cant in that they are the first to demonstrate that individuals with low initial intramuscular TCr have heightened response to creatine supplementation during resistance training. Pre- vious studies have demonstrated that individual vegetarian subjects respond to creatine supplementation with a greater increase in TCr than usual (16). Also, those with the greatest changes in TCr with creatine supplementation demonstrate greater increases in work output during fatiguing exercise tasks (5) and greater rates of PCr resynthesis after fatiguing exercise (14). An increase in ability to perform work and an increase in rate of PCr resynthesis would improve one’s ability to perform work during individual training sessions, and this should result in a greater stimulus for muscle hypertrophy. This is supported by the results of the current study where vegetarians supplementing with creatine had greater increases in ability to perform work and a greater increase in lean tissue mass compared with nonvegetarians. The greater gain in lean tissue mass experienced by the subjects supplementing with creatine in the present study is in agreement with previous creatine and weight training reports (4,21). In the present study, subjects supplementing with creatine had a 4% increase in lean tissue mass, which was greater than the 2% increase in the placebo group. Kreider et al. (21) used doses of 15.75 g·d�1 for 4 wk and demonstrated increases in DXA determined lean tissue mass of 3.28% in subjects on creatine compared with 2% for placebo. Stout et al. (29) and Burke et al. (4) found an increase of 2.3– 4.6% in lean tissue mass after 3– 8 wk of resistance training and creatine supplementation. The in- crease in lean tissue mass demonstrated by those subjects supplementing with creatine in the present study parallels FIGURE 7—Graph of total work for knee flexion and extension (50 reps at 180°·s�1) at baseline (BL) and posttraining (Post). VGCr, vegetarians on creatine; VGPl, vegetarians on placebo; NVCr, non- vegetarians on creatine; NVPl, nonvegetarians on placebo. Values are mean � standard error for N � 42 subjects. * Indicates significant pre- to postchange (P < 0.05). ** Indicates significant group � supplement � time interaction (P < 0.05). FIGURE 8 —Graph of weekly training volume for all subjects supple- menting with creatine (CM) and placebo (PL). Values are mean train- ing volume (reps � weight) for N � 42 subjects. Standard error bars were excluded for purposes of clarity. * Indicates significant difference between supplements (P < 0.05). TABLE 3. Muscle fiber cross-sectional areas and percentages. Fiber Type Area (�m2) Percentage VGCr VGPl NVCr NVPl VGCr VGPl NVCr NVPl Type I Pre 3230 � 477 3291 � 229 3121 � 284 3470 � 394 46 � 3 44 � 2 42 � 4 43 � 4 Post 3944 � 201 3622 � 189 3674 � 229 3714 � 246 44 � 3 44 � 3 41 � 3 43 � 3 � (post�pre) 715 � 266 331 � 223 553 � 277 244 � 237 4 � 2 1 � 2 1 � 3 0 � 3 Type II Pre 3792 � 358 4189 � 381 4310 � 299 4601 � 511 54 � 2 56 � 4 58 � 3 57 � 3 Post 5019 � 349 4611 � 199 5287 � 473 4924 � 431 56 � 3 56 � 4 59 � 3 57 � 4 � (post�pre) 1227 � 255 422 � 311 977 � 263 323 � 455 2 � 2 0 � 3 1 � 3 0 � 4 VGCr, vegetarian creatine; VGPl, vegetarian placebo; NVCr, nonvegetarian creatine; NVPl, nonvegetarian placebo; vegetarian, lacto-ovo or vegan; values are mean � standard error. CREATINE AND VEGETARIANS Medicine & Science in Sports & Exercise� 1953 the increase in other variables such as muscle phosphocre- atine and total work output resulting from creatine supple- mentation. Increased muscle phosphocreatine concentration resulting from creatine supplementation enhances phospho- creatine recovery, and this has been suggested as a reason for augmented increases in work performance during resis- tance training with subsequent increases in lean tissue mass (14,30). Our finding of an increase in self-selected training volume in subjects supplementing with creatine in the cur- rent and one previous study (6) supports this contention. Extracellular, intracellular, and total body water increased in all subjects from pre- to posttraining, and there were no differences between groups or