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