How Does Caffeine Increase The Heart Rate?

You might feel your heart racing after gulping down a cup of coffee in the morning, and it's not just because you're eager to face the day. The caffeine in coffee and other caffeinated beverages increases your heart rate and causes other physiological effects. Knowing whether an increased heart rate is a risk for your particular body and health condition can help you determine whether to incorporate caffeine into your diet.

Heart Rate

When caffeine encounters your body's cells, it blocks a chemical called phosphodiesterase, or PDE, from taking effect, according to University of Texas at Arlington biologist Neal J. Smatresk. Within your cells, PDE plays the role of breaking down another chemical called adenosine monophosphate, or cAMP. Since not all hormones and neurotransmitters can cross cell membranes to do their jobs, they rely on "messengers" such as cAMP to help take care of business. As caffeine's effects stop the breakdown of cAMP, effects can be felt throughout the body --- including in the heart. Your heart's rate and contractions become amplified as the adrenal glands and sympathetic nerves react by sending "fight or flight" messages.

Other Effects

Your heart isn't the only body part affected by caffeine. Caffeine can also increase blood flow and respiration. Your mood can be affected, and caffeine can also act as a mild diuretic, according to the University of California, Berkeley, dining department. Too much caffeine can result in nervousness, insomnia, intestinal complaints and hallucinations. Regular caffeine can lead to addiction, and you might experience headaches and lowered blood pressure.

Caffeine Levels

The average American consumes about 300 mg of caffeine daily, according to the University of Berkeley. One 16 oz. cup of coffee from a coffee shop might contain 550 mg of caffeine. In comparison, a 1 oz. serving of espresso contains 35 mg of caffeine, and an 8 oz. serving of green tea contains 30 mg of caffeine.

Athletes

Caffeine's physiological effects have prompted athletes to incorporate caffeine in attempts to boost endurance and ability, according to Chicago fitness instructor Jon Gestl. Not all aspects of athletic performance have been shown to improve following caffeine consumption; more studies are required. But caffeine has been shown to increase endurance in some aerobic activities and increase performance times for distance swimmers. Caffeine hasn't been proven effective in helping improve maximum muscle force, however. Some professional associations prohibit caffeine among competing athletics, so be careful before partaking in caffeinated beverages or caffeine pills.

Considerations

Encouraging hormonal fluctuation throughout the day with regular infusions of caffeine might not be the best choice for your body, especially if you have heart problems or high blood pressure. However, the American Heart Association states that moderate coffee drinking, defined as 1 or 2 cups daily, isn't a problem for most consumers.