NUTRITIONAL SUPPLEMENTS FOR ATHLETES LIV ENGELSEN, MS Ergogenic Aids.

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Transcript of NUTRITIONAL SUPPLEMENTS FOR ATHLETES LIV ENGELSEN, MS Ergogenic Aids.

  • Slide 1
  • NUTRITIONAL SUPPLEMENTS FOR ATHLETES LIV ENGELSEN, MS Ergogenic Aids
  • Slide 2
  • Outline Regulation of nutritional supplements In-depth review of 5 popular ergogenic aids Caffeine Creatine Monohydrate Sodium Bicarbonate Alanine HMB Overview of research to support/refute additional supplements/practices The best recovery beverage of all time Summary/Conclusion
  • Slide 3
  • Definition Substances, devices or practices that enhance an athletes energy use, production or recovery
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  • Regulation Regulated by the Dietary Supplement Health and Education Act of 1994 (DSHEA) http://www.youtube.com/watch?v=3vxrTMYXpZo
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  • Caffeine Most popular social drug in the US Average adult ingests 3 mg/kg of caffeine daily Alkaloid stimulant found in coffee, tea, colas, sports drinks, chocolate, etc. Has been studied for its ergogenic effects for ~100 years Levels of caffeine in foods vary greatly depending on preparation Coffee: 60-150 mg/cup Tea: 40-60 mg/cup Cola: 40-50 mg/cup Chocolate (1.5 oz): 20 mg dark/9 mg milk Ergogenic effectiveness varies, depending on: o Age o Gender o Body size o Caffeine tolerance o Habituation o Cessation patterns
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  • Mechanisms of Action Global effects on the CNS Caffeine is a competetive, nonselective adenosine receptor antagonist Leads to delayed fatigue, increased mental alertness, mood improvement, energetic arousal Enhances concentration, visual acuity, reaction time and self-reported fatigue Effects on hormonal, metabolic, muscular, cardiovascular, pulmonary and renal functions during rest and exercise. Leads to decreases in respiratory exchange ratio (RER), peripheral fatigue, rating of perceived exertion (RPE), and threshold for exercise-induced cortisol and B-endorphin release Leads to increases in oxygen uptake, cardiac output, ventilation, circulating levels of epinephrine, metabolic rate, and fat oxidation during endurance exercise in trained and untrained individuals multifactorial Bottom Line: The mechanisms by which caffeine improves athletic performance is multifactorial and extends well beyond any one biologic mechanism!
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  • Effects on Body Systems & Sports Performance
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  • Tolerance Diminished responsiveness resulting from repeated exposure Caffeine tolerance has been associated with increased adenosine receptor activity and a decrease in -adrenergic activity Lower caffeine doses are well tolerated by nonusers Complete tolerance can occur in 5-6 days of moderate caffeine intake Effective strategy for a nonuser: 3-4 days of consecutive caffeine use to aid intense workout sessions Begin with 1-2 mg/kg and increase progressively over the next few days
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  • Psychological Factors
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  • Withdrawal Withdrawal symptoms peak in 28 to 48 hours Takes an average of 4 to 7 days to return to baseline Main symptom is frequent and severe headaches 2/2 vasodilation of cerebral blood vessels Resumed or acute caffeine intake almost entirely reverses withdrawal symptoms, including headache Regular caffeine users can optimize benefits by cutting back, but must be careful to avoid withdrawal symptoms Reduce caffeine intake gradually at least 1 wk before competition Resuming caffeine on the day of competition will again provide the desired ergogenic effects, as it would for a nonuser
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  • Intake Strategy Caffeine reaches a peak plasma level between 30 and 75 minutes of ingestion Half-life is 4 to 5 hours with modest intake, but longer when dose exceeds 300 mg In 6 to 7 hours, 75% of caffeine is cleared from the body because it is rapidly absorbed and metabolized by the liver Intake strategy is crucial for those seeking to improve athletic performance through caffeine use
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  • Dosing As little as 1 mg/kg to as much as 13 mg/kg had positive effects on time to fatigue in endurance events, sports, and sprint or power events. 1 to 7 cups of coffee 3 to 18 cups of tea or soda Some studies have found better ergogenic effect with lower dose (3-6 mg/kg) than higher doses No evidence of greater ergogenic effects with more than 9 mg/kg Higher caffeine intake may blunt cognitive performance Gender differences Men tolerate higher doses than women
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  • Safety Concerns The common belief that caffeine leads to dehydration and causes poor athletic performance is a misconception! Claims of adverse effects of caffeine on the cardiovascular system are inconclusive. The high levels of antioxidants found in coffee and tea have been linked to a number of health benefits Protection against heart disease and type II DM
