Exercising in the morning is a great way to start your day and ensures that you get at least some exercise before family, work, and life in general bogs you down and prevents you from any semblance of "free time." Additionally, many of us just don't feel up to hopping on the exercise bike or treadmill after ten hours on the job. However, morning exercise presents its own set of issues that must be addressed in order to have a successful workout.
A large portion of the energy needed for endurance activity comes from carbohydrate which is stored within your muscles and liver.
In order to counter this a.m. "bonk," you should eat something small as soon as you wake up. Something easily digestible, relatively rich in carbohydrates, and low in fat should do the trick. It's OK if this snack, or the accompanying coffee, has some caffeine in it, if you normally consume caffeinated foods. The carbohydrates will be used while you're running and the caffeine will help your body utilize a higher percentage of those calories you just ate and possibly spare the carbohydrate you have stored in your muscles for later in the workout. For example, a PowerBar, PowerGel, a piece of fruit, some carbohydrate drink, and even a regular eight-to-ten-ounce mug of coffee can be great pre-morning-workout snacks to optimize your training performance. If you're going to eat within an hour of your workout, somewhere around 0.25-0.5 grams of carbohydrate per pound of bodyweight should be just about right.
Be sure to eat a complete breakfast that's rich in carbohydrate and some quality protein (eggs, yogurt, low-fat milk, lean meats, etc.) immediately following your morning workout. Your pre-workout snack does not have enough calories to get you through a productive morning, and your muscles are most efficient at replenishing carbohydrate and protein for recovery during the first hour after exercise.