CARDIFF SCHOOL OF SPORT
DEGREE OF BACHELOR OF SCIENCE
(HONOURS)
SPORT AND EXERCISE SCIENCE
TITLE
EFFECT OF REDBULL ENERGY DRINK ON POWER DECREMENT AND PEAK
POWER OUTPUT IN THE UPPER AND LOWER BODY
NAME
Owain John Smallwood
UNIVERSITY NUMBER
ST09001839
OWAIN SMALLWOOD
ST09001839
SCHOOL OF SPORT
UNIVERSITY OF WALES INSTITUTE CARDIFF
EFFECT OF REDBULL
ENERGY DRINK ON
POWER DECREMENT
AND PEAK POWER
OUTPUT IN THE UPPER
AND LOWER BODY
Cardiff Metropolitan University
Prifysgol Fetropolitan Caerdydd
Certificate of student
I certify that the whole of this work is the result of my individual effort, that all
quotations from books and journals have been acknowledged, and that the word
count given below is a true and accurate record of the words contained (omitting
contents pages, acknowledgements, indexes, figures, reference list and
appendices).
Word count:
11978
Signed:
Date:
5/3/2012
Certificate of Dissertation Tutor responsible
I am satisfied that this work is the result of the student’s own effort.
I have received a dissertation verification file from this student
Signed:
Date:
Notes:
The University owns the right to reprint all or part of this document.
TABLE OF CONTENTS
CHAPTER 1

LITERATURE REVIEW....................................................................... 1
-
Stimulatory Mechanisms 2
-
Sources of Caffeine 3
-
Legality 3
-
Caffeine and Resistance Exercise 4
-
Variation of Dosage 4
-
Timing of Ingestion 5
-
Upper and Lower Body Performance
-
Participant Training Status 7
-
Nutrients used alongside Caffeine 8
6
CHAPTER 2

INTRODUCTION.................................................................................. 10
CHAPTER 3

METHODS…..……………………………………………………………... 16
-
Experimental Summary 17
-
Pre-Experimental Procedure 17
-
Instructions Provided to Participants 18
-
Performance Measures 18
-
Lifting Procedures 20
-
Experimental Procedures 21
-
Supplementation 21
-
Statistical Analysis 22
CHAPTER 4

RESULTS………………………………………………………………… 23

Bench Throw
 Mean Peak Power Output 24
 Power Decrement 25
 Rating of Perceived Exertion 26

Loaded Squat Jumps
 Mean Peak Power Output 27
 Power Decrement 28
 Rating of Perceived Exertion 29
CHAPTER 5

DISCUSSION…………………………………………………………….. 30

Mean Peak Power Output 32

Power Decrement 35

Rating of Perceived Exertion 38

Limitations 40

Conclusion 41
 REFERENCES…………………………………………………………… 43

APPENDICIES……………………………………………………………. 59
List of Tables

Table 1: Red Bull Energy-Drink Ingredients…………………………….. 22
List of Figures

Figure 1: Bench throw peak power output across sets, mean ± standard
deviation…………………………………………………………………… 24

Figure 2: Bench throw power decrement across sets, mean ± standard
deviation…………………………………………………………………… 25

Figure 3: Bench throw rating of perceived exertion, mean ± standard
deviation…………………………………………………………………… 26

Figure 4: Loaded squat jump peak power output across sets, mean ±
standard deviation………………………………………………………... 27

Figure 5: Loaded squat jump power decrement across sets, mean ± standard
deviation…………………………………………………………………… 28

