THE INFLUENCE OF HIGH FRUCTOSE CORN SYRUP ON ENDURANCE EXERCISE METABOLISM by Erika Leigh Rauk A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Health and Human Development MONTANA STATE UNIVERSITY Bozeman, Montana May 2014 ©COPYRIGHT by Erika Leigh Rauk 2014 All Rights Reserved ii ACKNOWLEDGEMENTS Special thanks are due to Kyle Masterson, Becky Quigley, Jana Shank, Kendra Dennis, and John Seifert for all your early morning help and hard work in the Movement Science Lab. Thank you! iii TABLE OF CONTENTS 1. INTRODUCTION ............................................................................................... 1 Purpose Statement ................................................................................................ 2 Rationale .............................................................................................................. 2 Delimitations ....................................................................................................... 3 Limitations ........................................................................................................... 4 Assumptions ........................................................................................................ 4 Hypothesis ........................................................................................................... 4 2. REVIEW OF RELATED LITERATURE ............................................................ 6 Introduction ......................................................................................................... 6 Substrate Utilization ............................................................................................. 7 Exogenous Carbohydrate Absorption ................................................................... 8 Carbohydrate Dose Response ............................................................................. 11 Chronic Fructose Induced Lipid Formation ........................................................ 15 Fructose Metabolism during Endurance Exercise ............................................... 19 Conclusion ......................................................................................................... 21 3. THE INFLUENCE OF HIGH FRUCTOSE CORN SYRUP INGESTION ON ENDURANCE EXERCISE METABOLISM ......................... 22 Contribution of Authors and Co-Authors ............................................................ 22 Manuscript Information Page ............................................................................. 23 Abstract ............................................................................................................. 24 Introduction ....................................................................................................... 25 Methodology ...................................................................................................... 26 Informed Consent ................................................................................... 26 Subjects .................................................................................................. 27 Experimental Design .............................................................................. 27 Procedures .............................................................................................. 28 Exogenous Carbohydrate Beverage ........................................................ 30 Biochemical Analysis ............................................................................. 30 Statistical Analysis ................................................................................. 31 Results ............................................................................................................... 32 Subject Characteristics............................................................................ 32 Percent Plasma Volume .......................................................................... 32 Measured Maximal Oxygen Consumption .............................................. 33 Respiratory Exchange Ratio ................................................................... 33 Serum Lipids .......................................................................................... 33 Blood Glucose ........................................................................................ 34 Heart Rate .............................................................................................. 34 iv TABLE OF CONTENTS – CONTINUED Rating of Perceived Exertion .................................................................. 34 Blood Lactate ......................................................................................... 35 Discussion .............................................................................................. 40 Conclusion ............................................................................................. 47 4. CONCLUSIONS ............................................................................................... 49 REFERENCES CITED ............................................................................................ 52 APPENDICES ......................................................................................................... 57 APPENDIX A: Additional Tables ..................................................................... 58 APPENDIX B: Informed Consent ..................................................................... 61 APPENDIX C: Thesis Data Collection Packet & Health History ....................... 65 v LIST OF TABLES Table Page 2.1. Carbohydrate Dose Response (Jentjens, 2005a, Jentjens, 2004a, 2004b, 2005b, Jeukendrup, 2008, Wallis, 2005).............................................. 14 3.1. Procedure cycling timeline ............................................................................. 29 3.2. Hypotheses, dependent measured variables, and predictions ........................... 32 3.3. Descriptive data for study subjects (Mean ± SD) ............................................ 32 3.4. Maximal HR, relative and absolute VO2max, and %VO2max for the cycling trials (Mean ± SD)........................................................................ 33 A.1. Mean (±SD) of dependent variables. .............................................................. 59 A.2. Mean ± SD of the dependent variables after combining treatments For RER, HR, and RPE the initial sample was taken at 20 min of exercise, midway sample at 50 min, and the final sample at 115 minutes. For TG, CHOL, LDL, HDL, VLDL, glucose, and lactate the initial sample was taken 20 min prior to the start of exercise, midway sample at 60 minutes of exercise, and the final sample at 140 min after the start of exercise. ................................................................ 60 vi LIST OF FIGURES Figure Page 2.1. Hepatic carbohydrate metabolism (Havel, 2005). Fructose metabolism does not have a negative feedback loop as glucose does in glycolysis, therefore fructose metabolized for energy utilization in negative energy balance and for energy storage in positive energy balance. ................................................................................. 16 2.2. Potential fructose chronic disease development pathways .............................. 20 3.1. Mean respiratory exchange ratio prior to and after consumption of HFCS or glucose and cycling for 120 minutes (n=11) .................................... 35 3.2. Mean triglycerides prior to and after consumption of HFCS or glucose and cycling for 120 minutes (n=11) ................................................... 36 3.3. Mean total cholesterol prior to and after consumption of HFCS or glucose and cycling for 120 minutes (n=11) ................................................... 36 3.4. Mean low density lipoprotein prior to and after consumption of HFCS or glucose and cycling for 120 minutes (n=11) .................................... 37 3.5. Mean high density lipoprotein prior to and after consumption of HFCS or glucose and cycling for 120 minutes (n=11) .................................... 37 3.6. Mean very low density lipoprotein prior to and after consumption of HFCS or glucose and cycling for 120 minutes (n=11) ................................ 38 3.7. Mean glucose prior to and after consumption of HFCS or glucose and cycling for 120 minutes (n=11) ................................................................ 38 3.8. Mean heart rate prior to and after consumption of HFCS or glucose and cycling for 120 minutes (n=11) ................................................... 39 3.9. Mean rating of perceived exertion prior to and after consumption of HFCS or glucose and cycling for 120 minutes (n=11) ................................ 39 3.10. Mean lactate prior to and after consumption of HFCS or glucose and cycling for 120 minutes (n=11) ................................................................ 40 vii ABSTRACT Athletes are advised to ingest adequate amounts of carbohydrate (CHO) prior to competitions, during exercise, and after to replenish glycogen storages. Performance outcomes can be determined by the amount, timing, and sources of CHO ingested. High fructose corn syrup (HFCS) is thought to be one of the main contributors in the development of obesity and chronic disease, therefore making this CHO source controversial. The study purpose was to determine if a HFCS-sweetened beverage is an acceptable CHO source for prolonged moderate intensity exercise by determining its effects on substrate metabolism