ArticlePDF Available

Caffeine Potentiates the Ergogenic Effects of Creatine

Authors:

Abstract

Jerônimo DP, Germano MD, Fiorante FB, Boreli L, Neto LVS, Souza RA, Silva FF, Morais AC. Caffeine Potentiates the Ergogenic Effects of Creatine. JEPonline 2017;20(6):66-77. The aim of this study was to determine the effect of caffeine on creatine supplementation on electromyographic activity and torque. Sixteen males were supplemented with caffeine (6 mg·kg-1) and creatine (3 g). They did the knee extension test on the isokinetic dynamometer while electromyographic activity was monitored. The caffeine group achieved 4.57% increase in EMG activity and 4.25% increase in torque. The creatine group achieved a 17.07% decrease in the EMG activity and a 3.45% increase in torque. The caffeine and creatine group achieved a 3.07% increase in EMG activity and a 5.79% increase in torque. The findings indicate that the consumption of caffeine at 6 mg·kg-1 in association with 3 g of creatine for 7 days generated a significant improvement in performance, increased the production of torque, and improved the EMG muscle activity. Thus, it is more than reasonable to conclude that caffeine potentiates the effects of creatine during a physical exercise.
66
Journal of Exercise Physiology
online
December 2017
Volume 20 Number 6
Editor
-
in
-
Chief
Tommy Boone, PhD, MBA
Review Board
Todd Astorino, PhD
Julien Baker, PhD
Steve Brock, PhD
Lance Dalleck, PhD
Eric Goulet, PhD
Robert Gotshall, PhD
Alexander Hutchison, PhD
M. Knight-Maloney, PhD
Len Kravitz, PhD
James Laskin, PhD
Yit Aun Lim, PhD
Lonnie Lowery, PhD
Derek Marks, PhD
Cristine Mermier, PhD
Robert Robergs, PhD
Chantal Vella, PhD
Dale Wagner, PhD
Frank Wyatt, PhD
Ben Zhou, PhD
Official Research Journal
of the American Society of
Exercise Physiologists
ISSN 1097-9751
Official Research Journal of
the American Society of
Exercise Physiologists
ISSN 1097-9751
JEPonline
Caffeine Potentiates the Ergogenic Effects of Creatine
Diego Pereira Jerônimo1,2,4, Moisés Diego Germano2,4, Fábio Baccin
Fiorante2, Leandro Boreli2, Luiz Vieira da Silva Neto1, Renato
Aparecido de Souza3, Fabiano Fernandes da Silva3, Antônio Carlos
de Morais1
1Faculdade de Educação Física, Universidade Estadual de Campinas
(UNICAMP), Avenida Érico Veríssimo, 701, Cidade Universitária Zeferino
Vaz, Barão Geraldo CEP 13.083-851, Campinas, SP, Brasil,
2Departamento de Educação Física, Faculdades integradas ASMEC /
UNISEP, Av. Prof. Dr. Antônio Eufrásio de Toledo, 100, CEP 37.572-000,
Ouro Fino, MG, Brasil, 3Grupo de Pesquisa em Ciências da Saúde (GEP-
CS), Instituto Federal de Educação, Ciência e Tecnologia do Sul de Minas
Gerais (IFSULDEMINAS), Campus Muzambinho, Rua Dinah, Bairro
Canaã, 75, Muzambinho, Minas Gerais 37890-000, Brasil, 4University
Amparense, Amparo, SP, Brazil, School of Arts, Sciences and Humanities
ABSTRACT
Jerônimo DP, Germano MD, Fiorante FB, Boreli L, Neto LVS,
Souza RA, Silva FF, Morais AC. Caffeine Potentiates the
Ergogenic Effects of Creatine. JEPonline 2017;20(6):66-77. The
aim of this study was to determine the effect of caffeine on creatine
supplementation on electromyographic activity and torque. Sixteen
males were supplemented with caffeine (6 mg·kg-1) and creatine (3
g). They did the knee extension test on the isokinetic dynamometer
while electromyographic activity was monitored. The caffeine group
achieved 4.57% increase in EMG activity and 4.25% increase in
torque. The creatine group achieved a 17.07% decrease in the EMG
activity and a 3.45% increase in torque. The caffeine and creatine
group achieved a 3.07% increase in EMG activity and a 5.79%
increase in torque. The findings indicate that the consumption of
caffeine at 6 mg·kg-1 in association with 3 g of creatine for 7 days
generated a significant improvement in performance, increased the
production of torque, and improved the EMG muscle activity. Thus, it
is more than reasonable to conclude that caffeine potentiates the
effects of creatine during a physical exercise.
Key Words: Creatine, Caffeine, Dietary Supplements, Performance
67
INTRODUCTION
Recently, the consumption of food supplements have become highly diffused and adopted by
athletes and sportsmen in search for an improvement in physical performance and for the
general individual health. These food supplements are characterized as ergogenic aids that
enhance energy production and, therefore, provide athletes with a competitive advantage.
The term is derived from two Greek words: “ergon” (work) and “gennan” (produce)
Several studies indicate the benefits generated by the supplementation (32,43,47), among
others that indicate the ingestion of food supplements can reduce the athletes’ fatigue (13,20)
and injury level, as well as optimizing energy for muscular work and promoting a faster
recovery (3,19). As a result of these physiological benefits, there is a bigger demand and
consumption for these products.
Among the many available substances on the market, two of them are distinguished from the
others. They are caffeine and creatine. These substances are responsible for the largest sale
of performance-enhancing supplements during the last several years (10,13). In 2000,
creatine was estimated by the American College of Sports Medicine to have reached a world
consumption of 2500 tons (13). Clearly, the supplement market is growing each year as a
result of the use by professional athletes (42). Yet, neither caffeine nor creatine is currently on
the list of banned substances of any sports federation (2,41). More research is needed to
better determine the effects of these substances on physical performance.
Creatine (Cr) plays an important role in the fast energy supply during the muscle contraction.
It is involved in the transfer of a phosphate group from the phosphorylcreatine (Pcr) to ADP to
regenerate adenosine triphosphate (ATP) through a reversible reaction catalyzed by kinase
phosphorylcreatine kinase (PCK) (16,40). Physiologically, the Cr is predominantly used by
tissues with higher energy demand (13,19). The main location for Cr storage is in the skeletal
muscle tissue, which is ~95% of the body’s Cr (16,42).
Since the 1990s, creatine supplementation has been an ergogenic resource in sports to help
increase the athletes’ performance (27) due to a reduction from the muscle protein
degradation, an amplification in the increase of the protein synthesis, and/or indirectly as a
result of the increase in training load performed as a function of its ergogenic effect (8,19,35).
The underlying mechanisms include the increase in mRNA of myosin heavy chain and protein
expression (8), increase in liquid nitrogen retention (22,34,39), and anti-catabolic effects in
some tissues (34).