Figure 6: Loaded squat jump power decrement across sets, mean ± standard
deviation…………………………………………………………………… 29
Acknowledgements
The author gratefully acknowledges the support and assistance provided by Dr Jon
Oliver throughout the research study.
i
Abstract
This counter-balanced, cross-over study examined the effects of Red Bull™ on peak
power output (PPO), power decrement (PD) and rating of perceived exertion (RPE)
in the upper and lower body. Ten resistance trained males 21.3 ± 8 years old
volunteered for the study; body mass 76.2 ± 28 kg and height 177.4 ± 14 cm. The
testing procedure comprised of two exercises, bench throws and loaded squat
jumps, both consisted of 3 sets of 8 repetitions. Red Bull™ was administered 1 hour
prior to testing; with a linear position transducer (LPT) used to measure PPO in both
upper and lower body exercises. There was an overall supplementation effect on
bench throw when Red Bull™ had been ingested, whereby mean PPO (MPPO) was
significantly greater after consumption (Red Bull™ = 554 ± 21 VS. control = 523 ± 23
Watts over the 3 sets, P = 0.008). An effect of borderline significance was noted
between Red Bull™ and control MPPO, during loaded squat jumps (Red Bull™ =
715 ± 17.3 VS. control = 692.1 ± 18.1 Watts, P = 0.053). An overall significant
difference was observed in bench throw RPE, whereby RPE was significantly lower
after Red Bull™ ingestion (Red Bull™ = 11.6 ± 1.3 VS. control = 13.4 ± 2.0 over all 3
sets, P = 0.042). Similarly, RPE in loaded squat jumps displayed an overall
significant effect, RPE was significantly lower after Red Bull™ consumption (Red
Bull™ = 11.6 ± 1.5 VS. control = 12.7 ± 1.4 over all 3 sets, P = 0.011). However, in
bench throws (Red Bull™ = 6 ± 2 VS. Control = 5 ± 3.4 % over the 3 sets, P = 0.774)
and loaded squat jumps (Red Bull™ = 3.3 ± 2 VS. control = 4 ± 2.3 % over all sets, P
= 0.093), no overall significant difference was found in PD between interventions.
These findings suggest that Red Bull™ supplementation is an effective ergogenic
aid, for resistance trained males who perform upper body resistance exercises. This
finding potentially relates to caffeine’s antagonism of adenosine receptors, muscle
fibre distribution and its stimulation of central and peripheral pathways.
ii
CHAPTER 1
Literature Review
Stimulatory Mechanisms
One of the most commonly used drugs worldwide is caffeine (Juhn, 2003; Ellender
& Linder, 2005; Desbrow & Leveritt, 2006; Woolf et al., 2008). Caffeine has been
shown to have benefits to aerobic exercise (Graham & Spriet, 1995; Van Soeren &
Graham, 1998), yet its affect on anaerobic performance is inconclusive. When
caffeine is absorbed in the body it crosses the blood-brain-barrier, it is then
distributed in the intracellular fluid (Arnaud, 1987). Caffeine’s properties enable it to
affect numerous tissues in the body including the cardio-vascular system (CVS),
central nervous system (CNS), smooth and skeletal muscles (Arnaud, 1987;
Williams, 1991). Caffeine’s stimulatory affect on the nervous system has been
attributed to its binding with specific pre-synaptic adenosine receptors, blocking the
inhibitory effects of adenosine (Varma et al., 2010). This is proposed to increase an
individual’s ability to excite a motor unit bundle, by lowering the motor neuron
threshold, facilitating maximal muscle activation (Kalmar & Cafarelli, 1999; Archna &
Jaspal, 2008). This shows that caffeine potentially has a positive impact on intense
and resistance exercise. Biaggioni et al. (1991) reported that caffeine reversed
central dopamine deficiencies and reduced perceptions of effort and fatigue,
resulting in an increased work output. In this study adenosine and caffeine were fed
intravenously to observe their affect on platelet adenosine receptors. When
adenosine binds with the pre-synaptic receptors it limits the calcium ion
transportation across the cell membrane, this inhibits neurotransmitter release at the
synapses (Dunwiddie & Fredholm, 1984). When caffeine binds to the adenosine
receptors it prevents the inhibitory effects of adenosine, allowing greater
transportation of calcium across the cell membrane (Lopes et al., 1983; Beck et al.,
2006), facilitating the release of stimulatory neurotransmitters including epinephrine
(Costill et al., 1978; Graham, 2001; Beck et al., 2006; Goldstein et al., 2010; Varma
et al., 2010). All of which could have a positive influence on anaerobic and
specifically resistance performance.
Previous studies have suggested that caffeine may alter substrate utilization by
increasing fat oxidation and as a result spare glycogen utilization (Ivy et al., 1979;
Essig et al., 1980), thus having an aerobic benefit. However, this view is no longer
held, as most recent studies could provide no evidence that caffeine alters substrate
2
utilization (Cole, 1996; Nienhueser et al., 2011). Nienhueser et al. (2011) reported
that caffeine (420 mg) ingested 90-min prior to high intensity exercise, had no
sparing effect on muscle glycogen. This study implied the ergogenic effects of
caffeine in some individuals are not due to an alteration in substrate utilization, but
may be related to an alteration in neural perception of effort.
Sources of Caffeine
Caffeine can be found in a variety of foods and drinks, Rouhola et al. (2004) stated
that 53% of the world’s caffeine ingestion comes from the consumption of coffee,
with the drinking of tea adding up to 43% of the world’s caffeine intake. This
suggests that only 3% of the world’s caffeine consumption comes from other caffeine
containing products. Other caffeine containing products include cola, chocolate and
energy drinks (Rouhola et al., 2004; Forbes et al., 2007; Woolf et al., 2008; Davis &
Green, 2009; Goldstein et al., 2010). Caffeine energy drinks are a relatively new type
of beverage; they contain greater caffeine concentrations than that of soft drinks i.e.
cola (40mg), but similar caffeine amounts to that found in coffee (80mg) (Mandel,
2002). These energy drinks have become important ergogenic aids for many
athletes, in attempting to improve sporting performance (Beck et al., 2006).
Legality
Caffeine has only recently been removed from the World Anti-Doping Agency
(WADA) banned substance list; it has now been placed on a competition monitoring
programme (World Anti-Doping Agency, 2007b). The International Olympic
committee (IOC) still monitors caffeine levels in competitive athletes (World AntiDoping Agency, 2005). The National Collegiate Athletic Association (NCAA)
monitors urinary caffeine concentrations, in order to prevent caffeine abuse by the
athletes. A urinary caffeine concentration below 15 µg-ml-1 prior to competition is an
acceptable level, at or above this level is still classed as illegal (National Collegiate
Athletic Association, 2007). This acceptable level equates to the consumption of
around 8 cups of coffee or about 600 mg of caffeine. The use of caffeine has been
banned altogether in the sport of skiing. The World Anti-Doping Agency monitors
caffeine concentrations during competitions, in order to detect its misuse in sport
3
(World Anti-Doping Agency, 2007a). The WADA anti-doping code has been
accepted by the IOC and many other sporting organisations (Woolf et al., 2008).
Caffeine and Resistance Exercise
When compared to other ergogenic aids, few studies have examined caffeine’s
affects on resistance training performance (Davis & Green, 2009; Ganio et al., 2009;
Astorino & Roberson, 2010). Studies that have examined this have produced
contradictory results (Collomp et al., 1992; Bell et al., 1998; Denadai & Denadai,
1998; Doherty et al., 2004). For example, Lorino et al. (2006) found that consumption
of caffeine (432 mg) by young occasionally active individuals had no significant affect
on power output. Bell et al. (2001) reported that caffeine (355 mg) ingested 1.5-hrs
prior to testing, did not affect peak power output (PPO). In contrast, Jacobson (1992)
stated that caffeine ingestion between 150-675 mg in strength and power exercises,
significantly improved PPO. Anselme et al. (1992) found a 250 mg dose of caffeine,
consumed 30-min prior to testing, improved PPO. These contradictory results may
be due to differences in the exercise protocols employed, training status of the
participants, habitual intake of caffeine, caffeine abstinence, the dose of caffeine
used, the sample size and the performance outcome measures used in the studies.
Furthermore, Astorino & Roberson (2010) advocated that any future research should
also take into account the impact of caffeine ingestion on psychological variables
post resistance exercise. The rating of perceived exertion (RPE) data suggested that
caffeine ingestion lowers participants RPE, during aerobic exercise (Doherty et al.,
2004; Doherty & Smith, 2005). However, Astorino & Roberson (2010) concluded that
data related to resistance exercise was not clear, as caffeine ingestion appeared not
to alter participant RPE. They recognised however that because of the scarcity of
data in this area, further investigation is needed.
Variation of Dosage
A common theme highlighted in the literature is the variation of caffeine dosages
used in previous studies, variation in dosage maybe a cause of contradictory study
findings. Archna & Jaspal (2008) studied the effect of different caffeine doses on
strength and endurance; the dosages used included 350, 630, and 910 mg. The
4
study found caffeine could be used as an ergogenic aid for endurance events, as it
reduced fatigue even when consumed in low doses. Caffeine consumption at low
dosage was found to have no significant affect on short-duration, or high-intensity
events. Only the highest caffeine dose (910 mg) significantly affected PPO and
average power output (APO). Other studies have found significant strength
increases are only evident after the consumption of high doses of caffeine (Williams
et al., 1988; James et al., 2003). Pasman et al. (1995) stated caffeine (639 and 923
mg) had an ergogenic affect on participants, significant increases in PPO were found
for both caffeine doses. In contrast, some studies have found significant increases in
PPO and APO at low to moderate doses of caffeine i.e. 420 mg (Plaskette &
Cafarelli, 1991; Hudson et al., 2007). Conversely, Astorino et al. (2007) indicated
that caffeine (420 mg) does not significantly affect muscular strength or endurance
during bench press or leg press exercise. Jacobson et al. (1992) inferred that
differences between studies employing the same caffeine dosage, maybe
attributable to participant fibre type, motivation and caffeine sensitivity. Furthermore,
Archna & Jaspal (2008) suggested differences between studies were likely to result
from variability in their methodologies, subject selection, caffeine dosage, method of
caffeine administration and individual sensitivities to acute doses of caffeine.
Timing of Ingestion
Bell & McLellan (2002) studied the effects of the timing of caffeine ingestion on
endurance performance. They examined caffeine’s ergogenic affects on aerobic
performance when it was ingested 1, 3, or 6-hrs prior to testing. This study found that
only caffeine ingested 1-hr prior to exercise had a significant ergogenic affect on
performance. Wiles et al. (1992) stated caffeine ingested 1-hr prior to exercise, is the
time period that has been shown to produce the greatest ergogenic affect on
anaerobic and aerobic performance. Bell et al. (2001) reported caffeine ingested 1.5hrs prior to testing, did not affect PPO in bench press. In contrast, Anselme et al.
(1992) found that a caffeinated beverage, consumed 30-min prior to testing
significantly improved PPO in bench press exercises. It appears that short term
acute doses of caffeine i.e. 1hour or less may have the greatest ergogenic impact on
resistance performance. Wiles et al. (1992) indicated that the mechanisms behind
5
the timing of caffeine ingestion and performance were not fully understood, with
further research in this area merited.
Upper and Lower Body Performance
Woolf et al. (2008) suggested that caffeine ingestion significantly improved
participants muscle endurance and PPO during the bench press, but not during the
leg press. This was unexpected, if caffeine acted directly on skeletal muscles or
increased muscle fibre recruitment, its affect on the leg press should have been
greater, as the legs have greater muscle mass than that of the chest. This relates to
work by Jacobson et al. (1992), who noted caffeine may have a greater ergogenic
impact on the upper body, due to larger numbers of type II fibres in comparison to
the lower body. They suggested caffeine acted more on type II fibres when
compared to type 1. Beck et al. (2006) noted that caffeine caused an acute increase
in the upper-body PPO of resistance-trained men. This study also showed caffeine
had no effect on lower-body PPO, muscular endurance, anaerobic capabilities, or
upper-body muscular endurance. It is worth noting that participants in this study did
not inform the researchers of any medication or additional supplementation they
were taking, all of which may have affected the study’s findings. However, Kalmar &
Cafarelli (1999) reported that caffeine (432 mg) significantly improved PPO and APO