supplements regarding the changes that occurred. Francaux and Poortmans (12) re- ported a significant increase in intracellular water after 42 d of strength training and creatine supplementation. These authors used the same method to detect hydration status (BIA) and a similar program of exercise and supplementa- tion as the present study. Compared with the current study, the increase in intracellular water was almost the same (~1 L) for creatine supplementing subjects, but like the present study, the percentage of intracellular water to body weight did not differ substantially. This would indicate that the increase in intracellular water paralleled an increase in mus- cle dry matter and occurred proportionately due to osmo- regulatory changes. Hultman et al. (18) measured 24-h urine output volume and suggested that a short-term loading phase resulted in water retention similar in magnitude to that of Francaux and Poortmans (12). These results are limited, however, because the authors did not measure fluid con- sumption. In the present study, hydration status was mea- sured by bioelectrical impedence (BIA) and body composi- tion was assessed by DXA. The results of the BIA indicate that there was a significant increase in body water content (TBW, ECW, and ICW) from pre to post but that there were no significant differences between groups or supplements. DXA measures indicated that the subjects supplementing with creatine demonstrated a greater change in lean tissue mass than subjects on placebo. These combined results of body compartment fluid and composition would suggest that there was an increase in dry muscle mass due to creatine supplementation and resistance training that was superior to resistance training and placebo supplementation. Assessment of muscle fiber morphology indicated that creatine supplementation resulted in greater increases in Type II fiber area compared with placebo supplementation (28% vs 9%). One year of creatine supplementation (1.5 g·d�1) was found to increase Type II fiber area by 34% in a group of patients with gyrate atrophy (27). Volek et al. (32) reported that 12 wk of creatine supplementation and resistance training resulted in ~35% in Type II and Type I fiber area compared with ~10% for placebo. Likewise, Hes- pel et al. (17) found significant increases in fiber area of all fiber types during creatine supplementation combined with 2 wk of immobilization and 10 wk of strength training. From the results of the current study and those cited above, it is difficult to determine whether certain fiber types are more responsive to creatine supplementation than others. The preferential hypertrophy of Type II muscle fibers in the current study may be related to the training stimulus (32) in addition to the Cr supplementation. Creatine supplementation resulted in a 19% increase in 1-RM bench press compared with an 11% increase for placebo supplementation, which is similar to the results reported by Stout et al. (29) and Volek et al. (32). After 8 wk of resistance training and creatine supplementation (21 g·d�1), Stout et al. (29) reported an increase of 13% for 1-RM bench press. Volek et al. (32) found a 24% increase in 1-RM bench press after 12 wk of creatine supplementation and weight training, which compared with a 16% increase for 1-RM bench press for placebo subjects. Improved strength after creatine supplemen- tation and resistance training has been thought to be due to the ability to increase training volume at a greater rate (6,9). In the present study, creatine subjects had a greater increase in train- ing volume (kg � reps) compared to placebo subjects. Earnest et al. (9) reported similar improved training volume for bench press associated with creatine supplementation. Volek et al. (32) also reported significantly greater training volume asso- ciated with creatine supplementation, which corresponded to statistically greater improvements in 1-RM bench press as compared with placebo supplementation. There was a signifi- cant increase in 1-RM leg press with training, but no differ- ences between groups. The exercise program in the present study only included two leg