The ingestion of caffeine also generates interesting physiological effects on the athletes’
physical performance. At the cellular level, caffeine increases the release of calcium from the
sarcoplasmic reticulum. This is due to the inhibition of the enzymes, butyrylcholinesterase
(BuChE) and acetylcholinesterase (1,29). Both facilitate the contractile response of skeletal
muscle (29), blockade of the adenosine receptors, alters the neuromodulation functions from
the synaptic transmission and hemostatic (9), increases the intracellular concentration of
adenosine-5’-monophosphate (AMP) and cyclic guanosine monophosphate (GMP). This is
done by the inhibition from the enzyme hydrolyzer, phosphodiesterase, that activates the
protein kinase A (PKA) resulting in the phosphorylation of several cytosolic proteins, which
generates a specific cellular response between them and lipolytic activities (4,8,48). Also,
68
there is the decrease in the cells’ sensitivity to insulin that results in a reduction in the glucose
storage (17,18).
Caffeine exerts beneficial effects on glucose metabolism through the increase in the
uncoupling protein expression and from the lipid oxidation that in turn decreases the diabetes
mellitus extension (38). These changes are also subordinate from other components that play
an important role (12,17). According to Vandenberghe et al. (36), the interaction between
caffeine and creatine can reduce the creatine supply and the pharmacokinetics, which
could influence in a negative manner the protein synthesis process, the Caf action in the
calcium sarcoplasmic reticulum release is associated with a chronic depletion of intracellular
calcium that changes the fatigue process but damages protein synthesis (46). However, this
understanding of the antagonistic action between the caffeine and creatine association is
being clarified by recent research in animals (10,11,21), Even though, such research is
relatively rare in humans. In fact, it is hard to find research that allows for the categorization
of the real action on the athletes’ physical performance. Hence, the present research is
important in order to better understand the influence of these compounds on athletic
performance and sports nutrition.
METHODS
Subjects
This study examined 16 physically active subjects 18 and 30 yrs of age. The subjects were
not using either anabolic steroids or any nutritional supplements. The test consisted of a
protocol that required the subjects to perform 45 reps of knee extension and flexion with a
constant angular speed of 120º·sec-1 on the isokinetic dynamometer Biodex. Torque was
monitored in the extension phase along with the subjects’ EMG activity from the vastus
lateralis (VL), vastus medialis (VM), and rectus femoris (RF). The subjects were submitted to
a period of 3 days to become familiarized with the protocol and adaptation to the isokinetic
dynamometer as well as the electrodes. Then, the control group (Con = 16) was submitted to
the first test. Immediately after the test, the same subjects began the supplementation phase
for 3 days that consisted of 6 mg·kg-1 caffeine (Caf) followed by a detox period of 5 days.
After the detox period, the subjects began the supplementation with 3 g of creatine (Cr) for a
period of 7 consecutive days. At the end of the 7th day the subjects continued to supplement
with creatine (3 g), but also supplemented with 6 mg·kg-1 caffeine (CrCaf) for 3 days.
Acquisition of the EMG Signal
The electrical activity of the muscles (i.e., the EMG activity) was recorded by a 16-channels
model MP150™ (Biopac System®, USA) eletromyography with sampling frequency of 2000
Hz. The relationship between the differential gains and limits of signal input was established
in . The reference electrode (terra) was placed on the left elbow (lateral epicondyle).
Before the beginning of each test, each subject’s skin was cleaned and prepared with a razor,
alcohol, and cotton. Just after the active bipolar electrodes model TSD 150™ (BIOPAC
Systems®, USA) the rejection was from 95 dB, with distance between the electrodes fixed to
2 cm, the electrodes were fixed in the dominant limb with hypoallergenic adhesive tape
(Transpore) on the VL, VM, and RF muscles in accordance with the standardization proposal
69
by SENIAM (14).
For the capture and processing of signals, the software AcqKnowledge 3.8.1™ (BIOPAC
Systems®, USA) was used. The integrals EMG signals were submitted to digital filtering
using band-pass filter to 20 Hz and 500 Hz and, then rectified and smoothed (moving window
of 10 samples). For the analysis of the corresponding EMG signal values, the normalized 5
sec values from RMS (Root Mean Square, µV) were used.
Isokinetic Dynamometer Biodex
An isokinetic dynamometer Biodex Model System 3 (Biodex Medical System, Shyley, NY,
USA) was used to determine the torque produced during the maximal voluntary contractions
(both concentric and eccentric isokinetic). The subjects were sitting in the chair of the
isokinetic dynamometer. They were fixed to the chair with tracks from the trunk, pelvic, and
thighs in order to keep the body stable during the maximum effort. The hip and knee were
positioned at ~90º of flexion (24,33) with the non-tested limb fixed by straps to maintain
stability. When the subject was positioned in the isokinetic dynamometer chair, the knee joint
axis (lateral epicondyle of the femur) was aligned with the rotation axis from the isokinetic
dynamometer mechanical arm.
After the subject was positioned in the chair and before the beginning of the test, the
dynamometer was calibrated. The test provided the subject’s EMG and at the same time the
torque signs, positioning, time of execution, and electrical activity from the evaluated muscle
on the computer that was connected to the equipment through the software AcqKnowledge
3.8.1™ (BIOPAC Systems®, USA) that allowed for a better interpretation of the data.
Statistical Analysis
The data were extracted and treated in statistical programs where they were analyzed
through a One-Way ANOVA. The torque values were quantified and paired trough repeated
measures ANOVA and Tukey´s Multiple Comparison Test to compare the results with the
evaluations from different supplementation protocols. Variance analyses (One-Way ANOVA)
were used to evaluate and normalize maximum work and maximum torque for muscle
fatigue.
RESULTS
Figure 1 shows the values from normalized RMS that were from the EMG of the VL, VM, and
RF muscles during the implementation of the knee extension on the isokinetic dynamometer
Biodex. A statistically significant difference (P<0.05) was found in the groups. In relation to
the Pre group, we observed a greater signal activation in the groups supplemented with
caffeine (7,47), which reached higher values compared to the other groups. In relation to the
Pre group, the Caf group reached an increase of 4.57% in the EMG activity during the whole
work, the CrCaf group reached an increase of 3.07%, and the group supplemented with 3 g
of Creatine (Cr) had a significant decrease of 17.07% in the EMG activity.
70
Figure 1. The Normalized RMS Values for the EMG of the VL, VM, and RF Muscles are
Presented. *, # Statistically Significant (P<0.05), δ No Significance
In Figure 2A and 2B, the behavior of the curves shows a drop in the work or torque efficiency.
For a better visualization of the results, the data for the 45 executions are divided into two
parts. Figure 2A is characterized from the beginning of the test to the twenty-fifth (25ª)
execution while Figure 2B is characterized from the twenty-fifth to the forty-fifth (45ª)
execution of the dynamometer protocol. Note that there is a similar behavior in all the groups
tested. These values are consistent with the fatigue pattern generated during the protocols
with higher execution numbers and intermediate speed (5,26,28).
