Distance running, as well as other forms of intense exercise, drains your muscles of precious energy stores in the form of glycogen. The first 2 hours after a run is the crucial window when your muscles will absorb the highest amount of glycogen to replace what it just lost.
Adequately replacing glycogen stores requires not only the right carbohydrates, but also some protein to aid your muscles in absorbing the carbohydrates. The best part about finishing a run is that it is OK to eat some of the more sugary, higher glycemic foods.
A runner needs 1 gram of medium to high glycemic food per pound of body weight in addition to 1 gram of protein per every 4 grams of carbs. A 150 pound runner would need 150 grams of carbs and 37 grams of protein within the first two hours after a run. It is best to eat half of that within the first 30 minutes and rest an hour or so later.
There are replenishing drinks with this 4:1 ratio sold. A replenishing drink is best during that first 30 minutes. Later eat a good meal to get the rest of the nutrition before the two hours is up. This one trick will speed up your recovery dramatically and recharge those drained legs for your next run
There are several Pre-Mixed drink options that work really well, you can also make your own protein shakes. A great idea is to eat a piece of fruit with some string cheese, or a similar combination of food within an hour of exercising.
** Despite popular belief, chocolate milk is not a great option to get your protein; it is loaded with simple sugars that aren't ideal for an athlete.