Changes in bone density, joint movements, and muscles are normal with age, but older adults who stay active and fit can decrease the effects of these changes and remain strong and flexible.

As they age, people experience a gradual net loss of bone density. Calcium intake, exercise, and sex hormones play important roles in normal skeletal aging. For example, bone density is greater in areas of the skeleton that are directly stressed by activities. Consequently, weight-bearing exercise can help decrease bone loss.

On the other hand, inactive adults may experience accelerated bone and joint deterioration. Women going through menopause also experience accelerated bone loss. Joint movements often slow with age because of changes in the increased amount of calcium in the cartilage and a thickening of the synovial membrane of the joints. Aging muscles experience a loss in the number and size of muscle fibers. By age 80, approximately 30% of muscle mass is lost.

Common Disorders

Although they are not part of the normal aging process, osteoporosis and arthritis are two disorders that commonly affect older adults. Osteoporosis is a disease that causes bones to lose mass and break easily. One out of every two women over the age of 50 has an osteoporosis fracture in their lifetime; for men it is one out of every eight. Arthritis causes pain, stiffness and swelling in or around joints. Arthritis affects almost 1 in every 6 Americans, and almost half of all older adults.

Implications for Older Adults

With declines in the musculoskeletal system, the capacity to endure strenuous effort gradually declines. Older adults gradually become less able to walk as far, lift as much, etc. as previously able. Degenerative changes in the musculoskeletal system make the body weaker and more susceptible to specific diseases like arthritis. These can make daily activities difficult and painful and may lead to a sedentary lifestyle. Older persons are particularly at risk for muscle decline after an acute illness that restricts mobility. The greatest decline occurs in the antigravity muscles (those used to sit, stand, and pull up), which are essential to activities of daily living.

Consider This

References and Further Resources on Aging Bones & Joints

Web Sites

Arthritis Foundation

National Institutes of Health Osteoporosis and Related Bone Diseases~National Resource Center

National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health

National Osteoporosis Foundation

Articles & Reports

Benedict, Annette & Freeman, Ruth. (1993). Effect of aquatic exercise on aged person's bone density, body image, and morale. Activities, Adaptation and Aging, 17 (3): 67-85.

Bravo, Gina, et. al. (1996). Impact of a 12-month exercise program on the physical and psychological health of osteopenic women. Journal of the American Geriatrics Society, 44 (7): 756-762.

McCulloch, Robert G. (1996). Bone measurement, physical activity and the aging skeleton. Canadian Journal on Aging, 15 (1): 54-64.

National Institutes of Health Osteoporosis and Related Bone Diseases~National Resource Center. (1999). Nutrition And The Skeleton: The Role Of Calcium And Other Nutrients. NIH ORBD~NRC News. [Washington, DC]: National Institutes of Health.
http://www.osteo.org/nutr_1.html

National Institute of Nursing Research. (1994). Chapter 3: Mobility, functional status, and personal care in late life. Long-Term Care for Older Adults, v.3 of series: Priority expert panel reports. Bethesda, MD: National Institute of Nursing Research.
http://www.nih.gov/ninr/vol3/index.html

National Institute on Aging. (1999). Exercise: a guide from the national institute on aging. (1999). Washington, DC: National Institute on Aging.
http://www.nih.gov/nia/health/pubs/nasa-exercise/