exercises, emphasizing the knee extensors. The minimal focus on leg exercises may partly explain the lack of significant difference between creatine and placebo subjects for the leg press. Subsequent study with a greater emphasis on lower-limb exercises might elicit a signif- icant difference similar to that for bench press 1-RM. In summary, vegetarians have lower basal total creatine and urinary excreted creatine than nonvegetarian peers and that creatine supplementation combined with resistance training yields greater changes in muscle phosphocreatine, total creat- ine, Type II fiber area, lean tissue mass, and total work per- formed as compared with placebo supplementation. Further- more, the increase in muscle concentrations of phosphocreatine and total creatine, lean tissue mass, and total work performed were greater in vegetarians supplementing with creatine com- pared with nonvegetarians supplementing with creatine. Future studies are needed to determine whether short-term dietary manipulation (vegetarian) can affect muscle concentrations of creatine and also whether there is supercompensation in crea- tine transport once it is reintroduced into the diet. The work of Lukaszuk et al. (23) indicated a trend toward this with a short duration (5 d) of supplementation. As well, additional work is necessary to further understand the mechanisms that regulate muscle concentrations of total creatine to determine why there is such individual variation in the magnitude of muscle creatine accumulation during loading. This study was funded by a grant from MuscleTech Research and Development Inc., Mississauga, Ontario, Canada. The results of the present study do not constitute endorsement of the product by the authors or ACSM. 1954 Official Journal of the American College of Sports Medicine http://www.acsm-msse.org REFERENCES 1. AMERICAN COLLEGE OF SPORTS MEDICINE. Position stand on pro- gression models in resistance training for healthy adults. Med. Sci. Sports Exerc. 34:363–380, 2002. 2. BROOKE, M., and K. KAISER. Three “myosin ATPase” systems: the nature of their pH lability and sulfhydryl dependence. J. Histo- chem. Cytochem. 18:670 – 672, 1970. 3. BURKE, D. G., P. D. CHILIBECK, K. S. DAVISON, D. G. CANDOW, J. FARTHING, and T. SMITH-PALMER. The effect of whey protein sup- plementation with and without creatine monohydrate, combined with resistance training on lean tissue mass and muscle strength. Int. J. Sports Nutr. Exerc. Metab. 11:384 –399, 2001. 4. BURKE, D. G., S. SILVER, L. E. HOLT, T. SMITH-PALMER, C. J. CULLIGAN, and P. D. CHILIBECK. The effect of continuous low dose creatine supplementation on force, power, and total work. Int. J. Sports Nutr. Exerc. Metab. 10:235–244, 2000. 5. CASEY, A., D. CONSTANTIN-TEODOSIU, S. HOWELL, E. HULTMAN, and P. L. GREENHAFF. Creatine ingestion favorably affects performance and muscle metabolism during maximal exercise in humans. Am. J. Physiol. 271:E31–E37, 1996. 6. CHRUSCH, M. J., P. D. CHILIBECK, K. CHAD, K. S. DAVISON, and D. G. BURKE. Creatine supplementation combined with resistance training in older men. Med. Sci. Sports Exerc. 33:2111–2117, 2002. 7. CURETON, K., M. COLLINS, D. HILL, and F. MCELHANNON. Muscle hypertrophy in men and women. Med. Sci. Sports Exerc. 4:338 – 344, 1988. 8. DELANGHE, J., J. DE SLYPERE, and M. DE BUYZERE. Normal refer- ence values for creatine, creatinine and carnitine are lower in vegetarians. Clin. Chem. 35:1802–1803, 1989. 9. EARNEST, C., P. SNELL, R. RODRIQUEZ, A. ALMADA, and T. MITCH- ELL. The effect of creatine monohydrate ingestion on anaerobic power indices, muscular strength and body composition. Acta Physiol. Scand. 153:207–209, 1995. 10. EVANS, W. J., S. D. PHINNEY, and V. R. YOUNG. Suction applied to a muscle biopsy maximizes sample size. Med. Sci. Sports Exerc. 14:101–102, 1982. 11. FEBBRAIO, M. A., T. R. FLANAGAN, R. J. SNOW, S. ZHAO, and M. F. CAREY. Effect of creatine supplementation on intramuscular TCr, metabolism and performance during intermittent, supramaximal exercise in humans. Acta Physiol. Scand. 155:387–395, 1995. 12. FRANCAUX, M., and J. POORTMANS. Effects of training and creatine supplementation on muscle strength and body mass. Eur. J. Appl. Physiol. 