How Not to Bonk

"Bonking" and "Hitting the wall" are nutrition terms referring to a lack of sugar as fuel in the body. "Hitting the wall" occurs when the approximately 1700 calories of stored muscle glycogen runs out. "Bonking" occurs when liver glycogen runs out; another 480 calories are stored here.
   Ok, lots of technical terms but what do they mean? What follows is a basic explanation of how food will affect your athletic performance. For a more detailed, personalized nutrition program, consult a Registered Dietician.
   There are 3 macronutrients; protein, fats and carbohydrates, or carbs. Carbs are our "primary" energy source as they are easily accessible, and convert from their stored form to their usable form with little effort. Logic tells us that if carbs provide us with fuel and we run out, we stop moving, not unlike running out of gas in your car. It doesn't matter how much oil and transmission fluid there is, if you run out of gas, you stop. This holds true for our bodies, when we run out of stored carbs and we don't top up our stores by eating, we can not burn fat as fuel. At the beginning of an activity session your body primarily burns carbs, with a small percentage of fat. As your session progresses this changes to more fat than carbs. If you were thinking, "great because I'm running out of carbs", you would be wrong. Like oxygen to a fire, fat will only burn when carbs are present, hence "hitting the wall" or "bonking".
   So what is a runner to do? You must lay down a solid foundation of stored carbs. That means ensuring you are getting at LEAST 55% of your daily calories from carbs. If you count grams, every gram has 4 calories. For activities over 90 minutes, after 1 hour you should start ingesting carbs every 15-30 minutes depending on your body size. Your carb of choice should be ingested and absorbed easily with little chewing. Common choices are gels such as Power gels or Carb Booms and liquid such as Gatorade, Cytomax or Accelerade. Ju jubes, Real Fruit, M & M's and miniature chocolate bars have also worked well for some. Bananas, oranges and sport bars can be good choices but are a little harder to store during activity and take a little more effort to eat. Each individual athlete should track their own nutrition for at least 2 weeks and relate it to training performance to determine what works best for them.
   After activity you have a 2-hour window to replace all the used sugar from your muscles, with the first 30 minutes being the most critical time. Getting in at least 30 grams or 120 calories worth of carbs during this time will reduce recovery time and make your next exercise session better due to increased carb stores. After your initial 30-minute ingestion, continue eating carbs but include some protein, as now is the time for muscle repair. Good choices for post-workout are yogurt with fruit, fruit smoothies, Endurox, Cytomax Recovery and Protein bars.