ABSTRACT
Effects of Arachidonic Acid Supplementation on Training Adaptations in Resistance-Trained Males
Michael D. Roberts, B.S.
Committee Chairperson: Richard B. Kreider, Ph.D.
The purpose of this study was to determine if 50 days of resistance training and
arachidonic acid (AA) supplementation elicited changes in body composition, performance variables, hormonal/cytokine levels (i.e. prostaglandins, free and total testosterone, cortisol, and interleukin-6) and/or intramuscular markers [i.e. myosin heavy chain (MHC) I, -IIa, -IIx mRNA and protein levels] in resistance-trained males. Thirty- one subjects (22.1±5.0 yrs, 86.1±13.0 kg, 178.9±3.4 cm, 18.1±6.4 % body fat) were randomly assigned to a placebo (P: n=16; 1 g corn oil/day) or AA group (AA: n=15; 1 g
AA/day) and were given supplemental protein in order attain an optimal protein intake of
2 g/kg/day while participating in a 2 d/wk upper body and 2 d/wk lower body resistance training regimen. Body composition, bench press one-repetition maximum (1-RM), leg press 1-RM and Wingate bike sprint tests were completed at 0, 25 and 50 days. Fasting
blood was taken on days 0, 25, and 50 and muscle biopsies were taken from the vastus
lateralis on days 0 and 50. Body composition, performance variables, hormonal levels
and MHC mRNA and protein concentrations were analyzed by ANOVA with repeated
measures while independent t-tests were used to assess changes in MHC mRNA
expression. A significant increase was observed in Wingate relative peak power in the
AA group (p=0.015). Statistical trends were found for PGE2 increases (p=0.06) and IL-6 decrements (p=0.07) in the AA group and a significant decrement in percent changes in
MHC IIx mRNA expression was present in the AA group (p=0.015). Results suggest that AA supplementation in trained males may exert favorable alterations in training adaptations and fasting prostaglandin and IL-6 levels. However, additional research is needed to examine this hypothesis.
TABLE OF CONTENTS
LIST OF FIGURES v
LIST OF TABLES vi
ACKNOWLEDGEMENTS vii
CHAPTER ONE 1 Introduction and Rationale 1 Background 2 Problem Statement 2 Purpose 2 Hypothesis 2 Delimitations 3 Limitations 3 Assumptions 4 Definition of Terms 4
CHAPTER TWO 7 Literature Review 7 Introduction to Arachidonic Acid and Prostaglandins 7 Mitogenic Signaling Pathways Initiated by Prostaglandins 10 Dietary AA Supplementation in Humans 15
CHAPTER THREE 16 Methods 16 Subjects 16 Study Design 17 Entry and Medical Screening Session 18 Familiarization Session 18 Baseline Testing 20 Randomization and Supplementation Protocol 20 Resistance-training Protocol 21 Medical Monitoring 21 Analytical Methods 22 Statistical Analysis 34
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CHAPTER FOUR 35 Results 35 Subject Demographics 35 Dietary Intake and Lifting Volume 36 Body Composition Variables 37 Strength and Power Variables 39 Whole Blood Variables 42 Serum Chemistry Variables 44 Muscle Damage Markers 47 Serum PGF2α and PGE2 Levels 48 Hormonal Alterations 50 FP and EP3 Receptor Levels 52 Myosin Heavy Chain Isoform and mRNA Content 54 Correlations 55
CHAPTER FIVE 58 Discussion 58 Non-significant Changes in Body Composition and Strength 58 Significant Changes in Relative Peak Power 62 Alterations in FP and EP3 Receptor Densities 65 Changes in Prostaglandins and other Hormones 67 MHC Content and Gene Transcription Alterations 70 Changes in Whole Blood and Serum Chemistry Markers 73 Conclusions 74
APPENDICES 76
BIBLIOGRAPHY 87
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LIST OF FIGURES
Figure 1. Changes in bodyweight (∆kg) over the course of the study 39
Figure 2. Changes in fat-free mass (∆kg) over the course of the study 39
Figure 3. Changes in 1-RM bench press (∆kg) over the course of the study 42
Figure 4. Changes in 1-RM leg press (∆kg) over the course of the study 42
