If you read the nutritional labels of energy sports drinks and fat loss supplements, you'll notice a common ingredient. Caffeine. Caffeine is a CNS (central nervous system) stimulant that belongs to a group of drugs called the methylxanthines. Methylxanthines are found in more than 600 species of plants. The most common sources include coffee, tea, guarana, cocoa, mate and cola (kola) nut.
In various studies, caffeine ingestion was found to cause:
- an increased mobilization of free fatty acids (FFA)
- to spare glycogen (energy)
- stimulate the release of epinephrine
- block the effects of adenosine
- alter the calcium levels in the muscle
- increase blood pressure
- stimulate the CNS
Many studies have tried to demonstrate caffeine's ability to increase sports performance, but trial results have been unfounded. Caffeine has been found (but not necessarily proven) to influence performance lasting 30 to 120 minutes by increasing FFA release from adipose cells (body fat), possibly sparing glycogen utilization during endurance training. Caffeine may also increase oxygen uptake and lower the respiratory exchange ratio (RER).
Using caffeine in pill form has been found to be the most effective. Coffee does not appear to enhance performance in the same way. One study found that coffee was less effective than a caffeine pill (3-6 mg/kg pure caffeine).
However, the disadvantages outweigh the benefits of intaking large amounts of caffeine. Studies have used anywhere from 300 to 500 mg of caffeine in pill form (2.5 cups of percolated coffee = approximately 300 mg). The side effects would include headaches, increased heart rate and a potent diuretic effect (promoting dehydration) that could be detrimental during activity. Caffeine should definitely not be used as an ergogenic (sports performance) aid.