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Effect of Acute Creatine Supplementation and Subsequent Caffeine Ingestion on Ventilatory Anaerobic Threshold

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Ventilatory anaerobic threshold (VT) is an important indicator of cardiorespiratory fitness and metabolic adaptations. Creatine and caffeine are popular and effective ergogenic aides during aerobic and anaerobic exercise. The purpose of this study is to assess the effects of acute creatine supplementation and subsequent caffeine ingestion on VT. Seven moderately active males (age = 20.8 yrs ± 1.7, height = 178.9 cm ± 17.4, weight = 83.9 kg ± 17.4) completed the randomized, single blind, crossover design supplementation and interval running protocol. All subjects completed a placebo trial (PBO), creatine plus caffeine trial (CRE+CAFF), and caffeine plus placebo trial (CAFF). Two hours before the running protocol, subjects ingested 100 mgkg-1 of creatine or placebo, and 20 min before the protocol ingested 6 mgkg-1 of caffeine or placebo. The interval running protocol started at 6.0 mileshr-1 and increased 0.6 mileshr-1 every 3 min until volitional exhaustion. Ventilatory anaerobic threshold, maximal oxygen consumption (VO2 max), heart rate (HR), rating of perceived exertion (RPE), and time to exhaustion (TTE) were measured. Ventilatory anaerobic threshold in CAFF (35.08 mLkg-1min-1 ± 5.7) was significantly higher (P<0.05) than PBO (29.05 mLkg-1min-1 ± 2.3). No difference between CRE+CAFF (32.68 mLkg-1min-1 ± 4.02) and PBO or CAFF and CRE+CAFF occurred. Maximal oxygen consumption, HR, RPE, and TTE were not significantly different (P<0.05) between groups. These results suggest that acute combination supplementation of creatine and caffeine does not improve VT, possibly due to their opposing metabolic mechanisms.
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112
Journal of Exercise Physiology
online
August 2013
Volume 16 Number 4
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
Effect of Acute Creatine Supplementation and
Subsequent Caffeine Ingestion on Ventilatory
Anaerobic Threshold
Taylor Quesada, Trevor Gillum
California Baptist University, Riverside, CA, USA
ABSTRACT
Quesada TD, Gillum T. Effect of Acute Creatine Supplementation
and Subsequent Caffeine Ingestion on Ventilatory Anaerobic
Threshold. JEPonline 2013;16(4):112-120. Ventilatory anaerobic
threshold (VT) is an important indicator of cardiorespiratory fitness and
metabolic adaptations. Creatine and caffeine are popular and effective
ergogenic aides during aerobic and anaerobic exercise. The purpose of this
study is to assess the effects of acute creatine supplementation and
subsequent caffeine ingestion on VT. Seven moderately active males (age =
20.8 yrs ± 1.7, height = 178.9 cm ± 17.4, weight = 83.9 kg ± 17.4) completed
the randomized, single blind, crossover design supplementation and interval
running protocol. All subjects completed a placebo trial (PBO), creatine plus
caffeine trial (CRE+CAFF), and caffeine plus placebo trial (CAFF). Two
hours before the running protocol, subjects ingested 100 mg·kg
-1
of creatine
or placebo, and 20 min before the protocol ingested 6 mg·kg
-1
of caffeine or
placebo. The interval running protocol started at 6.0 miles·hr
-1
and increased
0.6 miles·hr
-1
every 3 min until volitional exhaustion. Ventilatory anaerobic
threshold, maximal oxygen consumption (VO
2
max), heart rate (HR), rating
of perceived exertion (RPE), and time to exhaustion (TTE) were measured.
Ventilatory anaerobic threshold in CAFF (35.08 mL·kg
-1
·min
-1
± 5.7) was
significantly higher (P<0.05) than PBO (29.05 mL·kg
-1
·min
-1
± 2.3). No
difference between CRE+CAFF (32.68 mL·kg
-1
·min
-1
± 4.02) and PBO or
CAFF and CRE+CAFF occurred. Maximal oxygen consumption, HR, RPE,
and TTE
were not significantly different (P>0.05) between groups. These
results suggest that acute combination supplementation of creatine and
caffeine does not improve VT, possibly due to their opposing metabolic
mechanisms.
Key Words: VO
2
max, Ergogenic Aides, Metabolic Adaptations
113
INTRODUCTION
Physically active individuals and athletes often use multiple complementary ergogenic aides to
enhance performance during aerobic and anaerobic exercise. Athletes, in particular, will supplement
their training routine with creatine and/or caffeine to gain ergogenic effects such as increases in
power, time to exhaustion (TTE), delay fatigue, and improved recovery (1,3,6,7,10,16,22,23).
Combined supplementation of creatine and caffeine has been discouraged in the past (27,28), but
more recent studies suggest that these supplements may be beneficially used simultaneously
(6,16,23).
Creatine is stored in skeletal muscle as phosphocreatine (PCr), where it helps to rapidly resynthesize
adenosine triphosphate (1,3,26). Creatine monohydrate supplementation facilitates phosphocreatine
storage and has shown to be most effective in improving high-intensity, repeated bout, sprint
performance with a short rest periods (3,10). Most studies that test the ergogenic effects of creatine
use a 3 to 6 day loading regimen, which has exhibited increased skeletal muscle phosphocreatine
storage, increased power, increased lean body mass, and positively affected ventilatory threshold
(1,3,4,10). Schedel et al. (21) demonstrated that acute creatine supplementation enhanced secretion
of human growth hormone, with the highest concentration measured between 2 to 6 hrs after
ingestion. Cook and Crewther et al. (4) found that acute supplementation of creatine 90 min before a
rugby passing skills protocol exhibited better accuracy and execution than the placebo or control
groups.
Caffeine works as an A
1
and A
2a
adenosine receptor antagonist, which is thought to be the main
mechanism for caffeine’s ergogenic effects of fatigue resistance, lowered pain perception, and
reduced RPE, while maintaining muscular excitability, especially during anaerobic activity (5,6,18,29).
Furthermore, caffeine supplementation stimulates the central nervous system to produce effects such
as increased TTE, mean power, mean speed, and agility at doses ranging from 3 to 7 mg·kg
-1
(7,6
22,25).
