DEAR DR. DONOHUE: I’m a 13-year-old boy who doesn’t have much athletic skill. I like sports, but I don’t go out for any team because I know I won’t make it. Is it possible to get good at a sport through practicing a lot, even if you don’t have much talent? – A.J.

ANSWER: You might not become the star athlete but, through practice, you can acquire enough skills that you will be better than average and much, much better than worst. Natural endowment and genetics put a few on a different plane from the rest of us. We can make up for what nature hasn’t given us by training hard.

Practicing effects changes in the part of the brain that controls muscle movement: Muscles move with greater ease and more fluidly. The brain doesn’t have to strain by constantly telling muscles what to do. They do so out of habit and instinct. Some call this “muscle memory.” It’s not. It’s brain memory ingrained through practice.

In addition, links are established between the brain, the hands and the feet that speed up reactions and make them more likely to be successful. That’s called eye-hand coordination.

Furthermore, practice teaches muscles how to move more economically and more skillfully and using less energy.

I am by nature a klutz, probably much worse than you. Through practice, I have become good enough to play several sports without embarrassing myself.

DEAR DR. DONOHUE: I’m a senior in high school and have been athletically active for all four years. This year I have played basketball, volleyball, tennis and am now running track. My periods started when I was 13, and they had been quite regular. But I haven’t had a period for the past four months. What could cause this? – S.W.

ANSWER: There’s a good chance that your active sports life might be responsible for your loss of periods.

Have you ever heard of the female triad? It consists of three elements that strike many female athletes. One is an inadequate diet. Thinness is the goal of many young women, and it’s something desired by gymnasts, long-distance runners and ballerinas (who are true athletes). Even if a young woman isn’t deliberately trying to cut back on calories, she might not be getting enough calories to support her calorie expenditure.

The second element of the triad is a diminution or loss of periods. The calorie deficit interrupts the coordination between pituitary gland and ovaries in their production of hormones needed for menstrual periods. This is a potentially great problem. Without enough female hormones, a young woman athlete can suffer stress fractures of her bones – minute bone cracks that are very painful and can sideline a woman for six weeks.

The third and worst aspect of the triad is osteoporosis. Women between the ages of 18 and 25 are in the years when their bones attain their peak calcium content. Osteoporosis results when menstrual hormones are deficient. Not only is the osteoporosis threat immediately possible, it is a future threat that can pop up down the road well before menopause sets in.

Increase the amount of food you’re eating. You should try to gain one or two pounds a week. Cut back on your activities by 10 percent to 20 percent. You don’t have to stop, but you have to reduce the time and intensity of your training.

If things have not turned around in another month, you must see the family doctor. There are many more reasons for period loss than the female triad, and these should be considered.

DEAR DR. DONOHUE: What’s considered a good pedaling rate in biking? I’ve just started it. – A.B.

ANSWER: At first, pedal at a rate that’s comfortable for you. As you gain skill, try for 70 to 80 pedal revolutions a minute. A complete pedal revolution is one that moves one pedal from the topmost position through the bottommost position and back to the top position. Elite bikers pedal 90 times a minute.

A 150-pounder, pedaling at 5 miles an hour, burns 4 calories a minute. At racing speeds – speeds greater than 9.5 miles an hour – 11 calories are burned in a minute.

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

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