Too much of a good thing

IF YOU EXERCISE regularly, you know how great exercise can make you feel. But you may also know how bad you can feel if you get too much of this good thing.

John C., a bank vice president, found that jogging perked him up after a hard day. He would come home from the office, burdened by impending decisions. But then he would go out and jog, and by the time he was halfway through his run, he would not even remember what was bothering him.

Unfortunately, the euphoria lasted only 6 to 18 hours. The next day, he would again deal with the pressures of his job by jogging.

As his fitness improved, John found that it took more miles of running to make him feel good. He raised the ante, first to six miles a week, then 10, then 20. When he reached 30 miles a week, one of his knees started to hurt too much for him to run. Depressed and unable to work, he asked his doctor for tranquilizers.

After several weeks of this misery, his injury healed, he was able to resume jogging, and he felt good again.

If you are a regular exerciser and have ever been unable to work out because of an injury, you can empathize with John.

Exercise does make you feel good, although scientists are not sure why. Regardless of the cause of the euphoria, too much exercise can end it, by leading to an injury.

Your muscles are made up of thousands of stringy fibers. Each is a tiny engine with its own fuel supply in the form of stored muscle sugar called glycogen.

Every time you exercise, some muscle fibers are injured. Others use up their stored sugar. It takes at least 48 hours for muscle fibers to heal after vigorous exercise, and 10 hours to 10 days for them to replenish their sugar after prolonged exercise.

If you exercise strenuously two days in a row, only the uninjured fibers with replenished sugar will function properly the second day. The others will either lack fuel or still remain injured. Since your muscles must now do the same job with fewer fibers, greater stress is placed on the working fibers, and they are more likely to be torn.

Nearly 50 years ago, Dr. Hans Selye, a physician at McGill University in Montreal, demonstrated that if rats underwent stress and were then allowed to recover, they become stronger. But, if the rates suffered stress again before they recovered, they became weaker. The same symptoms that Selye found in rats appear in you when you exercise too much.

That is why nobody can exercise strenuously every day without injury. To protect yourself, set up an exercise program that alternates vigorous exercise days with days that are far less vigorous.

Another way to protect yourself is to “listen” to your body. The body will send you many signals when you are overdoing it.

TAKE THE CASE OF Fred D., the general manager of a radio station. He took up running with the same determination that led his station to first place ratings in the broadcast industry. He started by working out once a day. After three months, he entered races and did quite well. He started to run twice a day.

Six weeks later he developed a cold that hung on and on. Although he was tired all the time and his muscles hurt, he continued to run.

The lymph nodes in his neck, armpits and groin started to swell. He was so tired that he did not have the strength to get out of bed. His doctor ran many tests, including a bone marrow test, but was unable to find a cause for his symptoms.

Fred rested, and three weeks later, all his symptoms disappeared. He resumed running–only this time, he took days off when he felt weak or tired.

Early symptoms of overexercise are soreness in your muscles and joints and a loss of interest in exercising. Later signals are heaviness in the legs; nervousness and depression; inability to relax; a drop in performance at work; headaches; loss of appetite or weight; swelling of lymph nodes in the neck, groin or armpits; constipation or diarrhea; and irregular menstrual periods.

If you have any of these warning signs, take a day or two off from your exercise program. If you do not stop when these signs occur, you are risking an injury or an infection.

But if you allow yourself a few days off, your body will feel fresh and ready to exercise again.