According to their respective mechanisms, creatine is an anabolic substance and caffeine is a
catabolic substance. Earlier research concerning the combination of these supplements has
suggested that caffeine inhibits the ergogenic effects of creatine during isokinetic muscle
contractions, possibly due to the supplements’ opposite effects on muscle relaxation time (13,28).
Vanakoski (29) found that the ergogenic effects of caffeine were not affected by creatine, but that
creatine did not improve aerobic or anaerobic performance when taken with caffeine. Conversely,
Doherty and Smith et al. (6) found that creatine absorption was not affected by acute caffeine
ingestion 20 min before high intensity interval training (HIIT). Recent studies suggest that both
creatine and caffeine may work together to produce effective aerobic and anaerobic enhancements
when creatine loading occurs for approximately five days and caffeine is ingested in an acute manner
20 min to 1 hr prior to a running or cycling protocol (6,16,23). Previous studies have shown that
consuming an energy supplement containing creatine and caffeine 10 min prior to a resistance
training, endurance, or running protocol improved performance indicators such as VO
2
max, training
volume, and power output (9,20,23).
Ventilatory anaerobic threshold (VT) is an important indicator of cardiorespiratory fitness and can aid
in the prediction of onset of anaerobic/lactate threshold (8). Individuals that have similar maximal
oxygen consumption (VO
2
max) may differ in regards to their VT depending on their level of training.
Highly trained athletes will perform at a higher percentage of their VO
2
max with less lactate
accumulation (8). Ventilatory anaerobic threshold occurs at the breakpoint when pulmonary
ventilation (V
E
) and oxygen consumption (VO
2
) begin to rise in a non-linear trend. Also, aerobic
114
metabolism during exercise transitions to anaerobic metabolism at the VT. Creatine has
demonstrated the ability to improve VT by 16% during high intensity interval training (HIIT) (10).
Caffeine has not exhibited significant improvements in VT (14,19), but has demonstrated positive
effects regarding VO
2
peak (6).
Research has been clear that both creatine and caffeine are effective ergogenic aides to enhance
various aspects of aerobic and anaerobic performance (1,2,3,6,7,10,11,12,22,25,26). Research
regarding the effects of combination supplementation needs to be conducted so that active people
can become more confidently educated regarding the effects of the supplements they choose to
ingest for performance enhancement. More specifically, research is needed regarding the effects of
combining creatine and caffeine on VT. Thus, the purpose of this study is to assess the effect of
acute creatine supplementation and subsequent caffeine ingestion on VT. The hypothesis of this
study is that combination supplementation of creatine and caffeine will cause VT to occur at a higher
VO
2
when compared to placebo or caffeine alone.
METHODS
Subjects
Seven moderately active, college age, males participated in this study (age = 20.8 yrs ± 1.7, height =
178.9 cm ± 17.4, weight = 83.9 kg ± 17.4). Anthropometric data for height (cm) was measured using a
stadiometer (Tanita; Tokyo, Japan) and weight (kg) was measured on a Tanita scale (Tokyo, Japan).
Moderately active is defined in this study as performing moderate to intense exercise 3 to 5 d·wk
-1
.
Potential participants were excluded if they had a musculoskeletal injury in the past year,
supplemented with creatine in the last 90 days (10), were caffeine naïve, or consumed in excess of
300 mg of caffeine per day (16). Subjects were recruited through social networking. Each subject
filled out a Physical Activity Readiness Questionnaire (PAR-Q). Subjects answered “no” in response
to all questions on the PAR-Q to be eligible to participate in the study. All participants signed a written
consent form explaining the supplementation and running protocol procedures. Subjects were asked
to maintain their normal physical activity and diet throughout the duration of the study (10).
Supplementation Procedures
This study utilized a randomized, single-blind, crossover, and placebo-controlled design. First,
subjects underwent a placebo trial (PBO) to provide familiarization to the running protocol and
supplementation methods. Two hours before their scheduled trial time, the subjects consumed 100
mg·kg
-1
of the creatine placebo substance, Stevia, mixed in 590 ml of Gatorade. The second drink
was ingested twenty minutes before the scheduled trial time, which consisted of one 1 oz packet of
the caffeine placebo Crystal Light mixed in 236 ml of water. Subjects were unaware that the PBO
trial occurred first because the method of supplementation did not change between trials. The
subjects were then randomly placed into either a creatine plus caffeine group (CRE+CAFF) or a
caffeine plus placebo group (CAFF) for the second trial and switched supplement groups for the third
trial. Trials were scheduled at least 72 hrs apart, with no more than 7 days between trials. Subjects
were asked to refrain from caffeine and alcohol consumption 24 hrs before each trial and to refrain
from exercise 24 hrs before each trial (4,6). Subjects reported to the kinesiology lab after a 3hr fast to
reduce the interference of food on supplementation protocol (16). All subjects ingested two beverages
before each trial. The first beverage was ingested two hours prior to the scheduled trial time, which
contained 100 mg·kg
-1
of creatine (Creatine Monohydrate 500, Metabolic Response Modifiers;
Oceanside, CA.), or placebo (Stevia), mixed by the researcher in 590 ml of Gatorade (4,21). The
second drink was ingested 20 min before the running protocol, which contained 6 mg·kg
-1
of caffeine,
or placebo, mixed in 236 ml of water and powered Crystal Light (6).
115
Running Protocol
The subjects completed three trials of the interval running protocol throughout the study. The running
protocol consisted of 3-min intervals, which increased by 0.6 miles·hr
-1
from the previous stage,
starting with 6 miles·hr
-1
and ending at volitional exhaustion (15).
Determination of VO
2
max, VT, HR, RPE, and TTE
Maximal oxygen consumption was measured through expired gases using indirect calorimetry on a
Viasys metabolic cart (Yorba Linda, CA.). Ventilatory anaerobic threshold was determined through
the V-slope method, in which VT is identified by the non-linear breakpoint between VO
2
and
pulmonary ventilation (V
E
) (15). Heart rate was measured continuously by a Polar heart rate monitor
strapped to the subjectschest (Kempele, Finland). Rating of perceived exertion was measured every
3 min by the researcher using Borg’s RPE scale.