in leg extensions. Goldstein et al. (2010) reported caffeine (390 mg) significantly
increased upper body PPO, while also stating more studies are need to examine
caffeine’s effects on the lower body. This study used 15 resistance trained females;
as a result its findings are only generalisable to this specific population. Furthermore,
as only 15 participants were examined, its results must be treated with caution, due
to lack of weighting behind this research. Whereas Hudson et al. (2007)
demonstrated that caffeine (420 mg) significantly improved performance in leg
extensions and arm curls. These previous studies recognised caffeine’s affect on
upper and lower body performance needs further investigation. Bruce et al. (2000) &
Bell et al. (2001) indicated the ergogenic effects of caffeine may be specific to
muscle groups, accounting for the reported differences in caffeine’s affects on the
upper and lower body.
6
Participant Training Status
As previously stated, the training status of the participants used maybe a cause of
contradictory findings between studies examining the ergogenic effects of caffeine.
Jacobson et al. (1992) used participants who were highly trained resistance athletes;
a caffeine dose of 525 mg was administered. The study found caffeine had a
significant affect on PPO. In accordance with this study Beck et al. (2006) noted
caffeine caused an acute increase in the upper-body PPO of resistance-trained men.
In addition, Duncan & Oxford (2011) reported that experienced resistance trained
males, demonstrated significant PPO improvements during bench press, as a result
of acute caffeine ingestion. However, this study acknowledged that the resistance
protocol used was brief and may not be representative of resistance exercises
performed in training and sporting contexts. Some studies including Hendrix et al.
(2010) examined caffeine’s ergogenic affect on untrained participants, during
resistance exercise. This study discovered that acute caffeine ingestion, did not
significantly affect untrained participant’s PPO in bench press and leg extension
exercises. Although, it appears this study did not inform participants to refrain from
strenuous activity prior to testing, therefore this may be a reason why caffeine had
no impact on resistance performance; participants could have been fatigued prior to
testing. Moreover, Lorino et al. (2006) found that consumption of (438 mg) caffeine
by young occasionally active individuals had no significant affect on power output.
Although the mechanisms behind these training status differences are not fully
understood; it is thought caffeine may have a greater ergogenic affect on resistance
athletes over untrained or occasionally active individuals. This is possibly due to
neural adaptations to training and caffeine’s affect on the CNS (Beck et al., 2006;
Duncan & Oxford, 2011). Resistance athletes are believed to benefit from neural
training adaptations, to resistance exercise. These adaptations include improved
neuromuscular pathways between the brain and working muscle, and an increase in
the release of neurotransmitters such as epinephrine (Dunwiddie & Fredholm, 1984;
Astorino & Roberson, 2010; Varma et al., 2010). As stated previously, caffeine
allows greater calcium transportation across the cell membrane, facilitating the
release of stimulatory neurotransmitters. As a result of training adaptations
resistance athletes may have improved neuromuscular pathways; the ergogenic
benefits of caffeine may therefore result in further pathway stimulation. As a
7
consequence, caffeine may significantly improve the performance of resistance
trained athletes when compared to untrained participants (Hudson et al., 2008;
Astorino & Roberson, 2010; Duncan & Oxford, 2011).
Nutrients used alongside Caffeine
As formerly mentioned, caffeine energy drinks are a relatively new type of beverage
(Mandel, 2002). One of the leading brands in caffeine energy drinks is Red Bull™; it
is commonly used as an ergogenic aid by athletes, in an attempt to improve
performance. A study conducted by Forbes et al. (2007) found Red Bull™ increased
upper body muscle endurance during bench press, but had no significant affect on
power during a 30 seconds wingate test. However, increased muscle endurance
cannot with any degree of certainty be attributed solely to the caffeine in Red Bull™.
This is due to the fact that Red Bull™ contains other ingredients which may impact
on performance. The other ingredients found in Red Bull™ include carnitine, B
vitamins, and taurine. Carnitine’s affect on performance is controversial; some
studies have shown an ergogenic benefit from enhanced fat metabolism and
improved recovery (Brass, 2004), thus providing oxidative benefits. In contrast, most
studies have shown no ergogenic benefit of carnitine ingestion. For example, Trappe
et al. (1994) stated carnitine ingestion had no affect on high intensity performance or
metabolism. Furthermore, a study by Barnett et al. (1994) investigated carnitine’s
affect on metabolism during high intensity exercise. This study concluded carnitine
had no affect on metabolic response to high intensity exercise. Forbes et al. (2007)
suggested if carnitine did have any ergogenic benefits, this may aid aerobic
endurance performance. However, this study also suggested that pre-exercise
ingestion of an acute dose of carnitine is unlikely to provide any ergogenic affect on
high intensity exercise.
A study by Woolf & Manore (2006) stated vitamin B12 is essential for chronic
adaptations to training. Vitamin B12 is needed for the synthesis of red blood cells
and to repair damaged cells. B vitamins including riboflavin and vitamin B6 are
important to the energy producing pathways of the body; poor nutritional status of
these B vitamins may result in a reduced ability to perform anaerobically (Woolf &
Manore, 2006). This study highlighted that vitamin B12 ingested before an acute
8
exercise session, would have minimal or no effect on performance. In contrast,
riboflavin and vitamin B6 could, in acute doses, positively impact on anaerobic
performance. Taurine is a sulfonic amino acid that is primarily found in skeletal
muscle (Huxtable, 1992). Supplementation of taurine (6 g/d) has been shown to
significantly increase an individual’s exercise time to exhaustion, VO2max and
maximal workload in a cycle-ergometer exercise (Zhang et al., 2004). However, Red
Bull™ contains only 1 gram of taurine, this is a relatively low amount as a 70kg
individual will have 70 grams of taurine in their body naturally. Therefore, it is unlikely
that the amount of taurine found in Red Bull™ will have any significant affect on
resistance exercise performance.
Although individually many of the ingredients are though to have limited or no affect
on anaerobic performance, the potential for interaction effects between these
ingredients may provide a way in which anaerobic activities are enhanced (Forbes et
al., 2007). There is only limited research into this area and no study has examined
the interaction effects of all the nutrients found in Red Bull™ (Forbes et al., 2007).
9
CHAPTER 2
INTRODUCTION
Caffeine (1, 3, 7- trimethylxanthine) is one of the most commonly used drugs
worldwide (Juhn, 2003; Ellender & Linder, 2005; Desbrow & Leveritt, 2006; Woolf et
al., 2008), yet its affect on anaerobic performance is inconclusive. The impact of
caffeine on performance has been recognised by the World Anti-Doping Agency
(WADA) and the International Olympic committee (IOC). Many studies have
observed an improvement in aerobic performance following caffeine ingestion (Ivy et
al., 1979; Essig et al., 1980; Biaggioni et al., 1991; Goldstein et al., 2010). In
contrast, few studies have examined caffeine’s affects on anaerobic and specifically
resistance training performance (Davis & Green, 2009; Ganio et al., 2009; Astorino &
Roberson, 2010). Studies that have examined this have produced contradictory
results (Collomp et al., 1992; Bell et al., 1998; Denadai & Denadai, 1998; Doherty et
al., 2004). For example, Bell et al. (2001) reported that caffeine ingestion (355 mg)
1.5-hrs prior to testing, did not affect peak power output (PPO). Conversely,
Jacobson (1992) stated that caffeine ingestion (150-675 mg) in strength and power
exercises, significantly improved exercise PPO and reduced power decrement (PD).
As with most ergogenic aids individual responses varied dramatically (Hudson et al.,
2007). Contradictory findings maybe due to differences in the exercise protocols
employed, training status of the participants, habitual intake of caffeine, differences
in caffeine abstinence, dose of caffeine used, timing of ingestion, sample size and
the performance outcome measures used in the studies.
Woolf et al. (2008) suggested that caffeine ingestion significantly improved subjects
muscle endurance and PPO during bench press, but not during leg press. This may
be attributable to differences in fibre type distribution between the upper and lower
body, as the upper body has higher numbers of type II fibres compared with greater
type I fibres in the lower body (Jacobson et al., 1992). Woolf et al. (2008) used 19
highly trained participants, 12 of which were caffeine naïve. If this study had used
high caffeine consumers, caffeine’s impact on resistance performance may have
been different. Beck et al. (2006) noted that caffeine caused an acute increase in the
upper-body PPO of resistance-trained men; caffeine had no affect on lower-body
PPO, muscular endurance, anaerobic capabilities, or upper-body muscular
endurance. It is worth noting participants in this study did not inform the researchers
of any medication or additional supplementation they were taking, all of which may
have affected the study’s findings. However, Kalmar & Cafarelli (1999) reported
11
caffeine significantly increased muscle activation in leg extensions. This study
focused on caffeine’s affect on neuromuscular function, compared to the previous
studies that have focused on performance. Differences in the studies’ aims possibly
explain conflicting findings. Whereas Hudson et al. (2007) demonstrated that
caffeine significantly improved PPO in leg extensions and arm curls. These studies
highlighted that caffeine’s affect on upper and lower body performance needs further
investigation.
Peak power output and power decrement have been employed as performance
measures in studies examining caffeine’s affect on resistance exercise (Jacobson,
1992; Forbes et al., 2007; Woolf et al., 2008; Astorino & Roberson, 2010). Peak
power output has been defined as the maximal amount of force produced in a given
movement or exercise (McArdle et al., 2008). This performance measure is
especially important to resistance exercise as PPO corresponds to muscle
activation, the level of muscle activation during resistance exercise greatly impacts
upon performance (Wilmore et al., 2008). Power decrement is the degree to which
performance levels are compromised, with a corresponding reduction in power
output (PO) (Baechle & Earle, 2008). The ability to maintain PO is essential to
performance in many physical activities. This is due to the fact most sports require
prolonged bouts of physical activity, as a result the ability to maintain high levels of
PO is invaluable to the performer (McArdle et al., 2008).
Many studies have examined the physiological effects of caffeine on the body
(Kalmar & Cafarelli, 1999; Archna & Jaspal, 2008; Varma et al., 2010). However, few
studies have examined caffeine’s affects on participant psychology during anaerobic
exercise (Doherty & Smith, 2005). Furthermore, Astorino & Roberson (2010)
advocated that any future research should also take into account the impact of
caffeine ingestion on psychological variables post resistance exercise. The rating of
perceived exertion (RPE) literature has suggested that caffeine ingestion lowers
participants’ perception of fatigue, during aerobic exercise (Doherty et al., 2004;
Doherty & Smith, 2005). However, Astorino & Roberson (2010) concluded that data
related to resistance exercise was not clear, as caffeine ingestion appeared not to
alter participant RPE. They recognised however, that because of the scarcity of
research in this area further investigation is needed.
12
A common theme highlighted in the literature is the variation of caffeine dosage
used in previous studies, variation in dosage maybe a cause of contradictory study
findings. Archna & Jaspal (2008) studied the effect of different caffeine doses on
strength and endurance; the dosages used included 350, 630, and 910 mg. Only the
highest caffeine dose (910 mg) significantly affected PPO in isometric contractions.
In contrast, some studies have found significant increases in PPO with lower doses
of caffeine i.e. 420 mg (Plaskette & Cafarelli, 1991; Hudson et al., 2007). Jacobson
et al. (1992) inferred that differences between studies may be attributable to
participant fibre type, motivation and caffeine sensitivity. However, in the real world
dosage is often determined by the level of caffeine contained in commercially
available products, such as energy drinks i.e. Red Bull™. Therefore, the ecological
validity and real world relevance of the aforementioned studies may be questioned.
