Caffeine is one of the most widely talked about nutritional supplement topics in the media. The FDA has classified caffeine as both a drug and a food additive and reports that 90 percent of people in the world use caffeine in one form or another. In the U.S., 80 percent of adults consume caffeine every day – the average adult has an intake of 200 mg per day, the amount in two 5-ounce cups of coffee or four sodas. So chances are it may already be a normal part of your clients’ nutrition, and understanding the basics on caffeine and factors associated with your clients’ fitness goals, is great ammo to always have ready for any spur-of- the-moment discussions or questions they may have.
Caffeine itself is technically a psychoactive stimulant drug that is metabolized by the liver. Caffeine occurs naturally in more than 60 plants including coffee beans, tea leaves, kola nuts used to flavor soft drink colas, and cacao pods used to make chocolate products. Caffeine is absorbed through the small intestine and stomach within 30 to 45 minutes after ingestion, and can stay elevated in the system for up to three to six hours after consumption. As it’s metabolized, caffeine breaks down into three compounds that have an influence on vasodilation, triggering fat oxidation and decreasing airway constriction in the lungs (in other words, opening up ventilation). It works by stimulating the central nervous system, heart, muscles and the centers that control blood pressure.
The amount of caffeine included in some common foods & beverages are:
- Coffee, brewed – 40 to 180 milligrams (mg) per cup
- Coffee, instant – 30 to 120 mg per cup
- Coffee, decaffeinated – 3 to 5 mg per cup
- Tea, brewed American – 20 to 90 mg per cup
- Tea, brewed imported – 25 to 110 mg per cup
- Tea, instant – 28 mg per cup
- Tea, canned iced – 22 to 36 mg per 12 ounces
- Caffeine-containing cola and other soft drinks – 36 to 90 mg per 12 ounces
- Cola and other soft drinks, decaffeinated – 0 mg per 12 ounces
- Cocoa – 4 mg per cup
- Chocolate, milk – 3 to 6 mg per ounce
- Chocolate, bittersweet – 25 mg per ounce.
Caffeine & Fitness
Caffeine’s effect in the body has an impact on some key processes that may have a positive affect on your clients’ fitness. These effects are centered around exercise strength & endurance, muscle blood flow & circulation and metabolism, which are all core pieces of your clients’ workout sessions.
Endurance & Strength
Endurance athletes, in particular, have found caffeine beneficial to performance. Researchers reported the effects of a moderate dose of caffeine (6 mg/kg) on a one-hour time-trial cycling performance. The caffeine condition resulted in the cyclists riding significantly farther during the hour-long time trial, as compared to placebo and control. In fact, time-trial performance was improved 4 to 5 percent by the caffeine treatment over the other two treatments. The use of caffeine in anhydrous (without water) form, as compared to a cup of caffeinated coffee, seems to be of greater benefit for the purpose of enhancing endurance performance.
The effects of caffeine in sport aren’t limited to improving endurance. Research also indicates the benefits of caffeine in strength performance. Studies on the effects of caffeine in strength-power sports or activities, while varied in results and design, suggest that supplementation may help trained strength and power athletes. Specifically, researchers examined the effects of 5 mg/kg of caffeine in highly conditioned team sport male athletes. The protocol consisted of a leg press, chest press and the Wingate test (an anaerobic test performed on a cycle ergometer). The leg and chest press consisted of repetitions to failure (i.e., muscular endurance) and all exercises were separated by 60 seconds of rest. Results indicated a significant increase in performance for the chest press and peak power on the Wingate
Researchers recently discovered that people who were not regular coffee drinkers experienced a 30 percent boost in capillary blood flow after drinking five ounces of regular coffee, compared to those drinking decaf. Improved blood circulation typically equates to improved oxygenation of your tissues, which may boost your exercise performance.
Caffeine stimulates the nervous system, which sends direct signals to the fat cells to tell them to break down fat. Caffeine also increases our blood levels of the hormone Epinephrine, which is also known as Adrenaline. Epinephrine travels through the blood, to the fat tissues and send signals to break down fats and release them into the blood. This is how caffeine helps to mobilize fat from the fat tissues, making it available for use as free fatty acids in the blood.
In a study, published in the International Journal of Sport Nutrition and Exercise Metabolism, found that trained athletes who took in caffeine pre-exercise burned about 15% more calories for three hours post-exercise, compared to those who ingested a placebo. The dose that triggered the effect was 4.5 mg of caffeine per kilogram of body weight. For 150-pound woman (68 kg), that’s roughly 300 mg of caffeine, the amount in about 12 ounces of brewed coffee.
While it’s true that caffeine can possibly help improve fitness & performance, it’s important to stay within recommended daily consumption limits. According to the Mayo Clinic, up to 400 milligrams (mg) of caffeine a day appears to be safe for most healthy adults. Adolescents should ingest no more than 100 mg of caffeine per day and children should not consume caffeine. Adults exceeding this recommended daily limit may experience side effects such as insomnia, muscle tremors and a rapid heart beat.