Statistical Analyses
Power analysis suggested that a sample size of 7 subjects would produce a power of 0.84 (6,10). A
repeated measures ANOVA was used to determine differences in VT, VO
2
, and TTE. A 2-way (group
x time) repeated measures analysis of variance (ANOVA) was performed using Statistica software
(version 10) to examine differences between CRE+CAFF, CAFF, and PBO supplementation for RPE
and HR. A Tukey Post-Hoc analysis was conducted if a significant P value of P<0.05 occurred. Data
were screened for normality and homogeneity of variance before statistical analysis.
RESULTS
Subjects
Out of the 9 subjects that were recruited, 7 male participants completed this study. One subject was
unable to finish all three trials due to caffeine intolerance and a second subject did not complete all
three trials due to scheduling conflicts. Three of the 7 subjects that completed the study reported mild
gastrointestinal discomfort only during the CRE+CAFF trial. The subjects demonstrated a significantly
(P<0.05) higher VT during CAFF (35.08 mL·kg
-1
·min
-1
± 5.7) when compared to PBO (29.06 mL·kg
-
1
·min
-1
± 2.3) as revealed by a Tukey Post Hoc analysis (Figure 1). There was no difference in VT
between CRE+CAFF compared to CAFF or PBO. Subjects did not exhibit a significantly (P>0.05)
higher VO
2
max between PBO (46.57 mL·kg
-1
·min
-1
± 4.14), CAFF (49.24 mL·kg
-1
·min
-1
± 6.2), and
CRE+CAFF (47.15 mL·kg
-1
·min
-1
± 5.9) (Figure 1).
Figure 1. Ventilatory Anaerobic Threshold in Relation to VO
2
max
Between Supplements.
VT and VO
2
max after consuming placebo, caffeine, or creatine and caffeine. *CAFF group exhibited a significantly
higher VT than PBO, P<0.05. PBO vs. CAFF, P=0.04.
*
116
Rating of perceived exertion was not significantly (P=0.7) different between CRE+CAFF, CAFF, and
PBO (Figure 2). Heart rate was not significantly different between CRE+CAFF, CAFF, and PBO
throughout the running protocol, P=0.8 (refer to Table 1). Time to exhaustion was not statistically
significant (P=0.88) between PBO (14:50 min ± 2:51), CAFF (15:51 min ± 4:26), and CRE+CAFF
(15:07 min ± 3:24). Time to exhaustion was not statistically significant (P=0.88) between PBO (14:50
min ± 2:51), CAFF (15:51 min ± 4:26), and CRE+CAFF (15:07 min ± 3:24).
Figure 2. Rating of Perceived Exertion after Consuming Creatine and Caffeine, Caffeine Alone,
and Placebo at the End of Each Stage during the Running Protocol.
Table 1. Heart Rate (beats·min
-1
) at Different Time Points during the Running Protocol.
3 min
6 min
9 min
12 min
15 min
18 min
141.4 ± 12.2
156.1 ± 13.2
166.8 ± 13.6
172.6 ± 13.5
177 ± 13.5
183 ± 14.7
140.6 ± 15
158.1 ± 13.2
168.4 ± 21.1
176.3 ± 18.5
179.6 ± 21.5
178.7 ± 19.7
145.4 ± 7.9
156.6 ± 12.2
167.3 ± 10.6
175.3 ± 11.2
180.2 ± 10.1
182.3 ± 11.8
DISCUSSION
Ventilatory threshold did not differ between the CRE+CAFF trial and PBO. However, VT was
significantly higher in the CAFF trial, when compared to PBO. This may suggest that an interaction
between the creatine (ingested 2 hrs prior to exercise) and caffeine supplements (ingested 20 min
prior to exercise) occurs when taken in an acute manner, or simultaneously, as suggested by
previous studies conducted by Hespel et al. (13) and Vandenberghe et al. (28). The anabolic
mechanism of creatine and the catabolic mechanism of caffeine may have counteracted and caused
a less than optimal utilization of each supplement during the running protocol. Also, Hespel et al. (13)
117
suggests that the opposing mechanisms may also account for each supplements’ opposite effects on
muscle relaxation time.
Unlike some previous studies that used 3 to 6 days creatine loading regimens with subsequent
caffeine ingestion 15 min to 20 min prior to exercise (6,16,23), this study used an acute
supplementation approach for both creatine and caffeine. Acute supplementation of creatine and
caffeine may have been the difference between the results of this study and others that found
combination supplementation to be beneficial to athletic performance (6,16,23). According to Schedel
et al. (19), acute creatine supplementation exhibited maximum human growth hormone blood serum
concentrations between 2 hrs and 6 hrs after ingestion. This would suggest that the optimum
performance outcomes should occur 2 to 6 hrs after creatine ingestion (21). Research by Gonzalez
(9) and Ratamess (20) found that ingesting a beverage that consisted of creatine and caffeine 10 to
20 min prior to exercise increased power, training volume, and endurance. Vanakoski (27) found that
the ergogenic effects of caffeine were not affected by creatine, but that creatine did not improve
aerobic or anaerobic performance when taken with caffeine. Conversely, although not statistically
significant, this study suggests that creatine may negatively affect the ergogenic properties of caffeine
because both VT and VO
2
max were lower in the CRE+CAFF trial when compared to the CAFF trial.
Smith et al. (23) exhibited that ingesting a supplement containing creatine and caffeine 30 min prior to
a high intensity running protocol improved VO
2
max. Although VT was significantly higher in the CAFF
trial, VO
2
max was not significantly different between groups. This may indicate that VT is a more
sensitive indicator of cardiorespiratory fitness than VO
2
max alone (8).
According to previous studies, caffeine should have produced a lower RPE than the placebo group
(5,6,18,29). A reduced RPE is due to caffeine’s mechanism as an A
1
and A
2
adenosine receptor
antagonist, which causes ergogenic effects such as lowered pain perception, while maintaining
muscular excitability (5,6,7,18,29). Doherty and Smith (7) suggest that caffeine supplementation
causes an altered perceptual response to exercise, which causes subjects to voluntarily exercise at a
higher capacity with less effort and more motor unit recruitment.