71
Figure 2. The Torque Behavior Generated from the 45 Executions of Knee Extension on
the Isokinetic Dynamometer. Figure 2A is characterized from the beginning of the test to the
twenty-fifth (25ª) execution. Figure 2B is characterized from the twenty-fifth to the forty-fifth (45ª)
execution (P<0.01). Figure 2C presents the subjects’ torque behavior generated during the 45
executions of knee extension on the isokinetic dynamometer (*P<0.01), δ No Significance (P>0.05).
We found an increase of 4.25% in the amount of torque generated by the Caf group, an
increase of 3.45% in the Cr group, and 5.79% in the CrCaf group. These values represent the
data from the electromyographic activity in Figure 1.
In the Figure 3, the behavior in the peak torque and the fatigue values from % (B) generated
during the study are presented. There were no significant differences in these values
between the groups, even though there was an interesting decrease in fatigue in the CrCaf
group.
72
Figure 3. Figure A Presents the Subjects’ Peak Torque in Each Group. Figure B
Presents the Subjects’ Fatigue during the Work on the Isokinetic Dynamometer
(P>0.05).
Although the subjects’ peak torque data and % fatigue do not show significant differences,
these findings are complementary and may, therefore, not change the importance of the
results in regards to the Cr and Caf supplementation.
Figure 4 presents the comparison of the torque produced in relation to the total time on the
isokinetic dynamometer. The findings indicate, while it can be observed that in some groups
torque was increased, the time of work was reduced. This finding confirms the effectiveness
of the protocol used.
Figure 4. The Correlation between the Torque Produced and the Time for Execution of
Work.
DISCUSSION
Figure 1 indicates that the ingestion of caffeine increased the EMG activity in both the Caf
group and the CrCaf group. An explanation for this finding is caffeine inhibiting the action of
butyrylcholinesterase (BuChe) and acetylcholinesterase enzymes (AChE) (1,6,23).
73
Another important finding in the present study was that the CrCaf group obtained values in
the EMG activity similar to the Caf group. This demonstrates that the association between
these two compounds do not interfere with the ergogenic action of one another, which is
contrary to some studies (15,45). This finding indicates that this association can inhibit or
even eliminate the ergogenic action from the supplementation.
When torque production was analyzed throughout the work (Figure 2), there was a significant
increase in torque (P<0.01). This can be explained in the groups supplemented with Cr, given
the increase in the PCr concentration by the Cr supplementation in the skeletal muscle tissue.
Thus, the increase in PCr improves the subjects’ ability to resynthesize ATP (adenosine
triphosphate) (13,30). This means PCr provides energy during high-intensity exercise along
with the decrease in reliance on anaerobic glycolysis to attend the demand for energy during
the maximum workloads (20,31). Also, PCr decreases the concentration in the intramuscular
H+ accumulation while increasing the buffering capacity (10,25,37,44). The result is an
increase in the force production force and delay in the onset of fatigue.
Interestingly, the group that achieved greater torque values was the CrCaf group. The
subjects achieve an increase of 5.79%, which corroborates with the findings of other
researchers in animals (11,21). This indicates that the ergogenic effect is greater due to the
combination of Cr and Caf.
Despite the fact that this study found significant values in EMG activity and torque, there were
no significant changes in the peak torque and fatigue index (Figure 3) despite the fact that
there was a non-significant decrease in the subjects’ fatigue of 4.58% in the CrCaf group. In
Figure 4, when we correlated the torque produced during the work and the total time that the
subjects performed the protocol, the supplemented groups obtained higher values of torque
at lower total time, and the group CrCaf in particular got the best correlation torque and time.
This study determined that the ingestion of caffeine improved primarily the EMG activity, and
the Cr ingestion improved mainly the rate torque production in the protocol used. However, it
is clear that there were better results in both EMG activity and torque production when
creatine and caffeine were combined.
Limitations of this Study
A limitation of the present research is the fact that we did not perform tests of dosages of
metabolites (such as creatine dosage absorption by the tissue), which may have provided
addition information (16). However, this research technique requires costly equipment and
acquisition of skeletal muscle tissue for analysis, which is frequently not possible to carry out.
CONCLUSIONS
The findings indicate that there was a significant increase in torque in the supplemented
groups with creatine and caffeine. Also, the consumption of 6 mg·kg-1 caffeine in combination
with 3 g of creatine for 7 days generated significant change in the subjects’ resistant
performance. Thus, the data highlight the fact that the supplementation of both creatine and
caffeine does not inhibit the Cr ergogenic effect, but rather potentiates the effect.
74
Address for correspondence: Diego Pereira Jerônimo, Faculty of Physical Education, State
University of Campinas (UNICAMP), Av. Érico Veríssimo, 701, City University Zeferino Vaz,
Barão Geraldo CEP 13.083-851, Campinas, SP, Brazil. Tel.: +55 35 9839-1004. Electronic
mail: diego-jeronimo@hotmail.com
REFERENCES
1. Acquas E, Tanda G, Chiara GD. Differential effects of caffeine on dopamine and
acetylcholine transmission in brain areas of drug-naive and caffeine-pretreated rats.
Neuropsychopharmacology. 2002:27(2):182-193.
2. Armstrong LE, Casa DJ, Maresh CM, et al. Caffeine, fluid-electrolyte balance,
temperature regulation, and exercise-heat tolerance. Exerc Sport Sci Reviews. 2007:
35:135-140.
3. Baume N, Mahler N, Kamber M, et al. Research of stimulants and anabolic steroids in
dietary supplements. Scand J Med Sci Sports. 2005:16:41-48.
4. Betz AJ, Vontell R, Valenta J, et al. Effects of the adenosine A< sub> 2A</sub>
antagonist KW 6002 (istradefylline) on pimozide-induced oral tremor and striatal c-Fos
expression: comparisons with the muscarinic antagonist tropicamide. Neuroscience.
2009:163(1):97-108.
5. Bond V, Gresham K, McRae J, et al. Caffeine ingestion and isokinetic strength. Brit J
Sports Med. 1986:20(3):135-137.
6. Brown DA. Acetylcholine. Brit J Pharmacol. 2006:147(S1):S120-S126.
7. Chen TC, Nosaka K, Tu J. Changes in running economy following downhill running. J
Sports Sci. 2007:25(1):55-63.
8. Curi RUI, Filho JPA. Fisiologia Básica. Rio de Janeiro, Guanabara Koogan, 2009.
9. Cunha RA. Adenosine as a neuromodulator and as a homostatic regulation in the
nervous system: Different sources and different receptors. Neurochem Int. 2001:38
(2):107-125.
10. DeVries MC, Phillips SM. Creatine supplementation during resistance training in older
adults: A meta-analysis. Med Sci Sports Exerc. 2014:46(6):1194-1203.
