The Effect of an Energy Drink on Acute Muscle Strength

152 Pages·2012·1.93 MB·English

by  Michelle Hawley

The Effect of an Energy Drink on Acute Muscle Strength
and Fatigue in Young Males
by
Michelle Hawley

A Thesis Presented in Partial Fulfillment
of the Requirements for the Degree
Master of Science

Approved April 2012 by the
Graduate Supervisory Committee:

Pamela Swan, Chair
Carol Johnston
Kathryn Campbell

ARIZONA STATE UNIVERSITY
May 2012
ABSTRACT

The popularization of energy drink use as a supplement to exercise is
steadily increasing, especially among young adult males. However, the effects of
energy drinks on muscular performance in young adults have yet to be clearly
elucidated. Eight male subjects (mean age: 23.3 ± 4.3 yrs, height: 181.0 ± 5.3
cm, fat percent 17.8 ± 5.2%, and weight 85.3 ± 12.6 kg) completed this
randomized double-blinded cross over study. The purpose of this study was to
determine differences in acute muscular strength and endurance and Profile of
Mood States (POMS) scores between three treatments (RockStar, sugar-free
RockStar, and sugar-free caffeine-free Placebo). It was hypothesized that there
would be no significant differences in acute peak torque and endurance of the
knee extensors and flexors or on fatigue and vigor subscores from the POMS
questionnaire. Each man was tested randomly at least 1 week apart. Diet and
time of day were held constant across trials. Peak torque of knee extensors and
flexors at 60, 180, 240 degress/second and fatigue index and total work were
calculated by performing 50 repetitions at 240 degrees/second. Table A indicates
no significant differences in peak torque, fatigue index, or total work measures or
in subjective measures of fatigue or vigor from the POMS between the treatments.
This study indicates that RockStar energy drinks have no acute ergogenic effects
in young men performing isokinetic strength or endurance testing.

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TABLE A- Abstract RockStar SF RockStar Placebo
Peak torque 60°/s Flexors (N-
106 + 22 103 + 27
meters) 101 + 26
Peak torque 60°/s Extensors (N-
187 + 64 182 + 48 169 + 53
meters)
Fatigue Index Flexors (% decline) 5 3 + 7 49 + 10 47 + 9
Fatigue Index Extensors (%
44 + 14 45 + 11 45 + 17
decline)
Total work Flexors (N-meters) 2286 + 499 2254 + 490 2312 + 403
Total work Extensors (N-meters)
3552 + 606 3497 + 330 3591 + 559
POMS Vigor - Fatigue 15 + 5 15 + 5 17 + 5
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DEDICATION

I would like to dedicate this project to my dad for always pushing me to be
the best me I can possibly be! Dad, you have no idea how much you have
influenced my life in both the academic and physical fitness aspects. Thank you
for providing the responsible, goal-setting, positive example! P.S. I cannot
express how appreciative I am for your support in this and especially for coming
to my defense.
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ACKNOWLEDGMENTS