Due to its properties as an adenosine receptor antagonist, caffeine has consistently exhibited the
effect of raising HR throughout exercise (5,6,18,29). In regards to this study, 6 mg·kg
-1
of caffeine did
not elicit a higher HR in the CAFF or CRE+CAFF groups when compared to PBO. Interestingly the
CRE+CAFF group had a higher HR than CAFF, especially during the first 3 min of the running
protocol and during the last 6 min, although the findings were not statistically significant. A well-
documented side effect of creatine, possibly due to its anabolic properties, is water retention (6,21).
Temporary water retention may have caused an increased HR. This may not be relevant in the
current study because creatine was ingested in an acute manner 2 hrs before the running protocol;
water retention due to creatine supplementation usually occurs when creatine is consistently loaded
for 5 to 6 days (6).
Spradley et al (24) found that ingesting an energy supplement containing creatine and caffeine 20
min before a muscular endurance protocol improved lower body endurance and improved perceived
energy. Lee et al. (17) suggests that combining creatine and caffeine actually improved TTE during a
cycling protocol. The current study suggests that combining creatine and caffeine does not improve
TTE. While the TTE in the CAFF trial lasted nearly 1min longer than PBO or CRE+CAFF, it was not
enough to elicit statistical significance.
118
CONCLUSIONS
This study assessed the effects of acute combination supplementation of creatine and caffeine on VT.
The findings from the current study suggest that acute creatine supplementation and subsequent
caffeine ingestion had no significant effect on VT; however, the caffeine trial had a significantly higher
VT than the placebo group. These findings can mainly be attributed to creatine and caffeine’s
opposing mechanisms. This study suggests that moderately active males should avoid combining
creatine and caffeine supplements for performance enhancement and that these supplements may
be more effective when used individually.
Address for correspondence: Taylor Quesada, Kinesiology, California Baptist University, Riverside,
CA, USA 92504. Email: taylor.quesada@calbaptist.edu.
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Disclaimer
The opinions expressed in JEPonline are those of the authors and are not attributable to JEPonline,
the editorial staff or the ASEP organization.
... Due to the large evidence supporting the ergogenic effect of CAF and CRE, many nutritional supplements include both substances. Nevertheless, this combination is controversial as although they appear to have no pharmacokinetic interaction (Vanakoski et al., 1998) and increase performance through different mechanisms (Maccaferri et al., 2012), some studies have shown that CAF may decrease the effectiveness of CRE (Hespel et al., 2002;Quesada & Gillum, 2013;Vandenberghe et al., 1996). ...
... 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). ...
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.
... Caffeine supplementation increases strength and endurance (Grgic et al. 2020(Grgic et al. , 2019, and reduces RPE (Tarnopolsky 2008) potentially by caffeine influencing adenosine receptor activity, phosphodiesterase, and excitation-contraction coupling (Graham 2001;Quesada and Gillum 2013;Trexler and Smith-Ryan 2015;Ayuso et al. 2019;Grgic et al. 2019). In regards to muscle accretion, research is mixed regarding the effects of caffeine on the mechanistic target of rapamycin (mTOR) pathway, a main regulator of muscle protein synthesis (Moore et al. 2017). ...
... When consumed on multiple days during a creatine loading phase (i.e. 20 g/day for < 7 days), caffeine appears to inhibit the ergogenic potential of creatine (Vandenberghe et al. 1996;Hespel et al. 2002;Harris et al. 2005), possibly by creatine and caffeine having opposing effects on calcium kinetics at the sarcoplasmic reticulum (Hespel et al. 2002) or by causing gastrointestinal issues (Harris et al. 2005;Quesada and Gillum 2013). However, the longer-term combined effects of creatine and caffeine supplementation during a resistance training program on measures of body composition, strength, endurance, RPE and fatigue are unknown. ...
... The primary purpose of this study was to determine the effects of creatine and caffeine supplementation, alone and in combination, during 6 weeks of resistance training on measures of body composition, strength, endurance, RPE and fatigue in trained young adults. Due to the possibility of caffeine increasing calcium release and creatine increasing calcium reuptake into the sarcoplasmic reticulum (Trexler and Smith-Ryan 2015) and/or gastrointestinal issues arising from the co-ingestion of creatine and caffeine (Harris et al. 2005;Quesada et al. 2013), it was hypothesized that creatine and caffeine supplementation alone would be superior to the co-ingestion of creatine and caffeine and placebo for increasing fat-free mass, muscle strength and endurance and reducing fat mass, RPE and fatigue. It was also hypothesized that the co-ingestion of creatine and caffeine would produce similar changes in fat-free and fat mass, muscle strength, endurance, RPE and fatigue compared to placebo. ...
Article
The primary purpose was to determine the separate and combined effects of creatine and caffeine supplementation during resistance training on body composition and muscle performance in trained young adults. Twenty-eight participants were randomized to supplement with creatine and caffeine (CR-CAF; n = 9, 22 ± 4 years; 0.1 g·kg⁻¹·d⁻¹ of creatine monohydrate + 3 mg·kg⁻¹·d⁻¹ of caffeine anhydrous micronized powder); creatine (CR; n = 7, 22 ± 4 years, 0.1 g·kg⁻¹·d⁻¹ of creatine + 3 mg·kg⁻¹·d⁻¹ of micronized cellulose), caffeine (CAF; n = 6, 19 ± 1 years, 3 mg·kg⁻¹·d⁻¹ of caffeine + 0.1 g·kg⁻¹·d⁻¹ of maltodextrin) or placebo (PLA; n = 6, 23 ± 7 years, 0.1 g·kg⁻¹·d⁻¹ of maltodextrin + 3 mg·kg⁻¹·d⁻¹ micronized cellulose) one hour prior to performing resistance training for 6 weeks. Before and after training and supplementation, fat-free and fat mass (air-displacement plethysmography), muscle thickness (elbow and knee flexors and extensors; ultrasound), muscle strength (1-repetition maximum [1-RM] for the leg press and chest press), and endurance (one set of repetitions to volitional fatigue using 50% baseline 1-RM for leg press and chest press) were assessed. There was a group x time interaction (p = 0.049) for knee extensor muscle thickness with CR experiencing an increase over time with no changes in the other groups. There were no other between group differences for any variable. In conclusion, creatine supplementation and resistance training results in a small improvement in knee extensor muscle accretion in trained young adults.