  • Slide 15
  • Research Author & Year Subjects & Methods MeasuresTreatmentResults Cox, et al., 2002 Effect of different protocols of caffeine intake on metabolism and endurance perf. 12 trained cyclists/triathletes in study A, 8 in study B Plasma/ urinry caff, rate of fat oxidation, 1)Precaf 2)Durcaf 3)Coca-cola 4)Placebo Coca-cola was equally effective in enhancing endurance Hogervorst et al., 2008 Caffeine improves physical and cognitive performance during exhaustive exercise 24 well-trained cyclists in a RCCT Series of cognitive and physiological tests 1)CHO (CHO) 2)Caffeine +CHO (CAF) 3)Placebo (BEV) Faster after CAF on both complex info processing Maridakis et al., 2007 Caffeine attenuates delayed onset muscle pain following eccentric exercise 9 low-caffeine consuming females Pain intensity, force loss during eccentric and MVIC exercise 1)Caffeine 2)Placebo Large reduction in pain following caffeine ingestion Pedersen et al., 2008 High rates of muscle glycogen resynthesis after exhaustive exercise when CHO is coingested with caff 7 trained cyclists/triathletes in a Randomized, DB Crossover design BG, insulin, caff levels, muscle metabolites, muscle glycogen, protein kinases 1)CHO 2)CHO + Caff After 4 hrs of recovery, muscle glycogen was higher in Caff
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  • Think Fast! What has the highest caffeine content? a) Brewed tea b) Shot of espresso c) Brewed coffee d) Dark chocolate bar
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  • Creatine Monohydrate An amine found naturally in some foods, particularly meat products. Can be formed in the kidney and liver from glycine and arginine Delivered to the muscle and combined with phosphate to create phosphocreatine: a high-energy phosphagen in the ATP-PCr energy system. ATP-PCr energy system is important for rapid energy production, such as in speed and power events Supplements come in various forms; powders, pills, candy, gels, etc. Marketed to both strength and endurance athletes Appears most effective for activities that involve repeated short bouts of high-intensity physical activity
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  • Ergogenic Benefits Recent studies have shown significant improvements in: Total and maximal force in repetitive isometric muscle contractions Muscular strength and endurance in isotonic strength tests Muscular force/torque and endurance in isokinetic strength testing Cycle ergometer performance in maximal tests ranging from 6 to 30 seconds Field performance tests such as jumping, running, swimming, and skating. Less consistent, but overall favorable
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  • Exogenous Sources Average adult needs to replace ~2 grams of creatine/day for maintenance of normal creatine and PCr levels. Daily creatine intake of carnivores is ~1 g/day Daily intake may be nearly zero for vegetarians Endogenous creatine formation helps complement dietary sources to achieve 2 grams Excessive amounts of exogenous creatine will not be stored, but will be excreted unchanged in the urine
  • Slide 20
  • Proposed Mechanisms Most of the creatine in the body is stored in the muscles Research suggests that performance benefits are related to increased creatine within type II muscle fibers 60% of total muscle creatine is PCr, and 40% is free creatine Increasing the amount of PCr will provide more substrate for generating ATP during high-intensity exercise, and higher levels of free creatine will help re-synthesize PCr. Alternative theory: creatine supplementation and anabolic hormones?
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  • Creatine Dosing Very effective quick strategy 20-30 g/day (5-7 g per dose over the course of the day) Significant effects seen after only 2 days Long-term supplementation at lower dose is just as effective 4-5 g/day Significant effects seen after 6 days Once loaded, ~2 g/day for maintenance Creatine supplementation appears safe when the recommended loading and maintenance doses are followed
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  • Special Considerations Research suggests people may be responders or non-responders Characteristics of nonresponers include : 1) Higher initial levels of creatine and PCr 2) Fewer type II muscle fibers Individuals with initially low levels of intramuscular creatine are more responsive to supplementation Vegetarians Caffeine counteracts the ergogenic action of muscle creatine loading! Vandenberghe et al., 1996 Effect on body mass >50 studies have shown an increase in body mass during the first week of creatine supplementation Increased creatine in the muscle draws water Formulation- creatine monohydrate Theoretically, dehydration, muscle cramps and heatstroke can occur Drink plenty of water!!!!!
  • Slide 23
  • Creatine supplementation enhances muscular performance during high-intensity resistance exe