First, I would like to acknowledge those who made it possible for me to
complete this project. Dr. Swan, thank you for all of your help and guidance
throughout this process. Without you, I would have been stuck collecting calorie
expenditures for subjects carrying groceries up and down the stairs! Bleh! Also,
thank you for your kindness, generosity, and availability even in those crazy time
crunches. Dr. Campbell, you have been such a vital source of support and
wisdom since the first day I stepped foot on the ASU campus. Thank you for
always taking care of things and for your humor, which always brought the stress
level down a few notches for me. I will fondly remember the nickname you gave
me. . . “uh oh, here comes trouble!”. Even though I was high maintenance,
according to the graduate college, you dealt with all the headaches and I can’t
express enough how appreciative I am. Dr. Johnston, thank you for building a
strong base of knowledge in research methods and for setting the bar high.
Because of you, this study was extremely well-designed and controlled. Also,
thank you for your help with the POMS and stats! A special thank you to Julian
Baez and Zach Zeigler, without whom I would have been involved in some
seriously uncomfortable situations involving speedos and hair caps. I also want to
thank you guys for your time, availability, and willingness to come to the lab very
early in the morning even on the weekends. Especially since it was football
season. . . I know the deal! I could not have finished this study without you two!
Secondly, I want to take the time to extend my gratitude to the Charles B.
Corbin President’s Council who awarded me with a research scholarship of
$500.00. This grant allowed me to purchase the necessary supplies for this study,
relieving the financial burden associated with research costs.
Finally, I would like to acknowledge my family for hanging in there with
me even when times got tense and a bit crazy. Who knew I would contract the
Bird Flu in November of 2011 right smack dab in the middle of my data
collection? I’ll never forget the time you took out of your days and nights to stay
with me while I was in the hospital, especially you Christine and Terry (Dad, I
know you were dealing with tons of stuff during that time and you wanted to be
there more, I appreciate the days you were able to come see me). Now that this
project is done, you will definitely see more of me - sans Bird Flu that is! To my
sister, Christine, you will forever be my best friend and confidante, the one who
can always sympathize and offer words of comfort. One day, we will be
celebrating the completion of your doctorate from A.T.Still University! Last but
certainly not least, I want to acknowledge my boyfriend, Wes. I will be eternally
grateful for your patience, support, and encouragement throughout this long and
grueling process. Without you I would not have made it through that awful
November of 2011. You were there every single day and night. I saw firsthand
what true love is and what true love can do. I love you and am excited to start the
rest of my life with you.
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TABLE OF CONTENTS
Page
LIST OF TABLES .................................................................................................... viii
CHAPTER Page
1 INTRODUCTION .................................................................................. 1
Energy Drink Use and Research ........................................................ 1
Purpose ................................................................................................ 4
Hypothesis and Specific Aims ........................................................... 5
Definition of Terms ............................................................................ 5
Limitations .......................................................................................... 6
Delimitations ....................................................................................... 7
2 REVIEW OF LITERATURE ................................................................ 9
Energy Drinks ..................................................................................... 9
Bod Pod and Other Body Composition Methods ............................ 27
Muscular Performance and Fuel Utilization .................................... 32
Fatigue Definitions and Mechanisms ............................................... 34
Subjective Measures of Fatigue ....................................................... 37
Objective Measures of Fatigue ......................................................... 39
Isokinetic Dynamometry .................................................................. 42
3 METHODS ............................................................................................ 46
Study Design ..................................................................................... 46
Subjects ............................................................................................. 46
Inclusion and Exclusion Criteria ...................................................... 47
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General Overview of Procedures ..................................................... 48
Randomization and Blinding Methods ............................................ 50
Treatments ......................................................................................... 51
Body Composition ............................................................................ 52
POMS Questionnaire ........................................................................ 54
Isokinetic Assessment ....................................................................... 54
Procedures ......................................................................................... 56
Subject Sample Size ......................................................................... 59
Statistical Analysis ............................................................................ 59
4 RESULTS ............................................................................................. 61
Normality .......................................................................................... 61
Anthropometric Variables ................................................................ 61
Isokinetic Variables .......................................................................... 63
Profile of Mood States Subscores .................................................... 69
Pearson’s Correlations for Overall Data .......................................... 71
5 DISCUSSION........................................................................................ 74
Rationale ........................................................................................... 74
Isokinetic Variables .......................................................................... 75
Profile of Mood States Subscores .................................................... 80
Limitations ........................................................................................ 82
Future Implications ........................................................................... 83
Conclusion ........................................................................................ 84
REFERENCES ........................................................................................................ 86
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APPENDIX Page
A TIMELINE AND PROCEDURES OF THE STUDY .................. 100
B CONSENT FORM ......................................................................... 102
C ROCKSTAR FLYER ..................................................................... 107
D RECRUITMENT SCRIPT .............................................................. 109
E PRE-SCREENING SURVEY ........................................................ 112
F NIH CERTIFICATION .................................................................. 114
G MEDICAL AND HEALTH HISTORY QUESTIONNAIRE ...... 116
H BEVERAGE CONSUMPTION SURVEY ................................... 119
I PREVIOUS NIGHT’S DINNER RECORD ............................... 121
J PROFILE OF MOOD STATES QUESTIONNAIRE ................... 123
K DETAILED INSTRUCTIONS FOR THE ISOKINETIC
DYNAMOMETER ....................................................................... 125
L RANDOMIZATION CHART ........................................................ 129
M SUBJECT INFO SHEET VISITS 1 AND 2 ................................... 132
N SUBJECT INFO SHEET VISIT 3................................................... 134
O SUBJECT INFO SHEET VISIT 4.................................................. 136
P TABLE 1 A AND B ....................................................................... 138
Q PLACEBO INGREDIENTS ........................................................... 140
R IRB APPROVAL LETTER ............................................................ 142
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LIST OF TABLES
Table Page
A. Table A- Abstract ................................................................................. ii
1. A & B RockStar Energy Drink Ingredients and Sugar-Free RockStar
Ingredients ........................................................................................ 139
2. Caffeine Content in Energy Drinks ..................................................... 12
3. Amount of Sugar in Energy Drinks ..................................................... 20
4. Anthropometric Variables .................................................................... 63
5. Peak Torque Measures in Newton-meters ........................................... 66
6. Fatigue Index and Total Work Measures ........................................... 69
7. Profile of Mood States Subscores ........................................................ 70
8. Correlations Table ................................................................................ 73

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Chapter 1
INTRODUCTION
Since the distribution of the first energy drink in 1997 (Red Bull), the
consumption of energy drinks has consistently increased among young adults over
the years (Malinauskas, Aeby, Overton, Carpenter-Aeby, & Barber-Heidal, 2007).
The energy drink market has launched over 500 brands of energy drinks in less
than 15 years all targeting adolescents and young adults (Reissig, Strain, &
Griffiths, 2009). Furthermore, there is a notable increase in the utilization of
energy drinks as an ergogenic aid and supplement in physically active young
adults, with only the multivitamin surpassing its popularity in use (Walsh,
Gonzalez, Ratamess, Kang, & Hoffman, 2010). In a survey conducted in 2004,
approximately 73% of college athletes aged nineteen years and older reported the
use of energy drinks as a supplement for physical activity with a 20% higher
reported use in male athletes than in female athletes (Froiland, Koszewski, Hingst,
& Kopecky, 2004).
The primary claims made by the energy drink companies are that these
drinks will increase performance, decrease fatigue, and allow one to work harder
(Ballard, Wellborn-Kim, & Clauson, 2010). Red Bull’s ubiquitous slogan “It
gives you wings” refers to the claim that Red Bull was developed “for people
who want to have a clear and focused mind, perform physically, are dynamic and
performance-oriented whilst also balancing this with a fun and active lifestyle”
(Red Bull Gmbh, 2012). The notorious declaration, “Unleash the Beast”, by
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