11. Franco FSC, Costa NMB, Ferreira SA, et al. The effects of a high dosage of creatine
and caffeine supplementation on the lean body mass composition of rats submitted to
vertical jumping training. J Inter Soc Sports Nutri. 2011:8(3).
12. Greenberg JA, Boozer CN, Geliebter A. Coffee, diabetes, and weight control. Am J
Clin Nutr. 2006:84(4):682-693.
75
13. Greenhaff PL. The creatine-phosphocreatine system: There’s more than one song in
its repertoire. J Physiol. 2001:537(3):657-657.
14. Hermens HJ, Freriks B, Disselhorst-Klug C, Rau G. Development of recommendations
for SEMG sensors and sensor placement procedures. J Electromyogr Kines. 2000:
10(5):361-374.
15. Hespel P, OP’T Eijnde B, Van Leemputte M. Opposite actions of caffeine and creatine
on muscle relaxation time in humans. J Appl Physiol. 2002:92(2): 513-518.
16. Jeronimo DP, De Souza RA, Da Silva FF, et al. Detection of creatine in rat muscle by
FTIR spectroscopy. Annals Biomed Engineer. 2012:40(9):2069-2077.
17. Kato M, Noda M, Inoue M, et al. Psychological factors, coffee and risk of diabetes
mellitus among middle-aged Japanese: A population-based prospective study in the
JPHC Study Cohort. Endocr J. 2009;56(3):459-468.
18. Keijzers GB, De Galan BE, Tack CJ, et al. Caffeine can decrease insulin sensitivity in
humans. Diabetes Care. 2002:25(2):364-369.
19. Kreider RB, Wilborn CD, Taylor L, et al. Exercise & sport nutrition review: Research &
recommendations. J Intern Society Sports Nutr. 2010:7(7):1-43.
20. Kreider RB. Effects of creatine supplementation on performance and training
adaptations. Mol Cell Biochem. 2003:244:89-94.
21. Lee C-L, Jung-Charng C, et al. Effect of caffeine ingestion after creatine
supplementation on intermittent high-intensity sprint performance. Euro J Appl
Physiol. 2011;111(8):1669-1677.
22. McArdle WD, Katch FL, Katch VL. Fundamentos de Fisiologia do Exercício. (2nd
Edição). Rio de Janeiro: Guanabara Koogan, 2006.
23. Nehlig A, Debry G. Caffeine and sports activity: A review. Intern J Sports Med. 1994;
15:215-223.
24. Ocarino JDM, Silva PLPD, Vaz DV, et al. Eletromiografia: Interpretação e aplicações
nas ciências da reabilitação. Fisioterapia. Brasil. 2005:6(4):305-310.
25. Parise G, Mihic S, MacLennan D, et al. Effects of acute creatine monohydrate
supplementation on leucine kinetics and mixed-muscle protein synthesis. J Appl
Physiol. 2001:91(3):1041-1047.
26. Pascoa MRS, Alvim CR, Rodrigues LOC. Efeitos da cafeína sobre a força muscular.
Min J Phys Educ. 1994;2(1):S56.
76
27. Persky AM, Brazeau GA. Clinical pharmacology of the dietary supplement creatine
monohydrate. Pharmacol Rev. 2001:53(2):161-176.
28. Pinto RS, Cadore EL, Correa CS, et al. Relationship between workload and
neuromuscular activity in the bench press exercise. Med Sports. 2013:17(1):1-6.
29. Pohanka M, Dobes P. Caffeine Inhibits acetylcholinesterase, but not
butyrylcholinesterase. Intern J Molecular Sci. 2013:14(5): 9873-9882.
30. Prevost MC, Nelson AG, Morris GS. Creatine supplementation enhances intermittent
work performance. Res Quart Exerc Sport. 1997;68(3):233-240.
31. Roschel H, Gualano B, Marquezi M, et al. Creatine supplementation spares muscle
glycogen during high intensity intermittent exercise in rats. J Intern Society Sports
Nutr. 2010;7(1):2-7.
32. Ross GW, Abbott RD, Petrovitch H, White LR, Tanner CM. Relationship between
caffeine intake and Parkinson disease. JAMA. 2000:284:1378-1379.
33. Sacco ICNE, Tanaka C. Cinesiologia e Biomecânica dos Complexos Articulares.
Rio de Janeiro: Guanabara Koogan, 2008.
34. Silverthorn DU. Fisiologia Humana: Uma Abordagem Integrada. (5th Edição). Porto
Alegre, Ed. Artmed, 2010.
35. Smith AE, Walter AA, Herda TJ, et al. Effects of creatine loading on electromyographic
fatigue threshold during cycle ergometry in college-aged women. J Intern Society
Sports Nutr. 2007:4(20):1-6.
36. Vandenberghe K, Gillis N, Van Leemputte M, et al. Caffeine counteracts the ergogenic
action of muscle creatine loading. J Appl Physiol. 1996;80(2):452-457.
37. Vandenberghe K, Goris M, Van HP, et al. Long-term creatine intake is beneficial to
muscle performance during resistance training. J Appl Physiol. 1997; 83(6):2055-
2063.
38. Van Dijk AE, Olthof MR, Meeuse JC, et al. Acute Effects of decaffeinated coffee and
the major coffee components chlorogenic acid and trigonelline on glucose tolerance.
Diabetes Care. 2009;32(6):1023-1025.
39. Volek JS, Ratamess NA, Rubin MR, et al. The effects of creatine supplementation on
muscular performance and body composition responses to short-term resistance
training overreaching. Euro J Appl Physiol. 2004:91(5-6):628-637.
40. Walker JB, Creatine: Biosynthesis, regulation and function. Adv Enzymol Relat
AreasMol Bio. 1979:50(1):177-242.
77
41. Warren GL, Park ND, Maresca RD, et al. Effect of caffeine ingestion on muscular
strength and endurance: A meta-analysis. Med Sci Sports Exerc. 2010:42(7):1375-
1387.
42. Wilder N, Deivert RG, Hagerman F, et al. The effects of low-dose creatine
supplementation versus creatine loading in collegiate football players. J Athl Train.
2001:36 (2):124-129.
43. Williams J, Abt G, Kilding AE. Effects of creatine monohydrate supplementation on
simulated soccer performance. Inter J Sports Physiol Perform. 2014:3:503-510.
44. Williams MH, Kreider RB, Branch JD. Creatina. São Paulo: Ed. Manole, 2000.
45. Wyss M, Kaddurah-Daouk R. Creatine and creatinine metabolism. Physiologic
Rev. 2000;80(3):1107-1213.
46. Xing H, Azimi-Zonooz A, Shuttleworth CW, et al. Caffeine releasable stores of Ca2+
show depletion prior to the final steps in delayed CA1 neuronal death. J
Neurophysiol. 2004;92(5):2960-2967.
