Slowly the parameters of our world of physical abilities creep in on us. Each year we have a little less strength, stamina, flexibility, and ability to withstand infection and trauma.
We lose a few ounces of muscle, a little range of motion each year, and a few seconds off our personal records. This process will occur more quickly if we are not active. When we exercise we are placing demands on the body that send a message to the body that the stamina, muscle, and flexibility are needed for survival. The body will do what it can do accommodate those demands as an act self-protection.
How often does the body need to be exercised? Too much exercise can result in taking steps backward when there are repetitive-use injuries or when there is insufficient recovery from the stress of exercise. The body need not be constantly stimulated to retain or add to our physical abilities. In one flexibility study one group stretched three days a week and the other group stretched five times a week. At the end of the study both groups increased their flexibility by an equal amount.