... However, the scarce research directly investigating combined supplementation has indicated that 3-4 d of CAF supplementation (consumed for multiple consecutive days during CRE loading) may blunt the ergogenic effect of CRE loading (17,19,38). This apparent incompatibility could potentially be explained by CRE and CAF imposing opposite effects on muscle relaxation time (19), or by gastrointestinal distress caused by concurrent ingestion of both ingredients (17,31). It is currently unclear if these discrepant findings may relate to differences in the dose or source of caffeine consumed. ...
... While CAF appeared to blunt the ergogenic effect of CRE, the authors (17) suggested that this effect was explained by GI discomfort with CRE+CAF, which was reported in four out of ten subjects completing the study. Gastrointestinal discomfort was also noted in another recent study involving CRE+CAF supplementation (31), in which three out of seven subjects reported symptoms. In agreement with past studies, GI discomfort was reported in four of thirteen participants in the CRE+CAF group in the current study. ...
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The purpose of this study was to determine the effect of 5 d of creatine (CRE) loading alone or in combination with caffeine anhydrous (CAF) or coffee (COF) on upper and lower body strength and sprint performance. Physically active males (n=54; Mean ± SD; Age = 20.1 ± 2.1 yrs; Weight = 78.8 ± 8.8 kg) completed baseline testing, consisting of one-repetition maximum (1RM) and repetitions to fatigue (RTF) with 80% 1RM for bench press (BP) and leg press (LP), followed by a repeated sprint test of five, 10 s sprints separated by 60 s rest on a cycle ergometer to determine peak power (PP) and total power (TP). At least 72 hr later, subjects were randomly assigned to supplement with CRE (5 g creatine monohydrate, 4 times*d; n=14), CRE+CAF (CRE + 300 mg*d of CAF; n=13), CRE+COF (CRE + 8.9 g COF, yielding 303 mg caffeine; n=13), or placebo (PLA; n=14) for 5 d. Serum creatinine (CRN) was measured prior to and following supplementation and on day six, participants repeated pre-testing procedures. Strength measures were improved in all groups (p<0.05), with no significant time × treatment interactions. No significant interaction or main effects were observed for PP. For TP, a time × sprint interaction was observed (p<0.05), with no significant interactions between treatment groups. A time × treatment interaction was observed for serum CRN values (p<0.05) that showed increases in all groups except PLA. Four subjects reported mild gastrointestinal discomfort with CRE+CAF, with no side effects reported in other groups. These findings suggest that neither CRE alone, nor in combination with CAF or COF, significantly affected performance compared to PLA.
... While the findings of Hespel et al. (2002) suggest that MRT may explain how chronic caffeine ingestion blunts the ergogenic effect of creatine, Harris et al. suggested that GI distress from the combination of creatine and caffeine may explain the lack of performance improvement. Subsequent research by Quesada and Gillum (2013) demonstrated similar GI issues, with 3 of 7 participants reporting GI distress in response to concurrent supplementation of creatine and caffeine. While there do not appear to be pharmacokinetic interactions between creatine and caffeine (Vanakoski et al., 1998), the scarce data available indicate that GI disturbance and/or differential effects on muscle relaxation time may present potential mechanisms by which caffeine may blunt the effectiveness of creatine. ...
... There do not appear to be significant health concerns regarding caffeine or creatine ingestion, either alone or in combination, within recommended doses. Caffeine and creatine present no pharmacokinetic interactions (Vanakoski et al., 1998), and the most notable adverse event reported from concurrent ingestion is mild GI disturbance (Harris et al., 2005;Quesada & Gillum, 2013). ...
Article
Nutritional supplementation is a common practice among athletes, with creatine and caffeine among the most commonly used ergogenic aids. Hundreds of studies have investigated the ergogenic potential of creatine supplementation, with consistent improvements in strength and power reported for exercise bouts of short duration (≤30 seconds) and high intensity. Caffeine has been shown to improve endurance exercise performance, but results are mixed in the context of strength and sprint performance. Further, there is conflicting evidence from studies comparing the ergogenic effects of coffee and caffeine anhydrous supplementation. Previous research has identified independent mechanisms by which creatine and caffeine may improve strength and sprint performance, leading to the formulation of multi-ingredient supplements containing both ingredients. Although scarce, research has suggested that caffeine ingestion may blunt the ergogenic effect of creatine. While a pharmacokinetic interaction is unlikely, authors have suggested that this effect may be explained by opposing effects on muscle relaxation time or gastrointestinal side effects from simultaneous consumption. The current review aims to evaluate the ergogenic potential of creatine and caffeine in the context of high-intensity exercise. Research directly comparing coffee and caffeine anhydrous is discussed, along with previous studies evaluating the concurrent supplementation of creatine and caffeine.
... Furthermore, caffeine (1,3,7-trimethylxanthine) is a common ingredient found in multi-ingredient compounds containing creatine (O'Bryan et al., 2020). However, there is a potential interference effect from the co-ingestion of caffeine and creatine (Trexler and Smith-Ryan, 2015) compared to creatine alone (Vandenberghe et al., 1996;Hespel et al., 2002;Harris et al., 2005), potentially due to gastrointestinal distress impacting creatine uptake (Harris et al., 2005;Quesada and Gillum, 2013) or via opposing effects on calcium kinetics at the sarcoplasmic reticulum (Hespel et al., 2002;Trexler and Smith-Ryan, 2015). Vandenberghe et al. (1996) examined the effects of 6 days of creatine loading (0.5 g/kg/day) with and without caffeine (5 mg/kg/d) on muscle PCr content and performance. ...
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It is well-established that creatine supplementation augments the gains in muscle mass and performance during periods of resistance training. However, whether the timing of creatine ingestion influences these physical and physiological adaptations is unclear. Muscle contractions increase blood flow and possibly creatine transport kinetics which has led some to speculate that creatine in close proximity to resistance training sessions may lead to superior improvements in muscle mass and performance. Furthermore, creatine co-ingested with carbohydrates or a mixture of carbohydrates and protein that alter insulin enhance creatine uptake. The purpose of this narrative review is to (i) discuss the purported mechanisms and variables that possibly justify creatine timing strategies, (ii) to critically evaluate research examining the strategic ingestion of creatine during a resistance training program, and (iii) provide future research directions pertaining to creatine timing.