Caffeine energy drinks are a relatively new type of beverage (Mandel, 2002). One
of the leading brands in caffeine energy drinks is Red Bull™. This product holds 65%
of the worldwide sales of stimulant energy drinks, and considered to be the most
popular energy of its type (Alford et al., 2000). Red Bull™ is commonly used as an
ergogenic aid by athletes, in an attempt to improve performance (Forbes et al.,
2007). Red Bull™ state that the product should be consumed in the hour prior to
exercise, to maximise enhanced performance. This reinforces the rationale of many
studies that have examined caffeine’s affect on performance, after ingestion 1 hour
prior to exercise (Anselme et al., 1992; Wiles et al., 1992; Bell & McLellan, 2002). A
study conducted by Forbes et al. (2007) found Red Bull™ increased upper body
muscle endurance during bench press, but had no significant affect on power during
a 30 seconds Wingate test. However, increased muscle endurance cannot with any
degree of certainty be attributed solely to the caffeine in Red Bull™. This is due to
the fact that Red Bull™ contains other ingredients (see Table 1), which may impact
on performance.
Carnitine’s affect on performance is controversial; some studies have shown an
ergogenic benefit from enhanced fat metabolism and improved recovery i.e.
oxidative benefits (Brass, 2004; Forbes et al., 2007). In contrast, most studies have
shown no ergogenic benefit of carnitine ingestion on anaerobic performance or
metabolism (Barnett et al., 1994; Trappe et al., 1994). Forbes et al. (2007)
13
suggested that pre-exercise ingestion of an acute dose of carnitine is unlikely to
provide any ergogenic effect on high intensity exercise.
Woolf & Manore (2006) stated vitamin B12 is essential for chronic adaptations to
training. Vitamin B12 is needed for the synthesis of red blood cells and the repair of
damaged cells. B vitamins including riboflavin and vitamin B6 are important to the
energy producing pathways of the body; poor nutritional status of these B vitamins
may result in a reduced ability to perform anaerobically (Woolf & Manore, 2006). This
study highlighted that vitamin B12 ingested before an acute exercise session, would
have minimal or no effect on performance. In contrast, riboflavin and vitamin B6
could, in acute doses, positively impact on anaerobic performance.
Taurine is a sulfonic amino acid that is primarily found in skeletal muscle (Huxtable,
1992). Supplementation of taurine (6 g/d) has been shown to significantly increase
an individual’s exercise time to exhaustion, VO2max and maximal workload in a cycleergometer exercise (Zhang et al., 2004). Red Bull™ contains only 1 gram of taurine,
a relatively low amount. Therefore, it is unlikely that the amount of taurine found in
Red Bull™ will have any significant affect on exercise performance. Although, few
studies have examined taurine’s affect on resistance exercise (Zhang et al., 2004).
However, it is worth stating that when all the nutrients in Red Bull™ are combined,
there maybe interaction effects between nutrients that impact on performance
(Forbes et al., 2007). The interaction of nutrients is an area that merits further
investigation; there is only limited research into interaction effects on anaerobic
performance. No study has examined the interaction effects of all the nutrients found
in Red Bull™ (Forbes et al., 2007).
Red Bull™ alludes to improving aspects of performance (Alford et al., 2000). Only
two previous studies have investigated the effects of Red Bull™ on performance
(Alford et al., 2000; Forbes et al., 2007), and only Forbes et al. (2007) used
standardised testing procedures. Furthermore, no studies have examined the effect
of Red Bull™ on upper and lower body PD, RPE and PPO in resistance exercise.
Contradictory findings throughout the literature on caffeine’s affect on these 3
measures need to be elucidated. The possible difference in the effects of caffeine on
upper and lower body exercise is a key issue that needs further investigation (Beck
et al., 2006). These are important issues to resolve, so that coaches and athletes
14
can be sure that the use of caffeine as an ergogenic aid can improve resistance
performance. The rationale for this study is to provide information that could be
useful to competitive and recreational athletes who perform high intensity anaerobic
activities, such as resistance training. Therefore, the aims of present study are to
establish if Red Bull™ a caffeine energy drink affects PD, RPE and PPO in the upper
and lower body, of resistance trained males.
15
CHAPTER 3
METHODS
Ten healthy resistance trained males (21.3 ± 8 years old) volunteered for the study;
body mass (76.2 ± 28 kg) and height (177.4 ± 14 cm). The study’s requirements
stated subjects must have been resistance training for at least one year. All
participants were required to complete a Physical Activity Readiness Questionnaire
(PARQ) and consent form, examples of which are provided in appendix (a) and (b).
This study was approved by the University of Wales Institute Cardiff Ethics
Committee. Participants were provided with an information sheet, this informed them
of the purpose and risks involved in the study, an example of which can be viewed in
appendix (c). This information was provided before participants gave their written
consent.
Experimental Summary
The study employed a cross-over design so all participants performed the tests with
and without the intervention. It comprised of two exercises, bench throws (BTs) and
loaded squat jumps (LSJs), both consisting of 3 sets of 8 repetitions. Warm up sets
were performed prior to both test exercises to reduce injury potential. A linear
position transducer (LPT) (Tendo Sports Machines, Tendo Weightlifting Analyser,
Trencin, Slovak Republic) measured PPO in both upper and lower body exercises.
Prior to testing the participant’s one repetition maximum (1RM) was calculated, this
allowed individual optimal loading to achieve PPO to be calculated. Red Bull™ was
administered to participants 1 hour prior to testing. Each individual was tested in the
laboratory twice, once with and once without the Red Bull™. A RPE measure was
taken during each exercise. Data regarding PPO, PD and RPE was gathered and
inputted into Microsoft Excel, in order to examine if Red Bull™ impacted upon
resistance performance in the upper and lower body.
Pre-Experimental Procedure
All participants underwent familiarisation sets on BTs and LSJs during the
calculation of individual optimal loading. Training with optimal load is the most
effective method to improve PPO and reduce PD (Kaneko et al., 1983; Wilson et al.,
1993; Kawamori et al., 2005). The participant’s 1RM for both exercises were
calculated by adding 5kg until failure, with a rest period of 3 minutes between each
repetition, in accordance with procedures outlined by Baechle & Earle (2008). A 5
17
minute rest period was provided between exercises; this ensured the effects of
fatigue on performance would be minimised (Baechle & Earle, 2008; McArdle et al.,
2008). Prior to optimal load testing, participants were required to rest for 15 minutes.
This allowed for adequate recovery, while providing participants with an opportunity
to re-hydrate and prepare for testing (Baechle & Earle, 2008; Wilmore et al., 2008).
Each participant performed 1 set of 8 repetitions for both exercises at 40, 50 and
60% of their 1RM. This is thought to be the loading range that maximises PPO and
minimises PD, especially in squat and bench press exercises (Izquidero et al., 2002;
Siecel et al., 2002). The sets were performed from highest to lowest loading i.e. 6040%. The order of load testing compensated for potential fatigue, due to the
reduction in the weight (kg) of the load being examined (Izquidero et al., 2002). A 60
second rest period was employed between sets during both exercises; this amount
of time has been shown to allow for adequate recovery, reducing the effects of
fatigue on resistance performance (Baechle & Earle, 2008).
Instructions Provided to Participants
The participants in this study were asked to refrain from all caffeinated foods, drugs
and beverages for 24 hours prior to the experimental sessions. Participants were
also told to refrain from strenuous exercise 24 hours prior to any testing.
Furthermore, participants were informed to keep to the same caffeine free diet 24
hours prior to re-testing, in order to standardise the effect of diet on exercise
performance.
Performance Measures
During each of the 3 sets performed for both exercises, PPO data was recorded for
each repetition. The LPT measured PPO during testing; this calculated power output
as shown in equation (1). A mean PPO (MPPO) was then calculated over the 3 sets
in Microsoft Excel. This provided an average measure that allowed the exercise as a
whole to be examined. The mean is the most commonly used measure of central
tendency (Baechle & Earle, 2008). Peak power output has been shown to be a
reliable measure of resistance performance (Forbes et al., 2007; Woolf et al., 2008;
Astorino & Roberson, 2010).
18
(Distance/Time) × Force
(1)
Power decrement was calculated in Microsoft Excel, with the use of MPPO and
maximum power output (MXPO) data, as displayed in equation (2). Power
decrement was displayed as a percentage reduction out of 100, measured using
MPPO calculated over the exercises’ 3 sets. The use of a mean score i.e. MPPO in
the calculation of PD, has been suggested by some to be a more reliable measure of
fatigue (Oliver, 2007). Oliver (2007) stated that as the mean is an average over a
number of efforts, it would be expected to be more reliable compared to the use of a
single effort, such as maximum or minimum values. This is because any large
variation in a single effort could have an amplified affect on the PD score, reducing
the results reliability (McGawley & Bishop, 2006). However, when multiple efforts
and/or sets are taken into account, an averaging effect reduces the impact of single
efforts on overall PD, improving the findings reliability (Oliver, 2007).
Power decrement = ((MPPO – MXPO) /MXPO) × 100
(2)
Bench throws were performed and measured using the same methods as Newton
et al. (1997), Baker (2001) and Falvo et al. (2006). In the BT exercise the LPT was
attached to the outside of the Smith Machine bar, this prevented any cables affecting
lifting movement and provided the LPT with ample space to operate. During the LSJ
exercise the LPT was attached to the centre of the Olympic bar, the participant
performed the LSJs with the LPT cable against their back. This was the safest
method found that reduce the tripping risk sufficiently, while also allowing the LPT to
operate efficiently. The procedure was in accordance with Cormie et al. (2007); they
examined the optimal loading for maximal power output during LSJs. During each
exercise set, ratings of perceived exertion were collected for the participants using a
Borg CR10 RPE scale. This provided self perceptions of fatigue, to observe whether
psychological perceptions of fatigue were altered after the ingestion of Red Bull™.
19
Lifting Procedures
The BT exercise was examined using the participant’s optimal load to achieve
PPO. Bench throws were performed on a Smith Machine (Nova Fitness, Radstock,
UK) in accordance with procedures outlined by Falvo et al. (2006). The participants
were required to lie supine on the bench, with their body position displaying a natural
curvature of the back. Participants gripped the bar with a closed, pronated grip
slightly wider than shoulder width apart. Their feet were placed flat on the floor and
the bar was lifted off the safety hooks by the participant, with support from the
spotter. The participant then informed the spotter when they were ready to begin the
set; this was done with a count down controlled by the participant i.e. “3, 2, 1 my
bar”. The participant then lowered the bar to touch the chest with forearms
perpendicular to the floor. Participants then benched the bar upwards until their
elbows were fully extended and the bar left their hands. The bar was then caught on
the way down by the participants; they repeated the BT process for 8 repetitions.
The LSJ exercise was examined using individual optimal loads calculated in the
pre-experimental procedures. The LSJs were performed using a lifting cage (Cybex,
Power Cage Station, Owatonna & Medway, USA) in accordance with procedures
used by Cormie et al. (2007) and Baechle & Earle (2008). Participants entered the
lifting cage where the safety bars were altered dependent on participant height (cm),
to meet their individual requirements. This was tested during the warm up set, where
participant squat depth was noted, with safety bars then adjusted accordingly. The
Olympic bar was placed at the individual’s optimal height on the supports of the
cage. The bar was gripped with a closed, pronated grip slightly wider than shoulder
width apart, with the bar resting on their shoulders. With assistance from the spotter
the participant moved forward until bar was clear of supports and lifting cage struts.
The participants performed LSJs for 8 repetitions using methods outlined by Baechle
& Earle (2008). Participants entered the squat position with thighs slightly above
