DEAR DR. DONOHUE: I am a 38-year-old male and have been physically active my entire life. I walk, run, lift weights and play ice hockey. Recently I have had frequent injuries. I tore a chest muscle, strained right and left groin muscles, strained a calf muscle, tore my right plantaris muscle, pulled a neck muscle, strained my left biceps muscle and pulled a forearm muscle. I have tried vitamins, increased fluid intake and stretching, to no avail. My doctor suggests that I am simply getting old. Your thoughts? – J.K.

ANSWER: Thirty-eight, old? Please. Give some thought to what’s called the overtraining syndrome.

There is a fine line in exercise between increasing the amount and intensity of training for improvement and exercising too vigorously without giving the body time to recover. Estimates have it that 60 percent of runners, 50 percent of soccer players and 21 percent of swimmers overtrain. I am sure other sports would have similar percentages.

One sign of overtraining is a decline in the level of performance. Chronic fatigue is another sign of overdoing it. Or — and this fits you – the athlete collects an astonishing number of injuries.

The decline in performance and the rise of injuries can be related to the trauma exercise imposes on muscles, joints, ligaments and tendons. The traumatized tissues are in a weakened state and are prone to suffer injury. They need time to recuperate.

Another explanation says that the depletion of muscle glycogen sets people up for injury if they have not given the body a chance to restore its glycogen reserves. Glycogen is muscle sugar that provides the energy for exercise.

Take some time off. When you resume your active life, decrease the amount of time and the intensity devoted to exercise. Schedule your exercises to give your body time to repair itself. Weightlifters never exercise the same muscles on successive days. Take a leaf from their book.

DEAR DR. DONOHUE: I am a 54-year-old male who runs 3.3 miles at least five days a week. I am 5 feet 6 inches tall and weight 148 pounds. I read in one of your articles that the pulse rate should return to the resting rate in just a few minutes. My resting pulse is 62 beats a minute. Twelve minutes after exercise it is 88. What do you think? – W.D.

ANSWER: I think I have made you a nervous wreck for no good reason.

After an exercise stress test – the test where a person runs on a treadmill while the ECG is constantly monitored – there should be a 12-beat slowing of the pulse from its maximum after one minute of rest. Say your pulse rose to 160 beats a minute. The pulse should be 148 after one minute of stopping the exercise.

Looking at only one element of heart health – time for pulse recovery – can be misleading. There are far too many other, more important criteria for judging heart health than the time it takes for the resting pulse rate to slow.

Your exercise program deserves kudos. Forget the 12-beat-decrease-in-one-minute pulse rule. If your doctor has not told you that you have heart trouble, you do not.

Readers, I need to clarify the subject of pulse. The pulse is the same as the heartbeat. You feel the beat in a distant artery as the pulse. You can get the same information by putting your hand over your heart and counting the number of beats in a minute. Whichever you find easier to do, adopt that method.

DEAR DR. DONOHUE: I have a glider, and the computer says that at the rate I exercise I burn 104 calories a mile. How does that compare with jogging? – D.M.

ANSWER: A glider is an exercise machine that looks a bit like cross-country skiing with the feet on ski-like supports that are suspended off the ground. The hands hold onto bars that are similar to ski poles. It is hard to turn on the television without seeing an advertisement for the apparatus.

Burning 104 calories an hour on a glider translates into jogging at the rate of a mile in 12 minutes — a good clip.

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.