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15. 3. 2012.

Caffeine – effects and use

Caffeine is organic compound; white colour, bitter flavour and plant origin. It is natural ingredient of coffee and cocoa grain, tea leaves and some other plants. Amount of caffeine in following compounds:
  • Cup of  “turkish” coffee – 100mg
  • Cup of instant coffee – 70mg
  • Cup of tea – 70mg
  • Glass of coca-cola – 65mg
  • Glass of diet coke – 40mg

Normal therapeutic dose is 100-300mg.
Caffeine doesn’t have any nutrition value(unless some amount of niacine) for human. However, caffeine usage is very widespread all over the world due to farmacology effects that it products.

Average amounts of caffeine(mg)

Cooked, espresso
Tea, 30g, cooked
Ice Tea, 3.5 dcl
Hot cocoa, 2.5 dcl
Sweet gasified drinks, 3.5 dcl
Pepsi light
Dr. Pepper
Pepsi cola
Coca-cola Light
Anacine, 2 pills
Excedrine, 1 pill
Daxatrim, 1 pill

Structural formula

Physiological caffeine effects

There are differences according to various researches. It is thought that caffeine in dose of 250mg increases awakeness and activity, while at some people this amount can cause overnervous reactions. Like at other substances that are taken in group of drugs, regular caffeine usage can lead to tolerance development, so some caffeine effects do not manifest, but some reactions can be aggressive at people that don’t take caffeine.
30-60 minutes at caffeine taking is needed for maximum amounts of this substance to be reached in blood, and it is also related to its physiological effects.
Caffeine stimulates CNS functions, so effects manifest directly, or/and indirectly to various tissues(through CNS). Dose of 50-200mg increases activity or liveliness, and doses of 300-500mg lead to nervous and/or muscular tremor development.
Caffeine stimulates adrenaline releasing, so its effects manifest indirectly through this catecholamine(especially on heart and blood system).
Caffeine has ability to influent to the brain, and we think that activity is lighter. Due to its stimulative action, it can decrease fatique connected to long-term training. In one research students trained 2 hours on bicycle ergometers as stronger as they could. When they took caffeine, they trained 7% harder than, though effort was survived equally.
If you are chronically tired from hard training program, you can take caffeine due to suggestion of fatique. But if you are hyperactive, additional stimulans before competition will not be needed. Actually, caffeine can disrupt you if you cannot handle it well.
Stimulative heart effect is manifested through heart frequency and contraction power increase, and that leads to heart volume increase.
Caffeine releasing also leads to fat acids releasing in blood, so they can be more easily used for energy gaining in muscles.
Caffeine also stimulates gastric acid secretion, which can cause nuisances at athletes that have problems with this organ.
Very important feature of caffeine is increased diuresis causing, and though, bigger fluid loss from organism. It is thought that increased secretion of fluid lead by caffeine, especially at long term activities at high outside temperature, effects negatively to termoregulation processes during intense physical activity; by decreasing physical work capacity, or causing fatique and activity stop.
Some researches also say that caffeine will not cause increased diuresis if taken during the activity.
One or two cups of coffee can be beneficial, and bigger intake has small value, and it can also cause harmful effects.
Caffeine intake is not recommended for people with hypertensia, cardiovascular system illnesses, gastric problems and neurotic problems due to heart, blood circulation and CNS influences.
Too big caffeine intake can be manifested through hyperactivity, irritiability, nervousness, headache, gastric problems, cold sweat…
Caffeine is present on the list of prohibited substances of International Olympic Comitee. Presence of more than 12µg/ml of urine is thought to be sufficient for athlete disqualification. To achieve that big amount of caffeine, it is needed to enter the large amount of this substance(in the period of 2-3 hours):
·         ½ litres of coffee
·         16 coca-colas(3dcl cans)
·         24 anacines
·         4 vivarines
These are abnormal high amounts. However, it is scientifically approved that extremely big amounts have negative effects on athletes’ training.

"Athletes' nutrition", Marina Djordjevic Nikic 
"Sports nutrition", Nancy Clark

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