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Transcript of Ergogenic Aids
Nutritional Supplements for Athletes
Liv Engelsen, MSErgogenic AidsOutlineRegulation of nutritional supplementsIn-depth review of 5 popular ergogenic aidsCaffeineCreatine MonohydrateSodium Bicarbonate AlanineHMBOverview of research to support/refute additional supplements/practicesThe best recovery beverage of all timeSummary/Conclusion
DefinitionSubstances, devices or practices that enhance an athletes energy use, production or recovery
Talk about significance for RDs!!
Based on this definition, many things are ergogenic aids3RegulationRegulated by the Dietary Supplement Health and Education Act of 1994 (DSHEA)
Dietary supplements can voluntarily have their products tested for quality assuranceUSP vs USP labsNSFsport.com - Protect against adulteration of products Verify label claims against product contents Identify athletic banned substances in the finished product or ingredients
4CaffeineMost popular social drug in the USAverage adult ingests 3 mg/kg of caffeine dailyAlkaloid stimulant found in coffee, tea, colas, sports drinks, chocolate, etc.Has been studied for its ergogenic effects for ~100 yearsLevels of caffeine in foods vary greatly depending on preparationCoffee: 60-150 mg/cupTea: 40-60 mg/cupCola: 40-50 mg/cupChocolate (1.5 oz): 20 mg dark/9 mg milk Ergogenic effectiveness varies, depending on:Age Gender Body sizeCaffeine toleranceHabituationCessation patterns
You are all very familiar with caffeine, as it is the most popular social drug in the US.Caffeine is an alkaloid that occurs naturally in many plants, including coffee beans, tea leaves, chocolate, cocoa beans and cola nuts.Studied extensively for its ergogenic effects which include a broad range of metabolic, hormonal and physiologic effects.
The performance enhancing effects of caffeine may be beneficial in all types of exercise in which endurance, concentration, and reaction times play a role
5Mechanisms of ActionGlobal effects on the CNSCaffeine is a competetive, nonselective adenosine receptor antagonistLeads to delayed fatigue, increased mental alertness, mood improvement, energetic arousalEnhances concentration, visual acuity, reaction time and self-reported fatigueEffects 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 releaseLeads 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
Bottom Line: The mechanisms by which caffeine improves athletic performance is multifactorial and extends well beyond any one biologic mechanism!The effects on the CNS greatly affect cognition and mood. The positive effects of acute caffeine intake include decreased tiredness, increased mental alertness, mood improvement and energetic arousal. In addition, caffeine enhances concentration, visual acuity, reaction time and self-reported fatigue in a dose-dependent manner. Caffeine also stimulates the secretion of serotonin in the cerebral cortex, enhancing the action of the sympathetic system.
EFFECTS ON THE CNSCompetetive, nonselective adenosine receptor antagonistAdenosine is a neromodulator that binds to adenosine receptors and slows nerve cell activity. By blocking adenosine, caffeine speeds up the activity of nerve cells. Crosses the blood-brain barrier to impact both the periperal and central nervous systemUpregulation and downregulation of adenosine receptors result in habituation and withdrawl effects.
All these effects depend on the quantity of acute caffeine intake, tolerance to caffeine and cessation from caffeine. 7Effects on Body Systems & Sports Performance
ToleranceDiminished responsiveness resulting from repeated exposureCaffeine tolerance has been associated with increased adenosine receptor activity and a decrease in -adrenergic activityLower caffeine doses are well tolerated by nonusersComplete tolerance can occur in 5-6 days of moderate caffeine intakeEffective strategy for a nonuser: 3-4 days of consecutive caffeine use to aid intense workout sessionsBegin with 1-2 mg/kg and increase progressively over the next few days
This graph shows different responses to caffeine based on tolerance. The theoretical responses to caffeine in nonusers, average users (3 mg/kg), and heavy users (6 mgkg). Doseresponse curves are shifted to the right and ergogenic effectiveness is blunted with increased caffeine intake. On the vertical axis, 10 represents the greatest effect and 1 is negligible. For all 3 habituation levels, peak effects may be achieved over a range of doses, rather than at a single dose. The shaded areas represent dose ranges for which negligible positive ergogenic effects are expected; this may be the result of negative cognitive and mood effects at higher doses.