Figure 5. Changes in relative anaerobic peak power (∆W/kg) performed during the 30-sec Wingate anaerobic bike sprint 43
Figure 6.Changes in PGE2 levels (∆pg/ml) over the course of the study 50
Figure 7. Changes in PGF2α levels (∆pg/ml) over the course of the study 50
Figure 8. Changes in IL-6 levels (∆pg/ml) over the course of the study 52
Figure 9. FP receptor density values (INT*mm2/mg) over the course of the study 53
2 Figure 10. EP3 receptor density values (INT*mm /mg) over the course of the study 54
Figure 11. Changes in MHC I mRNA expression relative to β-actin over the course of the study 56
Figure 12. Changes in MHC I mRNA expression relative to β-actin over the course of the study 56
Figure 13. Changes in MHC I mRNA expression relative to β-actin over the course of the study 57
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LIST OF TABLES
Table 1. Subject Demographics 35
Table 2. Dietary/Supplement Intake Levels over the Course of the Study 37
Table 3. Body Composition Variables 38
Table 4. Performance Variables 41
Table 5. Differential White Blood Cell Values 44
Table 6. Serum Chemistry Values 46
Table 7. Serum Muscle Damage Markers 48
Table 8. Prostaglandin Levels 49
Table 9. Hormonal Variables 51
Table 10. Prostaglandin Receptor Densities 53
Table 11. Myofibrillar Protein mRNA and Content 55
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ACKNOWLEDGMENTS
I would like to extend a sincere thanks to Dr. Richard Kreider for entrusting me with such a large project as well as guiding me throughout its entirety. Furthermore, I would like to extend a special thanks to Dr. Darryn Willoughby for his time and diligence invested in assisting me with the biochemical analysis for this project. His persistence in assisting his pupils is deeply appreciated and admired and it has undoubtedly molded my future research intentions. I would also like to especially thank my parents JoAnna and
Edward Roberts for all the emotional and moral support they have provided me over course of my life. Both of you are always in my thoughts and you all’s wisdom and companionship will continue to fuel my inspiration. Thanks to my committee members for their patience to realize the conclusion of this process. I want to especially thank my fellow colleagues Chad Kerksick, Bill Campbell, Paul La Bounty, Dr. Mike Iosia, Colin
Wilborn, Lem Taylor, Travis Harvey, Mark Faries, Chris Moulton and Erika Nassar for their assistance as well as their guidance and friendship throughout my graduate school tenure. Thank you to my friend Jerry Gray who kept me in line during this entire process. Finally, I would like to thank my loving girlfriend Anna Lowery for having providing emotional and moral support as well as having the utmost patience and understanding ever since I started my thesis.
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CHAPTER ONE
Introduction and Rationale
Background
Arachidonic acid (AA) is a polyunsaturated essential fatty acid (PUFA) which is primarily found in fatty parts of red meat and fish and is normally consumed in small amounts in the regular diet (Li, Ng, Mann, & Sinclair, 1998). Much like omega-3 and omega-6 fatty acids, research has indicated a number of potential health benefits from
AA supplementation (Driss, Vericel, Lagarde, Dechavanne, & Darcet, 1984; James,
Gibson, & Cleland, 2000; Kelley, Taylor, Nelson, & Mackey, 1998; Nelson et al., 1997;
Safayhi, Koopmann, & Ammon, 1993; Uauy, Hoffman, Peirano, Birch, & Birch, 2001).
Of particular interest in this study is the purported role that AA appears to have on prostaglandin (PG) synthesis and regulation of protein synthesis (Kelley, 2001;
Rodemann & Goldberg, 1982; Rodemann, Waxman, & Goldberg, 1982; Vandenburgh,
Shansky, Karlisch, & Solerssi, 1993). Research has indicated that AA stimulates PG synthesis (Goldberg, Baracos