parallel to the ground, feet were placed shoulder width apart. Participants then
produced an explosive upward movement to jump to their maximum height. On
landing participants immediately re-entered the squat position and the jump was
repeated for 8 repetitions. Using these lifting procedures for both test exercises
would result in high reproducibility if employed in future studies (Falvo et al., 2006;
20
Baechle & Earle, 2008). Also note that spotters were used during all lifting exercises
to ensure the safety of the participants (Falvo et al., 2006; Cormie et al., 2007;
Baechle & Earle, 2008; Wilmore et al., 2008).
Experimental Procedures
During the investigation a counter-balance testing procedure was used, with half
the participants receiving the intervention and half without. In re-testing a cross-over
protocol was implemented, those who had not previously then received the
intervention. This helped to improve the study’s reliability and validity, as more data
was gathered and each individual acted as their own control. A warm up set was
performed prior to both test exercises, followed with a rest period of 3 minutes before
testing began. The warm ups consisted of 6 repetitions at 50% of 1RM. Baeche &
Earle (2008) suggested resistance warm ups should consist of one or more sets with
relatively light weights, to reduce injury potential. Participants performed 3 sets of 8
repetitions on each test exercise, at their individual optimal load. Bench throws were
tested prior to LSJs in both testing sessions. This is because lower body (leg)
muscles provide a stabilising affect on bench exercises, while leg drives have been
shown to increase PPO in BTs (Falvo et al., 2006; Baechle & Earle, 2008). If BTs
were tested post LSJs, BT PPO may be affected by lower body fatigue (Falvo et al.,
2006). A rest period of 60 seconds was employed between each set on both
exercises, to allow for adequate recovery (Baechle & Earle, 2008). A 5 minute rest
period was taken between test exercises to reduce the possible effects of fatigue on
LSJs (Baechle & Earle, 2008; McArdle et al., 2008). The raw data was then entered
into Microsoft excel where MPPO and PD were calculated.
Supplementation
Red Bull™ energy drink was chosen for this study as it alludes to improving
aspects of performance (Alford et al., 2000). Red Bull™ was administered to the
participants 1 hour prior to testing. This amount of time was chosen because this
was the time shown in the literature for caffeine concentrations to reach its peak
(Graham, 2001). Red Bull™ energy drink contains 80mg/250ml; an optimal amount
21
to improve performance according to the Red Bull™ label. The ingredients that are
contained in Red Bull™ energy drink are displayed in Table 1.
Table 1: Red Bull Energy-Drink Ingredients
Ingredients
Amount (per 100 ml)
Sugar
11 g
Caffeine
32 mg
Taurine
28 g
Glucuronolactone
240 mg
Niacin
8 mg / 50% RDA
Pantothenic acid
2 mg / 33% RDA
Vitamin B6
2 mg / 143% RDA
Riboflavin
Trace
Vitamin B12
2 µg / 80% RDA
Statistical Analysis
Mean and standard deviations (SD) were calculated for PPO, PD and RPE
measures. The variables in this study were analysed using the statistical package for
the social sciences (SPSS), in Windows software (version19, Inc., Chicago, IL).
Means were entered into SPSS; to test for differences between interventions a
paired t-test was employed. A repeated measures ANOVA was used to identify any
differences within interventions, across the 3 sets. The level of statistical significance
was set at a p-value of less than 0.05 (P < 0.05).
22
CHAPTER 4
RESULTS
Bench Throw
Mean Peak Power Output
Out of the 10 participants who volunteered, all 10 completed the study. There was an
overall supplementation effect on bench throw when Red Bull™ had been ingested,
whereby MPPO was significantly greater after consumption (Red Bull™ = 554 ± 21
VS. control = 523 ± 23 Watts over the 3 sets, P = 0.008). In both interventions set 2
was significantly different to sets 1 and 3 (see Figure 1). There were no significant
differences between sets 1 and 3 during either intervention. The set-by-set analysis
Bench Throw Mean Peak Power
Output (W)
revealed significant differences between interventions for all 3 sets (see Figure 1).
*ac
600
*c
580
*a
560
540
Control
520
RedBull
500
480
ac
c
a
460
Set 1
Set 2
Set 3
Figure 1: Bench throw peak power output across sets, mean ± standard deviation. *
indicates a significant difference between Red Bull™ and control (P < 0.05), in a setby-set analysis between interventions. For the within comparison analysis a indicates
a significant difference between sets 1 and 2, with b indicating a significant
difference between sets 1 and 3. c displays a significant difference between sets 2
and 3.
24
Power Decrement
There was no overall significant difference found between control and Red Bull™
power decrement (Red Bull™ = 6 ± 2 VS. Control = 5 ± 3.4 % over the 3 sets, P =
0.774). In the control intervention no significant differences were found between any
sets (see Figure 2). Within the Red Bull™ intervention set 1 was significantly
different to set 2, no significant differences were found between any other sets (see
Figure 2). The set-by-set analysis revealed a significant difference between
interventions for set 1 only (see Figure 2).
Bench Throw Power Decrement
(%)
12
10
*
8
Control
6
RedBull
4
2
a
a
0
Set 1
Set 2
Set 3
Figure 2: Bench throw power decrement across sets, mean ± standard deviation. *
indicates a significant difference between Red Bull™ and control (P < 0.05), in a setby-set analysis between interventions. For the within comparison analysis a indicates
a significant difference between sets 1 and 2, with b indicating a significant
difference between sets 1 and 3. c displays a significant difference between sets 2
and 3.
25
Rating of Perceived Exertion
An overall supplementation effect was observed in bench throw RPE, whereby RPE
significantly decreased after Red Bull™ ingestion (Red Bull™ = 11.6 ± 1.3 VS.
control = 13.4 ± 2.0 over all 3 sets, P = 0.042). Within both control and Red Bull™
interventions there were significant differences between all 3 sets (see Figure 3).
The set-by-set analysis revealed significant differences between interventions for all
3 sets (see Figure 3).
Bench Throw Rating of
Perceived Exertion
18
*bc
16
*ac
14
*ab
Control
12
RedBull
10
bc
ac
8
ab
6
Set 1
Set 2
Set 3
Figure 3: Bench throw rating of perceived exertion, mean ± standard deviation. *
indicates a significant difference between Red Bull™ and control (P < 0.05), in a setby-set analysis between interventions. For the within comparison analysis a indicates
a significant difference between sets 1 and 2, with b indicating a significant
difference between sets 1 and 3. c displays a significant difference between sets 2
and 3.
26
Loaded Squat Jumps
Mean Peak Power Output
The supplementation effect was of borderline significance between Red Bull™ and
control MPPO, during loaded squat jumps (Red Bull™ = 715 ± 17.3 VS. control =
692.1 ± 18.1 Watts, P = 0.053). The control intervention showed significant
differences between sets 1 and 3, no other significant differences were found (see
Figure 4). In the Red Bull™ intervention there were no significant differences
between any of the sets (see Figure 4). The set-by-set analysis revealed a significant
difference between interventions for set 3 only (see Figure 4).
Loaded Squat Jump Mean Peak
Power Output (W)
740
*
730
720
710
700
Control
690
680
RedBull
b
670
b
660
650
Set 1
Set 2
Set 3
Figure 4: Loaded squat jump peak power output across sets, mean ± standard
deviation. * indicates a significant difference between Red Bull™ and control (P <
0.05), in a set-by-set analysis between interventions. For the within comparison
analysis a indicates a significant difference between sets 1 and 2, with b indicating a
significant difference between sets 1 and 3. c displays a significant difference
between sets 2 and 3.
27
Power Decrement
Power decrement in loaded squat jumps showed no overall significant difference
between control and Red Bull™ interventions (Red Bull™ = 3.3 ± 2 VS. control = 4 ±
2.3 % over all sets, P = 0.093). Within both control and Red Bull™ interventions, no
significant differences were found between any of the 3 sets (see Figure 5). The setby-set analysis revealed no significant differences between interventions (see Figure
5).
Loaded Squat Jump Power
Decrement (%)
7
6
5
4
Control
3
RedBull
2
1
0
Set 1
Set 2
Set 3
Figure 5: Loaded squat jump power decrement across sets, mean ± standard
deviation. * indicates a significant difference between Red Bull™ and control (P <
0.05), in a set-by-set analysis between interventions. For the within comparison
analysis a indicates a significant difference between sets 1 and 2, with b indicating a
significant difference between sets 1 and 3. c displays a significant difference
between sets 2 and 3.
28
Rating of Perceived Exertion
The RPE in loaded squat jumps displayed an overall supplementation effect, RPE
significantly decreased after Red Bull™ consumption (Red Bull™ = 11.6 ± 1.5 VS.
control = 12.7 ± 1.4 over all 3 sets, P = 0.011). Within both interventions there were
significant differences between all 3 sets (see Figure 6). The set-by-set analysis
revealed significant differences between interventions for all 3 sets (see Figure 6).
Loaded Squat Jump Rating of
Perceived Exertion
18
*bc
16
*ac
14
*ab
Control
12
bc
RedBull
10
8
ab
ac
6
Set 1
Set 2
Set 3
Figure 6: Loaded squat jump power decrement across sets, mean ± standard
deviation. * indicates a significant difference between Red Bull™ and control (P <
0.05), in a set-by-set analysis between interventions. For the within comparison
analysis a indicates a significant difference between sets 1 and 2, with b indicating a
significant difference between sets 1 and 3. c displays a significant difference
between sets 2 and 3.
29
CHAPTER 5
DISCUSSION
To the author’s knowledge this is the first study that has examined the effect of Red
Bull™ energy drink on power decrement and peak power output, in the upper and
lower body of resistance trained males. Results showed that overall MPPO was
significantly increased after the consumption of Red Bull™, during bench throw
exercises. Mean peak power output increased in loaded squat jumps, during the Red
Bull™ intervention, this improvement was of borderline significance. No overall
significant differences in power decrement were found for both interventions during
either exercise. However, RPE scores were significantly lower between Red Bull™
and control interventions for both BTs and LSJs.
Caffeine is the main active ingredient present in Red Bull™. When caffeine is
absorbed in the body it crosses the blood-brain-barrier, it is then distributed in the
intracellular fluid (Arnaud, 1987). Although the underlying mechanisms of caffeine’s
ergogenic effects are not fully understood, there are theories attempting to explain
these effects, including antagonism of adenosine receptors (Varma et al., 2010).
Caffeine’s stimulatory affect on the nervous system has been attributed to its binding
with specific pre-synaptic adenosine receptors, blocking the inhibitory effects of
adenosine (Varma et al., 2010). This has been shown to increase calcium release
and re-uptake across the sarcoplasmic reticulum, facilitating the release of
stimulatory neurotransmitters including epinephrine (Costill et al., 1978; Graham,
2001; Beck et al., 2006; Goldstein et al., 2010; Varma et al., 2010). This is believed
to result in increased central nervous system (CNS) activation (Arnaud, 1987),
increasing an individual’s ability to excite a motor unit bundle, by lowering the motor
neuron threshold, facilitating maximal muscle activation (Archna & Jaspal, 2008).
Caffeine has also been shown to decrease plasma potassium levels, which is
believed to aid membrane contractility in exercise (Williams, 1991). These
mechanisms of caffeine potentially have the ability to improve resistance
performance.
31
Mean Peak Power Output
Overall, bench throw MPPO was shown to significantly increase after Red Bull™
ingestion. Furthermore, in both interventions set 2 was significantly higher than sets
1 and 3; this was unexpected as performance would be expected to decrease across
sets as a result of fatigue (see Figures 1 & 4). However, Anselme et al. (1992)
argued that performance may not decrease over a small number of sets, this maybe
due to insufficient exercise time and load to initiate fatigue or participants
familiarising exercise movements, which may result in improved or maintained
performance across sets. In all 3 sets MPPO was significantly higher in the Red
Bull™ intervention when compared to the control. This supports findings by Anselme
et al. (1992), Goldstein et al. (2001) and Woolf et al. (2008) which found PPO was
significantly increased during bench press, after the ingestion of caffeine. However,
studies by Bell et al. (2001) and Lorino et al. (2006) found caffeine had no significant
affect on PPO during bench press exercises. Possible explanations for differences
observed between these and the present study may include the exercise protocols
employed, training status of the participants, habitual intake of caffeine, differences
