Are you one of those individuals who waits until your car's gas gauge needle is just barely on "E" before you fill the tank?  I am not, but I know many people who do.  I have heard them discuss the "thrill" of pushing the limit until they are almost "riding on fumes" to their destination.  I suppose they figure running out of gas is not a big problem - just a minor inconvenience until the gas can be brought to the car, then they are on the road again.

     On the contrary, having your body "run on fumes" is not very thrilling.  It needs to have its stores replenished in a timely fashion for optimal performance.  This time occurs post-exercise, during the recovery phase. 

     Adequate recovery from exercise involves refueling the body to replenish carbohydrate stores (glycogen) in the muscles and liver, replacing fluids lost from sweating, and reestablishing electrolyte balance (e.g. sodium and potassium levels).  The optimal time to consume the post-exercise meal is dependent upon the number of workouts in a given day, the exercise mode, and the intensity and duration of the physical activity.  In general, to maximize your body's ability to replenish glycogen stores and repair muscle tissue, the meal should be consumed within the first 30 minutes, and preferably before 2 hours, post-exercise.  This is because the glycogen forming enzyme, glycogen synthetase, circulates at high levels during this time frame (refer to my posting "Milking Endurance").  Eating within this period is especially important if you will be participating in more than one exercise session in a day (e.g. triathlon competition, softball tournament, etc.)

     The meal chosen should be a mixture of the macronutrients carbohydrate, protein, and fat, with carbohydrate assuming the greatest percentage.  It is recommended that your meal contain a ratio of 4 grams of carbohydrate to 1 gram of protein in order to maximize the processes of glycogen repletion and rebuilding of muscle tissue.  Approximately 1.0-1.5 grams of carbohydrate per kilogram of body weight should be consumed at 2 hour intervals over the next 6 hours post-exercise, particularly if you have engaged in vigorous exercise or will be exercising on consecutive days.

     The type of carbohydrate ingested post-exercise may impact the rebuilding of glycogen stores.  Food sources that contain glucose and sucrose appear to be more effective than those that contain fructose alone.  The glycemic index of the food source may play a role as well.  The glycemic index measures how fast and how much the type of carbohydrate (simple versus complex) found in a food raises blood sugar levels after ingestion.  Carbohydrate foods with a high glycemic index tend to result in greater levels of muscle glycogen stores.  However, this can be affected by your overall diet.

     If you are an individual who prefers not to eat a meal right after exercise, drinking a high-carbohydrate liquid supplement is adequate.  Consuming such an energy source will aid in fluid replacement as well.  After exercise you should aim to ingest at least 16-24 ounces of fluid per pound of body weight lost through sweat.  Choosing fluids that contain sodium (0.5 -0.7 grams per liter) and potassium (0.8-2.0 grams per liter) are important to reestablish electrolyte balance, especially if you have participated in endurance exercise lasting more than 2 hours.

Post-Exercise Meal Ideas

• Cereal with low-fat milk
  
• Bagel with peanut butter or low-fat cream cheese
  
• Pancakes with slices of banana
  
• Low-fat yogurt and fruit juice
  
• Energy bar and an apple
  
• Carbohydrate liquid supplement and a handful of nuts/seeds
  

Resources:

ACSM Fitness Book: a proven step-by-step program from the experts, 3rd edition.

McKinley Health Center Website (www.mckinley.uiuc.edu/) "Nutrition for Optimal Exercise Recovery"

Montana State University-Bozeman Website  (btc.montana.edu/olympics/nutrition/default.htm) "Sports Nutrition: What Can Foods and Fluids Do For You?"

American College of Sports Medicine, American Dietetic Association, and Dietetians of Canada Joint Position Statement "Nutrition and Athletic Performance", Medicine & Science in Sports & Exercise, pp. 709-731.