Eye-opening Article about Caffeine

An article by Alex Brylske in the February 2009 issue of Dive Training magazine provided some facts about caffeine that may be as eye-opening for some as the substance itself. Following are some highlights from the article, which begins on page 32 of the above-named issue.

Caffeine, Brylske states, is one of a group of related compounds called methylxanthines. These compounds are commonly added to medications and to carbonated drinks. Because of the wide range of places they're found, it's virtually impossible to know how much caffeine you actually take in during a given day.

Caffeine reaches its highest concentrations in most people about an hour after being consumed and can take up to fourteen hours to be entirely eliminated. Some drugs, including quite a few antibiotics, interfere with caffeine elimination.

Caffeine effects us in multiple ways. These include:
-Stimulation of the central nervous system (this is why most of us drink it)
-Increase in the effectiveness of painkilling meds (think "extra strength")
-Stimulation of breathing as part of the effect on the central nervous system
-Increase of the heart rate and force of cardiac contractions, thus the amount of blood output
-Irregular heartbeat in some individuals
-Reduction in flow of blood to the brain
-Increase in blood pressure

For divers, some of the specific effects of caffeine can have significant, possibly negative consequences. For one thing, caffeine could increase a diver's susceptibility to oxygen toxicity. If you're a nitrox diver and you've been consuming caffeine before a dive, you may want to avoid diving near your maximum operating depth, where you're exposed to higher partial pressures of oxygen.

Caffeine also increases the secretion of digestive acids from the stomach. This can lead to heartburn and an increased possibility of vomiting, which can lead to an increased risk of drowning at depth.

Finally, caffeine is a diuretic, which can contribute to dehydration (dehydration could be the topic of a whole separate article here). As a diuretic, it causes the user to need to urinate more frequently, which can be inconvenient at best for divers, especially those wearing drysuits.

The article also notes two positive effects of caffeine. It increases the force of muscle contractions and reduces muscle fatigue, meaning the user can work harder for a longer period of time. It also increases the portion of energy gained from the metabolism of fat.

Want more information? You can read the entire article by Mr. Brylske beginning on page 32 of the February 2009 issue of Dive Training magazine. The article is part one of a two-part series, and also discusses the use of decongestants.