DEAR DR. DONOHUE: I play baseball in the spring and football in the fall. I am also into a strengthening program with weights. Do I ease up on the strengthening program during baseball and football seasons, or do I continue it year round? – S.H.

ANSWER: Ever hear of periodization? It’s planned variation in a strengthening program, one that puts emphasis on muscle building and endurance for one “period,” strength training for another, peak conditioning for a third and maintenance for the fourth. You can decide how long a complete program should be. You could devote three months to each period for a yearlong program, or you could divide the program into shorter segments – whatever fits your schedule the best.

Let me give you a year program, and you can adapt it. The first quarter of the program is devoted to building muscle size and muscle endurance. In this period, you exercise by doing five sets of eight to 20 repetitions. (A set is the number of times in a row that a person lifts the weight without pausing to rest. A repetition is a single lift.)

In the second period, the period of strength training, you lift heavier weights but perform fewer repetitions. Do three sets of two to six repetitions.

The peak period is one where the heaviest weights are used. Only three sets of three repetitions are done. The rest break between sets is long – five minutes or so.

The last period is one of maintenance, in which only a moderate amount of weight is lifted for a few sets and few reps. You should devise your schedule so that this is the period when you are actively playing baseball and football. That way you have two complete cycles each year.

Don’t exercise the same muscles every day. At no time should you strain to lift a weight. Use weights you can comfortably lift for the prescribed number of sets and repetitions in good form without cheating.

DEAR DR. DONOHUE: I’ve been lifting weights for four months. At first I made unbelievable progress, and by the end of the second month I could lift twice the amount of weight that I could when I started. Now my progress has been very slow. What’s happened? – T.S.

ANSWER: Nothing bad has happened. You are following a predicted course.

When a person starts a weightlifting program, progress is rapid in the first two months. Muscles are getting stronger, but muscle strength is not responsible for the rapid gain in lifting heavier weights. The brain is. In this initial phase, the brain learns how to recruit more muscle fibers into the lift. Once the maximum of muscle fibers that can take part in a lift has been attained, then progress slows down. It’s something to be expected.

DEAR DR. DONOHUE: I am 44 and have been running for many years. I happen to have flat feet. I wonder if the flat feet and running are compatible. Should I be using arch supports? – K.J.

ANSWER: If you have no foot pain, there is no reason for you to invest in arch supports, and there is no reason for you to fear that continued running will become a problem in the future.

This applies only to those people with flat feet who have no foot pain.

I know I’ll be hearing from the ones who do have pain. They need other instructions.

DEAR DR. DONOHUE: Do swimmers sweat? I swim, and I have wondered about this for some time. I certainly can’t check myself for sweat after I have been swimming. – R.T.

ANSWER: You would be surprised at how often this question pops up, so I give it some press every year or so.

At first, I thought that swimmers did not sweat. Sweating is a way to dissipate body heat. The fact that water temperature is lower than body temperature made me reason that sweating was unnecessary.

A reader pointed out that weight is lost after a swim. That weight is not all fat – very little is fat. The majority is fluid, and the fluid must be exiting through sweat glands. It sounded reasonable to me, and I have stuck with that explanation ever since.

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.