in caffeine abstinence, dose of caffeine used, timing of ingestion, sample size and
the performance outcome measures used in the studies.
During loaded squat jumps, Red Bull’s affect on MPPO was bordering on
significance (P = 0.053), and is open to personal interpretation of whether or not
results are significant. This finding was potentially in accordance with Woolf et al.
(2008) who reported caffeine had no significant impact on PPO in lower body
exercises. However, it is worth noting that this study used leg extensions as a
measure of lower body PPO, so direct comparisons between this and the present
study must be taken with caution. Furthermore, during the LSJ set-by-set analysis
set 3 MPPO was significantly higher in the Red Bull™ intervention compared to the
control. When results are taken together it suggests Red Bull™ may have a
significant effect, although this may not be apparent until latter sets. This provides a
rationale for increasing the number of sets in future studies, expanding on work by
Bruce et al. (2000) who inferred that the effects of caffeine on resistance exercise
may only become evident in more prolonged exercises. Davies & Green (2009) put
forward that multiple sets may show caffeine affects performance in leg musculature
32
later; this is when fatigue becomes more prominent and when caffeine may show its
greatest impact on lower body performance. This idea is reinforced further by the
LSJ power decrement starting to reduce, although not significantly, in set 3 (see
Figure 5). Again possibly displaying the fact that more sets are needed to observe
caffeine’s potentially delayed impact on lower body performance.
A key issue this study aimed to examine was the potential difference in the effect of
Red Bull™ on upper and lower body performance. This study’s findings suggest
there are potential differences between the upper and lower body, with differences
more apparent in BTs. This reinforces work by Woolf et al. (2008) which found
caffeine ingestion significantly improved PPO during bench press, but not during leg
press exercises. Beck et al. (2006) also noted caffeine caused an acute increase in
the upper-body PPO of resistance-trained men, with no affect on lower-body PPO.
Although, once again direct comparison between these studies and the present
study are hard due to differences in exercise protocols employed. Conversely,
Kalmar & Cafarelli (1999) reported that caffeine significantly increased muscle
activation in leg extensions. Moreover, Hudson et al. (2007) demonstrated that
caffeine significantly improved PPO in leg extensions and arm curls, showing
caffeine affected both the upper and lower body. Differences in findings maybe due
to the training status of participants, exercise protocols, dose of caffeine and the use
of caffeine solely rather than Red Bull™ in the present study.
Mechanisms behind upper and lower body differences are potentially caused by the
training status of participants. Jacobs et al. (2003) investigated the effect of caffeine
on bench and leg press. They used recreational athletes and found no significant
difference between caffeine and placebo trials for either exercise. Furthermore,
Hendrix et al. (2010) examined caffeine’s ergogenic affect on untrained participants,
during resistance exercise. This study discovered acute caffeine ingestion, did not
significantly affect untrained participant’s performance in bench press and leg
extension exercises. This study did not inform participants to refrain from strenuous
activity prior to testing, this may be a reason why caffeine had no impact on
resistance performance; participants could have been fatigued prior to testing.
Moreover, Lorino et al. (2006) found consumption of caffeine by young occasionally
active individuals had no significant affect on power output. In contrast, Woolf et al.
(2008) used highly trained athletes to examine the same variables as Jacobs et al.
33
(2003). They found a significant improvement in bench press but not in leg press
exercises. Jacobson et al. (1992) employed highly trained resistance athletes and
discovered significant increases in bench press but not in leg extensions. Hudson et
al. (2007) examined caffeine’s affect on the upper and lower body using experienced
resistance trained participants. This study showed caffeine significantly improved
both leg extension and arm curl PPO. In addition, Duncan & Oxford (2011) reported
experienced resistance trained males, demonstrated a significant PPO increase
during bench press 1 RM, as a result of acute caffeine ingestion. However, this
study’s resistance protocol was brief and may not be representative of resistance
exercises performed in training and sporting contexts. Woolf et al. (2008) argued
elite athletes would generally have more muscle mass than recreational or untrained
participants, and that males would usually have greater muscle mass than that of
females. Caffeine is believed to act directly on muscle fibres (Jacobson et al., 1992;
Bruce et al., 2000; Bell et al., 2001); therefore individuals with a larger muscle mass
may benefit more from caffeine ingestion. This theory provides a possible
explanation for differences observed between studies. However, throughout the
literature studies that have used more experienced participants have generally
employed higher doses of caffeine i.e. 400 mg upwards. As a result it may be the
use of this higher caffeine dose which causes an ergogenic affect on short duration,
high-intensity exercise (Woolf et al., 2008). In contrast, the present study found
ergogenic benefits i.e. increased PPO, at a comparatively low dose of caffeine (80
mg).
Jacobson et al. (1992) stated contradictory findings on caffeine’s influence on upper
and lower body performance, may be attributable to differences in fibre type
distribution. The upper body has higher numbers of type II fibres when compared
with greater type I fibres in the lower body. They argued that caffeine may be fibre
specific; caffeine may have a greater ergogenic impact on type II fibres during
resistance exercise. Explaining why many studies including the present study have
found caffeine significantly affected upper but not lower body performance (Anselme
et al., 1992; Beck et al., 2006; Woolf et al., 2008; Goldstein et al., 2010). However,
while the results of the present study support previous findings; more research is
needed to identify the exact mechanisms responsible.
34
A further cause of differences between upper and lower body findings may include
the training status of participants’ neurological system. Caffeine may have a greater
ergogenic affect on resistance athletes over untrained or occasionally active
individuals. This is due to neural adaptations to training and caffeine’s affect on the
CNS (Beck et al., 2006; Duncan & Oxford, 2011). Resistance athletes are believed
to benefit from neural training adaptations to resistance exercise. These adaptations
include improved neuromuscular pathways between the brain and working muscle,
and an increase in the release of neurotransmitters such as epinephrine (Dunwiddie
& Fredholm, 1989; Astorino & Roberson, 2010; Varma et al., 2010). As stated
previously, caffeine allows greater calcium transportation across the cell membrane,
facilitating the release of stimulatory neurotransmitters. As a result of training
adaptations resistance athletes may have improved neuromuscular pathways; the
ergogenic benefits of caffeine may therefore result in further pathway stimulation
(Duncan & Oxford, 2011). As a consequence, caffeine may significantly improve the
performance of resistance athletes when compared to untrained participants
(Hudson et al., 2007; Astorino & Roberson, 2010; Duncan & Oxford, 2011). This
research has implications for the present study; participants employed were
resistance trained males. Therefore, this population may have the most to gain from
caffeine supplementation, due to potential adaptations gained from resistance
training. The present study’s results appear to partially support this idea, as MPPO
was significantly increased in BTs, during Red Bull™ intervention. However, similarly
to Woolf et al. (2008), only borderline significant differences were observed in lower
body exercises, even when highly trained individuals were used. The present study
confirms that caffeine’s mechanisms improved upper body performance, with more
research merited into its apparent reduced significance in lower body exercises.
Power Decrement
There was no overall effect of Red Bull™ on power decrement during BTs and
LSJs. Only in the set-by-set analysis for BTs was a significant difference found
between set 1 in control and Red Bull™ interventions. No significant differences
were found in the set-by-set analysis in LSJs. To the author’s knowledge the present
study is the first piece of research to examine PD in relation to Red Bull™ and
resistance performance in the upper and lower body. Therefore, direct comparisons
35
with other studies are difficult and limitations of this must be recognised. Many
studies have examined PD in repeated sprint and intense intermittent exercises
(Fitzsimmons et al., 1993; Tomlin & Wenger, 2002; McGawley & Bishop, 2006). The
use of PD in the present study was chosen on the basis that it provided greater
reliability than the use of other fatigue measures, such as fatigue index (FI) (Hughes
et al., 2006). Many studies have found FI to be unreliable and suggest its scores
should be treated with caution (Psotta & Bunc, 2005; McGawley & Bishop, 2006;
Hughes et al., 2006). Power decrement is considered to be a more reliable measure
of fatigue because all data is incorporated, producing an averaging effect which
reduces the impact of single events on the whole performance (Oliver, 2007).
Moreover, the use of mean scores in the calculation of PD is more reliable than the
use of single events i.e. maximum or minimum values, as used in FI (Oliver, 2007).
However, recent studies have shown there still to be a large variability in results,
when using PD as a fatigue measure in repeated sprints (McGawley & Bishop, 2006;
Hughes et al., 2006). This variability is caused by the need to express fatigue as a
reduction in performance (Oliver et al., 2006). Oliver et al. (2006) stated that
subtracting one value from another caused greater within-subject variability, in
relation to the magnitude of the measure. For this reason the reliability of PD as a
measure of fatigue may be questioned, due to coefficients of variation being reported
as ranging from 11 to 50% (McGawley & Bishop, 2006; Hughes et al., 2006). This
makes detecting changes difficult, as the measure contains so much inherent
random variation. Although, it is worth noting that the present study used
familiarisation sets for both exercises, during the pre-experimental procedures.
Familiarisation trials have been shown in some studies to improve the reliability of
PD scores (McGawley & Bishop, 2006), but not all (Hughes et al., 2006; Oliver et al.,
2006). Oliver (2007) highlighted that although the use of familiarisation trials would
appear to be an obvious way to increase the reliability of fatigue measures, findings
in the research are inconclusive. In any case, Oliver (2007) argued that as the time
scale over which familiarisation effects last is unknown, familiarisation trials would be
needed prior to each testing procedure. Major conceptual differences are evident
between the present and aforementioned studies, which include exercise protocols,
participant training status and importantly the absence of caffeine supplementation.
As a result, comparisons with the present study may be misleading and must be
taken with caution.
36
Caffeine has only recently been investigated as a tool to influence fatigue, affecting
both central and peripheral pathways (Kalmar & Cafarelli, 2004). The mechanisms
behind the present study’s PD findings are possibly explained by Bruce et al. (2000),
as previously stated in the MPPO section. They suggested caffeine’s affect on lower
body resistance performance may only be shown in more prolonged exercises.
Mechanisms relating to this process are not fully understood, but it is thought the
effects of caffeine may be so small in short duration and resistance exercises, its
effects can only be seen once fatigue becomes more prominent (Davies & Green,
2009). They presented this was especially true in lower body musculature and may
relate to fibre distribution. This potentially relates to the present study, as no
significant differences were seen in PD scores, when comparing interventions over 3
sets for LSJs. The aforementioned research has argued that 3 sets may not be
enough to initiate high levels of fatigue in LSJs. Thus any supplementation effects
would not have become as evident as those observed in BTs. Rouhola et al. (2004)
proposed caffeine may act more on type 1 fibres, but little evidence is available to
support this theory. Conversely, their experiment on repeated 35 metre sprints found
caffeine improved FI over 6 repetitions, contradicting the idea that caffeine’s effects
are not evident in short duration exercises. In contrast to other ideas, Woolf et al.
(2008) stated caffeine may have an instant affect on PD in resistance activities of 4
