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Ergogenic Aids: Caffeine. Caffeine  Characterization – Member of methylxanthine group of compounds Mild stimulant that affects multiple organ systems.

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Presentation on theme: "Ergogenic Aids: Caffeine. Caffeine  Characterization – Member of methylxanthine group of compounds Mild stimulant that affects multiple organ systems."— Presentation transcript:

1 Ergogenic Aids: Caffeine

2 Caffeine  Characterization – Member of methylxanthine group of compounds Mild stimulant that affects multiple organ systems – Absorbed rapidly from the gastrointestinal tract – Blood half-life of 3 to 6 hours  Sources – Found in many food, beverage, and pharmaceutical sources – Occurs naturally in coffee beans, tea leaves, cocoa, and cola nuts

3 Caffeine Sources Data from product labels and manufacturers, and National Soft Drink Association. 1997. a Brewing tea or coffee for longer periods slightly increases the caffeine content. b Prescription, 1 oz; 30 mL. Reprinted from Mc Ardle WD, et al. Sports and Exercise Nutrition, 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009:338. SubstanceCaffeine content (mg) Beverages and foods Coffee a Coffee, Starbucks, decaf, 12 oz10 Coffee, Starbucks, grande, 16 oz550 Coffee, Starbucks, tall, 12 oz375 Coffee, Starbucks, short, 8 oz250 Caffe, Starbucks, Americano, grande, 16 oz105 Caffe, Starbucks, Americano, tall, 12 oz70 Caffe, Starbucks, Americano, short, 8 oz35 Caffe, Starbucks, latte or cappucino, grande, 16 oz70 Caffe Mocha, Starbucks, short (8 oz) or tall (12 oz)35 Espresso, Starbucks, 8 oz280 Brewed, drip method110-150 Brewed, percolator64-124 Instant40-108 Espresso100 Decaffeinated, brewed or instant; Sanka2-5 Coffe Frappuccino, Starbucks, grande, 16 oz170 Tea, 5 oz cup* Brewed, 1 min9-33 Brewed, 3 min20-46 Brewed, 5 min20-50 Nestea Sweetened Lemon Ice Tea20 Iced tea, 12 oz; instant tea12-36 Green tea, 8 oz30 Chocolate Baker's semi-sweet, 1 oz; Baker's chocolate chips, 1/4 cup13 Cocoa, 5 oz cup, made from mix6-10 Milk chocolate candy, 1 oz6 Sweet/dark chocolate, 1 oz20 Baking chocolate, 1 oz35 Chocolate bar, 3.5 oz12-15 Jello chocolate fudge mousse12 Ovaltine0 Soft drinks 7-Eleven Big Gulp Cola, 64 oz190 Jolt100 Sugar Free Mr. Pibb59 Mellow Yellow, Mountain Dew53-54 Tab47 Table 1. Caffeine Content (mg) of Some Common Foods, Beverages, and Over-the-Counter and Prescription Medications SubstanceCaffeine content (mg) Coca Cola, Diet Coke, 7-Up Gold46 Shasta-Cola, Cherry Cola, Diet Cola44 Dr. Pepper, Mr. Pibb40-41 Dr. Pepper, Sugar Free40 Pepsi Cola38 Diet Pepsi, Pepsi Light, Diet RC, RC Cola, Diet Rite36 Red Bull, 8 oz80 Frozen Desserts Ben and Jerry's no fat coffee fudge frozen yogurt, 1 cup85 Starbucks coffee ice cream, assorted flavors, 1 cup40-60 Haagen-Dazs coffee ice cream, 1 cup58 Haagen-Dazs coffee frozen yogurt, fat free, 1 cup42 Haagen-Dazs coffee fudge ice cream, low fat, 1 cup30 Starbucks frappuccino bar, 1 bar (2.5 oz)15 Healthy Choice cappuccino, chocolate chunk, or cappuccino mocha fudge ice cream, 1 cup 8 Over-the-counter products Cold remedies Dristan, Coryban-D, Triaminicin, Sinarest30-31 Excedrin65 Actifed, Contac, Comtrex, Sudafed0 Diuretics Aqua-ban200 Pre-Mens Forte100 Pain remedies Vanquish33 Anacin; Midol32 Aspirin, any brand; Bufferin, Tyelenol, Excedrin PM0 Stimulants Vivarin tablet, NoDoz maximum strength caplet, Caffedrine200 NoDoz tablet100 Enerjets lozenges75 Weight control aids Dexatrim, Dietac200 Prolamine140 Pain drugs b Cafergot100 Migrol50 Fiorinal40 Darvon32

4 Caffeine and General Health  No consistent evidence for adverse effects on the cardiovascular system – Pre-existing heart arrhythmias or high blood pressure should limit consumption – Potential interactions with other compounds (eg, ephedrine) may increase risk of side effects  Sleeplessness and jitters are well-recognized side effects, especially in people not used to caffeine  Stomach irritation may occur with caffeinated beverages that increase stomach acid  No convincing links between caffeine and cancer or osteoporosis  Stimulant effects of caffeine on metabolic rate are minor and should not greatly affect weight control  Coffee may help to protect against type 2 diabetes and diseases such as Parkinson’s – Data are mainly observational and the relationships are not exceedingly strong  Abstinence or moderation of intake (≤ 2 cups per day) is advisable during pregnancy and lactation Williams MH. Nutrition for Health, Fitness, & Sport. 9th ed. New York, NY: McGraw Hill; 2010:539-542.