47. Xu K, Bastia E, Schwarzschild M. Therapeutic potential of adenosine A< sub>
2A</sub> receptor antagonists in Parkinson's disease. Pharmacol Ther. 2005:105(3):
267-310.
48. Zhan E, McIntosh VJ, Lasley RD. Adenosine A2A and A2B receptors are both required
for adenosine A1 receptor-mediated cardioprotection. Am J Physiol-Heart Circul
Physiol. 2011;301(3):H1183-H1189.
Disclaimer
The opinions expressed in JEPonline are those of the authors and are not attributable to
JEPonline, the editorial staff or the ASEP organization.
... The studies finally included were 10 randomized PLA-controlled trials, seven double blind (Doherty et al., 2002;Hespel et al., 2002;Lee et al., 2011Lee et al., , 2012Pakulak et al., 2021;Vanakoski et al., 1998;Vandenberghe et al., 1996), two single blind (Jerônimo et al., 2017;Quesada & Gillum, 2013), and a partially blind trial (Trexler et al., 2016). Eight of the 10 studies included had a crossover design (Doherty et al., 2002;Hespel et al., 2002;Jerônimo et al., 2017;Lee et al., 2011Lee et al., , 2012Quesada & Gillum, 2013;Vanakoski et al., 1998;Vandenberghe et al., 1996), whereas the remaining studies had a parallel design (Pakulak et al., 2021;Trexler et al., 2016). ...
... The studies finally included were 10 randomized PLA-controlled trials, seven double blind (Doherty et al., 2002;Hespel et al., 2002;Lee et al., 2011Lee et al., , 2012Pakulak et al., 2021;Vanakoski et al., 1998;Vandenberghe et al., 1996), two single blind (Jerônimo et al., 2017;Quesada & Gillum, 2013), and a partially blind trial (Trexler et al., 2016). Eight of the 10 studies included had a crossover design (Doherty et al., 2002;Hespel et al., 2002;Jerônimo et al., 2017;Lee et al., 2011Lee et al., , 2012Quesada & Gillum, 2013;Vanakoski et al., 1998;Vandenberghe et al., 1996), whereas the remaining studies had a parallel design (Pakulak et al., 2021;Trexler et al., 2016). In total, there were 170 participants in the 10 studies (157 men and 13 women). ...
... In total, there were 170 participants in the 10 studies (157 men and 13 women). Eight of the 10 studies included had fewer than 20 participants (Doherty et al., 2002;Hespel et al., 2002;Jerônimo et al., 2017;Lee et al., 2011Lee et al., , 2012Quesada & Gillum, 2013;Vanakoski et al., 1998;Vandenberghe et al., 1996); only two assessed the effects of CAF and CRE in a larger group of subjects (Pakulak et al., 2021;Trexler et al., 2016). Most of the studies included participants aged between 18 and 25 years. ...
Article
There is some controversy regarding the interactions between creatine (CRE) and caffeine (CAF) supplements. The aim of this systematic review was to study whether such ergogenic interaction occurs and to analyze the protocol to optimize their synchronous use. The PubMed, Web of Science, MEDLINE, CINAHL, and SPORTDiscus databases were searched until November 2021 following the PRISMA guidelines. Ten studies were included. Three studies observed that CRE loading before an acute dose of CAF before exercise did not interfere in the beneficial effect of CAF, whereas one study reported that only an acute supplementation (SUP) of CAF was beneficial but not the acute SUP of both. When chronic SUP with CRE + CAF was used, two studies reported that CAF interfered in the beneficial effect of CRE, whereas three studies did not report interaction between concurrent SUP, and one study reported synergy. Possible mechanisms of interaction are opposite effects on relaxation time and gastrointestinal distress derived from concurrent SUP. CRE loading does not seem to interfere in the acute effect of CAF. However, chronic SUP of CAF during CRE loading could interfere in the beneficial effect of CRE.
... To our knowledge, there is only a narrative review evaluating the potential ergogenic of CRE and CAF, in which authors concluded that ingestion of both supplements provides gastrointestinal side effects and concurrent responses on muscle hydration status and muscle relaxation time (Trexler and Smith-Ryan 2015). As several experimental studies have been published after this narrative review (Orange and Sadler 2015;Trexler et al. 2016;Pakulak et al. 2021;Jerônimo et al. 2017), it is recommended an updated and advance for a systematic review. In the present systematic review, we analyzed studies investigating the effects on exercise performance from combining CAF intake with CRE, either during or after a CRE loading period. ...
... The main characteristics of the 10 selected studies are described in Tables 1-3. Six studies were classified as methodologically strong (Doherty et al. 2002;Cheng 2011, 2012;Orange and Sadler 2015;Pakulak et al. 2021;Trexler et al. 2016), three as moderate (Hespel, 'T Eijnde, and Van Leemputte 2002;Vanakoski et al. 1998;Vandenberghe et al. 1996) and one as weak (Jerônimo et al. 2017). ...
... Only three studies recruited a mixed sample with men and women (Hespel, 'T Eijnde, and Van Leemputte 2002;Pakulak et al. 2021;Vanakoski et al. 1998); the remaining seven studies recruited only men (Doherty et al. 2002;Jerônimo et al. 2017; C. L. Cheng 2011, 2012;Orange and Sadler 2015;Trexler et al. 2016;Vandenberghe et al. 1996). Participants were described as healthy (Hespel, 'T Eijnde, and Van Leemputte 2002;Jerônimo et al. 2017; C. L. Cheng 2011, 2012;Orange and Sadler 2015;Trexler et al. 2016;Vandenberghe et al. 1996), resistance trained (Pakulak et al. 2021) or runners (Doherty et al. 2002;Vanakoski et al. 1998). ...
Article
Creatine (CRE) and caffeine (CAF) have been used as ergogenic aids to improve exercise performance. The present study reviewed the current evidence supporting the additional use of CAF intake during or after the CRE loading on exercise performance. The search was carried out in eight databases, with the methodological quality of the studies assessed via the QualSyst tool. From ten studies that met the criteria for inclusion, six had strong, three moderate, and one weak methodological quality. CAF was ingested ∼1 h before the performance trial (5–7 mg.kg⁻¹) after a CRE loading period (5–6 days with 0.3 g.kg⁻¹.d⁻¹) in five studies, with the combination CAF + CRE providing additional ergogenic effect compared to CRE alone in three of these studies. Furthermore, CAF was ingested daily during the CRE loading protocol in five studies, with CAF showing additive benefits compared to CRE alone only in one study (3 g.d⁻¹ of CRE during 3 days + 6 mg.kg⁻¹ of CAF for 3 days). The combination CAF + CRE seems to provide additional benefits to exercise performance when CAF is acutely ingested after a CRE loading. There is, however, no apparent benefit in ingesting CAF during a CRE loading period.
