Q: Are there any foods or nutrients that can help prevent muscle fatigue or soreness after long-distance running?

JENNY RINDT, Roswell

CHRIS ROSENBLOOM FIT TO EAT Have a question of general interest? E-mail Rosenbloom Related: • More on food and drink • Restaurant reviews and search More Rosenbloom You can work '101 Foods' into your diet  Know your nutrition: A quick quiz for fall  Three to be careful with in healthy diet  Grapefruit, cancer link considered preliminary  Beta carotene powers orange fruits, veggies  Our levels of the 'sunshine' vitamin decrease as we age  'Repair' muscles after long-distance running  Food-drug interaction an important issue  • Chris Rosenbloom, Ph.D., R.D., is a member of the nutrition faculty in the College of Health and Human Sciences at Georgia State University.

A: When runners are seeking nutrition solutions to muscle fatigue, I focus on three things in their diet: fluids, carbohydrates and recovery nutrition. You might need your calculator for this answer, because to individualize a plan, we need to do some math.

Dehydration can lead to tired muscles and general fatigue. While there are guidelines you can use to estimate how much fluid you should drink, try an individualized approach. Weigh yourself naked on an accurate scale before a training run. Run for an hour at your usual pace and note how much fluid you drink during your run.

After running, weigh yourself again and note the difference from the pre-run weight. For example, if you weighed 135.7 pounds before running and weighed 134 pounds after running, you lost 1.75 pounds. If you drank 1.36 cups, your sweat loss was about 4.76 cups. Therefore, in this example, the runner should drink about 37 ounces, or 4.5 cups, of fluid every hour to stay well-hydrated. In hot, humid conditions, try drinking a combination of sports drinks and water to provide fluids, carbohydrates and electrolytes, like sodium.

The second factor that can lead to muscle fatigue is inadequate intake of carbohydrates. Training intensity and duration can drain the muscles of stored carbohydrates (glycogen), and the only way to replace it is through diet.

Many female athletes are chronic dieters and dedicated exercisers, and the combination can result in tired muscles. A diet low in carbohydrates for three consecutive days can leave your muscles depleted of glycogen, especially if you run every day. For general training, aim for 5 to 7 grams of carbohydrates per kilogram of body weight (divide your weight in pounds by 2.2 to get kilograms), so if you weigh 124 pounds, that is 56.4 kilograms.

Multiply kilos by 5 to get 282 grams of carbohydrates per day as the minimum amount needed to maintain high-quality training and competition. This may sound like a large number, but a breakfast of granola, low-fat milk, large banana and glass of orange juice provides about 100 grams of carbohydrates.

As for recovery nutrition, there is a window of opportunity after exercise when muscles are most receptive to replacing lost glycogen. If you run more than an hour and a half most days, eat 1.5 grams of carbohydrates per kilogram as soon as possible after exercise (within the first hour is best). Using the example of the 124-pound runner, that equals about 85 grams of carbohydrates.

Combining it with some protein may also help muscle repair after hard exercise. Many energy bars contain carbohydrates and protein and are convenient to eat, but they are expensive and often taste like sawdust, so try real food. A peanut butter sandwich and sports drink will meet your needs, as will a small serving of trail mix that contains nuts, cereal and dried fruit.