80:165–168, 1999. 13. GREEN, A. L., E. HULTMAN, I. A. MACDONALD, D. A. SEWELL, and P. L. GREENHAFF. Carbohydrate ingestion augments skeletal mus- cle creatine accumulation during creatine supplementation in hu- mans. Am. J. Physiol. 271:E821–E826, 1996. 14. GREENHAFF, P. L., K. BODIN, K. SODERLUND, and E. HULTMAN. Effect of oral creatine supplementation on skeletal muscle phos- phocreatine resynthesis. Am. J. Physiol. Endocrinol. Metab. 266: E725–E730, 1994. 15. HARRIS, R. C., E. HULTMAN, and L. NORDESIO. Glycogen, glycolytic intermediates and high-energy phosphates determined in biopsy samples of musculus quadriceps femoris of man at rest: methods and variance values. Scand J. Clin. Lab Invest 33:109 –120, 1974. 16. HARRIS, R. C., K. SODERLUND, and E. HULTMAN. Elevation of creatine in resting and exercised muscle of normal subjects by creatine supplementation. Clin. Sci. 83:367–374, 1992. 17. HESPEL, P., B. OP’T EIJJNDE, M. VAN LEEMPUTTE, et al. Oral creatine supplementation facilitates the rehabilitation of disuse atrophy and alters the expression of muscle myogenic factors in humans. J. Physiol. 536:625– 633, 2001. 18. HULTMAN, E., K. SODERLUND, J. TIMMONS, G. CEDERBLAD, and P. L. GREENHAFF. Muscle creatine loading in man. J. Appl. Physiol. 81:232–237, 1996. 19. JAFFE, M. Ueber den Niederschlag, welchen Pikrinsaure in nor- malen Harn erzeugt und uber eine neue Reaktion des Kreatinins. Z. Physiol. Chem. 10:391–397, 1886. 20. KAMBIS, K., and S. PIZZEDAZ. Short term creatine supplementation improves maximum quadriceps contraction in women. Int. J. Sport Nutr. Exerc. Metab. 13:97–111, 2003. 21. KREIDER, R., M. FERREIRA, M. WILSON, et al. Effects of creatine supplementation on body composition, strength, and sprint per- formance. Med. Sci. Sports Exerc. 30:73– 82, 1998. 22. LEMMER, J., D. HURLBUT, G. MARTEL, et al. Age and gender responses to strength training and detraining. Med. Sci. Sports Exerc. 8:1505–1512, 2000. 23. LUKASZUK J., R. ROBERTSON, J. ARCH, et al. Effect of creatine supplementation and a lacto-ovo-vegetarian diet on muscle crea- tine concentration. Int. J. Sport Nutr. Exerc. Metab. 12:336 –348, 2002. 24. MCKENNA, M., J. MORTON, S. SELIG, and R. SNOW. Creatine sup- plementation increases muscle total creatine but not maximal intermittent exercise performance. J. Appl. Physiol. 6:2244 –2252, 1999. 25. PASSONEAU, J., and O. LOWRY. Enzymatic Analysis: A Practical Guide. Totawa, NJ: Humana Press, 1993, pp. 121–123. 26. SHOMRAT, A., W. YITZHAK, and A. KATZ. Effect of creatine feeding on maximal exercise performance in vegetarians. Eur. J. Appl. Physiol. 82:321–325, 2000. 27. SIPILA, I., J. RAPOLA, O. SIMELL, and A. VANNAS. Supplementary creatine as a treatment for gyrate atrophy of the choroid and retina. N. Engl. J. Med. 304:867– 870, 1981. 28. STARON, R., D. KARAPONDO, W. KRAEMER, et al. Skeletal muscle adaptations during early phase of heavy-resistance training in men and women. J. Appl. Physiol. 76:1247–1255, 1994. 29. STOUT, J., J. ECKERSON, D. NOONAN, G. MOORE, and D. CULLEN. Effects of 8 weeks of creatine supplementation on exercise per- formance and fat-free weight in football players during training. Nutr. Res. 19:217–225, 1999. 30. STOUT, J. R., J. M. ECKERSON, T. J. HOUSH, and K. T. EBERSOLE. The effects of creatine supplementation on anaerobic working capac- ity. J. Strength Cond. Res. 13:135–138, 1999. 31. VANDENBERGHE, K., M. GORIS, P. VAN HECKE, M. VAN LEEMPUTTE, L. VANGERVEN, and P. HESPEL. Long-term creatine intake is ben- eficial to muscle performance during resistance training. J. Appl. Physiol. 83:2055–2063, 1997. 32. VOLEK, J. S., N. D. DUNCAN, S. A. MAZZETTI, et al. Performance and muscle fiber adaptations to creatine supplementation and heavy resistance training. Med. Sci. Sports Exerc. 31:1147–1156, 1999. CREATINE AND VEGETARIANS Medicine & Science in Sports & Exercise� 1955

Expert paper writers are just a few clicks away

Place an order in 3 easy steps. Takes less than 5 mins.

Calculate the price of your order

You will get a personal manager and a discount.
We'll send you the first draft for approval by at
Total price:
$0.00