DEAR DR. DONOHUE: I have a friend who is quite knowledgeable about sport science. He majored in it in college. He told me about carbohydrate loading and how it improves stamina. I am interested, but I need more details. I can’t get them from him. He has moved. Can you help? – J.R.

ANSWER: Carbohydrates are sugars and starches. Stored carbohydrate is glycogen. It’s a primary energy source for exercising muscles.

The technique of carbohydrate loading involves packing muscles with more than their usual glycogen supply. Ordinarily 100 grams of muscle stores 1.7 grams of glycogen. Through carbohydrate loading, muscles can quadruple their glycogen stores.

There are a couple of ways to achieve glycogen packing. One is to begin the program seven to 10 days before an endurance event. In the first few days, exercise harder than usual while cutting down the amount of carbohydrates usually eaten. That creates a carbohydrate deficit and makes muscles avid for it. For the next few days, relax the amount of exercise but greatly increase dietary carbohydrates. Muscles will hoard it. On the day before the event, don’t do any exercise, but continue the high-carbohydrate diet.

Frankly, this isn’t something most athletes need to do. It appeals to those who are world-class athletes competing for world records. If you’re tempted to try it, do so as an experiment, well before you have entered any official contest. It doesn’t work for all.

You can replenish muscle glycogen with less fuss. Muscles grab onto carbohydrates most rapidly shortly after a bout of exercise. Eat a high-carbohydrate meal after an exhausting exercise session – within half an hour. And continue throughout the day to pack in carbohydrates. You’ll restore muscle glycogen quickly.

DEAR DR. DONOHUE: Fighting the battle of the bulge has been a lifelong effort. My daughter insists that stationary-bike riding doesn’t offer the needed movement for losing fat. I do have thunder thighs. Is it time to think differently about exercise and weight loss? – M.B.

ANSWER: You don’t have to rethink your program. One hour of pedaling a stationary bike at a rate of 5 miles per hour burns 240 calories. Increase the pedaling speed to 11 miles an hour, and you’ll burn twice that many calories. If you create a daily calorie deficit through exercise and watching what you eat, you have a sensible weight-loss program. However, you are not going to lose weight selectively from any one body area – the thighs, for example. It comes from all fat depots.

DEAR DR. DONOHUE: Lately I have developed a sharp pain on the outside of my left knee when running. Sometimes I can feel the pain in my thigh, too. What could this be, and what should I do about it? – W.W.

ANSWER: You have to realize that the causes of knee pain are many and what I am about to say is only a suggestion.

You might have iliotibial-band syndrome. The iliotibial band is a wide strip of tough tissue that runs from the upper thigh to the lower leg bone just below the kneecap. It’s on the lateral side of the knee and thigh, “outside” being your word for “lateral.” The band keeps the thigh muscles in place and stabilizes the kneecap.

Too much running with too little rest irritates and inflames the band. The result is pain described as sharp or burning. It’s in the same place you have your pain, and sometimes it shoots upward into the thigh or downward to the upper, lateral aspect of the lower leg.

Downhill running and biking make the pain worse.

Take a two-week break from all running. You can walk. If there’s no medical reason not to take anti-inflammatory medicines, one of them – ibuprofen, for example – might get rid of the inflammation more quickly.

Take a look at your shoes. If the big-toe side of the shoe is quite worn down, your foot rolls inward too much when it strikes the ground. That is one big cause of iliotibial-band syndrome, and a shoe insert can help. As always, if the pain doesn’t resolve, you must see your family doctor.

DEAR DR. DONOHUE: I am a 92-year-old man who, until last year, was happy, healthy and pain-free. Now I have terrible pain in my right hip that makes me an invalid. I take Aleve and Celebrex, but they do not help. Can’t my pain be relieved? – H.Q.

ANSWER: Your doctors are treating you with arthritis medicine, so I assume your pain comes from an arthritic joint. Yes, there ought to be treatment for your pain. There are many more arthritis medicines than the two you have tried. Furthermore, when oral medicines prove ineffective, arthritic joints can be injected with steroids. If injections are out of the question, surgery is not, even at age 92.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.