... Although these supplements achieve performance benefits via independent mechanisms, previous reports indicated that the simultaneous use of caffeine and creatine (usually in the form of repeated use of both supplements over several days) caused a loss of the ergogenic properties of [44,45]. This outcome was attributed to opposing effects of the two supplements on muscle relaxation time [44,45], although gastrointestinal effects from the acute intake of the combination of products were also reported, separately [46,47]. However, more recent investigations of chronic creatine supplementation have reported that the acute addition of caffeine prior to a protocol of exercise capacity or performance does not impair the improvements due to caffeine supplementation [48][49][50]. ...
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Current sports nutrition guidelines recommend that athletes only take supplements following an evidence-based analysis of their value in supporting training outcomes or competition performance in their specific event. While there is sound evidence to support the use of a few performance supplements under specific scenarios (creatine, beta-alanine, bicarbonate, caffeine, nitrate/beetroot juice and, perhaps, phosphate), there is a lack of information around several issues needed to guide the practical use of these products in competitive sport. First, there is limited knowledge around the strategy of combining the intake of several products in events in which performance benefits are seen with each product in isolation. The range in findings from studies involving combined use of different combinations of two supplements makes it difficult to derive a general conclusion, with both the limitations of individual studies and the type of sporting event to which the supplements are applied influencing the potential for additive, neutral or counteractive outcomes. The repeated use of the same supplement in sports involving two or more events within a 24-h period is of additional interest, but has received even less attention. Finally, the potential for individual athletes to respond differently, in direction and magnitude, to the use of a supplement seems real, but is hard to distinguish from normal day to day variability in performance. Strategies that can be used in research or practice to identify whether individual differences are robust include repeat trials, and the collection of data on physiological or genetic mechanisms underpinning outcomes.
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Background: Caffeine is isolated Methyl-xanthine, Alkaloid stimulants and it is the most commonly used drug in the world. The present study was to investigate the effect of caffeine on VO2max and Electrocardiograph in active male of student college after Bruce exhaustive exercise. Methods: 9 male active aged 25 (mean 20.9±1.37 years, fat percent 11.21±3.79 percentage and BMI 23.49±1.69 kg/m2) allocated into two equal conditions: the supplement (5 mg.kg-1 caffeine) and without caffeine consumtion. After 60 min supplementation, subjects were participated in a single session of exhaustive Bruce Test. Changes in the VO2max and QT interval distance were meatured. Results: The results showed that caffeine had significant effect on the increased levels of VO2max after Bruce exhaustive exercise compared to the control condition. Also, levels of QT interval increased significantly after the exercise (p<0.05). Conclusion: Caffeine could significantly increase the VO2max and increase QT after Bruce exhaustive test. Maybe, level and severity of exercise increase the ventricular depolarization and repolarization and cardiac performance.
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Amino acids contribute between 2–8% of the energy needs during endurance exercise. Endurance exercise training leads to an adaptive reduction in the oxidation of amino acids at the same absolute exercise intensity, however, the capacity to oxidize amino acids goes up due to the increase in the total amount of the rate limiting enzyme, branched chain 2-oxo-acid dehydrogenase. There appears to be a modest increase (range = 12–95%) in protein requirements only for very well trained athletes who are actively training. Although the majority of athletes will have ample dietary protein to meet any increased need, those on a hypoenergetic diet or during extreme periods of physical stress may need dietary manipulation to accommodate the need. Caffeine is a trimethylxanthine derivative that is common in many foods and beverages. The consumption of caffeine (3–7 mg/kg) prior to endurance exercise improves performance for habitual and non-habitual consumers. The ergogenic effect is likely due to a direct effect on muscle contractility and not via an enhancement of fatty acid oxidation. Creatine is important in intra-cellular energy shuttling and in cellular fluid regulation. Creatine monohydrate supplementation (20 g/d X 3–5 days) increases fat-free mass, improves muscle strength during repetitive high intensity contractions and increases fat-free mass accumulation and strength during a period of weight training. Given the increase in weight, there are likely neutral or even performance reducing effects in sports that are influenced by body mass (i.e., running, hill climbing cycling).
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The effect of a pre-workout energy supplement on acute multijoint resistance exercise was examined in eight resistancetrained college-age men. Subjects were randomly provided either a placebo (P) or a supplement (S: containing caffeine, taurine, glucuronolactone, creatine, β-alanine, and the amino acids; leucine, isoleucine, valine, glutamine and arginine) 10 minutes prior to resistance exercise. Subjects performed 4 sets of no more than 10 repetitions of either barbell squat or bench press at 80% of their pre-determined 1 repetition-maximum (1RM) with 90 seconds of rest between sets. Dietary intake 24 hours prior to each of the two training trials was kept constant. Results indicate that consuming the pre-workout energy drink 10 minutes prior to resistance exercise enhances performance by significantly increasing the number of repetitions successfully performed (p = 0.022) in S (26.3 ± 9.2) compared to P (23.5 ± 9.4). In addition, the average peak and mean power performance for all four sets was significantly greater in S compared to P (p < 0.001 and p < 0.001, respectively). No differences were observed between trials in subjective feelings of energy during either pre (p = 0.660) or post (p = 0.179) meaures. Similary, no differences between groups, in either pre or post assessments, were observed in subjective feelings of focus (p = 0.465 and p = 0.063, respectively), or fatigue (p = 0.204 and p = 0.518, respectively). Results suggest that acute ingestion of a highenergy supplement 10 minutes prior to the onset of a multi-joint resistance training session can augment training volume and increase power performance during the workout.