-adrenergic activity is responsible for cardiac output by increasing heart rate9Psychological Factors
WithdrawalWithdrawal symptoms peak in 28 to 48 hours Takes an average of 4 to 7 days to return to baselineMain symptom is frequent and severe headaches2/2 vasodilation of cerebral blood vesselsResumed or acute caffeine intake almost entirely reverses withdrawal symptoms, including headacheRegular caffeine users can optimize benefits by cutting back, but must be careful to avoid withdrawal symptomsReduce 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
Athletes must take care to avoid unintentional caffeine withdrawal, sometimes experienced during travel or when training in hot weather. A habituatedathlete who unintentionally reduces caffeine intake may fail to perform well without knowing why.11Intake StrategyCaffeine reaches a peak plasma level between 30 and 75 minutes of ingestionHalf-life is 4 to 5 hours with modest intake, but longer when dose exceeds 300 mgIn 6 to 7 hours, 75% of caffeine is cleared from the body because it is rapidly absorbed and metabolized by the liverIntake strategy is crucial for those seeking to improve athletic performance through caffeine use
DosingAs 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 coffee3 to 18 cups of tea or sodaSome studies have found better ergogenic effect with lower dose (3-6 mg/kg) than higher dosesNo evidence of greater ergogenic effects with more than 9 mg/kgHigher caffeine intake may blunt cognitive performanceGender differencesMen tolerate higher doses than women
A large part of the literature on caffeine has focused on dose-response effects.
1 mg/kg to as much as 13 mg/kg This is equivalent to ~ 1-7 cups of coffee or 3-18 cups of tea or soda13Safety ConcernsThe 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 benefitsProtection against heart disease and type II DM
ResearchAuthor & YearSubjects & MethodsMeasuresTreatmentResultsCox, et al., 2002Effect of different protocols of caffeine intake on metabolism and endurance perf.12 trained cyclists/triathletes in study A, 8 in study BPlasma/ urinry caff, rate of fat oxidation, PrecafDurcafCoca-colaPlaceboCoca-cola was equally effective in enhancing endurance Hogervorst et al., 2008Caffeine improves physical and cognitive performance during exhaustive exercise24 well-trained cyclists in a RCCTSeries of cognitive and physiological testsCHO (CHO)Caffeine +CHO (CAF)Placebo (BEV)Faster after CAF on both complex info processingMaridakis et al., 2007Caffeine attenuates delayed onset muscle pain following eccentric exercise9 low-caffeine consuming femalesPain intensity, force loss during eccentric and MVIC exerciseCaffeinePlaceboLarge reduction in pain following caffeine ingestionPedersen et al., 2008High rates of muscle glycogen resynthesis after exhaustive exercise when CHO is coingested with caff7 trained cyclists/triathletes in a Randomized, DB Crossover designBG, insulin, caff levels, muscle metabolites, muscle glycogen, protein kinasesCHOCHO + CaffAfter 4 hrs of recovery, muscle glycogen was higher in CaffThere is a TON of literature available to support caffeine as an effective ergogenic aid. Here I am focusing on a few studies that I thought were particularly interesting.
Cox et al., 2002. Effect of different protocols of caffeine intake on metabolism and endurance performance.The researchers concluded that replacing a sports drink with Coca-Cola during the latter stages of exercise was equally effective in enhancing endurance performance, primarily due to low intake of caffeine (1.5 mg/kg)
Hogervorst et al., 2008. Caffeine improves physical and cognitive performance during exhaustive exercise.Purpose: to examine the physical and cognitive effects of consuming a performance bar containing caffeine, before and during cycling.24 well trained cyclists consumed the either: 1) CHO bar 2) Caf bar (45 g CHO & 100 mg caff) or 3) Placebo beverage immediately before performing a vigorous 2.5 hr ride.Results: Participants in the Caff group were significantly faster onthe computerize complex information processing tests during exercise AND caff group had a significantly longer (27%) time to exhaustion than CHO or BEV.Conclusion: Caffeine in a performance bar