The aging process

As people age, changes take place in the nervous and muscular systems that make the body less able to activate the muscles. Studies show that this process can be slowed considerably through activity and exercise.

Bone density and muscle strength

A relationship has been established between bone density and inactivity. Increased stress on bones stimulates bone growth; lack of stress decreases bone growth. Weight-bearing activities (activities that make the muscles work against gravity, such as walking) produce the stress needed to stimulate bone growth. Lack of muscular stress on bones, as well as lack of weight-bearing stimuli will lead to decreased bone density.

Changes that occur as we age:
  • 18 to 24 — Peak bone density and strength in bones
  • 25 to 35 — Maximal muscle strength
  • 30 — Decline in arm strength at a steady rate
  • 35 — Loss of ½ lb muscle, gain of 1½ lbs fat each year
  • 40 to 50 — Declines in bone mineral density
  • 60 to 70 — Decline in strength force by 20 percent to 40 percent

Musculoskeletal changes with aging

A. Natural causes (biologic causes) — These include decreases in the number and size of muscle fibers and a cardiovascular system that loses efficiency over time. These are causes we cannot change.

B. Functional causes — A decrease in activity as people age can also decrease flexibility and strength. We can take steps to guard against this process. In other words, stay active.

Exercise choices
  • Osteoarthritis — Walking, swimming, biking, and stretching are recommended. Avoid activities that put excessive stress on the joint, such as aerobic workouts, running, or competitive sports.
  • Low back pain — Try daily stretching, followed by a more active exercise program that includes walking, swimming, biking, and strength training.
  • Osteoporosis — Recommended are weight-bearing activities such as walking, hiking, biking, stair climbing, dancing, racquet sports, and treadmill.
  • Total joint replacement — Recommended are activities that do not place repeated stress on the replacements, such as swimming, biking, golf, or doubles tennis.


This condition is an overall reduction in bone mass below the normal adult range. The chemical composition of bone is unchanged; there is simply less bone.


  • Hormone deficiency of the menopausal state (The hormone estrogen protects against bone loss. Levels of estrogen decrease after menopause.)
  • Nutritional deficiencies, specifically but not limited to dietary calcium
  • Decreased physical activity or immobilization

Exercise or simply increased physical activity has been shown to be associated with an increased bone mass.

Find a program you like and stick with it to be fit for life


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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 4/2/2012...#4383