to 6 seconds. They stated it was likely upper body performance would benefit most
due to greater numbers of type II fibres and closer proximity to the altered release of
stimulatory neurotransmitters from the brain. Some support for this theory was seen
in the present study, as a significant difference in PD was observed in BTs, between
Red Bull™ and control interventions in set 1. Increasing PPO as observed in set 1 of
BTs, is often associated with resulting in greater fatigue. This is because increased
PPO leads to greater immediate metabolic stress, depletion of phosphocreatine
(PCr), acidosis and accumulation of inorganic phosphates; linked to impairment of
calcium cycling (McArdle et al., 2008; Wilmore et al., 2008). Interestingly, this was
not the case in the present study. Red Bull™ was able to increase initial PPO in both
exercises, without having the negative effect of causing more fatigue.
37
The literature has highlighted that caffeine reduces fatigue in aerobic activities
(Graham & Spriet, 1991; Spriet et al., 1992; Graham & Spriet, 1995; Van Soeren &
Graham, 1998). Caffeine has also demonstrated its affect on sprint activities
(Rouhola et al., 2004; Davies & Green, 2009) and speed endurance exercises
(Doherty, 1998; Bell & Jacobs, 2001; Doherty et al., 2004) in lowering fatigue. This
provided strong evidence that caffeine reduces fatigue in both aerobic and anaerobic
contexts. However, there is clearly a lack of research into caffeine’s influence on
fatigue in resistance exercise. Therefore, comparison between these and the present
study’s findings are not easy, mainly due to differing exercise protocols, participant
training status and dose of caffeine used. In the present study, emphasis must be
drawn to the fact that an original piece of research has be presented, using a popular
commercial drink. This area needs to be elucidated and should form the basis of
future research into caffeine’s affect on resistance performance.
Rating of Perceived Exertion
In both exercises, overall RPE was significantly lower in the Red Bull™ intervention
when compared to the control. The set-by-set analysis revealed the Red Bull™
intervention was significantly lower across all 3 sets, during both BTs and LSJs (see
Figures 3 & 6). It is worth noting the effects of caffeine on RPE in aerobic
performance have been extensively examined and documented (Costill et al., 1978;
Cole et al., 1996; Spriet & Howlett, 2000). In contrast, research examining the effect
of caffeine on RPE in anaerobic and specifically resistance performance has been
scarce and only recently investigated. Studies conducted by Green et al. (2007) and
Hudson et al. (2007) found no significant differences in RPE between caffeine and
control interventions, during resistance training. However, these two studies did
observe an increase in repetitions in the caffeine intervention, implying RPE may be
reduced to some extent or that participants completed more work for a given RPE.
Furthermore, a study by Schneiker et al. (2006) showed caffeine had no affect on
RPE when compared with placebo, during resistance exercise. Although, they did
find that power output was significantly greater in the caffeine intervention,
suggesting a greater amount of work was performed at a given RPE. Davies &
Green (2009) stated the lack of differences between the findings of these studies
suggest the RPE scale is too gross to detect changes in perception, in high exercise
38
intensities. They acknowledged that this area should form the basis of future
research, so the extent of caffeine’s effect can be fully understood. Contradictory to
these previous studies, participants simultaneously significantly improved PPO and
lowered RPE in the BT exercise; this is a unique finding from the present study.
Caffeine’s antagonism of specific pre-synaptic adenosine receptors and its resulting
effects have been previously mentioned. Davies & Green (2009) stated it is these
properties of caffeine that modify pain and therefore effort perception, while
sustaining motor unit firing rates and neuro-excitability. The presence of pain has
been shown to increase effort perception and reduce the ability to produce forceful
muscle contractions (Lund et al., 1991). Correlations have been found between the
degree of muscle pain and the number of motor units recruited (Farina et al., 2004).
Studies have shown high pain intensities result in decreased neurological firing
rates, reducing the number of motor units recruited and the resulting forcefulness of
muscle contraction (Sohn et al., 2000; Farina et al., 2004; Kalmar, 2005). This may
help to explain the effects of Red Bull™ ingestion on greater power production and
lowered perceived exertion, observed in the present study. Adenosine has been
observed to increase muscular pain when fed intravenously into health participants
and individuals suffering with angina (Sylvan et al., 1988; Abreu et al., 1991).
Research has demonstrated that antinociceptive effects were evident through the
activation of A1 adenosine receptors, while the stimulation of A2 receptors has been
shown to produce a hyperalgesic response (Taiwo & Levine, 1990; Swynok, 1998).
Motl et al. (2003) proposed that caffeine bound more readily to A2 receptors,
resulting in a hypoalgesic response. Similarly to RPE, there is great paucity in
research into caffeine’s affect on pain perception, in an anaerobic paradigm (Davies
& Green, 2009). A sole study by Maridakis et al. (2007) displayed the hypoalgesic
effect of caffeine when compared to placebo. However, this study used a visual
analogue scale (VAS) to measure pain/effort perception. This method is open to the
subjective view of the recorder; as a result its findings may be treated with caution.
Furthermore, direct comparison with the present study’s findings is difficult due to
differences in exercise protocols and performance measures. Maridakis et al. (2007)
employed electrical stimulation of the quadriceps, therefore it was not known if these
findings applied to experienced resistance athletes during free weight exercises
(Davies & Green, 2009). The present study has provided information relating to effort
39
perception, which has contributed to filling this gap in the research. This study
showed the perceived effort of resistance trained individuals was lowered in Red
Bull™ interventions, during free weight exercises. The implications of these findings
are that a reduction in effort perception could improve work output, as seen
significantly in BTs and on borderline significance in LSJs.
Other potential mechanisms of caffeine involved in reducing participants RPE,
include its interaction with dopamine receptors (Ribeiro et al., 2003). Adenosine has
been shown to reduce many excitatory neurotransmitters in the brain, with dopamine
potentially the most inhibited (Ribeiro et al., 2003). Woolf et al. (2008) proposed that
as adenosine receptors are abundant in the brain, caffeine may act as an antagonist
blocking adenosines’ inhibitory neural signals, thus modifying pain perception,
sympathetic activity, motor unit recruitment, and fatigue. Therefore, as caffeine is
potentially a dopamine agonist, it could explain the present study’s findings that RPE
is reduced after Red Bull™ ingestion, resulting in increased work output.
Limitations
This study investigated the effect of Red Bull™ on resistance trained males,
narrowing its scope and generalisability as only one population was examined.
However, the use of this population was justified, due to the fact only limited
research existed into caffeine’s influence on this group (Davis & Green, 2009; Ganio
et al., 2009; Astorino & Roberson, 2010), with recognition that future work should
address this issue (Beck et al., 2006; Duncan & Oxford, 2011). Furthermore, this
study’s aim was to discover if Red Bull™ could be advocated as an ergogenic aid to
improve resistance performance. Therefore, the use of resistance trained
participants is conducive with this aim, as this represents the type of population likely
to use ergogenic aids to improve training performance. This is due to neurological
adaptations caused by resistance training, increasing CNS pathway stimulation
(Beck et al., 2006; Duncan & Oxford, 2011). Caffeine ingestion is considered to elicit
further pathway stimulation, on top of that observed from training adaptations
(Duncan & Oxford, 2011). It is therefore logical to conclude that resistance trained
individuals may experience greater performance improvements when compared to
untrained populations (Hudson et al., 2007; Astorino & Roberson, 2010; Duncan &
Oxford, 2011). The use of males in this study was reinforced by Woolf et al. (2008),
40
who proposed that as males generally have greater muscle mass, they may benefit
more from the ergogenic effects of caffeine. This is related to the theory that caffeine
acts directly on muscle fibres.
A further limitation could be the lack of investigation into possible interaction effects
between the ingredients present in Red Bull™ (see Table 1). Although considered a
valid and scarce research area (Forbes et al., 2007), due to time and equipment
limitations, the scope of this study has focused more on performance enhancement.
This leaves future studies the opportunity to examine this important and merited
topic. The lack of a placebo control inhibited this study from examining whether
participants could recognise if they had been administered Red Bull™. This would
have been worthwhile in observing if perception of Red Bull™ administration affected
participant performance. However, the use of a placebo was not practical, as Red
Bull™ is a commercially available product and due to popularity it is easily
recognisable. It would have been difficult and time consuming to find or create a
placebo that mimicked the taste and appearance of Red Bull™.
Conclusion
In summary, Red Bull™ ingested 1 hour prior to resistance exercise significantly
increased upper, and was of borderline significance in lower body PPO. Rating of
perceived exertion was lowered in both exercises as a result of Red Bull™
consumption. While no differences were found in PD between interventions in either
exercise, this may be due to lack of reliability in this measure or due to insufficient
sets to induce sufficient fatigue. These findings suggest that Red Bull™
supplementation could be an effective ergogenic aid, for resistance trained males
who perform upper and possibly lower body resistance exercises. Red Bull™
increased upper and lower body PPO, while causing no increase in fatigue and
lowered perceptions of effort. Therefore, it may offer a convenient and affordable
way to improve resistance training performance. These findings potentially relate to
caffeine’s antagonism of adenosine receptors, muscle fibre distribution and its
stimulation of central and peripheral pathways. This was a novel piece of research,
so as repeated throughout, direct comparison with other studies must be treated with
caution. Only two other studies had examined the effects of Red Bull™ on anaerobic
performance (Alford et al., 2000; Forbes et al., 2007). Further research is merited
41
comparing trained against untrained participants, gender differences, different
muscle groups and fibre types.
42
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APPENDICES
APPENDIX
a
60
Physical Activity Readiness Questionnaire (PAR-Q)
Participants name………………………………………………………………………………
Please circle the answers to the following questions:
1
Do you have asthma or any breathing problems?
Yes / No
2
Has your doctor ever said you have heart trouble ?
Yes / No
3
Do you frequently suffer from pains in the chest ?
Yes / No
4
Do you often feel faint or have spells of severe dizziness ?
Yes / No
5
Has a doctor ever said your blood pressure was too high ?
Yes / No
6
Has a doctor ever said that you have a bone or joint problem
such as arthritis that has been aggravated by exercise, or might be
7.
8.
made worse with exercise ?
Yes / No
Is there a good physical reason not mentioned here why you
should not take part in a fitness test ?
Yes / No
Are you unaccustomed to vigorous exercise ?
Yes / No
If you have answered yes to any of these questions, please add details below. Similarly, if
there are any situations which will prevent you from exercising write them here (or let us
know if they arise through the experiment).
If your situation changes regarding your responses to these questions, please notify the
appropriate staff/ Researcher member.
Signed (participant)………………………………………………….
Signed (investigator)……………………………………………….
Date…………………………………………………….
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APPENDIX
b
62
CONSENT FORM
PROJECT TITLE: Effect of Red Bull energy drink on Power Decrement and Peak Power
Output in the Upper and Lower Body
Principle researcher: Owain Smallwood
Contact details: [email protected]
(07949 252588)
I have read the Information Sheet regarding this research study and understand what is being
investigated, and what is required of me. Any questions have been answered to my understanding
and satisfaction. I understand that I can request further information at any stage of the study, relating
to me.
I understand that:

