You've hiked 10 miles, and your legs wobble like Jell-O as you stagger into camp. All you can do is collapse on the spot where you'll eventually pitch the tent. The problem: You're pooped, completely out of gas. In medical terms, you've depleted your muscles' stores of glycogen (which is converted into energy-providing glucose). You may be too tired to think about food, but you need to eat as quickly as possible to regain your strength.
"Too long of a delay before you munch," notes Ellen Coleman, R.D., author of Eating for Endurance, "will reduce muscle glycogen storage and impair recovery." Your "glycogen window," as some experts call it, is within 2 hours immediately following exercise, after which your body replaces glycogen stores at only half the normal rate. So if you lie in that spot enjoying the afternoon breeze for an hour or less, then whip out the snacks, you'll be fine. Wait much longer, and tomorrow's hike will feel like it's all uphill.
As for what to eat, carbohydrates have long been touted as the best recovery food. Actually, you'll get faster replacement of glycogen with carbohydrates and protein. According to Belinda Jenks, a registered dietitian specializing in muscle recovery, "You need two to four times more carbohydrates than protein" (see "Rx For Recovery," in sidebar, for menu suggestions).
Within 2 hours of a hard slog, drink lots of water to further speed your muscles' recovery. Staying aerobically fit helps, too, as does an at-home diet consisting of about 50 percent complex carbohydrates: fruits, vegetables, nuts, seeds, breads, pastas, and cereals.