Even if you already have a regular exercise regimen and are generally healthy, aging can cause some changes in your overall fitness. Some of them are preventable, while others are just an inevitable part of growing older. These changes don't mean that you can't exercise. In some cases, you might need to make modifications.
Many people began to experience a loss of balance, or disequilibrium, as they get older. Glaucoma and cataracts are culprits, due to how both conditions deteriorate eyesight. If your spatial perception is off, it's difficult to maintain balance. Problems in the vestibular system of the inner ear, such as chronic ear infections, can also lead to disequilibrium. Loss of muscle tone can make you feel unsteady, and so can changes to the brain. The cerebellum is the part of the brain responsible for regulating balance and motor function, and it shrinks with age.
You can also lose flexibility, simply because tendons and ligaments degrade over time. They dehydrate, and adhesions, or internal scar tissue, can form with minor injuries. Muscle tissue also goes through degradation over time, known as sarcopenia. After age 50, we lose muscle mass at a rate of 1 to 2 percent per year [source: Western Washington University]. Muscle is also replaced by fat.
Stamina and energy are often the next to go. This is partly related to the sarcopenia, but can also be caused by cardiomyopathy (a weakened heart) or diminished lung capacity. Loss of height is one cause of that diminishment in lung capacity -- there is literally less room for the lungs to expand. Losing height is a natural part of aging, but if it happens rapidly, it can be serious -- osteoporosis, a loss of bone mass, is a potential cause.
Finally, our immune systems are weaker as we get older because we produce fewer lymphocytes, the cells that fight infection. This can be due to nutritional deficiencies, but it's also just a part of aging.
These are just a few of the changes that take place in the body as we age. The good news is that a fitness regimen can help slow down all of them.