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The effect caffeine elicits on endurance performance is well founded. However, comparatively less research has been conducted on the ergogenic potential of anaerobic performance. Some studies showing no effect of caffeine on performance used untrained subjects and designs often not conducive to observing an ergogenic effect. Recent studies incorporating trained subjects and paradigms specific to intermittent sports activity support the notion that caffeine is ergogenic to an extent with anaerobic exercise. Caffeine seems highly ergogenic for speed endurance exercise ranging in duration from 60 to 180 seconds. However, other traditional models examining power output (i.e. 30-second Wingate test) have shown minimal effect of caffeine on performance. Conversely, studies employing sport-specific methodologies (i.e. hockey, rugby, soccer) with shorter duration (i.e. 4–6 seconds) show caffeine to be ergogenic during high-intensity intermittent exercise. Recent studies show caffeine affects isometric maximal force and offers introductory evidence for enhanced muscle endurance for lower body musculature. However, isokinetic peak torque, one-repetition maximum and muscular endurance for upper body musculature are less clear. Since relatively few studies exist with resistance training, a definite conclusion cannot be reached on the extent caffeine affects performance. It was previously thought that caffeine mechanisms were associated with adrenaline (epinephrine)-induced enhanced free-fatty acid oxidation and consequent glycogen sparing, which is the leading hypothesis for the ergogenic effect. It would seem unlikely that the proposed theory would result in improved anaerobic performance, since exercise is dominated by oxygen-independent metabolic pathways. Other mechanisms for caffeine have been suggested, such as enhanced calcium mobilization and phosphodiesterase inhibition. However, a normal physiological dose of caffeine in vivo does not indicate this mechanism plays a large role. Additionally, enhanced Na+/K+ pump activity has been proposed to potentially enhance excitation contraction coupling with caffeine. A more favourable hypothesis seems to be that caffeine stimulates the CNS. Caffeine acts antagonistically on adenosine receptors, thereby inhibiting the negative effects adenosine induces on neurotransmission, arousal and pain perception. The hypoalgesic effects of caffeine have resulted in dampened pain perception and blunted perceived exertion during exercise. This could potentially have favourable effects on negating decreased firing rates of motor units and possibly produce a more sustainable and forceful muscle contraction. The exact mechanisms behind caffeine’s action remain to be elucidated.
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aerobic to anaerobic transition intensity is one of the most significant physiological variable in endurance sports. Scientists have explained the term in various ways, like, Lactate Threshold, Ventilatory Anaerobic Threshold, Onset of Blood Lactate Accumulation, Onset of Plasma Lactate Accumulation, Heart Rate Deflection Point and Maximum Lactate Steady State. But all of these have great role both in monitoring training schedule and in determining sports performance. Individuals endowed with the possibility to obtain a high oxygen uptake need to complement with rigorous training program in order to achieve maximal performance. If they engage in endurance events, they must also develop the ability to sustain a high fractional utilization of their maximal oxygen uptake (%VO(2) max) and become physiologically efficient in performing their activity. Anaerobic threshold is highly correlated to the distance running performance as compared to maximum aerobic capacity or VO(2) max, because sustaining a high fractional utilization of the VO(2) max for a long time delays the metabolic acidosis. Training at or little above the anaerobic threshold intensity improves both the aerobic capacity and anaerobic threshold level. Anaerobic Threshold can also be determined from the speed-heart rate relationship in the field situation, without undergoing sophisticated laboratory techniques. However, controversies also exist among scientists regarding its role in high performance sports.
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This study investigated the effects of acute caffeine ingestion following short-term creatine supplementation on an incremental cycling to exhaustion task. Twelve active males performed the task under three conditions: baseline condition (BASE, no ergogenic aid), creatine plus caffeine condition (CRE+CAF), and creatine with placebo condition (CRE+PLA). Following the establishment of BASE condition, participants were administered CRE+CAF (0.3 g•kg-1•day-1 of creatine for 5 days followed by 6 mg•kg-1 of caffeine 1-h prior to testing) and CRE+PLA (0.3 g•kg-1•day-1 of creatine for 5 days followed by 6 mg•kg-1 of placebo1-h prior to testing) in a double-blind, randomized crossover protocol. No significant differences were observed in relative maximal oxygen consumption (VO2max) (BASE vs. CRE+CAF vs. CRE+PLA; 51.7 ± 5.5 vs. 52.8 ± 4.9 vs. 51.3 ± 5.6 ml•kg-1•min-1; p > 0.05) and absolute VO2max (BASE vs. CRE+CAF vs. CRE+PLA; 3.6 ± 0.4 vs. 3.7 ± 0.4 vs. 3.5 ± 0.5 l•min-1; p > 0.05). Blood samples indicated significantly higher blood lactate and glucose concentrations in the CRE+CAF among those in the BASE or CRE+PLA condition during the test (p < 0.05). The time to exhaustion on a cycling ergometer was significantly longer for the CRE+CAF (1087.2 ± 123.9-s) compared with the BASE (1009.2 ± 86.0-s) or CRE+PLA (1040.3 ± 96.1-s). This study indicated that a single dose of caffeine following short-term creatine supplementation did not hinder the creatine-caffeine interaction. In fact, it lengthened the time to exhaustion during an incremental maximum exercise test. However, this regime might lead to the accumulation of lactate in the blood.
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The purpose of this study was to determine the effects of the pre-workout supplement Assault™ (MusclePharm, Denver, CO, USA) on upper and lower body muscular endurance, aerobic and anaerobic capacity, and choice reaction time in recreationally-trained males. Subjective feelings of energy, fatigue, alertness, and focus were measured to examine associations between psychological factors and human performance. Twelve recreationally-trained males participated in a 3-week investigation (mean +/- SD, age: 28 +/- 5 y, height: 178 +/- 9 cm, weight: 79.2 +/- 15.7 kg, VO2max: 45.7 +/- 7.6 ml/kg/min). Subjects reported to the human performance laboratory on three separate occasions. All participants completed a baseline/familiarization day of testing that included a maximal graded exercise test for the determination of aerobic capacity (VO2max), one-rep maximum (1-RM) for bench and leg press to determine 75% of 1-RM, choice reaction tests, and intermittent critical velocity familiarization. Choice reaction tests included the following: single-step audio and visual, one-tower stationary protocol, two-tower lateral protocol, three-tower multi-directional protocol, and three-tower multi-directional protocol with martial arts sticks. Subjects were randomly assigned to ingest either the supplement (SUP) or the placebo (PL) during Visit 2. Subjects were provided with the cross-over treatment on the last testing visit. Testing occurred 20 min following ingestion of both treatments. Significant (p < 0.05) main effects for the SUP were observed for leg press (SUP: 13 ± 6 reps, PL: 11 ± 3 reps), perceived energy (SUP: 3.4 ± 0.9, PL: 3.1 ± 0.8), alertness (SUP: 4.0 ± 0.7, PL: 3.5 ± 0.8), focus (SUP: 4.1 ± 0.6, PL: 3.5 ± 0.8), choice reaction audio single-step (SUP: 0.92 ± 0.10 s, PL: 0.97 ± 0.11 s), choice reaction multi-direction 15 s (SUP: 1.07 ± 0.12 s, PL: 1.13 ± 0.14 s), and multi-direction for 30 s (SUP: 1.10 ± 0.11 s, PL: 1.14 ± 0.13 s). Ingesting the SUP before exercise significantly improved agility choice reaction performance and lower body muscular endurance, while increasing perceived energy and reducing subjective fatigue. These findings suggest that the SUP may delay fatigue during strenuous exercise.
