DEAR DR. DONOHUE: I have been a serious bodybuilder for five years. I made great progress in the first year, but now I’m stuck. I can’t lift heavier weights, and my muscles aren’t growing. I am 5 feet 10 inches, weigh 205 pounds and have a very low amount of body fat. What do I need to do to keep progressing? – S.W.

ANSWER: Part of bodybuilding is dictated by genes. Part depends on putting ever-increasing demands on the body. However, everyone reaches a plateau, and getting off it is difficult. You made fast gains at first because in the early days of lifting weights, the brain tells the body to involve more and more muscle fibers. Once the body has reached its utmost capability in recruiting muscle fibers, progress slows.

Periodization is one way to get off a plateau. Many professional bodybuilders cycle their training throughout the year to avoid sticking at one level. One way of doing this is to divide the year into quarters. In each quarter you vary the intensity, volume and frequency of exercise so you keep muscles from becoming used to a rigid routine.

For one quarter, you perform three to five sets of eight to 12 repetitions, using relatively light weights. The next quarter, you increase the difficulty of the exercise by increasing the amount of weight lifted. Do three to five sets with only five or six repetitions with each set.

For the third quarter, you increase the weight more, but perform only two to four repetitions in three to five sets. In this period, lifting the weight is a struggle.

The final quarter is one where you freelance, lifting weights some but not all days, and using a mixture of pounds. You also engage in different kinds of exercise to keep the body on its toes, so to speak.

Or you might have reached a plateau because you are doing too much. A couple of weeks of rest might be all you need to turn things around.

DEAR DR. DONOHUE: Who are the best-conditioned athletes? I am working on a paper for my phys-ed class, and I thought this would be an interesting topic to write about. – S.O.

ANSWER: It is an interesting topic, but I don’t want to touch it with a 20-foot pole. Singling out one sport is going to earn me the enmity of athletes in other sports.

One indication of superb conditioning is a slow resting pulse rate (heartbeat). The tennis player Bjorn Borg was said to have a resting pulse of only 40 beats a minute. The slow pulse represents superb conditioning, so he must have spent many hours in aerobic training – running, for example. Not all tennis players reach this level of cardiovascular health.

Another indication of superior fitness is a low percentage of body fat. Hockey players have some of the lowest body fat levels among all athletes. A good male athlete has a 12 percent to 20 percent body fat content, and a good female athlete has 15 percent to 25 percent. Nonathletes carry a higher body fat load. Hockey players average a body fat composition of around 10 percent. Most of their weight is muscle weight. An accurate assessment of body fat requires sophisticated techniques like comparing body weight in water to body weight on land. A rough estimate is made by measuring the width of skin fold pinches at various locations. An even rougher guess at body fat content can be gotten by pinching the skin and soft tissue beneath a site one-inch to the side of the navel. If the width of that pinch is greater than one inch, the person has too much body fat. This is an inaccurate test, but one that will do in a pinch.

DEAR DR. DONOHUE: How does cross-country skiing stack up as exercise? – M.Z.

ANSWER: Cross-country skiing comes as close to the perfect exercise as any exercise can. It works out both the upper and lower body. Using the poles exercises the upper body; using the skis, the lower body.

A person weighing 150 pounds can burn more than 500 calories in one hour of cross-country skiing. You won’t find many other exercise activities that come close to that amount in energy expenditure.

DEAR DR. DONOHUE: I am a 79-year-old man in good health except for arthritis. What is the medical community doing about it? One would think that a solution would have surfaced by now. – S.S.

ANSWER: I take it you’re talking about osteoarthritis, the most common kind – the kind due to a fraying and dissolution of the cushioning cartilage inside joints. It affects more than 25 million Americans.

The medical community has done much for it. In the past 25 years, more medicines have been developed for it than in all the preceding centuries of humankind’s history. Synvisc, a viscous fluid, can be injected into some arthritic joints, and it might restore cushioning properties lost by the joints. That’s a newer development. When all else fails and when a person is incapacitated with pain, joint replacement is a testimonial to what the medical community has achieved in dealing with this common problem.

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.