Normal changes occur in the bones, muscles, and joints as a person ages.

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Aging can affect the bones, muscles, and joints in different ways.

Bone

As a person ages, the cells that produce and absorb bone become disrupted. As a result, bone mass is lost. This loss is most rapid in women after menopause, or the change of life. Minerals such as calcium are lost. This can lead to osteoporosis, a condition in which the bones are weaker and more brittle. Osteoporosis is worsened by hormonal conditions, such as hypogonadism, which is a low level of sex hormones in men, and hyperthyroidism, which is a high level of thyroid hormone.

Bones in the wrists, hips, and back are most likely to fracture or break. If a person has severe osteoporosis, the weight of the body itself can even cause a bone fracture. Bone loss may also lead to a loss in height. The vertebrae may become thinner and more brittle. Between the vertebrae are gel-like fluid-filled discs that can lose fluid as a person ages. This can cause the spinal cord to compress and contribute to a curve in the spine. The result is the "stooped" look often seen as a person ages.

Muscle

The muscles tend to decrease in size as people age. Starting at age 20, muscle mass or size begins to decrease. By age 40, most people have lost muscle mass. As a person ages, there is a decrease in the number and size of muscle fibers. Muscle tissue and strength decreases. More fat is deposited into the muscles as well. These factors cause the decreased muscle strength that occurs as people age. Lack of exercise, poor nutrition, use of alcohol, and a variety of illnesses and diseases may also contribute to muscle changes.

Joints

The joints are the areas between the bones that contribute to flexibility and movement. They consist of fluid, membranes, and cartilage. As a person ages, the fluid in the joints decreases. This loss of fluid may cause cartilage to rub together.

Joints begin to wear down as a person ages. They lose some of their function due to changes from arthritis. These changes can lead to joint pain, stiffness, and deformity. The disks between the bones in the spine become less rubbery and more prone to rupture. This can also cause a decrease in height.

All of these changes can affect a person's coordination and posture. Walking may become more difficult. Movement is often slower, and falling becomes more likely.

Prevention

Bone and skeletal mass forms early in life. Thus, prevention of bone loss needs to start early too. Almost 90% of skeletal mass is formed by the end of the teenage years. Early lifestyle changes may help prevent or decrease the effects of aging on the bones, muscles, and joints.

Thirty minutes of moderate weight-bearing exercise a day can slow changes in the muscles, joints, and bones. Weight-bearing exercise includes low-impact aerobics, walking, running, lifting weights, tennis, and step aerobics. A person doing moderate exercise can talk normally without shortness of breath and is comfortable with the pace of the activity. The 30 minutes a day can be done all in one session or may be broken up into smaller time periods.

Low-impact aerobics and water aerobics are examples of exercises that minimize joint stress in elderly individuals and people with arthritis. Recent research has shown that people who do high-impact activities such as jogging have less bone loss as they age.

Individuals can also help protect bones, muscles, and joints by:

Elderly individuals who are at risk for bone fractures from falling can minimize some of the risk by wearing undergarments that have padded shields at the hips.