Progression

One of the common causes of injury is improper progression'increasing the overload too quickly. The basic concept is that in order to allow the body to adapt properly to a training program, one must progress the program slowly and appropriately. This principle applies even to the starting level of a program. If your current activity level is low, do not suddenly increase it to a vigorous level. Often the body can temporarily adjust to an excessive overload, but the chance of incurring an injury is much greater. Most of us can think of a time when we did a lot of work around the house and could barely move the next day. We overloaded the muscles beyond what they were ready to handle.

An equally important aspect of this principle, however, is that in order to create an overload, one must progress the program. If a person walks every day for 20 minutes at the same speed, she will reach a point when she is maintaining her cardiovascular fitness but not advancing it. This state may not be bad if she has reached the level she desires, but to improve further she must progress her program. I have had many patients complain that they were not getting stronger, even though they were doing their home exercise programs. Upon analyzing their programs, I found that they were doing the same exercises they were doing when they first left rehabilitation'they had reached a plateau. The principle of progression says that if a person wants to improve, the amount of work must change. For many of these patients the change was as simple as increasing the amount of resistance they were using.

Several factors determine the rate of progression, including age, previous experience, past injuries, the type of exercise involved, and current health. Most initial adaptations to exercise are neural changes; the body becomes more efficient at recruiting only the amount of muscle required and initializing the various physiological systems needed during exercise. As a person ages, the body relies even more on neural adaptations for some forms of exercise. In addition, one's ability to adapt slows down with increased age or health problems. Young children master new skills quickly, but older adults sometimes struggle to learn them. On the other hand, if a person has done an activity before, his neural system adapts more readily (thus the old adage about never forgetting how to ride a bike).

The process of healing also slows with aging, so one must progress more slowly after an injury to allow the tissues time to heal properly. Arthritis is similar to injuries in that it affects not only the joints but also the surrounding muscles, so the progression of activity must be slower. In some instances, one may even need to decrease exercise intensity slightly after an illness or arthritic flare-up and then build back up from this lower level. After he had a severe pulmonary infection, I had my father start by walking the length of a few houses, two or three times a day, even though he had been used to walking several miles before his illness. Because of his prior activity level he was able to progress steadily; he added a house or two each day and was back to his normal mileage within a month or two.