My participation is entirely voluntary and that I am free to withdraw from the research study at
anytime without any repercussions on me.

I will be required to attend four laboratory sessions to complete the research study.

During the research study I will have personal data recorded (height, weight, age, sport
played (or equivalent resistance exercise I participate in), as well as undergoing power testing
of power maintenance and peak power output.

My data will be stored in coded form ensuring that results can not be linked to me. My results
will only be accessible to and viewed by the principle investigator and the dissertation
supervisor. All data from the research will be stored by the principal investigator. Any hard
copy information (e.g. personal details) shall be store and secured in a locked filing cabinet.
Electronically stored information will only be accessible to the principal investigator and
dissertation supervisor.
Signed:……………………………………………………….
Print name:…………………………………………………..
Date:…………………………………..
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APPENDIX
c
64
INFORMATION SHEET – REQUEST FOR VOLUNTEERS
RESEARCH PTOJECT TITLE: Effect of Red Bull energy drink on Power Decrement and Peak
Power Output in the Upper and Lower Body
Principle researcher: Owain Smallwood
Contact details: [email protected]
(07949 252588)
Dear student,
Purpose of this letter
This document provides information about a research study being conducted in the Cardiff School of
Sport. The documents purpose is to provide you with information about the study, to allow you to
decide if would like to volunteer to participate in the study. As you are a volunteer, your participation
in the project would be voluntary and you would be able to withdraw from the project at any time.
Aims of the research
The aim of the present study is to establish if “Red Bull” a caffeine energy drink, affects power
maintenance (PM) and peak power output (PPO) in the upper and lower body, in resistance trained
males. As Red Bull is commonly used by athletes, its affect on performance must be researched
further. This study aims to provide information that could be useful to competitive and recreational
athletes who perform high intensity anaerobic activities, such as resistance training. If red bull was
found to have an ergogenic effect on anaerobic performance, strength and muscular endurance in the
upper and lower body, it could be used by athletes before training and competition to improve
performance.
What will happen if you decide to volunteer?
You will be asked to attend two sessions. Prior to testing your one rep max (1RM) will be calculated
by adding 5kg until failure. Your Optimal load to achieve PPO will be found by performing a set of
counter movement jumps (CMJ) and bench throws (BT) at 40, 50, and 60% of 1RM. This enables
individual optimal loads to be calculated, making the study’s findings more valid and reliable. This
study will employ a cross-over design so all participants perform the tests with and without the
intervention. The red bull will be administered to the intervention group 60 minutes prior to testing. A
warm up set will be performed prior to both exercises; it will consist of 6 reps at 60% of 1RM.
In testing session one (T1), half the group will perform a BT with the intervention. The other half is
not administered the red bull at this stage. They will perform 3 sets of 8 reps on the BT, at their
individual optimal load. The Tendo-accelerometer is attached to the Smith machine to measure
power. There will be a rest period of 3 minutes between each set, to allow for recovery.
65
There will be a 5 minute rest between the exercises to reduce the possible effects of fatigue on the
CMJ. 3 sets of 8 reps will be performed on the CMJ; there will be a rest period of 3 minutes between
each set. The Tendo-accelerometer is attached to the bar to measure power. The raw data is then
entered into excel where PPO, PM and PD can be calculated.
Testing session two (T2) will follow the same procedures as T1, apart from the other half of the
group being given the intervention 60 minutes prior to testing. This will improve the study’s reliability
and validity, as more data can be gathered and you will act as your own control.
.
What type of participants are wanted?
We want to recruit participants who are resistance trained male athletes; these can include
recreational gym users, rugby players, competition weight lifters and/or any individual that is both
upper and lower body resistance trained. You must have been resistance training for at least one year
prior to this study.
What are the risks of participating in the study?
There could be slight discomfort to you, as both exercises performed in each lab session are of high
intensity. This could lead to you becoming fatigued, with the discomfort being in the form of lactic acid
build up, causing slight discomfort. Red Bull (Caffeine containing products) in some cases has been
shown to cause headaches, nausea and stomach cramps; this could cause considerable discomfort
to you. As with any high intensity exercise you could pull or damage muscles as the movements are
explosive in nature. However, the risks associated with both test procedures are no more that if you
were performing explosive movements while competing or training. If you suffer any adverse effects
as a consequence of your participation in this study, you will be compensated through UWIC.
Benefits to the participant
You will be provided with a record of your performance during testing, if you so wish, this will help you
learn more about your abilities in power exercises, which could impact on your training and future
performance. Also you will discover the individual effects of caffeine on you and whether it
significantly affects your PPO and/or PD. This study will be linked with some of you to your SES
module work experience, you will have to produce a reflective practice essay on what you have learnt
and gained from the research experience. There will be a presentation of findings to all participants
involved in the study, to aid them in their reflective practice coursework.
What will happen to the information collected?
All participants will receive their own results for the tests they perform. The investigation data will be
stored in coded form (with each participant having an individual code i.e. subject 1) ensuring that
results can not be linked to an individual. Results will only be accessible to and viewed by the
principle investigator and the dissertation supervisor. All data from the research will be stored by the
principal investigator. Any hard copy information (e.g. personal details) shall be store and secured in a
locked filing cabinet. Electronically stored information will only be accessible to the principal
investigator and dissertation supervisor.
66
What to do next?
If you have any questions about the research study then please contact me (details given at top of
page). If you would like to participate in the study then please notify me by e-mail. You will then need
to collect, complete and sign an informed consent form. This must be returned to the principle
researcher (me) before you can take part in the study.
This project has been approved by the University Research Ethics Committee.
Many Thanks,
Owain
67