DEAR DR. DONOHUE: There’s something I don’t understand about muscles, body size and performance. I have seen very lean tennis players hit the ball 120 miles an hour while very beefy players hit it with a maximum speed of 70 miles an hour. I also have seen somewhat-small football players upend heavy players. Can you explain this to me? Don’t body size and muscle size mean anything? – D.J.

What you’re grappling with is the difference between strength and power. They’re not the same. Strength is the ability to move or lift great weights without any regard for the time it takes to do the moving or lifting. Power has to do with the movement of objects quickly. Power hitters hit long balls not because they are terribly muscular, but because they impact the ball with greater speed than do other players. The same goes for golfers. A fast golf swing imparts greater force to the ball and projects the ball longer distances.

This isn’t the entire explanation. Technique has something to do with this too. But the distinction between strength and power is a valid one.

Training for power is as essential as is training for strength. Power training can be achieved by mimicking the motions used in a sport with weights, but relatively light weights. Power bat swinging would entail imitating the batting motion with weights held in the hands. The same goes for any other sport movement.

Weight training for power involves training with light weights lifted more rapidly and more times, around eight to 12 consecutive lifts.

Strength training is directed to lifting heavy weights in fewer repetitions, say two to six times.

DEAR DR. DONOHUE: For warming up, I got the idea to spend some time in a sauna before playing or before exercising. Warm-ups are supposed to prevent injury, aren’t they? I don’t know if I’m preventing any injury, but I feel a lot better when I do this. What do you think of the idea? – T.R.

Warm-ups are advised in order to make the muscles and tendons more flexible and to theoretically prevent injury and improve performance. The usual warm-up is something like jogging in place or throwing a ball at less than game-time speed.

Sitting in a sauna raises body temperature, so I suppose muscles and tendons are “warmed.” But a rise in body temperature diverts blood from those structures to the skin, so the body can lose heat. It’s built-in protective mechanism.

Look; if this makes you feel better and perform better, stick with it.

DEAR DR. DONOHUE: I am under treatment for depression and am taking medicine for it. My doctor tells me to get physical. What exactly does that mean? I guess he means I should exercise. Does exercise really do something for depression? I’ll do it if it helps. – W.P.

ANSWER: Exercise does do something for depression. That’s been shown many times.

Depression has roots in an imbalance of the brain’s neurotransmitters, chemicals that are passed from one brain cell to the next and that increase the activity in certain brain areas. Exercise improves the neurotransmitter balance. It also generates chemicals called endorphins, substances that lift mood.

Getting physical will help you.

DEAR DR. DONOHUE: Four months ago, I had a TURP. I want to resume the exercise program I had before the operation. Is this long enough for me to start that program again? – L.H.

A TURP – transurethral resection of the prostate – is the common procedure used to trim an enlarged prostate gland. Most men can do whatever they want after a month’s recuperation.

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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