Are you one of those people who can't function during the day unless you have a cup of coffee?  If so, you might be saying that about your coffee and exercise performance.  Caffeine - a central nervous system stimulant naturally found in coffee, tea, and chocolate - is known to increase alertness, enhance the ability to concentrate, and offset drowsiness.  It can act as an ergogenic aid as well.

     Performance for endurance physical activity can be improved when caffeine is consumed an hour before or during exercise.  Doses of caffeine between 3-13 mg/kg of body weight have been found to be effective.  Drinking 1-2 cups (236-472 ml) of coffee or tea should suffice.  However, it should be noted that there are adverse side effects associated with caffeine consumption.  They include:

• Restlessness/jitters
• Increased heart rate
• Anxiety
• Sleep disturbances
• Gastrointestinal distress

     Taken in excess, caffeine can lead to dehydration because it acts as a diuretic.  However, this effect can be offset if adequate fluids are consumed.  New research has found that ingesting moderate amounts of caffeine does not lead to dehydration or electrolyte imbalances.

     Beware of high-energy drinks containing caffeine.  These drinks, when taken in excess or in combination with other stimulants and alcohol, can be potentially dangerous.  Furthermore, some may contain more sugar than you need.

     Both the benefits and risks associated with caffeine consumption should be considered before you make the decision to use it as an ergogenic aid.  It is recommended that you consult your physician and/or a sports nutritionist regarding the safety and effectiveness of this stimulant for you.

Caffeine Content of Some Beverages

• Drip coffee (6 oz.):  60-180 milligrams
• Black tea (6 oz.):  25-110 milligrams
• Green tea (6 0z.):  8-16 milligrams
• Cola (12 oz.):  29-99 milligrams

Resources:

Vegetarian Sports Nutrition - food choices and eating plans for fitness and performance, 2007, pp. 145-147, Larson-Meyer, D.E.

The Encyclopedia of Healing Foods, 2005, p. 670, Murray, M.

ACSM's Certified News, October-December 2008, volume 18, issue 4, "Nutrition: Popular Supplements for Performance and Recovery," p. 8, Barret, J.

Medicine & Science in Sports & Exercise, 2009, "Joint Position Statement: American College of Sports Medicine, American Dietetic Association, Dietitians of Canada - Nutrition and Athletic Performance," p. 722.