... Sesuai dengan pendapat(Nabawi, 2013) latihan fisik yang sistematis dapat menjadi fondasi yang kuat untuk mencapai prestasi puncak. Creatine (Cr) memainkan peran penting dalam pasokan energi cepat selama kontraksi otot(Jerônimo et al., 2017).Namun perlu di perhatikan, beberapa cabang olahraga yang memerlukan kekuatan otot yang maksimal dan daya tahan otot dengan jangka waktu yang cukup lama latihan fisik yang maksimal saja belum cukup.Pada penelitian(Zahra & Muhlisin, 2020) juga mendukung hasil penelitian ini, bahwa dengan mengkonsumsi creatine dan juga melakukan latihan dengan intensitas maksimal akan meningkatkan daya tahan. Mengkonsumsi creatine monohydrate dengan takaran yang sesuai akan membantu tubuh dalam menciptakan energi cadangan dari ATP.Produksi ATP akan di perbanyak dan ini akan membuat meningkatnya kontraksi otot dalam waktu yang lebih lama(Saragih & Mesnan, 2017). ...
Article
Abstrak kemampuan atlet dalam mempertahankan daya tahan anaerobik dapat diakibatkan oleh kurangnya asupan nutrisi berupa suplemen yang dapat membantu tubuh mempertahankan kebugaran sehingga mengatasi kelelahan fisik, dan dapatmenyediakan energi tambahan. Penelitian ini bertujuan untuk mengetahui pengaruh pemberian suplemen creatine monohydrate terhadap peningkatan daya tahan anaerobik atlet bola basket. Jenis penelitian yang digunakan adalah eksperimen semu dengan desain kelompok kontrol pre-posttest. Populasi adalah atlet putra FIK UNP dengan sampel 20 atlet yang dibagi menjadi satu kelompok eksperimen dan satu kelompok kontrol. Pengambilan sampel dilakukan dengan Total sampling. Instrumen dalam mengukur daya tahan anaerobik yaitu RAST Test. Teknik analisis data yang digunakan adalah uji T. Hasil menunjukkan perbedaan dalam peningkatan daya tahan anaerobik antara kelompok eksperimen dan kelompok kontrol yang di beri perlakuan selama 6 minggu. Kelompok eksperimen yang diberikan latihan dan creatine monohydrate mengalami peningkatan daya tahan anaerobik lebih baik dari kelompok kontrol yang hanya melakukan latihan saja. Kelompok eksperimen yang diberikan creatine monohydrate mengalami peningkatan daya taha n anaerobik 11,89% sedangkan kelompok kontrol yang hanya melakukan latihan mengalami peningkatan daya tahan anaerobik 4,08%. Kesimpulannya ada perbedaan peningkatan daya tahan anaerobik di antara kelompok eksperimen dan kelompok kontrol. Pemberian suplemen creatine monohydrate yang diikuti dengan latihan menjadi cara yang efektif untuk meningkatkan daya tahan anaerobik atlet. Abstract The low ability of athletes to maintain anaerobic endurance can be caused by a lack of intake of energy-boosting supplements that can maintain one's fitness reduce physical fatigue, and can provide additional energy. This has a look at goals to decide the effect of creatine monohydrate supplementation on increasing the anaerobic endurance of basketball athletes. The design in this observation became quasi-experimental with a pre-posttest control group design. The population was male athletes from FIK UNP, with a sample of 20 athletes who were divided into one experimental group and one control group. Sampling was done by total sampling. RAST test is used as an instrument in this research. The data analysis technique used is the T-test. The results showed a difference in the increase in anaerobic endurance between the experimental group and the control group after being treated for 6 weeks. The experimental group that was given exercise and creatine monohydrate experienced an increase in anaerobic endurance better than the control group who only did exercise. The experimental group that was given creatine monohydrate experienced an increase in anaerobic endurance of 11.89%, while the control group, which only did exercise, experienced an increase in anaerobic endurance of 4.08%. the belief is that there's a distinction in the boom in anaerobic persistence between the experimental group and the control group. Giving creatine monohydrate supplementation followed by exercise is an effective way to increase the athlete's anaerobic endurance
Article
Creatine monohydrate supplementation (CrM) is a safe and effective intervention for improving certain aspects of sport, exercise performance, and health across the lifespan. Despite its evidence-based pedigree, several questions and misconceptions about CrM remain. To initially address some of these concerns, our group published a narrative review in 2021 discussing the scientific evidence as to whether CrM leads to water retention and fat accumulation, is a steroid, causes hair loss, dehydration or muscle cramping, adversely affects renal and liver function, and if CrM is safe and/or effective for children, adolescents, biological females, and older adults. As a follow-up, the purpose of this paper is to evaluate additional questions and misconceptions about CrM. These include but are not limited to: 1. Can CrM provide muscle benefits without exercise? 2. Does the timing of CrM really matter? 3. Does the addition of other compounds with CrM enhance its effectiveness? 4. Does CrM and caffeine oppose each other? 5. Does CrM increase the rates of muscle protein synthesis or breakdown? 6. Is CrM an anti-inflammatory intervention? 7. Can CrM increase recovery following injury, surgery, and/or immobilization? 8. Does CrM cause cancer? 9. Will CrM increase urine production? 10. Does CrM influence blood pressure? 11. Is CrM safe to consume during pregnancy? 12. Does CrM enhance performance in adolescents? 13. Does CrM adversely affect male fertility? 14. Does the brain require a higher dose of CrM than skeletal muscle? 15. Can CrM attenuate symptoms of sleep deprivation? 16. Will CrM reduce the severity of and/or improve recovery from traumatic brain injury? Similar to our 2021 paper, an international team of creatine research experts was formed to perform a narrative review of the literature regarding CrM to formulate evidence-based responses to the aforementioned misconceptions involving CrM.
Article
Purpose: The aim of the present study was to investigate the effects of acute caffeine supplementation on the performance during a session of resistance training alone (RT) or in combination with aerobic training (i.e. concurrent training; CT). Method: Fourteen resistance-trained men (23.1 ± 4.2 years) were recruited and performed both RT and CT under three different conditions: control (CONT), placebo (PLA), and caffeine (CAF; 6 mg.kg−1) for a total of six experimental conditions. Results: Both total and per set number of repetitions, and total volume load were lower during CT as compared to RT, irrespective of the supplementation condition (all p < .001), whereas a supplementation main effect was observed for the total number of repetitions (p = .001), the number of repetitions in the first (p = .002) and second sets (p = .001), and total volume load (p = .001). RPE values were higher after the CT sessions than after the RT sessions (p < .001), whereas no differences were observed between supplementation conditions (p = .865). Conclusions: Caffeine supplementation was not sufficient to minimize the acute interference effect on strength performance in a CT session when compared to RT alone. In contrast, caffeine improved strength performance during the first set of both CT and RT, while maintaining a similar RPE between the supplementation conditions. However, the overall effect was small.