5 Why Is Caffeine Possibly Ergogenic?  Increased free fatty acids, glycogen sparing – Associated with higher levels of cAMP in adipose cells Adenosine receptor antagonism Phosphodiesterase inhibition (at high doses)  Inhibition of glycogen phosphorylase enzyme – Less breakdown of glycogen  Links excitation to contraction in muscle cells – Via release of Ca ++  Direct stimulation of central nervous system – Endorphin release causes decreased perception of effort  Stimulation of sodium/potassium pumps – Increased nutrient entry into cells by secondary active transport  Inhibition of phosphoinositide metabolism – Less signaling effects of insulin  Possibly other mechanisms as well Abbreviation: cAMP, cyclic adenosine monophosphate. Magkos F, Kavouras SA. Caffeine use in sports, pharmacokinetics in man, and cellular mechanisms of action. Crit Rev Food Sci Nutr. 2005;45(7-8):535-562.

6 Effects of Caffeine on Substrate Oxidation During Exercise Subjects: 2 female, 7 male cyclists Exercise: Cycle to exhaustion at 80% VO 2max Design: Crossover Caffeine: Decaffeinated or caffeinated coffee (330 mg caffeine) 1 hour before cycling Time to exhaustion was nearly 15 min longer for caffeine vs placebo Abbreviations: FFA, free fatty acid; SE, standard error; VO 2max, maximal oxygen consumption; R, ratio; VCO 2, carbon dioxide production. Reprinted from Costill DL, et al. Med Sci Sports. 1978;10(3):155-158.. Glycerol, mM 0.5 0.4 0.3 0.2 FFA, mM 1.0 0.9 0.8 R, VCO 2 /VO 2 0102030405060708090 Exercise time, minutes Caffeine trial Decaffeinated trial SE

7 Effect of Caffeine on 500-m Split Times During a 1,500-m Swim Subjects: 7 male (72.3 kg), 4 female (57.9 kg) swimmers Capable of swimming 1,500 m in < 25 minutes All subjects consumed < 300 mg caffeine/week All subjects abstained from caffeine for 48 hours before study Design: Randomized, double-blind, crossover Caffeine: 6 mg/kg body weight (BW) administered in a fruit juice drink 2.5 hours before the swim Placebo was fruit juice drink alone Reprinted from MacIntosh BR, et al. Can J Appl Physiol. 1995;20(2):168-177. Subjects swam faster after caffeine consumption and reported lower perceived exertion Placebo Caffeine 448 444 440 436 432 428 424 420 416 412 408 0 50010001500 Distance, meters Time, seconds/500 m

8 Effects of Different Doses of Caffeine on Performance Subjects: 9 well-trained cyclists Caffeine users (100 to 250+ mg/day) Abstained from caffeine for 3 days prior to exercise Exercise: Cycle to exhaustion at 80% VO 2max Caffeine: 0, 5, 9, or 13 mg/kg BW Caffeine given by capsule Abbreviations: BW, body weight; VO 2max, maximal oxygen consumption. Reprinted from Pasman WJ, et al. Int J Sports Med. 1995;16(4):225-230. There was no dose response observed for the dose range evaluated 80 Endurance time, minutes 70 60 50 40 30 20 10 0 05913 mg caffeine/kg BW *P < 0.05 placebo versus caffeine * * * 47 min 58 min 59 min

9 Urinary Caffeine Levels With Different Doses of Caffeine mg caffeine/kg BW Abbreviations: BW, body weight; IOC, International Olympic Committee. Reprinted from Pasman WJ, et al. Int J Sports Med. 1995;16(4):225-230. Only the 5-mg/kg BW dose always resulted in urine concentrations below previous IOC limits 5913 1 2 3 4 5 6 7 8 9 Subjects 30 25 20 15 10 5 0 Previous IOC limit > 12 doping limit Urinary caffeine, µg/mL 0

10 What Is the Ergogenic Dose of Caffeine?  3 to 6 mg/kg BW associated with ergogenic benefits for endurance exercise – No further benefits with higher doses  May have more pronounced effects on non-users or regular users who abstain from caffeine for several days – These data are not always consistent – There are potential adverse effects in athletes who don’t regularly use caffeine  Recommended to try caffeine in practice before competition conditions Abbreviation: BW, body weight. Mc Ardle WD, et al. Sports and Exercise Nutrition, 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009:340-341.

11 Is Caffeine Permissible as an Ergogenic Aid?  No longer listed by the World Anti-Doping Agency as a prohibited substance – Remains on their Monitoring List  Still on the National Collegiate Athletic Association (NCAA) Banned Substance List at a dose that results in a urine concentration of 15 μg/mL – Equivalent to 9 to 13 mg/kg BW consumed 1 hour before event Equals 630 to 910 mg caffeine/day for a 70-kg person – Roughly 6 to 9 cups of coffee Abbreviations: BW, body weight; NCAA, National Collegiate Athletic Association.

12 Position of the International Society of Sports Nutrition  Caffeine is effective as an ergogenic aid at 3 to 6 mg/kg BW – More effective when consumed in anhydrous state  Caffeine may – Enhance vigilance during extended exhaustive exercise or sleep deprivation – Be beneficial for sustained maximal endurance exercise, such as time trial performance – Be beneficial for high-intensity exercise with intermittent activity occurring over a long period of time (eg, team sports such as soccer or rugby)  Data are equivocal regarding effects of caffeine on strength and power  Scientific literature does not support the notion that caffeine is a diuretic during exercise Abbreviation: BW, body weight. Goldstein ER, et al. J Int Soc Sports Nutr. 2010;7(1):5.

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