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Autor Tema: Caffeine and Athletes  (Pročitano 8004 puta)

Van mreže The_Bulldog

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Caffeine and Athletes
« poslato: Decembar 12, 2009, 05:53:57 posle podne »
Caffeine and Athletes

Caffeine may be the most widely used and accepted stimulant in the world. It is found in a variety of plants, dietary sources (including coffee, chocolate, cocoa, and colas), and non-prescription medications. The average caffeine consumption in the USA is approximately 1000 mg. per day. Ingested caffeine is quickly absorbed from the stomach and peaks in the blood in 1 – 2 hours (1). Evaluating the effects of caffeine on performance is often diffi cult through research because of the variability of the type of participants tested (sex, training levels, source of caffeine, habituated or caffeine naïve, etc.), exercise protocols (anaerobic exercise bouts or endurance exercise/time to exhaustion trials or time trials versus time to exhaustion), caffeine dosages, and the sensitivity of the cognitive test used (simple RT tests and number recall versus more complex information processing tests) (6).

Benefits of Caffeine for Performance
Caffeine is considered to be an ergogenic “drug” with beneficial eff ects on both physical and mental performance with minimal side effects (7). Caffeine is thought to act as a central nervous system stimulant and have effects on cognitive psychomotor functioning, particularly during mental and physical fatigue, by enhancing alertness and vigilance. Caffeine may therefore play a role in all types of exercise in which concentration, reaction times (RT), and technical/tactical skills have a major infl uence on both physical and mental performance such as cycling, orienteering, Formula 1, and ultra endurance events (6).
Caffeine ingestion (3 – 9mg/kg bw) prior to exercise increases performance during prolonged endurance exercises and short-term intense exercises lasting approximately five minutes in the laboratory (5). This is true for both elite and recreational athletes. Caffeine does not appear to enhance performance during sprints lasting less than 90 seconds, although research in this area is still lacking (5).
The optimal dose of caffeine for maximizing the chance that exercise performance will be enhanced is about 3 – 6 mg/kg, where side effects are minimized and urine levels are legal (1).

Other Benefits of Caffeine
In addition to the sports performance aspect, caffeine has been shown to positively affect an individual’s health in the following areas (4):

• Alertness, mood change
• Alzheimer’s and Parkinson’s diseases
• Glucose levels and a lower risk of Type 2 diabetes
• Gallstones
• Liver function liver cirrhosis
• Decreasing LDL-cholesterol
• Providing antioxidants
* Coffee beans and tea both contain phenolic compounds and antioxidant compounds. However, phenolic compounds can be lost during the roasting process. Medium roasted coffee maintains the most antioxidant activity (4).



Other Concerns

High Blood Pressure
Contrary to what you might expect, in hypertensive subjects, the prolonged administration of caffeine is not associated with a significant elevation in blood pressure (2,4).

Dehydration
While athletes often refrain from caffeine use because of its role as a diuretic, caffeine consumption does not result in water-electrolyte imbalances, hyperthermia or reduced exercise-heat tolerance (2).

Side Effects
The side effects of caffeine ingestion include anxiety, jitters, inability to focus, gastrointestinal unrest, insomnia, irritability, and, with higher doses, the risk of heart arrhythmias and mild hallucinations (1,7).


Legalities
Effective January 1, 2004, the World Anti-Doping Agency (WADA), in conjunction with the medical commission of the International Olympic Committee, removed caffeine from the list of stimulants prohibited for use by athletes. This may be a reflection of the increased use of caffeine as a stimulant in supplements, sport drinks, and gels. These products, which may be larger and contain more caffeine, may be consumed in quantity by athletes. As noted earlier, caffeine is also found in a wide variety of other food products (7).
As a result of this new regulation, athletes in the Olympics do not need to be concerned with drinking caffeinated beverages and testing positive for the use of caffeine. However, WADA has placed caffeine on its monitoring list, meaning that caffeine levels in athletes are tested, and, if caffeine abuse increases, it may be returned to the prohibited list ( 8 ). On the other hand, the acceptable limit in sports, sanctioned by the National Collegiate Athletic Association (NCAA) in the U.S. is 15 ug/ml measured in the urine (1).
A large amount of caffeine can be ingested before reaching the banned limit. The odds of reaching the limit through normal caffeine ingestion are low, except where smaller volumes of coffee with very high caffeine concentrations are consumed (1).

Bottom Line
1. Be aware of how much caffeine is in your food, drinks, and medicine, including nonprescription drugs. Do not use caffeine as a possible ergogenic aid, for the first time, during a competition.
2. First use caffeine during practice, and not in a competition.
3. Listen to your body. If you have any unwanted side effects, limit your intake.
4. Caffeine withdrawal can cause mood shifts, headaches, nausea, tremors, and fatigue (7).


References
1. ACSM Current Comment. Caffeine and Exercise Performance. Retrieved October 26, 2009
2. Ahmed HN, Levitan EB, Wolk A, and Mittleman MA. Coffee consumption and risk of heart failure in men: an analysis from the Cohort of Swedish Men. Am Heart J. 158(4):667 – 72. Epub 2009 Aug 22. 2009
3. Armstrong LE, Casa DJ, Maresh CM, and Ganio MS. Caffeine, fl uidelectrolyte balance, temperature regulation, and exercise-heat tolerance. Exerc Sport Sci Rev. 35(3):135 – 140. 2007
4. Astorino, TA, Rohmann RL, and Firth, K. Effect of caffeine ingestion on one-repetition maximum muscular strength. Eur J Appl Physiol. 102(2):127 – 32. 2008.
5. Dorea JG, and Da Costa, TH. Is coffee functional food? British Journal of Nutrition. 93(6):773 – 782. 2005
6. Glaister M, Howarson G, Abraham C, Lockey R, Goodwin J, Foley P, and Mcinnes G. Caffeine supplementaion and multiple sprint running performance. Med Sci Sports Exerc. 0(10):1,835 –1,840. 2008
7. Hogervorst E, Bandelow S, Schmitt J, Jentjens R, Oliveira M, Allgrove J, Carter T, and Gleeson M. Caffeine improves physical and cognitive perfomance during exhaustive exercise. Med Sci Sports Exercise. 40(10):1,841 – 1,851. 2008
8. Williams M. Nutrition for health, fi tness, and sport. New York, New York: McGraw Hill.

Van mreže Naturalni

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Odg: Caffeine and Athletes
« Odgovor #1 poslato: Decembar 12, 2009, 07:30:49 posle podne »
meni svaki trening pocinje sa coffeinom sada uzimam 200mg pre treninga taman za dobar kick,a kad je definicija idem i do 300mg dva puta na dan plus zeleni caj oko 1g dnevno
Ubijam se od HEMIJE!!!!!!!!!!!!!!!!!!