Article
Full-text available
A eletromiografia (EMG) é uma técnica que permite o registro dos sinais elétricos gerados pelas células musculares, possibilitando a análise da atividade muscular durante o movimento. A compreensão de conceitos relativos a EMG é essencial para se assegurar a validade e confiabilidade desse instrumento de mensuração em pesquisas da área de reabilitação e na prática clínica de fisioterapeutas. Dessa forma, foi objetivo deste estudo discutir aspectos relevantes relacionados à coleta, processamento e análise de dados eletromiográficos de forma a facilitar a compreensão da instrumentação, aplicações e limitações da técnica. De acordo com a revisão realizada, diversos fatores que influenciam a qualidade dos dados coletados devem ser considerados, não apenas na utilização da técnica, mas também na interpretação e avaliação crítica de estudos que utilizam a EMG. Quando todos estes fatores são considerados, a EMG se torna uma ferramenta adequada para investigação da função muscular, tanto na pesquisa quanto na prática clínica de fisioterapeutas. Palavras-chave: eletromiografia, reabilitação, função muscular
Article
Full-text available
Caffeine is an alkaloid with a stimulant effect in the body. It can interfere in transmissions based on acetylcholine, epinephrine, norepinephrine, serotonin, dopamine and glutamate. Clinical studies indicate that it can be involved in the slowing of Alzheimer disease pathology and some other effects. The effects are not well understood. In the present work, we focused on the question whether caffeine can inhibit acetylcholinesterase (AChE) and/or, butyrylcholinesterase (BChE), the two enzymes participating in cholinergic neurotransmission. A standard Ellman test with human AChE and BChE was done for altering concentrations of caffeine. The test was supported by an in silico examination as well. Donepezil and tacrine were used as standards. In compliance with Dixon's plot, caffeine was proved to be a non-competitive inhibitor of AChE and BChE. However, inhibition of BChE was quite weak, as the inhibition constant, Ki, was 13.9 ± 7.4 mol/L. Inhibition of AChE was more relevant, as Ki was found to be 175 ± 9 µmol/L. The predicted free energy of binding was -6.7 kcal/mol. The proposed binding orientation of caffeine can interact with Trp86, and it can be stabilize by Tyr337 in comparison to the smaller Ala328 in the case of human BChE; thus, it can explain the lower binding affinity of caffeine for BChE with reference to AChE. The biological relevance of the findings is discussed.
Article
Full-text available
Objective: To investigate the relationship between strength and electromyographic (EMG) signal in different intensities in the bench press exercise. Methods: Eleven healthy resistance trained men (22.8 ± 3.5) participated into the present study. Maximal isometric strength was determined in the bench press exercise using a load cell. Muscle activation was assessed using surface electromyography (EMG) signals from the muscles pectoralis major, anterior deltoid and posterior deltoid at intensities ranging to 60-90% of maximal voluntary contraction (MVC), in the bench press exercise. This procedure allowed the analysis of the strength/EMG relationship. Results: In all muscles assessed, there were significant differences in the normalized muscle activation between the intensities of 60 and 70% of the MVC, as well as between 70 and 80% (P < 0.05), while there were no differences between 80 and 90% of MVC. In addition, there were significant correlations between strength and EMG signals for the muscles pectoralis major (r = 0.43, P = 0.04), anterior deltoid (r = 0.52, P = 0.01), and posterior deltoid (r = 0.32, P = 0.046). Conclusions: These results suggest that levels of muscle activation near to maximal are obtained at the intensity of 80 of MVC and no additional motor unit recruitment are achieved at 90% of MVC.
Article
Full-text available
There is a current lack of clarity regarding the use of Fourier-transform infrared spectroscopy (FT-IR) to evaluate intramuscular concentrations of creatine (Cr). Thus, the aim of this study was to assess the FT-IR spectral features of tibialis anterior muscle in rats submitted in conditions that were expected to perturb the Cr pool. First, an experiment was performed to ensure that FT-IR was able to detect the Cr intramuscular in sedentary and supplemented rats (Experiment 1). The effect of physical exercise on spectral muscle features was then examined, especially in relation to the spectroscopy markers (Experiment 2). Using pure Cr (control), it was possible to verify that only the peaks centered at 1308 and 1396 cm(-1) of all the spectra showed the same peak positions, indicating these FT-IR shifts as indirect markers of Cr intramuscular content. Experiment 2 revealed a higher Cr content for the Cr-supplemented and exercised animals than the rats of other groups. In conclusion, it was demonstrated that FT-IR spectroscopy using 1396 cm(-1) and mainly 1308 band was able to monitor Cr muscle content in rats sedentary, Cr-supplemented, and submitted to physical training. Besides, FT-IR could be a feasible method for the nondestructive assessment of Cr skeletal muscle content.
Article
Full-text available
The influences of creatine and caffeine supplementation associated with power exercise on lean body mass (LBM) composition are not clear. The purpose of this research was to determine whether supplementation with high doses of creatine and caffeine, either solely or combined, affects the LBM composition of rats submitted to vertical jumping training. Male Wistar rats were randomly divided into 8 groups: Sedentary (S) or Exercised (E) [placebo (Pl), creatine (Cr), caffeine (Caf) or creatine plus caffeine (CrCaf)]. The supplemented groups received creatine [load: 0.430 g/kg of body weight (BW) for 7 days; and maintenance: 0.143 g/kg of BW for 35 days], caffeine (15 mg/kg of BW for 42 days) or creatine plus caffeine. The exercised groups underwent a vertical jump training regime (load: 20 - 50% of BW, 4 sets of 10 jumps interspersed with 1 min resting intervals), 5 days/wk, for 6 weeks. LBM composition was evaluated by portions of water, protein and fat in the rat carcass. Data were submitted to ANOVA followed by the Tukey post hoc test and Student's t test. Exercised animals presented a lower carcass weight (10.9%; P = 0.01), as compared to sedentary animals. However, no effect of supplementation was observed on carcass weight (P > 0.05). There were no significant differences among the groups (P > 0.05) for percentage of water in the carcass. The percentage of fat in the group SCr was higher than in the groups SCaf and ECr (P < 0.05). A higher percentage of protein was observed in the groups EPl and ECaf when compared to the groups SPl and SCaf (P < 0.001). The percentage of fat in the carcass decreased (P < 0.001), while those of water and protein increased (P < 0.05) in exercised animals, compared to sedentary animals. Caffeine groups presented reduced percentage of fat when compared to creatine supplemented groups (P < 0.05). High combined doses of creatine and caffeine does not affect the LBM composition of either sedentary or exercised rats, however, caffeine supplementation alone reduces the percentage of fat. Vertical jumping training increases the percentages of water and protein and reduces the fat percentage in rats.