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We investigated the effects of sleep deprivation with or without acute supplementation of caffeine or creatine on the execution of a repeated rugby passing skill. Ten elite rugby players completed 10 trials on a simple rugby passing skill test (20 repeats per trial), following a period of familiarisation. The players had between 7-9 h sleep on 5 of these trials and between 3-5 h sleep (deprivation) on the other 5. At a time of 1.5 h before each trial, they undertook administration of either: placebo tablets, 50 or 100 mg/kg creatine, 1 or 5 mg/kg caffeine. Saliva was collected before each trial and assayed for salivary free cortisol and testosterone. Sleep deprivation with placebo application resulted in a significant fall in skill performance accuracy on both the dominant and non-dominant passing sides (p < 0.001). No fall in skill performance was seen with caffeine doses of 1 or 5 mg/kg, and the two doses were not significantly different in effect. Similarly, no deficit was seen with creatine administration at 50 or 100 mg/kg and the performance effects were not significantly different. Salivary testosterone was not affected by sleep deprivation, but trended higher with the 100 mg/kg creatine dose, compared to the placebo treatment (p = 0.067). Salivary cortisol was elevated (p = 0.001) with the 5 mg/kg dose of caffeine (vs. placebo). Acute sleep deprivation affects performance of a simple repeat skill in elite athletes and this was ameliorated by a single dose of either caffeine or creatine. Acute creatine use may help to alleviate decrements in skill performance in situations of sleep deprivation, such as transmeridian travel, and caffeine at low doses appears as efficacious as higher doses, at alleviating sleep deprivation deficits in athletes with a history of low caffeine use. Both options are without the side effects of higher dose caffeine use.
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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.
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A randomized, single-blinded, placebo-controlled, parallel design study was used to examine the effects of a pre-workout supplement combined with three weeks of high-intensity interval training (HIIT) on aerobic and anaerobic running performance, training volume, and body composition. Twenty-four moderately-trained recreational athletes (mean +/- SD age = 21.1 +/- 1.9 yrs; stature = 172.2 +/- 8.7 cm; body mass = 66.2 +/- 11.8 kg, VO2max = 3.21 +/- 0.85 l.min-1, percent body fat = 19.0 +/- 7.1%) were assigned to either the active supplement (GT, n = 13) or placebo (PL, n = 11) group. The active supplement (Game Time(R), Corr-Jensen Laboratories Inc., Aurora, CO) was 18 g of powder, 40 kcals, and consisted of a proprietary blend including whey protein, cordyceps sinensis, creatine, citrulline, ginseng, and caffeine. The PL was also 18 g of powder, 40 kcals, and consisted of only maltodextrin, natural and artificial flavors and colors. Thirty minutes prior to all testing and training sessions, participants consumed their respective supplements mixed with 8-10 oz of water. Both groups participated in a three-week HIIT program three days per week, and testing was conducted before and after the training. Cardiovascular fitness (VO2max) was assessed using open circuit spirometry (Parvo-Medics TrueOne(R) 2400 Metabolic Measurement System, Sandy, UT) during graded exercise tests on a treadmill (Woodway, Pro Series, Waukesha, WI). Also, four high-speed runs to exhaustion were conducted at 110, 105, 100, and 90% of the treadmill velocity recorded during VO2max, and the distances achieved were plotted over the times-to-exhaustion. Linear regression was used to determine the slopes (critical velocity, CV) and y-intercepts (anaerobic running capacity, ARC) of these relationships to assess aerobic and anaerobic performances, respectively. Training volumes were tracked by summing the distances achieved during each training session for each subject. Percent body fat (%BF) and lean body mass (LBM) were assessed with air-displacement plethysmography (BOD POD(R), Life Measurement, Inc., Concord, CA). Both GT and PL groups demonstrated a significant (p = 0.028) increase in VO2max from pre- to post-training resulting in a 10.3% and 2.9% improvement, respectively. CV increased (p = 0.036) for the GT group by 2.9%, while the PL group did not change (p = 0.256; 1.7% increase). ARC increased for the PL group by 22.9% and for the GT group by 10.6%. Training volume was 11.6% higher for the GT versus PL group (p = 0.041). %BF decreased from 19.3% to 16.1% for the GT group and decreased from 18.0% to 16.8% in the PL group (p = 0.178). LBM increased from 54.2 kg to 55.4 kg (p = 0.035) for the GT group and decreased from 52.9 kg to 52.4 kg in the PL group (p = 0.694). These results demonstrated improvements in VO2max, CV, and LBM when GT is combined with HIIT. Three weeks of HIIT alone also augmented anaerobic running performance, VO2max and body composition.
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Unlabelled: Caffeine has many diverse physiological effects including central nervous system stimulation. Ventilatory threshold and a recently described heart rate variability threshold both have a relationship with autonomic control that could be altered by caffeine consumption. The purpose of this investigation was to determine the influence of caffeine on lactate, ventilatory, and heart rate variability thresholds during progressive exercise. Using a randomized placebo controlled, double-blind study design, 10 adults performed 2 graded maximal cycle ergometry tests with and without caffeine (5 mg·kg⁻¹). Respiratory gas exchange, blood lactate concentrations, and heart rate variability data were obtained at baseline and throughout exercise. Results: At rest, caffeine (p<0.05) increased blood lactate, oxygen consumption, carbon dioxide production, and minute ventilation. For indices of heart rate variability at rest, caffeine increased (p<0.05) the coefficient of variation, while standard deviation, and mean successive difference displayed non-significant increases. During progressive exercise, minute ventilation volumes were higher in caffeine trials but no other parameters were significantly different compared to placebo tests. Conclusion: These data demonstrate the robustness of the lactate, ventilatory and heart rate variability thresholds when challenged by a physiological dose of caffeine.