A swimming reader responded to my Jan. 17 article on doing what you can do and building from that, regularly and gradually, whether it be swimming or some other form of exercise.

The reader questioned the scientific basis for my advice, and I am pleased to respond.

According to Hans Selye (1907-1982), internationally renowned expert in the field, there are two types of stress. Stress that is beneficial is eustress, and stress that is bad for you is distress.

Stress works on your body like an inoculation. A smallpox inoculation gives the body a small amount of the disease, and the body reacts by creating antibodies to resist the disease itself.

In the same way, when the body detects a stress such as exercise, all systems adapt to strengthen against that stress. If additional stress is added, additional adaptation takes place.

You can see from this that adaptive conditioning is not determined by what exercise you do, but how your body reacts physiologically to that stress.

If the stress is at an acceptable level (eustress), the body can become conditioned to it. On the other hand, if the stress is too great (distress), the body breaks down.

The science, or perhaps more the art, of conditioning is continually finding a level of stress that is sufficient to build the body’s capacity without going over the line into distress.

Selye’s findings include that all stress is cumulative. As a college coach, I had swimmers who had academic problems, financial problems, family problems, social problems, poor eating habits, lack of sleep, etc.

If I were to add a too-stressful workout on top of a swimmer’s accumulation of other stresses, the effect would be negative.

Obviously, each individual has a different stress tolerance, so group workouts need to be modified for individual swimmers.

Stress is a normal part of life. We are stressed in many ways by many various factors. What an individual person can do is first to accept this fact, recognize a particular stress for what it is, and respond appropriately so that it is manageable.

Without adding too many other stresses, it can be used positively to build up resistance to further levels of that stress.

Swimmers can use stress to develop muscular strength and endurance, cardio-respiratory capacity and endurance, and even the various rigors of competition. The key is not to view or consider stress negatively, but as a beneficial means to improvement.

Dr. Bob Colyer of Bluffton is an actively retired college professor, coach and author of “Swim Better: A Guide to Greater Efficiency for Swimmers & Instructors,” directed primarily to non-competitors. bobcolyer@yahoo.com