Article
Full-text available
The aim of this study was to investigate the effects of acute caffeine ingestion on intermittent high-intensity sprint performance after 5 days of creatine loading. After completing a control trial (no ergogenic aids, CON), twelve physically active men were administered in a double-blind, randomized crossover protocol to receive CRE + PLA (0.3 g kg(-1) day(-1) of creatine for 5 days then followed by 6 mg kg(-1) of placebo) and CRE + CAF (0.3 g kg(-1) day(-1) of creatine for 5 days and followed by 6 mg kg(-1) of caffeine), after which they performed a repeated sprint test. Each test consisted of six 10-s intermittent high-intensity sprints on a cycling ergometer, with 60-s rest intervals between sprints. Mean power, peak power, rating of perceived exertion (RPE), and heart rates were measured during the test. Blood samples for lactate, glucose, and catecholamine concentrations were drawn at specified intervals. The mean and peak power observed in the CRE + CAF were significantly higher than those found in the CON during Sprints 1 and 3; and the CRE + CAF showed significantly higher mean and peak power than that in the CRE + PLA during Sprints 1 and 2. The mean and peak power during Sprint 3 in the CRE + PLA was significantly greater than that in the CON. Heart rates, plasma lactate, and glucose increased significantly with CRE + CAF during most sprints. No significant differences were observed in the RPE among the three trials. The present study determined that caffeine ingestion after creatine supplements augmented intermittent high-intensity sprint performance.
Article
Full-text available
The effects of creatine (CR) supplementation on glycogen content are still debatable. Thus, due to the current lack of clarity, we investigated the effects of CR supplementation on muscle glycogen content after high intensity intermittent exercise in rats. First, the animals were submitted to a high intensity intermittent maximal swimming exercise protocol to ensure that CR-supplementation was able to delay fatigue (experiment 1). Then, the CR-mediated glycogen sparing effect was examined using a high intensity intermittent sub-maximal exercise test (fixed number of bouts; six bouts of 30-second duration interspersed by two-minute rest interval) (experiment 2). For both experiments, male Wistar rats were given either CR supplementation or placebo (Pl) for 5 days. As expected, CR-supplemented animals were able to exercise for a significant higher number of bouts than Pl. Experiment 2 revealed a higher gastrocnemius glycogen content for the CR vs. the Pl group (33.59%). Additionally, CR animals presented lower blood lactate concentrations throughout the intermittent exercise bouts compared to Pl. No difference was found between groups in soleus glycogen content. The major finding of this study is that CR supplementation was able to spare muscle glycogen during a high intensity intermittent exercise in rats.
Article
Age-related sarcopenia and dynapenia have negative effects on strength and the ability to perform activities of daily living. Resistance training (RT) increases muscle mass and strength in older adults and is an established countermeasure for sarcopenia and dynapenia and creatine may enhance this effect. We aimed to determine whether the addition of Cr to RT increased gains in muscle mass, strength and function in older adults over RT alone by conducting a systematic review and meta-analysis. Pubmed and Healthstar databases were searched. Randomized, placebo (PL) controlled trials that involved older adults supplemented with Cr and including RT regimes (>6wk) were included. Data were analyzed using fixed or random (if data were heterogeneous) effects meta-analysis using RevMan 5. The meta-analysis comprised 357 older adults (avg ± SD Cr: 63.6 ± 5.9, Pl: 64.2 ± 5.4) with 12.6 ± 4.9 wk of RT. Cr+RT increased total body mass (P = 0.004) and fat free mass (P < 0.0001) with no effect on fat mass as compared with RT alone. Cr+RT increased chest press (P = 0.004) and leg press (P = 0.02)1RM to a greater extent than RT alone, with no difference in effect on knee extension or biceps curl 1RM, isokinetic or isometric knee extension peak torque. Cr+RT had a greater effect than RT alone on the 30s chair stand test (P = 0.03). Retention of muscle mass and strength is integral to healthy aging. The results from this meta-analysis are encouraging in supporting a role for Cr supplementation during RT in healthful aging by enhancing muscle mass gain, strength and functional performance; however, the limited number of studies indicates further work is needed.
Article
To determine the effects of acute short-term creatine (Cr) supplementation on physical performance during a 90 minute soccer-specific performance test. A double-blind, placebo-controlled experimental design was adopted during which 16 male amateur soccer players were required to consume 20 g of Cr per day, for seven days or a placebo. A ball-sport endurance and speed test (BEAST) comprising measures of aerobic (circuit time), speed (12 and 20m sprint) and explosive power (vertical jump) abilities performed over 90 min was performed pre- and post-supplementation. Performance measures during the BEAST deteriorated during the second half relative to the first for both Cr (1.2 to 2.3%) and placebo (1.0 to 2.2%) groups, indicating a fatigue effect associated with the BEAST. However, no significant differences existed between groups suggesting that Cr had no performance enhancing effect or ability to offset fatigue. When effects sizes were considered, some measures (12m sprint: -0.53 ± 0.69; 20m sprint: -0.39 ± 0.59 showed a negative tendency, indicating chances of harm were greater than chances of benefit. Acute short-term Cr supplementation has no beneficial effect on physical measures obtained during a 90 minute soccer simulation test, thus questioning its potential as an effective ergogenic aid for soccer players.
Article
All four adenosine receptor subtypes have been shown to play a role in cardioprotection, and there is evidence that all four subtypes may be expressed in cardiomyocytes. There is also increasing evidence that optimal adenosine cardioprotection requires the activation of more than one receptor subtype. The purpose of this study was to determine whether adenosine A(2A) and/or A(2B) receptors modulate adenosine A(1) receptor-mediated cardioprotection. Isolated perfused hearts of wild-type (WT), A(2A) knockout (KO), and A(2B)KO mice, perfused at constant pressure and constant heart rate, underwent 30 min of global ischemia and 60 min of reperfusion. The adenosine A(1) receptor agonist N(6)-cyclohexyladenosine (CHA; 200 nM) was administrated 10 min before ischemia and for the first 10 min of reperfusion. Treatment with CHA significantly improved postischemic left ventricular developed pressure (74 ± 4% vs. 44 ± 4% of preischemic left ventricular developed pressure at 60 min of reperfusion) and reduced infarct size (30 ± 2% with CHA vs. 52 ± 5% in control) in WT hearts, effects that were blocked by the A(1) antagonist 8-cyclopentyl-1,3-dipropylxanthine (100 nM). Treatments with the A(2A) receptor agonist CGS-21680 (200 nM) and the A(2B) agonist BAY 60-6583 (200 nM) did not exert any beneficial effects. Deletion of adenosine A(2A) or A(2B) receptor subtypes did not alter ischemia-reperfusion injury, but CHA failed to exert a cardioprotective effect in hearts of mice from either KO group. These findings indicate that both adenosine A(2A) and A(2B) receptors are required for adenosine A(1) receptor-mediated cardioprotection, implicating a role for interactions among receptor subtypes.